DAF LF45, LF55 Service manual

6

ΛΦ45/55 series

STRUCTURE

Structure

TECHNICAL DATA

DIAGNOSTICS

BRAKE DIAGRAMS FOR THE FULLY PNEUMATIC BRAKE SYSTEM

OPERATION OF BRAKE COMPONENTS

BRAKE SYSTEM AND COMPONENTS

BRAKING PERFORMANCE AND BRAKE EQUALISATION

0

1

2

3

4

5

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200436 DW23259602

6

TECHNICAL DATA

ΛΦ45/55 series

0 Technical data

CONTENTS

Page Date

1. BRAKE SYSTEM AND COMPONENTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 . . . . . 200436

1.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 . . . . . 200436

1.2 Tightening torques. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-12 . . . . 200436

1.3 Lubricants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-16 . . . . 200436

Contents

0

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200436 1

TECHNICAL DATA

6

0

Contents

ΛΦ45/55 series

2

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200436

6

TECHNICAL DATA

ΛΦ45/55 series

1. BRAKE SYSTEM AND COMPONENTS

1.1 GENERAL

Coding of components

All components have been provided with number
codes.

Structure of the code
First digit

Often used:

1 Energy supply (pressure)
2 Energy discharge (outgoing command)
3Bleed
4 Control connection (incoming command)

Little used:

0 Suction connection
5Free
6Free
7 Anti-freeze connection
8 Lubricating oil connection
9 Coolant connection

Where one connection performs several
functions, additional 1
These are separated by a hyphen.

st

digits will be allocated.

Brake system and components

0

Second digit

If there are several connections with the same
function, a 2
after the 1

Application example: empty/load relay valve

Meaning:

1 Air compressor energy supply
2 Energy discharge (command) to the next

41 Control connection (incoming)
42 Second control connection (incoming)

COMPRESSOR

Knorr model

Type: LK3839
Version: 1-cylinder, liquid-cooled

nd

digit will be added immediately

st

one.

component

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200436 1-1

TECHNICAL DATA

6

0

Brake system and components

AIR SUPPLY UNIT

Front axle, leaf-sprung

A

D

F

C

1

12

A Air dryer/pressure regulator (unit)
B 4-circuit protection valve (unit)
C Filter/drying grid
D Pressure regulator
E Blow-off valve
F Pneumatic time switch for regeneration
G Heating element
H Pressure relief valve with bypass, circuit 1
J Pressure relief valve with bypass, circuit 2
K Pressure limiting valve, circuit 3
L Pressure relief valve, circuit 3
M Flowback valve, circuit 3
N Pressure relief valve with bypass, circuit 4
P Pressure sensors

E

0

G

6.1

3

6.2

21

B

2123 3 23 25

1

NJK

24

26

22

ΛΦ45/55 series

MH

L

P

P

P

U

U

R600702

6.2

6.3

6.4

6.5

6.6

6.7

Cut-out pressure of pressure regulator 10.0 ≥ 0.2 bar
Cut-in pressure of pressure regulator 1.2 ≥ 0.2 bar under cut-out pressure

Supply pressure in circuit 1, connection 21 max. 10 bar
Supply pressure in circuit 2, connection 22 max. 10 bar
Supply pressure in circuit 3, connection 23 8.5 - 0.4 bar
Supply pressure in circuit 3, connection 25 8.5 - 0.6 bar
Supply pressure in circuit 4, connection 24 max. 10 bar
Supply pressure in circuit 4, connection 26 max. 10 bar
Opening pressure of circuits 1, 2 and 4 8.5 bar
Opening pressure of circuit 3 7.0 bar
Closing pressure of circuits 1, 2 and 4 7 bar
Closing pressure of circuit 3 5.5 bar

Cut-in temperature of heating element 7C
Cut-out temperature of heating element 29C

Circuit 1 activation pressure for flowback function
of circuit 3 < 4.5 bar

1-2

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200436

6

TECHNICAL DATA

ΛΦ45/55 series

Pressure sensor reading, circuits 1 and 2
(connections 6.2 - 6.7 in the diagram above)

FOOT BRAKE VALVE

Ua(V)

5V
4V
3V

2V
1V
0V

Brake system and components

P21

bar

P22

10

9
8
7
6
5
4

3
2
1

0

123456789101112

Pressure difference between circuits 1 and 2 (be­tween 0 and 3 bar) 0.3 ≥ 0.15 bar

P21-P22 = 0,3

21

22

– 0,15

0

120246810

P

(bar)

21.22

R600701

bar

C (cm)

R600594

Pressure reduction in circuits 1 and 2 from 10 to
8 bar

Connection 11 circuit 1 supply
Connection 12 circuit 2 supply
Connection 21 circuit 1 braking pressure
Connection 22 circuit 2 braking pressure

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200436 1-3

TECHNICAL DATA

6

0

Brake system and components

LOAD-DEPENDENT CONTROL VALVE,
LEAF SPRING

Characteristic

LOAD-DEPENDENT CONTROL VALVE,
AIR SUSPENSION

Characteristic

0.6

10

9

p2 [bar]

8
7
6
5
4
3
2
1

–0.2

ΛΦ45/55 series

1:1

2345678910

10

p4 [bar]

R600704

p41

= 4.65 bar

p42

p41

= 3 bar

p42

p41

= 0.3 bar

p42

R600705

LOW-PRESSURE SWITCH

Cut-out pressure: 5.2 ≥ 0.2 bar

1-4

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200436

6

TECHNICAL DATA

ΛΦ45/55 series

RELAY VALVE

Fitted with internal filter and silencer

EMPTY/LOAD RELAY VALVE

10

Brake system and components

9

8

P2 (bar)

7
6
5
4
3
2
1

10 23456789

0

P4 (bar)

R 600363

9

P2(bar)

8
7
6
5
4
3
2
1

0

Maximum reduction ratio 1 : 2.7
Actuating pressure 0.25 bar
Fitted with internal filter and silencer

P

= P

42

41

1:2.7

P

= 0

42

1

2345678910

+

0,1

0,25

P41(bar)

R600330

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200436 1-5

TECHNICAL DATA

6

0

Brake system and components

ABS VALVE

Resistance of magnet coil 15 ≥ 5 ohm at 25C

Electrical connections

1. Bleed magnet coil

2. Earth

3. Aerate magnet coil

21

3

ΛΦ45/55 series

1

2

3

123

ASR solenoid valve

1. Supply

2. Port, two-way valve

3. Bleed

TRAILER VEHICLE CONTROL VALVE

Knorr model

Type: AC 597BA

Advance

Input pressure 3 bar
Output pressure 3.2 bar
(equals 0.2 bar advance = factory setting)

R600370

1

2

3

R600484

1-6

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200436

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TECHNICAL DATA

ΛΦ45/55 series

Advance adjustment

Adjusting screw (Allen type, 6 mm)
Clockwise increases the advance
Anti-clockwise decreases the advance

Knorr model

Type: AC 597C

Advance

Input pressure 3 bar
Output pressure 3.5 bar
(equals 0.5 bar advance = factory setting)

Advance adjustment

Adjusting screw (Allen type, 6 mm)
Clockwise increases the advance
Anti-clockwise decreases the advance

PARKING BRAKE VALVE WITH TRAILER
VEHICLE CONNECTION

Brake system and components

0

Wabco model

Type: 961 723 134 0
Max. output pressure in driving position approx. 8 bar

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200436 1-7

TECHNICAL DATA

6

0

Brake system and components

PARKING BRAKE VALVE WITHOUT TRAILER
VEHICLE CONNECTION

Wabco model

Type: 961 723 036 0
Max. output pressure in driving position approx. 8 bar

ΛΦ45/55 series

BRAKE PADS

A

C

Knorr model

Maximum brake block thickness (C) 30 mm
Maximum lining thickness (E) 2 mm (at the thinnest point)
Minimum brake block thickness (F) 11 mm (at the thinnest point) with 9mm rear plate

thickness (D)

Replacing: all brake pads at the same time for each axle, and

with the specified lining only.

B

ED

F

R600489

1-8

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200436

6

TECHNICAL DATA

ΛΦ45/55 series

Wabco PAN 17 version:

Maximum brake block thickness (C) 26 mm
Maximum lining thickness (E) 2 mm (at the thinnest point)
Minimum brake block thickness (F) 9 mm (at the thinnest point) with 7mm rear plate

thickness (D)

Replacing: all brake pads at the same time for each axle, and

with the specified lining only.

Wabco PAN 19-1+ and PAN 19-2 versions:

Maximum brake block thickness (C) 30 mm
Maximum lining thickness (E) 2 mm (at the thinnest point)
Minimum brake block thickness (F) 11 mm (at the thinnest point) with 9mm rear plate

thickness (D)

Replacing: all brake pads at the same time for each axle, and

with the specified lining only.

BRAKE DISC

Brake system and components

A

C

B

0

R600489

Knorr model

Maximum brake disc thickness (A) 45 mm
Minimum brake disc thickness (B) 37 mm (rejection dimension, disc must be

replaced)

Minimum thickness, turning dimension 40 mm

Note:

If it is established during brake pad replacement
that the brake thickness is less than or equal to
39 mm, the brake disc must also be replaced.

ED

F

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200436 1-9

TECHNICAL DATA

6

0

Brake system and components

The following signs of wear are permissible:

A1 Crazy cracking.
B1 Cracks running to the centre up to 1.5 mm

wide and deep, max. 0.75 x friction
surface width (a).

C1 Unevenness in the disc surface up to

1.5 mm.

Not permissible:

D1 Through-going cracks.

Wabco model

PAN 17 version:

Maximum brake disc thickness (A) 34 mm
Minimum brake disc thickness (B) 28 mm (rejection dimension, disc must be

Minimum thickness, turning dimension 30 mm

A

B

1

D

C

1

replaced)

a

ΛΦ45/55 series

1

max. 0,75 x a
max. 1,5 mm

1

R600471

The following signs of wear are permissible:

A1 Crazy cracking.
B1 Cracks running to the centre up to 1.5 mm

wide and deep,
max. 0.75 x friction surface width (a).

C1 Unevenness in the disc surface up to

1.5 mm.

Not permissible:

D1 Through-going cracks.

Brake disc wobble 0.15 mm

A Measuring distance is 35 mm

A

R600508

1-10

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200436

6

TECHNICAL DATA

ΛΦ45/55 series

PAN 19-1+ and PAN 19-2 versions:

Maximum brake disc thickness (A) 45 mm
Minimum brake disc thickness (B) 38 mm (rejection dimension, disc must be

replaced)

Minimum thickness, turning dimension 40 mm

The following signs of wear are permissible:

A1 Crazy cracking.
B1 Cracks running to the centre up to 1.5 mm

wide and deep,
max. 0.75 x friction surface width (a).

C1 Unevenness in the disc surface up to

1.5 mm.

Not permissible:

D1 Through-going cracks.

Brake disc wobble 0.15 mm

A Measuring distance is 35 mm

BRAKE CALLIPER
Knorr model

Brake system and components

0

A

R600708

Brake calliper play in axial direction (direction A) 0.6 - 1.0 mm
Brake calliper play on guide bushes ("Y" - "X") max. 2.0 mm
Play between brake calliper carrier and brake

pads ("Y" - "X" direction) 0.3 - 0.9 mm

Wabco model

Play between brake pad/brake disc:
Manually adjustable brake pad/brake disc play

after fitting brake pads: 0.7 mm

Y - X

R600712

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200436 1-11

TECHNICAL DATA

6

0

Brake system and components

1.2 TIGHTENING TORQUES

The tightening torques stated in this section are
different from the standard tightening torques
stated in the overview of the standard tightening
torques. The other threaded connections not
specified must therefore be tightened to the
torque stated in the overview of standard
tightening torques.
When attachment bolts and nuts are replaced, it
is important that - unless stated otherwise - these
bolts and nuts are of exactly the same length and
property class as those removed.

