BENDIX BW7273 User Manual

Premium wheel-end brake products

BBeennddiixx®®EESSDD--222255™™AAiirr DDiisscc BBrraakkee

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Table of Contents

General Information

Model Identifi cation . . . . . . . . . . . . . . . . . . . . . . . 2

Exploded View. . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Specifi cations

Disc Brake ESD225. . . . . . . . . . . . . . . . . . . . . . . 4

Tightening Torque. . . . . . . . . . . . . . . . . . . . . . . . . 5

Wear Limits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Description of Operation

Actuation/Release of the Brake . . . . . . . . . . . . . . 6

Self-Adjusting Adjustment . . . . . . . . . . . . . . . . . . 6

Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Release . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Safety Instructions. . . . . . . . . . . . . . . . . . . . . . . . 10

Service Instructions

Service Intervals. . . . . . . . . . . . . . . . . . . . . . . . . 11

Checking Pads. . . . . . . . . . . . . . . . . . . . . . . . 12

Checking Brake Disc. . . . . . . . . . . . . . . . . . . 12

Checking Sliding Function. . . . . . . . . . . . . . . 13

Checking Play in the Slide Pins. . . . . . . . . . . 13

Checking Boots for Slide Pins. . . . . . . . . . . . 14

Checking Bellows for Adjustment Screws . . . 14

Operating Test . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Initial Adjustment . . . . . . . . . . . . . . . . . . . . . . . . 16

Lubrication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Adjustment Mechanism. . . . . . . . . . . . . . . . . 16

Slide Pins and Bushings . . . . . . . . . . . . . . . . 16

Replacing Disc Brake

Removing Disc Brake Caliper . . . . . . . . . . . . . . 19

Replacing Disc Brake Caliper . . . . . . . . . . . . . . 19

Replacing Slide Pins, Slide Bushings, and Boots

Removing Slide Pins, Slide Bushings,

and Boots. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Inspection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Replacing Slide Bushings and Slide Pins . . . . . 22

Replacing Boots in Caliper. . . . . . . . . . . . . . . . . 23

Replacing Brake Chamber

Removing Brake Chamber. . . . . . . . . . . . . . . . . 25

Replacing Brake Chamber. . . . . . . . . . . . . . . . . 25

Replacing Spring Brake Chamber

Removing Spring Brake Chamber. . . . . . . . . . . 26

Replacing Spring Brake Chamber . . . . . . . . . . . 27

Replacing Rotor

Removing Rotor. . . . . . . . . . . . . . . . . . . . . . . . . 28

Replacing Rotor. . . . . . . . . . . . . . . . . . . . . . . . . 28

Rotor Runout Check. . . . . . . . . . . . . . . . . . . . . . 28

Cleaning and Inspection. . . . . . . . . . . . . . . . . . . 29

Rotor Resurfacing . . . . . . . . . . . . . . . . . . . . . . . 29

Troubleshooting. . . . . . . . . . . . . . . . . . . . . . . . . . 30

Table of Contents

Replacing Pads

Removing Pads . . . . . . . . . . . . . . . . . . . . . . . . . 17

Replacing Pads . . . . . . . . . . . . . . . . . . . . . . . . . 17

Initial Adjustment . . . . . . . . . . . . . . . . . . . . . . . . 18

1

Model Identifi cation

General Information

Bendix® ESD - 225

Wheel Size

Disc Brake

Extended Service

™

2

Product Identifi cation – Exploded View

General Information

5

6

7

13

14

Exploded view of conventional hub rotor

12

8

21

11

10

9

20

2

General Information

22

23

4

17

1

19

18

1 – Torque plate
2 – Carrier
4 – Caliper Assy.
5 – Retaining bar screw
6 – Retaining bar
7 – Pad retaining spring
8 – Pads
9 – Slider boot
10 – Boot retaining ring
11 – Slider bushing
12 – Slide pin

25

24

26

13 – Slider pin bolt
14 – Slider pin cap
17 – Flat washer
18 – Hex head screw (torque plates to frame)
20 – Air chamber
21 – Air chamber nut & air chamber washer
22 – Actuator plug
23 – Actuator assembly extension
24 – Rotor
25 – Rotor mounting cap screw
26 – Hub

3

Specifi cations

Specifi cations

Disc Brake ESD225

METRIC STANDARD

Max. brake chamber force 13.9 kN 3124.8 lbf.
Wheel size 571.5 mm 22.5 in.
Number of actuating pistons 2 2
Number of slide pins 4 4
Threshold force 28N 6.3 lbf.
Brake chamber stroke requirements min. 57 mm min. 2.2 in.
max. 65 mm max. 2.6 in.
Mechanical advantage 15:8:1 15:8:1
Max. adjustment distance brake lining 58 mm 2.3 in.
Lining thickness (friction material), new 22 mm 0.9 in.
Backplate thickness 8 mm 0.3 in.
Running clearance brake lining to brake disc 0.6 - 0.8 mm 0.02 - 0.03 in.
External diameter brake disc 430 mm 16.9 in.
Thickness brake disc, new 45 mm 1.8 in.
Thickness brake disc, worn 41 mm 1.61 in.
Effective radius 172.6 mm 6.8 in.
Swept area, brake disc 1808 cm2 280.2 cm
Lining area (per pad) 187 cm2 29.0 cm
Grease (GGLB - NGLI +350°F/+177°C to -35°F/-37°C Standard Chassis Grease
Weight, disc brake, approximately . (Exc. brake disc/pads/chamber and sensor) 42.0 Kg 112.5 lb.

2

2

4

Specifi cations

Tightening Torque Wear Limits

Torque fasteners to specifi cations in table.

Torque Torque
Fastener N•m lbs. ft.

