SEBM033000
MACHINE MODEL SERIAL No.
PC400-7 50001 and up
PC400LC-7 50001 and up
PC450-7 20001 and up
PC450LC-7 20001 and up
• This shop manual may contain attachments and optional equipment that are not available
in your area. Please consult your local Komatsu distributor for those items you may
require. Materials and specifications are subject to change without notice.
• PC400, 400LC, PC450, 450LC-7 mount the SAA6D125E-3 engine.
For details of the engine, see the 125-3 Series Engine Shop Manual.
© 2003
All Rights Reserved
Printed in Japan 10-03 (01)
00-1
GENERAL
CONTENTS
No. of page
01 GENERAL
............................................................................................................................ 01-1
10 STRUCTURE, FUNCTION AND
MAINTENANCE STANDARD
20 TESTING AND ADJUSTING
............................................. To be issued next time
30 DISASSEMBLY AND ASSEMBLY
90 OTHERS
................................................................................................................................ 90-1
............................................ 10-1
......................... To be issued next time
00-2
(1)
PC400/450(LC)-7
01 GENERAL
SPECIFICATION DRAWINGS ......................................................................................................................01- 2
SPECIFICATIONS ........................................................................................................................................01- 4
WEIGHT TABLE............................................................................................................................................01- 8
FUEL, COOLANT AND LUBRICANTS .........................................................................................................01- 12
PC400/450(LC)-7
01-1
GENERAL SPECIFICATION DRAWINGS
SPECIFICATION DRAWINGS
DIMENSIONS
WORKING RANGES
01-2
PC400/450(LC)-7
GENERAL SPECIFICATION DRAWINGS
DIMENSIONS
Fixed gauge specification
Item Unit PC400-7 PC400LC-7 PC450-7 PC450LC-7
A Overall length mm 11,940 11,940 12,040 12,040
B Overall height mm 3,635 3,635 3,660 3,660
C Overall width mm 3,340 3,440 3,340 3,340
D Track shoe width mm 600 700 600 600
E Height of machine cab mm 3,265 3,265 3,265 3,265
F Tail swing radius mm 3,645 3,645 3,645 3,645
G Track overall length mm 5,055 5,355 5,055 5,355
H Length of track on ground mm 4,020 4,350 4,020 4,350
Min. ground clearance mm 555 550 555 550
Variable gauge specification
Item Unit PC400-7 PC400LC-7 PC450-7 PC450LC-7
A Overall length mm 11,940 11,940 12,040 12,040
B Overall height mm 3,635 3,635 3,660 3,660
C Overall width mm 3,490 3,490 3,490 3,490
D Track shoe width mm 600 600 600 600
E Height of machine cab mm 3,265 3,265 3,265 3,265
F Tail swing radius mm 3,645 3,645 3,645 3,645
G Track overall length mm 5,055 5,355 5,055 5,355
H Length of track on ground mm 4,020 4,350 4,020 4,350
Min. ground clearance mm 685 685 685 685
WORKING RANGES
Working range Unit PC400-7 PC400LC-7 PC450-7 PC450LC-7
A Max. digging reach mm 12,025 12,025 12,005 12,005
B Max. digging depth mm 7,820 7,820 7,790 7,790
C Max. digging height mm 10,915 10,915 10,925 10,925
D Max. vertical wall depth mm 6,870 6,870 6,600 6,600
E Max. dumping height mm 7,565 7,565 7,625 7,625
F Min. dumping height mm — — — —
Max. reach at ground
G
level
mm 11, 820 11,8 20 11,8 00 11,800
PC400/450(LC)-7
01-3
GENERAL SPECIFICATIONS
SPECIFICATIONS
PC400-7, PC400LC-7
PC400-7 PC400LC-7
Machine model
Serial Number 50001 and up
Bucket capacity m
Weight of machine kg 41,200 42,400 42,200 43,500
Max. digging depth
Max. vertical wall depth
Max. digging reach
Max. reach at ground level
Max. digging height
Working ranges
Max. dumping height
Max. digging force
(using power max. function)
Performance
Swing speed
Swing max. slope angle
Travel speed
Gradeability
Ground pressure
[standard shoe width]
Overall length (for transport)
Overall width
Overall width of track
Overall width of track when extended
Overall height (for transport)
Overall height to top of machine
Ground clearance of upper structure
Min. ground clearance
Tail swing radius
Dimensions
Min. swing radius of work equipment
Height of work equipment
at min. swing radius
Length of track on ground
Track gauge
Height of machine cab
3
mm
mm
mm
mm
mm
mm
kN {kg}
kN {kg}
rpm
deg.