QUICK-RELEASE COUPLING

Parker 20 - 30 Nm

SPRING BRAKE CYLINDER

Attachment nuts 195 Nm
Release bolt 70 Nm
Clamping strip attachment nut 40 Nm

BRAKE CYLINDER

Attachment nuts 195 Nm

ΛΦ45/55 series

BRAKE CALLIPER - BRAKE CARRIER, Knorr
model

Sliding sleeve Allen screws (SB7000) 285 Nm
Sliding sleeve Allen screws (SN7000) 180 Nm + 90
Pressure tool, guide bush bellows 8 Nm
Rubber bearing bush pressure tool (only
SN7000) 8 - 45 Nm

(1) Always use new bolts, provided with locking compound.

New bolts are supplied with locking compound already
applied.

(1)

(1)

1-12

R600744

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200436

6

TECHNICAL DATA

ΛΦ45/55 series

Brake calliper attach­ment bolts, front axle 440 Nm

(1) From production date 2003-37 there is one fitted bolt and

flange bolts are also fitted.
The fitted bolt must be fitted at the position marked by a
small hole.

(2) In the case of versions with Knorr disc brakes, the

attachment of the brake calliper against the stub axle
changed starting from production week 2002-25. Five
bolts are now used instead of six bolts. There is still a hole

th

for the 6
the stub axle.

bolt on the brake carrier, but there is no hole on

Brake calliper attach­ment bolts, rear axle 440 Nm

(1) From production date 2003-37 there is one fitted bolt and

flange bolts are also fitted.

- In the case of the 11.26 rear axle, the fitted bolt must
be fitted at the position marked "X".

- In the case of the 11.32 rear axle, the fitted bolt must
be fitted at the position marked by a small hole.

(1) (2)

(1)

Brake system and components

0

BRAKE CALLIPER - BRAKE CARRIER,
Wabco model

Locking bracket bolt (PAN 17) 20 Nm
Locking bracket bolt (PAN 19-1+ and PAN 19-2) 37 Nm
Guide bush Allen screws (PAN 17) 340 Nm
Guide bush Allen screws (PAN 19-1+ and

PAN 19-2) 300 Nm
Brake calliper attachment bolts against stub axle
or back plate (PAN 17) 213 Nm
Brake calliper attachment bolts against stub axle

or back plate (PAN 19-1+ and PAN 19-2) 470 Nm

X

R600791

©

200436 1-13

TECHNICAL DATA

6

0

Brake system and components

Tightening sequence of brake calliper
attachment bolts, Wabco model

Tightening sequence of brake calliper attachment
bolts:

6 23 1 54

BRAKE DISC

Knorr model

Locking plate attachment bolts 32 Nm

Wabco model

PAN 17 version

Brake disc attachment bolts on front axle 115 ≥ 7 Nm
Brake disc attachment bolts on rear axle 130 Nm

ΛΦ45/55 series

R600520

PAN 19-1+ and PAN 19-2 versions

Brake disc attachment bolts on front axle 210 ≥ 21 Nm
Brake disc attachment bolts on rear axle 193 Nm

1-14

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200436

6

TECHNICAL DATA

ΛΦ45/55 series

Tightening sequence of brake disc on
F36 axle

Tightening sequence of brake disc on
F48 axle

Brake system and components

0

3

9

5

1

11

8

7

12

2

6

10

4

R600732

3

16

13

9

5

1

11

8

15

4

7

12

2

6

10

14

R600731

©

200436 1-15

TECHNICAL DATA

6

0

Brake system and components

1.3 LUBRICANTS

BRAKE CALLIPER, KNORR MODEL

SB7000 version

18

ΛΦ45/55 series

20

21

19

17

1

3

4

6

5

8

10

9

12

7

16

15

14

11

13

2

22

1-16

R600541

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200436

6

TECHNICAL DATA

ΛΦ45/55 series

Renolit HLT2 (white) for parts 6, 7, 8, the
adjusters (not shown), the brake cylinder lever
and the flange surface for attachment of the
brake cylinder 1448907

Syntheso GL EP1 (green), for parts 3, 5 1448908

Brake system and components

0

©

200436 1-17

TECHNICAL DATA

6

0

Brake system and components

SN7000 version

18

ΛΦ45/55 series

20

21

19

5

17

1

6a

6

3

7

4

8

11

10

2

Renolit HLT2 (white) for parts 3, 6, 7, 8, the
adjusters (not shown), the brake cylinder lever
and the flange surface for attachment of the
brake cylinder 1448907

22

16

23

15

14

R600698

BRAKE CALLIPER, WABCO MODEL

Renolit G-BRF 2

1-18

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200436

6

DIAGNOSTICS

ΛΦ45/55 series

1 Diagnostics

CONTENTS

Page Date

1. DISC BRAKE CONSTRUCTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 . . . . . 200436

1.1 Fault-finding table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 . . . . . 200436

Contents

1

©

200436 1

DIAGNOSTICS

6

1

Contents

ΛΦ45/55 series

2

©

200436

6

DIAGNOSTICS

ΛΦ45/55 series

Disc brake construction

1. DISC BRAKE CONSTRUCTION

1.1 FAULT-FINDING TABLE

SYMPTOM: SQUEALING/NOISE DURING BRAKING

Possible cause Remedy

Worn brake pads Check brake pads and brake disc thickness

Loose parts Check disc brake construction

Wear/damage to hub bearing Check hub bearing play

Wear to internal parts of disc brake construction Check internal parts

Incorrect vehicle combination Check vehicle combination

Incorrect front axle / rear axle brake pressure
balance

SYMPTOM: IRREGULAR BRAKE PAD WEAR

Possible cause Remedy

Check front axle / rear axle balance

1

Fouled/corroded guide bushes Check the guide bushes

Dirt accumulation between moving parts of the disc
brake construction

Moisture and dirt on internal mechanical parts Check and clean the brake calliper seals

Brake pad stuck in the brake calliper Incorrect play
between brake pads and brake carrier

SYMPTOM: VEHICLE PULLS TO ONE SIDE DURING BRAKING

Possible cause Remedy

Difference in tyre pressure Check / correct tyre pressure

Difference in tyre size Check tyres

Different brake cylinder diameters Check brake cylinder diameters

Broken springs in brake cylinders Check brake cylinders

Leaking brake cylinders Check brake cylinders

Fouled brake cylinders Check the brake cylinders for fouling

Excessive stub axle bearing play Check stub axle bearing play

Excessive steering ball joint play Check steering ball joint play

Clean the disc brake construction

Check the play between brake pads and brake
carrier

Excessive shackle pin play Check shackle pin play

Incorrect vehicle combination Check vehicle combination

Incorrect ABS operation Check ABS operation

Brake pad stuck in the brake calliper Incorrect play
between brake pads and brake carrier

©

200436 1-1

Check the play between brake pads and brake
carrier

DIAGNOSTICS

6

1

Disc brake construction

SYMPTOM: POOR BRAKING DECELERATION

Possible cause Remedy

Overload due to excessive loading Check vehicle loading condition

System pressure too low Check pressure regulator setting

Air leakage in the brake system Check the brake system for leakage

Insufficient braking power / poor condition of trailer
vehicle brake system

Pinched brake lines Check / replace brake lines

Brake cylinder stroke too large Check automatic slack adjuster

Frozen brake system Check brake system

Brake components affected by road salt Check the brake components for fouling.

Fouled brake cylinders Check the brake cylinders for fouling

Incorrect brake cylinder diameter Check brake cylinders

Incorrect operation / setting of load sensing valve Check operation / setting of load sensing valve

Incorrect vehicle combination Check vehicle combination

Check trailer vehicle

ΛΦ45/55 series

Incorrect ABS operation Check ABS operation

Brake pad stuck in the brake calliper Incorrect play
between brake pads and brake carrier

SYMPTOM: VIBRATIONS DURING BRAKING

Possible cause Remedy

Incorrect wheel tightening procedure Tighten wheels according to tightening procedure

Non-standard wheels fitted Fit only standard wheels

Overload due to excessive loading Check vehicle loading condition

Incorrect front axle / rear axle brake pressure
balance

Wrong brake pad quality Check brake pads

Dirt/deposits on brake disc Check/clean brake disc

Loose parts Check disc brake construction

Wear/damage to hub bearing Check hub bearing play

Damage to disc brake Check thickness and condition of brake disc

Play in cab suspension Check cab suspension

Check the play between brake pads and brake
carrier

Check front axle / rear axle balance

Incorrect vehicle combination Check vehicle combination

1-2

©

200436

6

DIAGNOSTICS

ΛΦ45/55 series

SYMPTOM: LOCKING OF THE BRAKES

Possible cause Remedy

Incorrect setting of load sensing valve Check setting of load sensing valve

Thermal overload of non-locking axle brake pads Check non-locking axle brake pads

Incorrect system pressure due to incorrect
pressure regulator setting

Defective trailer vehicle brake system Check trailer vehicle brake system

Incorrect vehicle combination Check vehicle combination

Incorrect ABS operation Check ABS operation

Tyres have too little tread Check tread

Brake pad stuck in the brake calliper Incorrect play
between brake pads and brake carrier

SYMPTOM: INCREASED BRAKE PAD WEAR

Possible cause Remedy

Check pressure regulator setting

Check the play between brake pads and brake
carrier

Disc brake construction

1

Overload due to excessive loading Check vehicle loading condition

Incorrect setting of load sensing valve Check setting of load sensing valve

Incorrect vehicle combination or front axle/rear
axle balance

Defective trailer vehicle brake system Check trailer vehicle brake system

Air pressure in spring brake cylinders too low
during driving, dragging brakes

Dragging brakes because parking brake is not
released

Dirt under foot brake valve / floor mat too high Check for free movement of foot brake valve

Dirty / blocked brake valve bleeders Check valve bleeders

Brake pad stuck in the brake calliper Incorrect play
between brake pads and brake carrier

Incorrect setting of the trailer vehicle control valve/
trailer vehicle reaction valve

Check vehicle combination or front axle/rear axle
balance

Check air pressure in spring brake cylinders with
the parking brake valve in the driving position

Check release of parking brake

Check the play between brake pads and brake
carrier

Check setting of the trailer vehicle control valve/
trailer vehicle reaction valve

©

200436 1-3

DIAGNOSTICS

6

1

Disc brake construction

SYMPTOM: DRAGGING BRAKES

Possible cause Remedy

Leaking foot brake valve to circuit 1 and/or 2 Check the foot brake valve for leaks

Dirt/deposits in brake calliper of disc brake Check freedom of movement of brake calliper

Brake pads turned back too tightly Check minimum brake pad play

Air pressure in spring brake cylinders too low
during driving

Output supply pressure from trailer vehicle control
valve to trailer/semi-trailer too low

Dirt under foot brake valve / floor mat too high Check for free movement of foot brake valve

Dirty / blocked brake valve bleeders Check valve bleeders

Brake pad stuck in the brake calliper Incorrect play
between brake pads and brake carrier

Check output pressure of the double-check relay
valve
Check four-circuit safety valve for dirt
Check output pressure of the parking brake valve
in the driving position

Check output supply pressure of the trailer vehicle
control valve

Check the play between brake pads and brake
carrier

ΛΦ45/55 series

1-4

©

200436

BRAKE DIAGRAMS FOR THE FULLY PNEUMATIC BRAKE SYSTEM

6

ΛΦ45/55 series

2 Brake diagrams for the fully pneumatic br ake system

CONTENTS

Page Date

1. GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 . . . . . 200436

1.1 Brake diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 . . . . . 200436

2. BRAKE DIAGRAMS FOR THE FULLY PNEUMATIC BRAKE SYSTEM . . . . . 2-1 . . . . . 200436

2.1 Legend, brake diagrams for the fully pneumatic brake system . . . . . . . . . 2-1 . . . . . 200436

2.2 Brake diagrams for the fully pneumatic brake system . . . . . . . . . . . . . . . . 2-2 . . . . . 200436

Contents

2

©

200436 1

BRAKE DIAGRAMS FOR THE FULLY PNEUMATIC BRAKE SYSTEM

6

2

Contents

ΛΦ45/55 series

2

©

200436

BRAKE DIAGRAMS FOR THE FULLY PNEUMATIC BRAKE SYSTEM

6

ΛΦ45/55 series

1. GENERAL

1.1 BRAKE DIAGRAMS

Due to the large number of variants for each
vehicle type and for each country, it is impractical
to list all these variants.