Frame Mounting Screw* 447 to 474 330 to 350
Slide Pin Screw 187 to 200 138 to 148
Retaining Bar Screw 42 to 48 31 to 35
Actuator Mounting Screw 24 to 30 18 to 22
Bridge Mounting Screw 100 +/-10 +50º 74 +/-7 +50º

+/-2º turn +/-2º turn
Air Chamber 176 130
Rotor to Iron Hub 339 to 373 250 to 275

(use Loctite 266)
Rotor to Aluminum Hub 190 +/- 19 140 +/- 14

* Use the Snap-on™ Torque Wrench Heavy Duty Offset 13/16"

(30mm) Box Adapter (part number XM300B) with the Snap-on™
400 lbs. ft. Torque Wrench (part number TQR400).

Snap-on™ Customer Service – 877-740-1900

METRIC STANDARD

Pads, min. lining thickness 3 mm 0.12 in.
Pads, max. uneven wear 1 mm 0.04 in.
Slide pins, max. play 1 mm 0.04 in.
Brake disc, max. wear per 2 mm 0.08 in.

side
Brake disc, max. lateral 0.5 mm 0.02 in.

runout
Brake disc, max. 0.1 mm (DTV) 0.004 in.

thickness variation

Specifi cations

5

Description of Operation

Description of Operation

Actuation/Release of the Brake

On braking, the lever is actuated by the brake chamber. The
external and internal radii of the inner part of the lever do not
have a common center, which means that the crossbar is moved
axially in the direction of the brake disc. The force is transferred
from the crossbar via adjustment screws and thrust plates to the
inner pad. When the pad comes into contact with the brake disc,
the caliper is moved on slide pins so that the outer pad also
comes into contact with the brake disc.

When the brake is released, the return spring forces the
crossbar back into its rest position, so that the design clearance
between pad and brake disc is achieved.

Self-Adjusting Adjustment

The brake operates according to the clearance principle. The
brake sequence is divided into three phases: Design Clearance

- C, Excess Clearance - Ce (which is to be adjusted out), and
Elasticity - E.

The housing of the adjuster is held in position against the
internal radius of the lever by a guide pin. The adjuster housing
consequently follows the movement of the lever. The rotational
motion is transferred from housing to adjustment spring which in
turn, after passing the design clearance, transmits the motion of
the companion sleeve, friction spring and hub.

e

C

C

1234

E

3/3

2/3

1/3

9

1 – Guide pin 4 – Friction spring
2 – Adjustment spring 5 – Hub
3 – Companion Sleeve 6 – Adjuster housing

56 7 8

1 – Caliper 6 – Return spring
2 – Outer pad 7 – Crossbar
3 – Brake disc 8 – Lever
4 – Inner pad 9 – Brake chamber
5 – Thrust plates

6

Application

Description of Operation

C - During the movement through C, the design clearance is

measured between the pad and brake disc by the adjuster.
There is a predetermined clearance between the tongue of the
adjustment spring and the slot in the companion sleeve, which
determines the free stroke before the adjustment.

e

C

C

5

4

6

E

3/3

2/3

1/3

7

Ce - If excess clearance remains after the mechanism has
moved radially in accordance with the design clearance C, the
adjuster, synchronization shaft, pinions, crown wheels, adjusting
shaft/readjustment shaft and the adjustment screws are turned.
The rotation of the adjustment screws means that a percentage
of the measured excess Ce is removed.

In the adjuster, the turning movement is transferred from the
housing via the adjustment spring, companion sleeve, and
friction spring to hub, which engages with the synchronization
shaft.

C

e

C

E

1 – Adjustment spring 5 – Brake disc
2 – Companion sleeve 6 – Inner pad
3 – Adjuster 7 – Adjuster
4 – Outer pad

3/3

2/3

8

7

1 – Adjuster 5 – Friction spring
2 – Adjuster spring 6 – Hub
3 – Housing 7 – Synchronization shaft
4 – Companion sleeve 8 – Adjuster

1/3

Description of Operation

7

Description of Operation

E - When the two (2) pads come into contact with the brake

disc, the braking sequence enters elasticity phase E, the torque
rises and the adjuster stops adjusting. The continued rotational
movement, which now occurs in the adjuster is allowed by
rotating the housing in relation to the adjustment spring.

C

e

C

5

4

6

E

3/3

2/3

1/3

Release

The fi rst part of the return stroke passes through C followed by
movement corresponding to E and Ce. During the return stroke,
the return spring ensures that the crossbar travels back.

C - During the fi rst part of the return stroke, transmitted force
decreases and the tongue of the adjustment spring changes
fl ank in the slot of the companion sleeve.

C

e

E

C

1 – Adjustment spring 4 – Outer pad
2 – Rotating housing 5 – Brake disc
3 – Adjuster 6 – Inner pad

1 – Adjustment spring
2 – Companion sleeve

3/3

2/3

1/3

8

Description of Operation

E - The next part of the return stroke corresponds to E. The

housing of the adjuster, the adjustment spring and companion
sleeve are rotated in relation to the hub, which is stationary.
Movement between companion sleeve and hub is allowed by
the friction spring.

e

C

6

C

E

Ce - During the last part of the return stroke (Ce), the rotational
movement continues in the adjuster as described under E until
the mechanism has reached its resting position. The friction
springs on the adjustment screws prevent the mechanism from
backing off.

C

e

E

C

3/3

1 – Adjustment spring 4 – Friction spring
2 – Rotating housing 5 – Hub
3 – Companion sleeve 6 – Inner pad

2/3

1/3

1 – Adjuster

Brake torque

Adjustment
phase (Ce)

3/3

2/3

1/3

1

Description of Operation

Free stroke Elasticity

9