km/h
deg.
kPa {kg/cm
[mm]
mm
mm
mm
mm
mm
mm
mm
mm
mm
mm
mm
mm
mm
mm
2
}
Fixed gauge
spec.
256.0 {26,100}
(274.6 {28,000})
Lo: 3.0, Mi: 4.4, Hi: 5.5
77.7{0.79}
[600]
11, 940
3,340
3,340
—
3,635
3,265
1,320
555
3,645
4,735
9,210
4,020
2,740
3,265
Variable
gauge spec
1.4 1.4
7,820
6,870
12,025
11,8 20
10,915
7,565
9.1
20
35
79.9 {0.82}
[600]
11,940
3,490
2,990
3,490
3,635
3,265
1,320
685
3,645
4,735
9,210
4,020
2,890
3,265
Fixed gauge
spec.
.
256.0 {26,100}
(274.6 {28,000})
Lo: 3.0, Mi: 4.4, Hi: 5.5
73.9 {0.75}
[700]
11, 940
3,440
3,440
—
3,635
3,265
1,320
555
3,645
4,735
9,210
4,020
2,740
3,265
gauge spec
7,820
6,870
12,025
11,8 20
10,915
7,565
9.1
20
35
65.3 {0.67}
Variable
.
[700]
11,9 40
3,490
2,990
3,490
3,635
3,265
1,320
685
3,645
4,735
9,210
4,020
2,890
3,265
: The “Mi” mode is on the multi-monitor specification machine only
01-4
PC400/450(LC)-7
GENERAL SPECIFICATIONS
Machine model PC400-7 PC400LC-7
Serial Number 50001 and up
Model
Typ e
No. of cylinders – bore × stroke
Piston displacement
Flywheel horsepower
Max. torque
Max. speed at no load
Engine
Min. speed at no load
Min. fuel consumption
Performance
Starting motor
Alternator
Battery
Radiator core type ALW-4
Carrier roller 2 on each side
Track roller 7 on each side 8 on each side
Track shoe
Undercarriage
Type × No .
Delivery
Set pressure
Hydraulic pump
Type × No .
mm
l {cc}
kW/rpm {HP/rpm}
Nm/rpm {kgm/rpm}
rpm
rpm
g/kWh {g/HPh}
l /min
MPa {kg/cm
2
}
4-cycle, water-cooled, in-line, vertical, direct injection,
with turbocharger and aftercooler
Assembly-type triple grouser,
45 on each side
HPV190+190, variable displacement, piston type x2
6-spool type + 1-spool type × 1
SAA6D125E-3
6 – 125 × 150
11.045 {11,045}
246.4/1,850 {330/1,850}
1,334/1,400 {136/1,400}
1,930
1,000
203 {151}
24V, 7.5 kW
24V, 35A
12V, 110 Ah × 2
Assembly-type triple grouser,
48 on each side
345 × 2
37.8 {380}
Control method
Control valve
Travel motor
Swing motor
Hydraulic motor
Hydraulic system
Type
Inside diameter of cylinder mm 160 185 160
Diameter of piston rod mm 110 120 110
Stroke mm 1,570 1,820 1,270
Hydraulic cylinder
Max. distance between pins mm 3,830 4,325 3,140
Min. distance between pins mm 2,260 2,505 1,870
Hydraulic tank
Hydraulic filter
Hydraulic cooler
KMV200ADT-2, Variable displacement, piston type
(with brake valve, parking brake): × 2
KMF230ABE-5, Fixed displacement piston type
(with safety valve, holding brake, reverse rotation preventive valve): × 1
Boom Arm Bucket
Double-acting
piston
Hydraulic
Double-acting
piston
Closed box type
Tank return side
CF40-1 (Air cooled)
Double-acting
piston
PC400/450(LC)-7
01-5
GENERAL SPECIFICATIONS
PC450-7, PC450LC-7
PC450LC-7 PC450LC-7
Machine model
Serial Number 20001 and up
Bucket capacity m
Operating weight kg 42,700 44,000 43,700 44,600
Max. digging depth
Max. vertical wall depth
Max. digging reach
Max. reach at ground level
Max. digging height
Working ranges
Max. dumping height
Max. digging force
(using power max. function)
Performance
Swing speed
Swing max. slope angle
Travel speed
Gradeability
Ground pressure
[standard shoe width]
3
mm
mm
mm
mm
mm
mm
kN {kg}
rpm
deg.