Thus a selection has been shown which can form
the basis for other variants.

General

2

©

200436 1-1

BRAKE DIAGRAMS FOR THE FULLY PNEUMATIC BRAKE SYSTEM

6

2

General

ΛΦ45/55 series

1-2

©

200436

BRAKE DIAGRAMS FOR THE FULLY PNEUMATIC BRAKE SYSTEM

6

ΛΦ45/55 series

Brake diagrams for the fully pneumatic brake system

2. BRAKE DIAGRAMS FOR THE FULLY PNEUMATIC BRAKE SYSTEM

2.1 LEGEND, BRAKE DIAGRAMS FOR THE FULLY PNEUMATIC BRAKE

SYSTEM

Component no. Description

1 Compressor

4 Air supply unit

A = ECAS connecting point
B = Auxiliary consumer connecting point

7 Air reservoir

12 Coupling head

13 Quick-release valve

14 Brake chamber

16 Foot brake valve

19 Parking brake low-pressure switch

2

21 Load sensing valve, leaf suspension

22 Load sensing valve, air suspension

33 Relay valve

35 Empty/load relay valve

46 Trailer control valve

49 Spring brake cylinder

52 Parking brake valve with trailer control

53 Parking brake valve without trailer control

62 Emergency filling/test connection

B237 ASR valve

B256 ABS valve, front axle

B257 ABS valve, front axle

B258 ABS valve, rear axle

B259 ABS valve, rear axle

©

200436 2-1

BRAKE DIAGRAMS FOR THE FULLY PNEUMATIC BRAKE SYSTEM

6

2

Brake diagrams for the fully pneumatic brake system

ΛΦ45/55 series

2.2 BRAKE DIAGRAMS FOR THE FULLY PNEUMATIC BRAKE SYSTEM

Brake diagram number Vehicle version

R600557 4x2 vehicle, FA configuration, LF45

- Without trailer connection

- With leaf-sprung rear axle

- With ABS, without ASR

R600558 4x2 vehicle, FA configuration, LF45

- With trailer connection

- With air-sprung rear axle

- With ABS, without ASR

R600563 4x2 vehicle, FA configuration, LF45

- Without trailer connection

- With leaf-sprung rear axle

- With ABS, with ASR

R600560 4x2 vehicle, FA configuration, LF55

- Without trailer connection

- With leaf-sprung rear axle

- With ABS, without ASR

R600734 4x2 vehicle, FA configuration, LF55

4x2 vehicle, FT configuration, LF55

- With trailer connection

- With air-sprung rear axle

- With ABS, without ASR

R600564 4x2 vehicle, FA configuration, LF55

- Without trailer connection

- With leaf-sprung rear axle

- With ABS, with ASR

R600733 6x2 vehicle, FAN configuration, LF55

- With air-sprung rear axle

- With ABS, without ASR

2-2

©

200436

BRAKE DIAGRAMS FOR THE FULLY PNEUMATIC BRAKE SYSTEM

6

ΛΦ45/55 series

BRAKE DIAGRAM R600557

4x2 FA

16

21

22

11

12

7

7

Brake diagrams for the fully pneumatic brake system

62

2

53

1/4

1

21

2

33

2

4

1

12

B258

19

1

21

22

11

49

12

12

B256

62

11

49

12

R600557

2

62

14

11

11

14

62

B

A

25

22

23

21

pp

uu

11
29
23

12

24 26

4

1

62

7

2

1

0

©

200436 2-3

BRAKE DIAGRAMS FOR THE FULLY PNEUMATIC BRAKE SYSTEM

6

2

Brake diagrams for the fully pneumatic brake system

BRAKE DIAGRAM R600558

4x2 FA

62

2

1/4

16

21

22

11

12

7

7

53

1

21

1

22

2

33

2

4

1

22

62

ΛΦ45/55 series

R600558

12

B258

19

11

49

12

7

12

B256

62

11

49

12

12

11

4341

42

22

124612

11

14

B

A

25

22

23

21

pp

uu

11
29
23

12

24 26

4

1

62

11

14

62

7

2

1

0

2-4

©

200436

BRAKE DIAGRAMS FOR THE FULLY PNEUMATIC BRAKE SYSTEM

6

ΛΦ45/55 series

BRAKE DIAGRAM R600560

4x2 FA

16

21

22

11

12

7

7

Brake diagrams for the fully pneumatic brake system

R600560

62

2

53

1/4

1

21

2

33

2

4

1

1

21

22

19

49

12

B258

11

12

62

11

49

12

2

2

1

41 42

35

14

62

1

2

11

B257

62

2

1

11

14

B256

62

B

A

25

22

23

21

pp

uu

11
29
23

12

24 26

4

1

62

7

2

1

0

©

200436 2-5

BRAKE DIAGRAMS FOR THE FULLY PNEUMATIC BRAKE SYSTEM

6

2

Brake diagrams for the fully pneumatic brake system

BRAKE DIAGRAM R600734

4x2 FT

4x2 FA

62

2

1/4

16

21

22

11

12

7

7

53

1

21

1

22

2

33

2

4

1

22

62

7

19

49

12

B258

11

12

ΛΦ45/55 series

R600734

62

11

49

12

12

11

4341

42

22

124612

2

1

41 42

B

A

25

22

23

21

pp

uu

11
29
23

12

24 26

4

1

62

35

14

62

1

2

11

B257

62

2

1

11

14

B256

7

2

1

0

2-6

©

200436

BRAKE DIAGRAMS FOR THE FULLY PNEUMATIC BRAKE SYSTEM

6

ΛΦ45/55 series

BRAKE DIAGRAM R600563

4x2 FA

16

21

22

11

12

7

7

Brake diagrams for the fully pneumatic brake system

62

2

1/4

1

21

2

12 11

2

33

2

4

1

19

53

1

21

22

49

62

B259

1

2

11

12

2

1

R600563

2

62

B258

11

49

12

14

62

1

2

11

B257

62

2

1

11

14

B256

62

B

A

25

22

23

21

pp

11
29
23

62

uu

24 26

12

4

1

1

2

B237

7

2

1

0

©

200436 2-7

BRAKE DIAGRAMS FOR THE FULLY PNEUMATIC BRAKE SYSTEM

6

2

Brake diagrams for the fully pneumatic brake system

BRAKE DIAGRAM R600564

4x2 FA

62

2

1/4

16

21

22

11

12

2

33

4

1

7

7

53

1

21

22

1

21

12 11

2

19

ΛΦ45/55 series

R600564

2

2

62

B258

11

49

12

49

62

B259

1

2

11

12

1

2

1

41 42

35

14

1

2

11

B257

62

62

1

2

11

14

B256

62

B

A

25

22

23

21

pp

11
29
23

62

uu

24 26

12

4

1

1

2

B237

7

2

1

0

2-8

©

200436

BRAKE DIAGRAMS FOR THE FULLY PNEUMATIC BRAKE SYSTEM

6

ΛΦ45/55 series

BRAKE DIAGRAM R600733

6x2 FAN

16

21

22

11

12

7

7

Brake diagrams for the fully pneumatic brake system

62

2

1/4

1

53

22

2

33

2

4

1

1

21

22

19

49

33

2

4

1

62

13

11

12

121312

R600733

2

33

2

4

1

62

11

49

12

2

1

41 42

35

62

62

62

B

A

25

22

23

21

pp

uu

11
29
23

12

24 26

4

1

11

49

12

2

112

B259

11

49

12

B258

62

7

2

1

0

14

62

1

2

11

B257

62

2

1

11

14

B256

©

200436 2-9

BRAKE DIAGRAMS FOR THE FULLY PNEUMATIC BRAKE SYSTEM

6

2

Brake diagrams for the fully pneumatic brake system

ΛΦ45/55 series

2-10

©

200436

6

OPERATION OF BRAKE COMPONENTS

ΛΦ45/55 series

3 Operation of brake com ponents

CONTENTS

Page Date

1. GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 . . . . . 200436

1.1 Overview drawing, Wabco PAN 17 and PAN 19-1+ disc brake

construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 . . . . . 200436

1.2 Overview drawing, Wabco PAN 19-2 disc brake construction. . . . . . . . . . 1-2 . . . . . 200436

1.3 Overview drawing, Knorr SB700 disc brake construction . . . . . . . . . . . . . 1-3 . . . . . 200436

1.4 Overview drawing, Knorr SN700 disc brake construction . . . . . . . . . . . . . 1-4 . . . . . 200436

2. DESCRIPTION OF COMPONENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 . . . . . 200436

2.1 Compressor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 . . . . . 200436

2.2 Air supply unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2 . . . . . 200436

2.3 Water blow-off valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5 . . . . . 200436

2.4 Foot brake valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6 . . . . . 200436

2.5 Relay valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7 . . . . . 200436

2.6 Empty/load relay valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-8 . . . . . 200436

2.7 Load sensing valve, air suspension. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-10 . . . . 200436

2.8 Load sensing valve, leaf suspension . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-13 . . . . 200436

2.9 ABS valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-16 . . . . 200436

2.10 Two-way valve. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-19 . . . . 200436

2.11 ASR solenoid valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-20 . . . . 200436

2.12 Emergency filling/test connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-21 . . . . 200436

2.13 Brake cylinder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-22 . . . . 200436

2.14 Parking brake valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-23 . . . . 200436

2.15 Spring brake cylinder. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-27 . . . . 200436

2.16 Trailer control valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-29 . . . . 200436

2.17 Coupling head . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-32 . . . . 200436

2.18 Disc brake construction, Wabco model . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-33 . . . . 200436

2.19 Disc brake construction, Knorr model . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-35 . . . . 200436

Contents

3

©

200436 1

OPERATION OF BRAKE COMPONENTS

6

3

Contents

ΛΦ45/55 series

2

©

200436

6

OPERATION OF BRAKE COMPONENTS

ΛΦ45/55 series

General

1. GENERAL

1.1 OVERVIEW DRAWING, WABCO PAN 17 AND PAN 19-1+ DISC BRAKE

CONSTRUCTION

1

4

3

5

6

7

3

16

2

3

9

10

1. Hexagon

2. Spring clip

3. Brake pads

4. Locking bracket

5. Cable strip

6. Cable clamp attachment screw

7. Brake calliper

8. Cap

9. Brake piston dust cover

10. Guide bush dust cover

11. Bearing bush

12. Guide bush (short)

13. Allen screw (short)

14. Cover

15. Allen screw (long)

16. Guide bush (long)

11

12

13

15

8

14

R600538

©

200436 1-1

OPERATION OF BRAKE COMPONENTS

6

3

General

ΛΦ45/55 series

1.2 OVERVIEW DRAWING, WABCO PAN 19-2 DISC BRAKE CONSTRUCTION

6

7

3

8

9

13

5

4

16

14

12

1

1. Brake calliper

2. Brake calliper carrier

3. Wheel-side brake pad

4. Drive-side brake pad

5. Spring clip

6. Hexagon

7. Locking bracket

8. Cable strip

9. Cable clamp attachment screw

10. Cap

11. Brake piston dust cover

12. Guide bush dust cover

13. Bearing bush

14. Allen screw (long)

15. Allen screw (short)

16. Guide bush (long)

17. Guide bush (short)

18. Cover

19. Cover

2

17

15

11

19

10

18

R600539

1-2

©

200436

6

OPERATION OF BRAKE COMPONENTS

ΛΦ45/55 series

1.3 OVERVIEW DRAWING, KNORR SB700 DISC BRAKE CONSTRUCTION

20

18

21

19

1

3

6a

4

6

7

General

17

3

22

5

16

8

15

14

11

10

2

9

1 Brake calliper 11 Allen screw
2 Brake calliper carrier 14 Bellows
3 Rubber bearing bush 15 Ring
4 Allen screw 16 Bearing bushes
5 Guide sleeve 17 Brake pad
6 Cap 18 Attachment bracket
7 Brass bearing bush 19 Sealing ring
8 Guide sleeve 20 Pin
9 Clamping strap 21 Retainer clip
10 Bellows 22 Thrust pieces with bellows

R600746

©

200436 1-3

OPERATION OF BRAKE COMPONENTS

6

3

General

ΛΦ45/55 series

1.4 OVERVIEW DRAWING, KNORR SN700 DISC BRAKE CONSTRUCTION

20

21

18

5

19

1

22

6a

6

3

7

17

4

8

23

16

15

11

14

10

2

1 Brake calliper 14 Bellows
2 Brake calliper carrier 15 Ring
3 Rubber bearing bush 16 Bearing bushes
4 Allen screw 17 Brake pad
5 Guide sleeve 18 Attachment bracket
6 Cap 19 Sealing ring
6a Adapter 20 Pin
7 Brass bearing bush 21 Retainer clip
8 Guide sleeve 22 Thrust pieces with bellows
10 Protective cover 23 Sealing rings
11 Allen screw

R600755

1-4

©

200436

6

OPERATION OF BRAKE COMPONENTS

ΛΦ45/55 series

2. DESCRIPTION OF COMPONENTS

2.1 COMPRESSOR

The compressor is a 225-cm3 one-cylinder
design with a water-cooled cylinder head. The
compressor is mounted on the left side of the
engine against the flywheel housing.
The compressor is driven by the camshaft gear
via a gear wheel.

Description of components

3

©

200436 2-1

OPERATION OF BRAKE COMPONENTS

6

3

Description of components

2.2 AIR SUPPLY UNIT

Purpose

The air supply unit is a combination of an air
dryer, pressure regulator and four-circuit safety
valve and has the following functions:

- removing water, oil and other foreign matter
from the air before it enters the brake
system;

- setting the system pressure by means of a
built-in pressure regulator;

- limiting the pressure build-up to a given
value;

- splitting the brake system into four circuits
and, should one circuit fail, protecting the
other circuits against running empty.

ΛΦ45/55 series

Air dryer function

Filling the system

The air supplied by the compressor reaches the
air dryer via connecting point 1/12. In the filter
element (1), the air passes through the coarse
filter (2), which sieves out the oil and dirt particles.
In addition, the air condenses against the cool
wall of the element. Subsequently, the air flows
through filter grains (3), which extract the water
vapour from the air. The air thus dried flows via a
non-return valve (4) to connecting point 21.

17
18

1

2

8

1/12

23

R600359

3

4

21

a

c

b

12
14

13
15
19

16
10

9

2-2

67115

R600504

©

200436

6

OPERATION OF BRAKE COMPONENTS

ΛΦ45/55 series

A

D

F

C

1

12

Operation, pressure regulator

The pressure increase occurring during filling is
returned to the built-in pressure regulator via
bore 12.
When the pre-set cut-out pressure is reached, the
control piston (13) is moved to the right against
the pressure of spring 14. This releases bore 15
in pin 16. The system pressure will enter space
"a" above blow-off valve 8 via bore 17, opening
the blow-off valve (8) against the pressure of the
spring (18).

E

0

G

6.1

3

6.2

24

21

Description of components

B

1

26

24

2123 3 23 25

H

22

P

K

P

6.2

U

6.3

6.4

6.5

U

6.6

6.7

3

R600580

If the pressure in the brake system drops to the
cut-in pressure due to air consumption, the
control piston (13) will move to the left and shut
bore 15 in pin 16. This bore, and therefore
channel 17 and space a, will now be bled via
bore 19. The blow-off valve (8) will close. The
compressor will now again build up the pressure
in the air system.

Regenerating

A regeneration tank is no longer necessary,
because the air inside the circuits is used.

A built-in pneumatic time switch controls the
regeneration process:

- throttle 5 determines the amount of air;

- throttle 6 determines the length of time.

©

200436 2-3

OPERATION OF BRAKE COMPONENTS

6

3

Description of components

Air is admitted to chamber "b" via throttle 6 and air
is also admitted to chamber "c" via bore 7 in the
piston (9). On cut-out by the pressure regulator,
the blow-off valve (8) is opened and chamber "c"
is bled via bore 7. The piston (9) is moved to the
right against the pressure of spring 10 as a result
of the difference in pressure between chambers
"b" and "c". This releases the piston (9) from its
seat (11) and air will flow in the opposite direction
via throttle 5 from the system through the filter
element. At the same time, pressure is reduced in
chamber "b" via throttle 6. The piston (9) moves
to the left until it abuts the seat (11). Regeneration
is now complete.

Four-circuit safety valve operation

The air supply enters via connecting point 1.
From there, the air flows to the built-in pressure
relief valves of circuits 1, 2 and 4.

As soon as the valve of circuit 1 and/or circuit 2
opens, the air will be able to flow through to
circuit 3, the trailer brake and parking brake
circuit. For reasons of safety, a built-in flowback
function empties circuit 3 when the pressure in
circuit 1 is too low. This is done to activate the
emergency brake function.

ΛΦ45/55 series

R600475

21 3 23 25

H

1

P

K

P

6.2

U

6.3

6.4

6.5

U

6.6

6.7

24

26 22

R600476

2-4

©

200436

6

OPERATION OF BRAKE COMPONENTS

ΛΦ45/55 series

2.3 WATER BLOW-OFF VALVE

Purpose

The purpose of the water blow-off valve is to
enable any condensation in the air reservoir or air
pipes to be drained and, if necessary, to bleed the
system.

Operation

The valve is kept closed by the spring and the
reservoir pressure. By pushing the pin sideways,
the valve is lifted off the seat, allowing
condensation and compressed air to escape.
When the pin is released, the valve is closed.

Check that no other components are present
under the blow-off plug, as these could get fouled
during the blow-off process.

Description of components

3

R600046

©

200436 2-5

OPERATION OF BRAKE COMPONENTS

6

3

Description of components

2.4 FOOT BRAKE VALVE

Purpose

The purpose of the foot brake valve is to allow
sensitive aeration and bleeding of both service
brake circuits, independently of each other.

Operation

The foot brake valve consists of two adjacent
parts (Circuit 1 and circuit 2).
If the brake pedal is depressed, a push rod will
exert pressure on the pressure plate (1). The
pressure plate will force the thrust piece (2)
downwards and close the bleed vent together
with the operating cylinder (3) and the shut-off
valve (4). If the brake pedal is depressed further,
the shut-off valve will force the control piston (5)
from its seat, causing a connection to be formed
between the supply and the outlet (brake
pressure). Due to the increase in pressure above
the control piston (5), it will be pressed down
against the spring tension. This action will
stabilise the pressure in P21-22 to the desired
value. If the brake pedal is released, the
operating piston (3) will be pushed up by the
spring tension and the bleed vent will be opened.
This will cause the pressure in P21-22 to drop
and the control piston (5) to be pushed up by the
spring tension, closing the connection between
the supply and outlet.

P22
P12

ΛΦ45/55 series

1

R600588

2

3

P21
P11

5

R600570

2-6

©

200436

6

OPERATION OF BRAKE COMPONENTS

ΛΦ45/55 series

2.5 RELAY VALVE

Purpose

The purpose of the relay valve is to allow fast
aeration and bleeding of the spring brake
cylinders and brake cylinders, shortening the
brake reaction/release time.

Note:

The hysteresis of the relay valve, which is used
for the parking brake, is greater and therefore is
not suitable for use in the service brake.

The air reservoir is connected to point 1. When
connecting point 4 is pressureless, inlet 5 is
closed and outlet 6 opened. The brake chambers
connected to point 2 have now been bled.

When compressed air passes through
connecting point 4 into chamber "a" above the
piston (7), the piston is forced downwards. Outlet
6 is closed and inlet 5 opened. The compressed
air now passes from the air reservoir to the brake
chambers.

A state of equilibrium is achieved when the
pressures on both sides of the piston (7) are
equal. Then, both the outlet and the inlet are
closed.

Description of components

3

7

4

1

A

2

6

5

3

The rubber flap over opening 3 prevents dirt from
entering, whilst providing a large opening for air
to be bled.

When the pressure in connecting point 4 and
consequently in chamber "a" drops, the piston (7)
is forced upwards. Inlet 5 is closed and outlet 6
opened and as a consequence the brake
chambers are bled through bleed opening 3.

R600490

7

4

A

2

1

6

5

3

R600491

©

200436 2-7

OPERATION OF BRAKE COMPONENTS

6

3

Description of components

2.6 EMPTY/LOAD RELAY VALVE

Purpose

The purpose of this valve is to adjust the braking
pressure to the front axle depending on the
output pressure from the load sensing valve of
the rear axle.

ΛΦ45/55 series

R600049

2-8

©

200436

6

OPERATION OF BRAKE COMPONENTS

ΛΦ45/55 series

Empty/load relay valve

In rest position, relay piston 4 is in its upper
position and connecting point 2 (brake cylinders
on front axle) is bled via connecting point 3.

When the foot brake is applied, the relay piston is
forced downwards via connecting point 41, thus
opening valve 5. At connecting point 2 pressure is
built up until a set value is reached. Relay piston
4 is then once again forced upwards until there is
a state of equilibrium.
Air has also entered simultaneously via
connection point 42 (load sensing valve). This will
force piston 6 to the left. Through a bore in piston
6 the pressure now also reaches the central
surface of the relay piston (4). This pressure will
depend on the loading of the rear axle. As a
consequence, the output pressure of this valve is
in part dependent on the braking pressure of the
rear axle.
The input pressure at connecting point 41 is also
applied to the left-hand side of piston 6, via two
openings. If no pressure enters via connecting
point 42, due to a fault, piston 6 will be forced to
the right. The pressure at connecting point 41 will
now also reach the central surface of relay piston

4. In this situation, the valve simply operates as a

relay valve, and will no longer reduce.

41

Description of components

46

1

5

3

42

3

2

R600493

When the foot brake is released, the pressure at
connecting points 41 and 42 will disappear. Relay
piston 4 will be forced upwards by the pressure
beneath it, thus opening the bleed system.

41

42

1

2

3

R600494

©

200436 2-9

OPERATION OF BRAKE COMPONENTS

6

3

Description of components

2.7 LOAD SENSING VALVE, AIR SUSPENSION

Purpose

Automatic control of the brake pressure is
dependent on the pressure in the bellows and
therefore on the load condition of the vehicle.
Thanks to the integrated relay valve, the brake
cylinders are aerated and bled quickly.

41 42

43

s

ΛΦ45/55 series

nomdgi

a

F

D

E

C

A

4

r

jf

k

h

Operation

The control valve is activated by the pressure of
the left and right bellows via connecting points 41
and 42. The actuated piston (i) that moves
against the pressure of the spring (j), brings the
tappet (g) to a position that corresponds to the
load condition. The calculated average of the
bellows pressure on the left and right is the
determining factor in this.

G

C

c b

B

el
21

3

R600455

The compressed air provided by the foot brake
valve flows via connecting point 4 into space A,
pushing piston b to the left. Outlet "d" is closed
and inlet "m" is opened, causing compressed air
to enter space C to the left of diaphragm "e".
Relay piston "f" is operated via duct F and
chamber G.

2-10

©

200436

6

OPERATION OF BRAKE COMPONENTS

ΛΦ45/55 series

At the same time, compressed air flows through
the open valve (a) and duct E into space D to the
right of diaphragm "e". Due to this control, the
output pressure at partial load and low control
pressures is increased to max. 1.4 bar). If the
control pressure increases further, piston "n" is
moved to the left against the pressure of spring
"o" and valve "a" closes.

As pressure builds up in space G, relay piston "f"
is pressed downwards. Outlet "h" closes and inlet
"k" opens. The air at connecting point 1 now flows
to the brake cylinders via connecting point 2.

Now pressure will start to build up in space B
under relay piston "f". As soon as this pressure is
somewhat higher than that in space G, the piston
is pushed upwards and closes inlet "k".

When piston "b" is moved to the left, the vanes (l)
attached to it will gradually loosen the diaphragm
(e) from the fixed vanes in the valve housing. As
a result, the effective diaphragm surface will
gradually increase. As soon as the force of the air
to the left of the diaphragm exceeds that to the
right, piston "b" will move to the right. The inlet
(m) will be closed and a set position is reached.

Description of components

3

43

41 42

nomdgi

a

s

F

D

E

C

A

G

r

B

C

c b

4

jf

el
21

k

h

3

R600455

©

200436 2-11

OPERATION OF BRAKE COMPONENTS

6

3

Description of components

The position of tappet "g", which depends on the
position of piston "i", is indicative of the effective
diaphragm surface and therefore of the output
brake pressure.
The position of tappet "g" determines to what
extent piston "b" must be moved with the vane
disc (l) to allow the valve to build up pressure.
Due to this movement, the effective surface of the
diaphragm will alter.
In full-load position, this surface and that of piston
"b" are equally large. The control pressure at
connecting point 4 is therefore let through (ratio
1:1) to spaces C and G. The output pressure at 2
will now be equal to the control pressure at
connecting point 4.

If the pressure decreases at connecting point 4,
piston "b" will be pushed to the right by the
pressure in space C. Bleed vent "d" will open and
the pressure in spaces C and G will fall. The relay
piston will be pushed up due to the pressure still
present in space B, causing bleed vent "h" to
open. The pressure at connecting point 2 will now
fall via bleed vent 3.

ΛΦ45/55 series

A stop bolt in front of tappet "g" ensures that this
valve can always provide the minimum brake
pressure if the bellows pressure delivered falls
below the minimum effective pressure due to a
fault. The factory setting of this bolt must not be
changed.

The simulation connection (43) is for controlling
the valve. By connecting an air hose to it, the
bellows will be pneumatically closed, allowing the
valve to be operated with a random test pressure.

2-12

©

200436

6

OPERATION OF BRAKE COMPONENTS

ΛΦ45/55 series

2.8 LOAD SENSING VALVE, LEAF SUSPENSION

Purpose

Automatic control of the brake force depends on
the deflection of the springs and therefore on the
loading condition of the vehicle. Thanks to the
integrated relay valve, the brake cylinders are
aerated and bled quickly.

p

F

C

G

i

f

B

j

k

Description of components

nomdgq

D

A

C

c b

el

21

a

3

E

4

h

Operation

The control valve is attached to the chassis and
connected to the rear axle by means of a rod.
With unladen vehicles, the distance between the
regulator and the axle is largest and the lever (j)
points fully downwards. When the vehicle is
loaded, this distance decreases and the lever
moves upwards, towards full load position.
Pin i rotates at the same time as the lever and as
a result thereof moves to the right via the control
groove in bearing cover p. Rod "q" brings the
tappet (g) in a position that corresponds with the
loading condition.

The compressed air provided by the foot brake
valve flows via connecting point 4 into space A,
pushing piston b to the left. Outlet "d" is closed
and inlet "m" is opened, causing compressed air
to enter space C to the left of diaphragm "e".
Relay piston "f" is operated via duct F and
chamber G.

3

R600456

©

200436 2-13

OPERATION OF BRAKE COMPONENTS

6

3

Description of components

At the same time, compressed air flows through
the open valve (a) and duct E into space D to the
right of diaphragm "e". Due to this control, the
output pressure at partial load and low control
pressures is increased (to max. 1.4 bar). If the
control pressure increases further, piston "n" is
moved to the left against the pressure of spring
"o" and valve "a" closes.

As pressure builds up in space G, relay piston "f"
is pressed downwards. Outlet "h" closes and inlet
"k" opens. The air at connecting point 1 now flows
to the brake cylinders via connecting point 2.

Now pressure will start to build up in space B
under relay piston "f". As soon as this pressure is
somewhat higher than that in space G, the piston
is pushed upwards and closes inlet "k".

p

ΛΦ45/55 series

nomdgq

a

i

f

j

k

h

When piston "b" is moved to the left, the vanes (l)
attached to it will gradually loosen the diaphragm
(e) from the fixed vanes in the fan housing. As a
result, the effective diaphragm surface will
gradually increase. As soon as the force of the air
to the left of the diaphragm exceeds that to the
right, piston "b" will move to the right. The inlet
(m) will be closed and a set position is reached.

F

D

E

C

4

G

A

C

c b

B

el

21

3

R600456

The position of the tappet (g), which is dependent
on the position of lever "j", is indicative of the
effective diaphragm surface and therefore of the
output brake pressure.

2-14

©

200436

6

OPERATION OF BRAKE COMPONENTS

ΛΦ45/55 series

The position of the tappet (g) determines to what
extent piston "b" must be moved with the vane
disc (l) to allow the valve to build up pressure.
Due to this movement, the effective surface of the
diaphragm will alter.

In full-load position, this surface and that of piston
"b" are equally large. The control pressure at
connecting point 4 is therefore let through
(ratio 1:1) to spaces C and G. The output
pressure at 2 will now be equal to the control
pressure at connecting point 4.

If the pressure decreases at connecting point 4,
piston "b" will be pushed to the right by the
pressure in space C. Bleed vent d will open and
the pressure in spaces C and G will fall. The relay
piston will be pushed up due to the pressure still
present in space B, causing bleed vent "h" to
open. The pressure at connecting point 2 will now
fall via bleed vent 3.

A stop bolt in front of the tappet (g) ensures that
this valve can always provide the minimum brake
pressure if lever "j" is in too low a position due to
a fault. The factory setting of this bolt must not be
changed.

Description of components

3

©

200436 2-15

OPERATION OF BRAKE COMPONENTS

6

3

Description of components

2.9 ABS VALVE

The ABS valve must keep the pressure constant
in the brake chamber during an ABS control, or
decrease the pressure in the brake chamber
regardless of the pressure leaving the foot brake
valve.
If the ABS valve is not operative, it has no
function and the input pressure at connecting
point 1 is the same as the output pressure at
connecting point 2 to the brake chamber.

ΛΦ45/55 series

1

2

Increasing pressure at connecting point 2

Input pressure at connecting point 1 coming from
the foot brake valve will lift diaphragm 5 from
seat 7, causing the brake pressure to be guided
to the brake chamber via connecting point 2.
The input pressure will also be guided through a
bore past the magnet coil (10) in space 19 under
diaphragm 6, causing diaphragm 6 to form a seal
on seat 8. Connecting point 2 is thus sealed off
from the bleed vent.

10

1

P (bar)

R600264

5

7

2

8
6

19

2

2-16

t (sec)

©

200436

R600629

6

OPERATION OF BRAKE COMPONENTS

ΛΦ45/55 series

Reducing pressure at connecting point 2

By activating the magnet coil (9), the solenoid
valve (11) will open bore 15 and close bore 22. As
a result, input pressure enters space 15 above
diaphragm 5 via a bore. Diaphragm 5 seals
against seat 7, so that no more pressure can
build up.
By activating the magnet coil (10) at the same
time, bore 16 opens and bore 23 closes.
By opening bore 16, the pressure under
diaphragm 6 can be reduced via the bleed vent.
The pressure in the brake chamber can now
escape via connecting point 2, space 20 and an
internal bore to the bleed vent.

15

11

22
23
10

12

Description of components

4

1

5

7

2

9

20

3

P (bar)

2

6

19
16

t (sec)

R600630

©

200436 2-17

OPERATION OF BRAKE COMPONENTS

6

3

Description of components

Maintaining pressure at connecting point 2

By deactivating the magnet coil (10), the input
pressure can be guided through a bore past the
magnet coil (10) into space 19 under diaphragm
6, thus sealing off diaphragm 6.
The pressure in the brake chamber can now no
longer be guided to the bleed vent via space 20.
This keeps the pressure in the brake chamber
constant.

23
10

12

1

P (bar)

ΛΦ45/55 series

2

20

6

19
16

2

t (sec)

R600631

2-18

©

200436

6

OPERATION OF BRAKE COMPONENTS

ΛΦ45/55 series

2.10 TWO-WAY VALVE

This valve is used in drum brakes as a double
check valve, that is to say a safety measure so
that the maximum service brake and parking
brake cannot operate the wheel brakes at the
same time.

Purpose

The purpose of this valve is to let through
unchanged the highest of two submitted pressure
signals.

Operation

When pressure is applied to one of the entrances
or if the pressure on one entrance is higher than
on the other, the little piston will shut off the other
entrance and the air can leave the valve
unhindered again via the exit.

11

Description of components

12

21

3

R600747

No connection can be established between the
two entrances.

©

200436 2-19

OPERATION OF BRAKE COMPONENTS

6

3

Description of components

2.11 ASR SOLENOID VALVE

The ASR valve serves to transfer brake pressure
to the ABS valve during an ASR differential brake
control. Depending on the slip, the ABS valve will
control the brake pressure to the respective brake
chamber.
The ASR valve is a simple electropneumatic
valve, which is normally closed, that transfers air
pressure when it is electrically energised.
The energising is controlled by the ABS/ASR
electronic unit.

Note:

The bleed vent (3) must always point downwards.

If coil E of the ASR valve is energised, core B will
move down against the pressure of spring F.
Seal A will now open connecting point 1, so that
supply pressure can leave the valve via
connecting point 2. Opening C and therefore
bleed vent 3 are also closed as core B moves
downwards.

2

ΛΦ45/55 series

1

A

When coil E is no longer energised, core B will
move upward under the influence of spring F.
This action will close connecting point 1 and open
opening C. Connecting point 2 is now linked to
bleed vent 3.

F

E

D

3

B

4

C

R600601

2-20

©

200436

6

OPERATION OF BRAKE COMPONENTS

ΛΦ45/55 series

2.12 EMERGENCY FILLING/TEST CONNECTION

In various places in the brake system there are
test connections for carrying out inspections and
adjustments. A pipe leads from point 24 of the air
dryer to the rear left of the cab. There is a test
connection here that can be used as an
emergency/tyre filling connection.

Note:

With a leaf-spring front axle this test connection is
on point 11 of the air dryer.
If a pipe is connected to the test connection,
screwing in the union will lift the spring-loaded
valve (A) from its seat, opening the supply. If the
union is removed, the valve is pushed onto its
seat by spring B, closing the supply.

Description of components

3

A

B

R600495

©

200436 2-21

OPERATION OF BRAKE COMPONENTS

6

3

Description of components

2.13 BRAKE CYLINDER

Purpose

The purpose of the brake cylinder is to apply the
brake shoes or pads to the brake drum/disc.

Operation

When the foot brake valve is operated,
compressed air is admitted at the pressure side
of the diaphragm (1). The diaphragm (1) and
push rod (2) are pushed outwards against the
pressure of the spring. As a result, the brake
shoes are forced against the brake drum via a
lever mechanism. The air on the other side of the
diaphragm can escape via bleed holes and the
clearance around the push rod.
When the brakes are released, the coil spring (3)
will force the push rod and the diaphragm back to
their initial position.
When the brakes are released, the brake cylinder
will always draw in outside air on the non­pressure side. When the brakes are released the
push rod should return fully to its initial position.
The actuating pressure should not exceed

0.5 bar.

ΛΦ45/55 series

R600505

1

3

2

R600506

2-22

©

200436

6

OPERATION OF BRAKE COMPONENTS

ΛΦ45/55 series

2.14 PARKING BRAKE VALVE

PARKING BRAKE VALVE WITH TRAILER
VEHICLE CONNECTION
Purpose

The parking brake valve enables simultaneous,
controlled operation of both the parking brake
system of the prime mover and the trailer brakes.

Operation

The parking brake valve has 3 positions:

-driving

- parking

-test

Description of components

3

7
8

2
3

4
5

6

9

10

Driving

With the handle in the driving position, there is a
through-connection in the valve of the supply
pressure (connecting point 1) to the connecting
points for the spring-brake cylinders (21) and the
trailer (22). The bleed vent is now closed.
The output pressure at connection points 21 and
22 is now approx. 8 bar (see graph).

1

21
22

21122

3

R600397

©

200436 2-23

OPERATION OF BRAKE COMPONENTS

6

3

Description of components

Emergency braking

If the handle is pulled a little backwards against
the spring pressure, tappet 3 will move
downwards via the eccentric (2). The space at
connecting point 21 can now be bled and as a
result the pressure at connecting point 21 will
drop. Via the bore in valve 10 the pressure at
connection point 22 will also drop. Spring 4 forces
piston 5 down until valve 6 comes into contact
with the seal collar of tappet 3. A state of
equilibrium has now been achieved.

When the handle is moved against stop 7, the
bleed vent will remain open, so that the spring
brakes and the trailer brakes will be applied to
their maximum (max. emergency-brake position).

ΛΦ45/55 series

7
8

2
3

4
5

6

9

10

Parking

When the handle is pulled past stop 7, it is locked
in position.
Connection points 21 and 22 will remain
pressureless, so that the spring brakes and the
trailer brakes are still applied to their maximum.

Test

When the handle is moved beyond the parking
position, cam 8 will move tappet 9 downwards,
causing the bore in valve 10 to be closed and this
valve to be lifted from its seat.
The supply pressure can now be passed to
connection point 22 via a bore in piston 5. As a
result, the trailer brakes will be released.
Connection point 21 remains bled, so that the
spring brakes keep the parking brake applied.
The combination is now braked only by the force
exerted by the spring-brake cylinders on the
tractor. It can now be checked whether the
combination remains motionless when the trailer
vehicle brakes are not applied. When the handle
is released, it will automatically return to the
parking position.

1

21
22

21122

3

R600397

Releasing the brakes

When the handle is once again moved fully
forwards, tappet 3 will move upwards, seat
against valve 6 and push it from its seat in piston

5. As a result, the pressure can reach connection

points 21 and 22.

2-24

21122

3

R600399

©

200436

6

OPERATION OF BRAKE COMPONENTS

ΛΦ45/55 series

PARKING BRAKE VALVE WITHOUT TRAILER
VEHICLE CONNECTION
Purpose

The parking brake valve enables controlled
operation of the parking brake system of the
prime mover.

Operation

The parking brake valve has 2 positions:

-driving

- parking

Description of components

7

3

2
3

4
5

6

Driving

With the handle in the driving position, there is a
through-connection of the supply pressure
(connecting point 1) to connecting point 2 for the
spring brake cylinders. The bleed vent is now
closed.
The output pressure at connecting point 2 is now
approx. 8 bar (see graph).

Emergency braking

If the handle is pulled a little backwards against
the spring pressure, tappet 3 will move
downwards via the eccentric (2). The space at
connecting point 21 can now be bled and as a
result the pressure at connecting point 21 will
drop. Spring 4 forces piston 5 down until valve 6
comes into contact with the seal collar of tappet

3. A state of equilibrium has now been achieved.

When the handle is moved against stop 7, the
bleed vent will remain open so that the spring
brakes are applied to maximum effect (max.
emergency brake position).

1

2

1

2

3

R600400

©

200436 2-25

OPERATION OF BRAKE COMPONENTS

6

3

Description of components

Parking

When the handle is pulled past stop 7, it is locked
in position.
Connecting point 2 is still pressureless, so that
the spring brakes operate at maximum capacity.

Releasing the brakes

When the handle is once again moved fully
forwards, tappet 3 will move upwards, seat
against valve 6 and push it from its seat in piston

5. As a result, the supply pressure can reach

connection point 2. The pressure at connecting
point 2 is now once more equal to the supply
pressure at connecting point 1.

ΛΦ45/55 series

3

21

R600402

2-26

©

200436

6

OPERATION OF BRAKE COMPONENTS

ΛΦ45/55 series

2.15 SPRING BRAKE CYLINDER

Purpose

The purpose of the spring brake cylinder is to
force the brake pads against the brake disc when
the service or parking brake is operated.

Spring brake cylinder operation

The spring brake cylinder consists of two parts: a
part for the service brake, which is designed as a
normal brake cylinder, and a part for the parking
brake, which is a spring brake cylinder.

Description of components

11

12

11

R600908

3

Normal position during driving.
The air reservoirs must be at a safe pressure
before you start driving. If this is not the case, a
warning signal (e.g. a buzzer) will be given.
If this pressure is admitted to the spring brake
cylinder, the piston will compress the powerful
spring. The push rod is no longer under load and
the vehicle brake will be released due to the
operation of the spring, etc.

Service brake

Because the brake cylinder and the spring brake
cylinder are separate, the spring brake cannot
affect the operation of the service brake.
When the service brake is applied, the powerful
spring continues to be compressed, while there is
air pressure on the diaphragm of the brake
cylinder. When the foot brake valve is operated,
the compressed air passes through connection
point 11 into the chamber behind the diaphragm.
The diaphragm with push rod is pushed out
against the spring pressure.
The air on the other side of the diaphragm can
escape via bleed holes. When the brakes are
released, the spring forces the push rod and the
diaphragm back into their original position.

12

R600909

©

200436 2-27

OPERATION OF BRAKE COMPONENTS

6

3

Description of components

Parking brake

Connection point 12 is bled.
The powerful spring then forces the piston with
the piston tube against the diaphragm, so that the
push rod is forced outwards. Here use is made of
the continuously available energy of the
compressed, powerful spring.

Release tool, spring brake cylinder with
unscrewable release bolt

If, due to a failure, no compressed air is available
in the spring brake cylinder, the vehicle brakes
are automatically applied.
But it must still be possible to tow the vehicle.
The spring brake cylinder is therefore fitted with a
release bolt at the rear. By turning this bolt anti­clockwise using a spanner, the powerful spring
will be compressed.
As the bolt is provided with a thrust bearing, the
torque required is not more than 20 - 40 Nm.
A pneumatic spanner must not be used for this
purpose.

ΛΦ45/55 series

11

12

11

R600908

Because the spring brakes have
been released mechanically, the

}

Once the failure has been remedied and
sufficient compressed air is available, the control
valve can be used to again admit air into the
spring brake cylinder.
The release bolt should then be screwed back in
with the spanner and tightened to the specified
torque. See "Technical data". The pressure in the
spring brake cylinder circuit should be at least

5.1 bar.

parking brake can no longer be
applied.

12

R600910

2-28

©

200436

6

OPERATION OF BRAKE COMPONENTS

ΛΦ45/55 series

2.16 TRAILER CONTROL VALVE

Purpose

The purpose of the trailer vehicle control valve is
to pass on the brake commands from the prime
mover to the trailer vehicle.

12

22

Description of components

41

3

42

43

11

Operation

Driving

Connecting point 11 is connected to a reservoir
and connecting point 43 to the parking brake
valve. Both are pressurised and in a state of
equilibrium. The service coupling head
communicates with the ambient air via
connecting point 22, valve 8 and the bleed vent
with damper.

R600335

R600340

©

200436 2-29

OPERATION OF BRAKE COMPONENTS

6

3

Description of components

Braking with the service brake

Pressure build-up

Using the foot brake valve, circuit 1, connecting
point 41, and circuit 2, connecting point 42, are
pressurised.

This pushes down the pistons (1 and 2), causing
valve 8 to close the outlet and open the inlet. The
brake pressure at connecting point 11 can now
flow via valve 8 to connecting point 22, (yellow)
trailer vehicle service coupling head, and will
cause the trailer vehicle to brake.

Adjusting

When a pre-set output pressure has been
reached at connecting point 22, this pressure will
once again force the piston (5) upwards, thus
closing valve 8.

There is now a state of balance between the input
pressure at connecting point 41 and the output
pressure at connecting point 22.

Releasing

When the foot brake valve is released, the input
pressure at connecting points 41 and 42 falls
away. Pistons 1 and 2 are pushed upwards by the
spring under the spring retainer (4).

As a result, valve 8 is closed and the outlet
opened, linking connecting point 22 with the
bleed vent.

ΛΦ45/55 series

R600340

2-30

©

200436

6

OPERATION OF BRAKE COMPONENTS

ΛΦ45/55 series

Advance

Pressure build-up

If the foot brake valve is used to build up pressure
at connecting points 41 and 42, the output
pressure at connecting point 22 will also move
piston 5 upwards, closing valve 8.

There is now a state of balance between the input
pressure at connecting point 41 and the output
pressure at connecting point 22.

Alteration

If adjusting screw 6 is turned clockwise, for
example, the spring retainer (4) will be moved
downwards, compressing the spring underneath
it. Therefore, if the operating pressure at
connecting points 41 and 42 remains the same, a
higher adjusting pressure will be needed under
piston 5. This adjusting pressure is also on the
yellow coupling head.

This increase of service pressure to the trailer
vehicle in relation to the braking pressure from
the prime mover is called advance.

Description of components

3

For the setting procedure, see "Inspection and
adjustment".

Emergency brake

When the parking brake valve is moved into the
locking position, connecting point 43 will be
gradually bled.

Piston 9 moves upwards and valve 8 is opened.

Depending on the drop in pressure at connection
point 43, a pressure build-up will occur at
connection point 22. When a pre-set value has
been reached, valve 8 will close, so that a state of
equilibrium is achieved.

Parking brake

When the parking brake valve is in its maximum
position, causing the lever to be locked,
connecting point 43 is bled. As a consequence,
there is still output pressure at connecting
point 22.

Protection against breakage of service line

During braking, pressure will build up at
connecting point 22. The air necessary for this is
supplied from connecting point 11.

R600340

If the service line is broken, pressure will not build
up in space E, which will cause piston 9 to move
up and close against the bottom of valve 8. The
supply from connecting point 11 stagnates,
causing pressure to be delivered from connecting
point 12.

The pressure in the reservoir pipe drops and the
trailer brakes are applied.

©

200436 2-31

OPERATION OF BRAKE COMPONENTS

6

3

Description of components

2.17 COUPLING HEAD

Application

With spring-loaded valve. Fitted in the dual-line
brake system of versions with trailer vehicle
connection.
If these automatic coupling heads are applied,
there is no need for an air cock.

Purpose

To connect the air brake system of the prime
mover with that of the trailer vehicle.

Operation

The spring-loaded valve (2) in the coupling head
ensures that the system is isolated from the
ambient air.
When coupling, turn the counter head until the
claws of the two heads rest against the stop
under the locking plates. This will prevent the
coupling head from disengaging spontaneously.
Because the two sealing rings (1) are pressed
against each other, the spring-loaded valve
remains open so that an air-tight connection is
achieved. When the heads are uncoupled, the
spring-loaded valve will seal off the pipe on the
prime mover.
The coupling head is equipped with a safety cam.
This is to prevent different coupling heads being
coupled to one another.
If no trailer vehicle is hooked up, the cover of the
coupling head must be closed, to avoid fouling.

ΛΦ45/55 series

R600899

1

2

R600900

2-32

R600901

©

200436

1

2

6

OPERATION OF BRAKE COMPONENTS

ΛΦ45/55 series

2.18 DISC BRAKE CONSTRUCTION, WABCO MODEL

PAN 17 and PAN 19-1+ versions

Operation

Brakes
This disc brake operates using a pneumatic
brake cylinder or spring brake cylinder.

If the brake is applied, the brake cylinder push
rod presses against the eccentrically mounted
lever (1).
Via brake cylinder 2 and pressure plate 3, the
brake pad is pressed against the inside of the
brake disc (4).
Due to the reaction force at the eccentric, the
floating brake calliper (5) will also press the
opposite brake pad with the same force.

Adjusting

If the eccentrically mounted lever (6) is operated
by the push rod of the brake cylinder, the pin (7)
on the lever will rotate the adjuster (8) and the
pressure cylinder (9) in the outgoing stroke until
the play has been eliminated.
If the brake is no longer being operated, the
lever (6) will turn the adjuster (8) back in the
opposite direction. The spring (10) in the adjuster
will ensure that the pressure cylinder will hardly
rotate. The result is that a small total play of about

0.5 mm will remain between the brake pads and

brake disc.

Brake pad wear wires

Brake pad wear wires are fitted to the brake pads.
These wires are cut through when the brake
lining has been worn down to the minimum
thickness.
This is the signal for the VIC system to activate
the "brake pad wear" warning symbol on DIP-4.

8

7

Description of components

1

35

R600573

4 2

R600574

10

9

R600579

3

6

©

200436 2-33

OPERATION OF BRAKE COMPONENTS

6

3

Description of components

PAN 19-2 version

Operation

Brakes
This disc brake operates using a pneumatic
brake cylinder or spring brake cylinder.

If the brake is applied, the brake cylinder push
rod presses against the eccentrically mounted
lever (1).
The brake pad is forced against the inside of the
brake disc via the brake piston (2) and the
pressure plate (3).
Due to the reaction force at the eccentric, the
floating brake calliper (4) will also press the
opposite brake pad with the same force.

Adjusting

This adjuster and the eccentric are equipped with
teeth (6) that engage each other.
If the play is too great, the adjuster (7) will be
rotated by these teeth the next time the brakes
are applied, so that the play will be reduced.
Under normal conditions, the adjuster will push
against the brake pad before rotation can take
place. However, if rotation does take place, it will
be absorbed by a slip coupling.

ΛΦ45/55 series

1

4

3

5

2

R600578

By removing one of the rubber caps (8) where the
automatic adjuster is located, a hexagon is
revealed. Using a ring spanner, the play can be
manually set by adjusting this hexagon.

Brake pad wear wires

Brake pad wear wires are fitted to the brake pads.
These wires are cut through when the brake
lining has been worn down to the minimum
thickness.
This is the signal for the VIC system to activate
the "brake pad wear" warning symbol on the
instrument panel.

7
6

8

R600577

2-34

©

200436

6

OPERATION OF BRAKE COMPONENTS

ΛΦ45/55 series

2.19 DISC BRAKE CONSTRUCTION, KNORR MODEL

The disc brake construction consists of the brake
disc and the brake calliper. There are two
variants of this construction:

- Knorr SB7000, recognisable by the divided
housing between the brake cylinder and the
brake pad holder.

- Knorr SN7000, recognisable by the
undivided housing between the brake
cylinder and the brake pad holder.

The operation of the two variants is identical.
Only the reconditioning of the brake calliper is
different.

The Knorr SB7000 construction has been used
since the introduction of the LF 45/55 series. The
Knorr SN7000 construction is used in production
from week 41-2002 on all front axles and on air­sprung rear axles (Class 3 vehicles). On leaf­sprung rear axles the Knorr SB7000 construction
is still used. The operation of the two variants is
identical. Only overhauling and the parts of the
brake calliper differ.

SB7000

SN7000

Description of components

3

Operation

Brakes
This disc brake operates using a pneumatic
brake cylinder or spring brake cylinder.

If the brake is applied, the brake cylinder push
rod presses against the eccentrically mounted
lever (1).
Via the bridge (2) and the threaded bushes (3),
the brake pad is pressed against the brake
disc (4) at two points on the inside.
Due to the reaction force at the eccentric, the
floating brake calliper (5) will also press the
opposite brake pad with the same force.

R600707

©

200436 2-35

OPERATION OF BRAKE COMPONENTS

6

3

Description of components

Adjusting

One of the two threaded bushes (3) is equipped
with the mechanics for automatic adjustment of
the play between the brake pads and brake disc.
This adjuster and the eccentric are equipped with
teeth (6) that engage each other.
If the play is too great, the adjuster (8) will be
rotated by these teeth the next time the brakes
are applied, so that the play will be reduced.

Under normal conditions, the adjuster will push
against the brake pad before rotation can take
place. However, if rotation does take place, it will
be absorbed by a slip coupling.
The rotation of the adjuster is transferred by
means of a chain (7) to the other adjuster.
By removing a rubber cap (9) where the
automatic adjuster is located, a hexagon is
revealed. Using a ring spanner, the play can be
manually set by adjusting this hexagon.

ΛΦ45/55 series

1

45

32

R600486

3

7

6

9

8

3

R600487

2-36

©

200436

6

OPERATION OF BRAKE COMPONENTS

ΛΦ45/55 series

Wear indicator

The wear sensor, which is fitted on the
adjustment mechanism of the brake calliper,
contains a series connection of a resistor and a
switch. The switch is normally closed and the
circuit has a resistance equal to the value of the
resistor. When the brake pads are worn, the
circuit is interrupted.
This is the signal for the VIC system to activate
the "brake pad wear" warning symbol on the
instrument panel.

Description of components

1

3

R600488

©

200436 2-37

OPERATION OF BRAKE COMPONENTS

6

3

Description of components

ΛΦ45/55 series

2-38

©

200436

6

BRAKE SYSTEM AND COMPONENTS

ΛΦ45/55 series

4 Brake system and comp onents

CONTENTS

Page Date

1. SAFETY INSTRUCTIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 . . . . . 200436

1.1 Safety instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 . . . . . 200436

2. INSPECTION AND ADJUSTMENT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 . . . . . 200436

2.1 Inspection, compressor capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 . . . . . 200436

2.2 Inspection, foot brake valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2 . . . . . 200436

2.3 Inspection and adjustment, load sensing valve, air suspension . . . . . . . . 2-3 . . . . . 200436

2.4 Inspection and adjustment, load sensing valve, leaf suspension . . . . . . . 2-5 . . . . . 200436

2.5 Inspection empty/load relay valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7 . . . . . 200436

2.6 Inspecting the relay valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-9 . . . . . 200436

2.7 Inspection, trailer vehicle control valve . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-10 . . . . 200436

2.8 Inspection and adjustment, advance in trailer vehicle control valve . . . . . 2-11 . . . . 200436

2.9 Inspection, parking brake valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-13 . . . . 200436

2.10 Check and adjust input and output pressures of the air supply unit . . . . . 2-15 . . . . 200436

2.11 Check air dryer regeneration function in the air supply unit. . . . . . . . . . . . 2-16 . . . . 200436

2.12 Check the 4-circuit security valve of the air supply unit . . . . . . . . . . . . . . . 2-17 . . . . 200436

2.13 Inspecting brake pads, Wabco model . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-19 . . . . 200436

2.14 Inspecting brake pads, Knorr model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-20 . . . . 200436

2.15 inspection, brake discs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-22 . . . . 200436

2.16 Checking automatic disc brake slack adjuster, Wabco model. . . . . . . . . . 2-23 . . . . 200436

2.17 Checking automatic disc brake slack adjuster, Knorr model . . . . . . . . . . . 2-24 . . . . 200436

2.18 Inspecting brake calliper play, Knorr model. . . . . . . . . . . . . . . . . . . . . . . . 2-25 . . . . 200436

2.19 Brake adjustment, disc brake version . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-27 . . . . 200436

2.20 Inspection, air tightness. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-28 . . . . 200436

Contents

4

3. REMOVAL AND INSTALLATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 . . . . . 200436

3.1 Removal and installation, quick-release coupling . . . . . . . . . . . . . . . . . . . 3-1 . . . . . 200436

3.2 Removal and installation, pipe on quick-release coupling. . . . . . . . . . . . . 3-2 . . . . . 200436

3.3 Removal and installation, brake cylinder . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3 . . . . . 200436

3.4 Removal and installation, spring brake cylinder . . . . . . . . . . . . . . . . . . . . 3-4 . . . . . 200436

3.5 Removal and installation, compressor cylinder head gasket. . . . . . . . . . . 3-5 . . . . . 200436

3.6 Removal and installation, air dryer filter element. . . . . . . . . . . . . . . . . . . . 3-6 . . . . . 200436

3.7 Removal and installation, brake pads, Wabco model . . . . . . . . . . . . . . . . 3-8 . . . . . 200436

3.8 Removal and installation, brake pads, Knorr model . . . . . . . . . . . . . . . . . 3-13 . . . . 200436

3.9 Removal and installation, brake disc, Wabco model . . . . . . . . . . . . . . . . . 3-15 . . . . 200436

3.10 Removal and installation, brake disc, Knorr model . . . . . . . . . . . . . . . . . . 3-16 . . . . 200436

3.11 Removal and installation, brake calliper, Wabco model . . . . . . . . . . . . . . 3-17 . . . . 200436

3.12 Removal and installation, brake calliper, Knorr SB7000 version . . . . . . . . 3-18 . . . . 200436

3.13 Removal and installation, brake calliper, Knorr SN7000 version. . . . . . . . 3-20 . . . . 200436

3.14 Removal and installation, brake calliper carrier. . . . . . . . . . . . . . . . . . . . . 3-23 . . . . 200436

3.15 Removing and installing thrust piece bellows, Wabco model . . . . . . . . . . 3-24 . . . . 200436

3.16 Removing and installing bellows with brake calliper thrust piece, Knorr

SB7000 version . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-27 . . . . 200436

3.17 Removing and installing bellows with brake calliper thrust piece, Knorr

SN7000 version . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-29 . . . . 200436

3.18 Removal and installation, bearing bushes, Wabco model. . . . . . . . . . . . . 3-34 . . . . 200436

3.19 Removing and installing brass bearing bush of brake calliper, Knorr

SB7000 version . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-37 . . . . 200436

3.20 Removing and installing brass bearing bush of brake calliper, Knorr

SN7000 version . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-39 . . . . 200436

3.21 Removing and installing rubber bearing bush of brake calliper, Knorr

SB7000 version . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-42 . . . . 200436

©

200436 1

BRAKE SYSTEM AND COMPONENTS

6

4

Contents

3.22 Removing and installing rubber bearing bush of brake calliper, Knorr

SN7000 version . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-43 . . . . 200436

3.23 Removing and installing bellows of brass bearing bush of brake calliper,

Knorr SB7000 version . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-45 . . . . 200436

3.24 Removing and installing bellows of brass bearing bush of brake calliper,

Knorr SN7000 version . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-47 . . . . 200436

3.25 Removal and installation, brake back plate in disc brakes . . . . . . . . . . . . 3-50 . . . . 200436

3.26 Removal and installation, brake-chamber diaphragm . . . . . . . . . . . . . . . . 3-51 . . . . 200436

ΛΦ45/55 series

Page Date

2

©

200436

6

BRAKE SYSTEM AND COMPONENTS

ΛΦ45/55 series

1. SAFETY INSTRUCTIONS

1.1 SAFETY INSTRUCTIONS

Always observe the local safety and
environmental regulations.

}

If the parking brake is deactivated
when working on the vehicle, place

}
}

chocks in front of and behind the
wheels to prevent the vehicle from
moving.

The substances and auxiliary
substances (to be) used may
constitute a direct or indirect health
hazard. For that reason, always wear
protective clothing and protective
equipment (e.g. goggles, gloves) to
prevent inhalation, skin contact, etc.

Use only the specified special tools.

Safety instructions

4

}
}
}

Parts of threaded connections have
to be clean and free of lubricants
before use.

Check the correct operation of the
vehicle, and the brake system in
particular if work has been carried
out on it, before handing over the
vehicle to the user.

©

200436 1-1

BRAKE SYSTEM AND COMPONENTS

6

4

Safety instructions

ΛΦ45/55 series

1-2

©

200436

6

BRAKE SYSTEM AND COMPONENTS

ΛΦ45/55 series

2. INSPECTION AND ADJUSTMENT

2.1 INSPECTION, COMPRESSOR CAPACITY

1. Bring the engine up to operating
temperature.

2. For a vehicle with air suspension, the
chassis should be at the normal driving
height.

3. Put chocks in front of and behind the rear­axle wheels to prevent the vehicle from
moving.

4. Position the parking brake in the driving
position.

Note:

If, when draining the air reservoirs, they
appear to hold an excessive quantity of oil,
check the condition of the compressor and
check the compressor for the presence of
carbon deposits in the compressor pipes.

Inspection and adjustment

4

5. Bleed the entire brake system.

6. The capacity test requires that a completely
empty system should be at operating
pressure within 5 minutes, at an engine
speed of 0.6 x maximum engine speed.

©

200436 2-1

BRAKE SYSTEM AND COMPONENTS

6

4

Inspection and adjustment

2.2 INSPECTION, FOOT BRAKE VALVE

Inspection, foot brake valve

1. Connect a pressure gauge to a brake
chamber of the front axle (in front of the
empty/load valve, if present).

2. Connect a pressure gauge to the test
connection of the load-dependent control
valve.

3. Pressurise the system.

4. Depress the brake pedal a few times,
alternately quickly and slowly, until the end
stop is reached. Check if there is a
discrepancy between both gauge readings
(discrepancy maximum 0.3 ≥ 0.15 bar, at
circuit 21 between 0 and 3 bar).

5. If the brake pedal is gradually depressed,
there must be no pressure jumps of more
than 0.3 ≥ 0.15 bar in either circuit, at circuit
21 between 0 and 3 bar.

ΛΦ45/55 series

6. When the foot brake valve is completely
depressed, the reading of both gauges
should indicate the max. output pressure.
See "Technical data".

7. When the brake pedal is not depressed, the
pressure gauges should not indicate any
pressure.

2-2

©

200436

6

BRAKE SYSTEM AND COMPONENTS

ΛΦ45/55 series

Inspection and adjustment

2.3 INSPECTION AND ADJUSTMENT, LOAD SENSING VALVE, AIR

SUSPENSION

Explanatory notes on instruction plate

The information contained on the plate relates to
the axle loads, the output pressures and bellows
pressures, in accordance with the order of axles
beneath the vehicle.

"1" refers to the (first) front axle, "2" to the
following axle, etc.

In the entire column, a reading of 6 bar has been
filled in under "1".

If the vehicle is equipped with an empty/load
valve, a pressure ratio is entered in the box under
the valve illustration, e.g. "i = 1 : 1.5". The
"delivery pressure p2" of axle "1" then indicates
variable readings.

These values can be used to check the brake
pressure values of the front axle and to carry out
the inspection/adjustment below at the same
time. To do this, connect a pressure gauge to the
test connection of one of the front axle brake
cylinders.

R6 00 548

4

Inspection/adjustment

1. Check that the correct valve has been fitted
(see instruction plate).

2. Connect pressure gauge 4 to the test
connection close to connecting point 1/4 on
the load-dependent control valve (input
pressure).

3. Connect pressure gauge 2 to the test
connection on one of the brake cylinders
(service brake connection) of the rear axle.

4. Connect a pressure gauge (43) with a
pressure-reducing valve to the simulation
connection near connections 41 and 42 of
the load-sensing valve (= simulated
adjustable bellows pressure).

5. Make sure that the reservoir pressure is
higher than 6.5 bar throughout the testing
process.

6. Set the simulated bellows pressure to its
second lowest value, as indicated on the
instruction plate.

41

43

s

r

42

4

1/4

1

2

2

R600473

7. Depress the brake pedal until pressure
gauge 4 indicates a pressure of 6 bar.

©

200436 2-3

BRAKE SYSTEM AND COMPONENTS

6

4

Inspection and adjustment

8. Read the brake pressure of the rear axle on
pressure gauge 2 and check that this brake
pressure matches the one listed on the
instruction plate in the table under "output
pressure p2" to the rear axle.

9. If the measured value is not correct,
depressurise connection 43 and, using a
special slotted-nut spanner, special tool
(DAF no. 1329464), turn the adjusting nut(s):

- brake pressure too high: unscrew the

adjusting nut

- brake pressure too low: screw in the

adjusting nut

Note:

When depressurising the simulation
connection (pressure gauge 43), the air hose
must remain connected to prevent the
(actual) bellows pressure from accidentally
activating the valve.
The small socket head screw in the centre of
the valve must not be adjusted.

10. Repeat the procedure described in point 6
until the measured brake pressure value is
within the tolerance limits.

ΛΦ45/55 series

R600478

11. Set the simulated bellows pressure to its
second highest value, as indicated on the
instruction plate.

12. Depress the brake pedal until pressure
gauge (4) indicates a pressure of 6 bar.

13. Read the pressure gauge (2) and check that
this braking pressure matches the pressure
indicated in the table on the instruction plate.

14. If the measured reading is not correct,
depressurise connection 43 and turn the
adjusting bolt (r) using a Torx screwdriver:

- brake pressure too high: screw in the

adjusting bolt

- brake pressure too low: unscrew the

adjusting bolt

Note:

When depressurising the simulation
connection (pressure gauge 43), the air hose
must remain connected to prevent the
(actual) bellows pressure from accidentally
activating the valve.
The small socket head screw in the centre of
the valve must not be adjusted.

41

43

s

r

42

4

1/4

1

2

2

R600473

15. If the adjusting bolt (r) has been turned,
repeat the procedure from point 6.

2-4

©

200436

6

BRAKE SYSTEM AND COMPONENTS

ΛΦ45/55 series

Inspection and adjustment

2.4 INSPECTION AND ADJUSTMENT, LOAD SENSING VALVE,

LEAF SUSPENSION

Explanatory notes on instruction plate

The data relating to axle loads and output
pressures are listed on the instruction plate
following the sequence of the axles beneath the
vehicle.

"1" refers to the (first) front axle, "2" to the
following axle, etc.

In the entire column, a reading of 6 bar has been
filled in under "1". If the vehicle is equipped with
an empty/load valve, a pressure ratio is entered
in the box under the valve illustration, e.g.
"i = 1 : 1.5". The "output pressure P2" of axle 1 will
give variable readings.

These values can be used to check the brake
pressure values of the front axle and to carry out
the inspection/adjustment below at the same
time. To do this, connect a pressure gauge to the
test connection of one of the front axle brake
cylinders.

R6 00 549

4

Inspection/adjustment

1. Measure the weight plus load of the rear
axle.

2. Check the attachment of the control lever
and its ease of operation.

3. Check that the right type of valve has been
fitted.

4. Check the length of the control lever (see "L"
on the instruction plate).

5. Connect a pressure gauge (4) to the test
connection near connection 1/4 on the load­sensing valve (input pressure).

6. Connect a pressure gauge (2) to the test
connection on one of the brake cylinders
(service brake connection) of the rear axle.

7. Make sure that the reservoir pressure is
higher than 6.5 bar throughout the testing
process.

8. Depress the brake pedal until pressure
gauge 4 indicates a value of 6 bar.

4

1/4

1

2

2

R600562

9. Read the brake pressure of the rear axle
from pressure gauge 2 and check that this
value matches the one listed on the
instruction plate in the table under "output
pressure p2" to the rear axle.

©

200436 2-5

BRAKE SYSTEM AND COMPONENTS

6

4

Inspection and adjustment

10. If necessary, correct the brake pressure by
adjusting the length of the vertical
connecting rod (2). Never attempt to alter
length L of the (horizontal) control lever.

11. Remove the ball coupling (1) and raise the
control lever. Check that the output pressure
is now allowed through (almost) without
reduction.

Note:

The small socket head screw in the centre of
the valve must not be adjusted.

ΛΦ45/55 series

L

1

2

R6 00 568

2-6

©

200436

6

BRAKE SYSTEM AND COMPONENTS

ΛΦ45/55 series

2.5 INSPECTION EMPTY/LOAD RELAY VALVE

1. Using a T-piece, connect a pressure gauge
to connecting point 41.

2. Connect a pressure gauge to the test
connection on one of the brake chambers of
the front axle.

3. Connect a pressure gauge to the test
connection on one of the brake chambers of
the rear axle.

4. Pressurise the system.

41

Inspection and adjustment

46

1

5

3

42

2

R600904

4

Testing when empty

1. Set the load sensing valve to the empty
position.

2. Slowly depress the brake pedal.
The pressure on the front axle should rise
gradually, not in jumps.
The pressure on the front axle will rise less
quickly than that on connecting point 41.
(With an empty vehicle, the difference will be
greater than with a partially loaded vehicle).

41

42

1

3

2

R600905

©

200436 2-7

BRAKE SYSTEM AND COMPONENTS

6

4

Inspection and adjustment

Testing when fully loaded

1. Set the load sensing valve to the full-load
position.

2. Slowly depress the brake pedal.
The pressure on the front axle should rise
gradually, not in jumps.
The pressure on the front axle will rise as
quickly (approx. 0.2 bar) as that on
connection point 41. It must be possible to
approximate the system pressure.

Inspection when faulty

1. Disconnect the pipe to connecting point 42
and plug off the pipe.

2. Repeat point 8.

3. Set the load sensing valve as specified.

4. Reconnect the pipes to points 41 and 42 in
the original manner.

5. Remove the pressure gauges.

ΛΦ45/55 series

10

=

P42P

41

=

P0

42

11223344556677889910

0

0,25

+

_

0,1

R600906

Inspection, output pressure to the front axle

1. Measure the rear axle load.

2. Check the load sensing valve setting.

3. Connect a pressure gauge to the test
connection for the load sensing valve (input
pressure) and a pressure gauge to the test
connection on the brake cylinder of the front
axle.

4. Make sure that the reservoir pressure
exceeds 6.5 bar.

5. Depress the brake pedal until the pressure
gauge on the test connection of the load
sensing valve reads 6 bar, and read off the
braking pressure on the pressure gauge of
the front axle.

6. Compare this value with the data in the table
attached to the door pillar.

10

2(bar)

p

0

=

P42P

41

1:1,5

1:2,7

=

P0

42

11223344556677889910

0,5

0,1

p

41(bar)

R600745

2-8

©

200436

6

BRAKE SYSTEM AND COMPONENTS

ΛΦ45/55 series

2.6 INSPECTING THE RELAY VALVE

Inspecting the relay valve

1. Connect a pressure gauge to connecting
point 4 of the relay valve.

2. Connect a pressure gauge to connecting
point 2 of the relay valve.

3. Pressurise the system.

4. Depending on the position of the relay valve
in the brake system, slowly activate the
service brake or parking brake.

5. The pressure in the pressure gauge
connected to connection point 4 must now
increase to approx. 0.8 bar (the increased
parking brake actuating pressure) or 0.5 bar
(service brake), without there being any
noticeable pressure on connection point 2.
From this point, the pressures in both
pressure gauges must increase identically.
The pressure on the gauge connected to
point 2 should not rise in jumps. Both gauges
should indicate a value corresponding to the
graph. See "Technical data".

Inspection and adjustment

7

4

A

2

1

6

5

4

3

R600490

©

200436 2-9

BRAKE SYSTEM AND COMPONENTS

6

4

Inspection and adjustment

2.7 INSPECTION, TRAILER VEHICLE CONTROL VALVE

1. Ensure there is sufficient system pressure.

2. Check whether air is escaping via the bleed
vent.

3. Depress the brake pedal, and again check
for leaks.

4. Disconnect the pipe at connecting point 42
and plug off this pipe.

5. Depress the brake pedal, and check for
pressure build-up in the service pipe (see
"Technical data").

6. Reconnect the pipe.

7. Repeat the last three points, but now for
connecting point 41.

8. Operate the parking brake: pressure should
build up in the service pipe (see "Technical
data").

ΛΦ45/55 series

9. Operate the parking brake to the stop, and
lock the lever: the service pipe should once
again become pressureless.

10. Simulate a leak in the service pipe, and
depress the brake pedal; within two seconds,
the outflow of air from the leak should slow
down considerably.

R600340

2-10

©

200436