km/h
deg.
kPa {kg/cm
[mm]
2
}
Fixed gauge
spec.
258.9 {26,400}
(275.5 {28,300})
Lo: 3.0, Mi: 4.4, Hi: 5.5
80.5 {0.82}
[600]
gauge spec
1.4 1.4
7,790
6,600
12,005
11,8 00
10,925
7,625
9.1
17
35
82.9 {0.85}
Var iable
[600]
Fixed gauge
spec.
.
258.9 {26,400}
(275.5 {28,300})
Lo: 3.0, Mi: 4.4, Hi: 5.5
76.5 {0.78}
[600]
gauge spec
7,790
6,600
12,005
11,8 00
10,925
7,625
9.1
17
35
Var iable
.
78.1 {0.80}
[600]
Overall length (for transport)
Overall width
Overall width of track
Overall width of track when extended
Overall height (for transport)
Overall height to top of machine
Ground clearance of upper structure
Min. ground clearance
Tail swing radius
Dimensions
Min. swing radius of work equipment
Height of work equipment
at min. swing radius
Length of track on ground
Track gauge
Height of machine cab
mm
mm
mm
mm
mm
mm
mm
mm
mm
mm
mm
mm
mm
12,040
3,340
3,340
—
3,660
3,265
1,320
555
3,645
4,805
9,230
4,020
2,740
3,265
: The “Mi” mode is on the multi-monitor specification machine only
12,040
3,490
2,990
3,490
3,660
3,265
1,320
685
3,645
4,805
9,230
4,020
2,890
3,265
12,040
3,340
3,340
—
3,660
3,265
1,320
555
3,645
4,805
9,230
4,350
2,740
3,265
12,040
3,490
2,990
3,490
3,660
3,265
1,320
685
3,645
4,805
9,230
4,350
2,890
3,265
01-6
PC400/450(LC)-7
GENERAL SPECIFICATIONS
Machine model PC450-7
Serial Number 20001 and up
Model
Typ e
No. of cylinders – bore × stroke
Piston displacement
Flywheel horsepower
Max. torque
Max. speed at no load
Engine
Min. speed at no load
Performance
Min. fuel consumption
Starting motor
Alternator
Battery
Radiator core type ALW-4
Carrier roller 2 on each side
Track roller 7 on each side 8 on each side
mm
l {cc}
kW/rpm {HP/rpm}
Nm/rpm {kgm/rpm}
rpm
rpm
g/kWh {g/HPh}
4-cycle, water-cooled, in-line, vertical, direct injection,
with turbocharger and aftercooler
SAA6D125E-3
6 – 125 × 150
11.045 {11,045}
246.4/1,850 {330/1,850}
1,334/1,400 {136/1,400}
1,930
4,000
203 {151}
24V, 7.5 kW
24 V, 35 A
12V, 110 Ah × 2
PC450LC-7
Track shoe
Undercarriage
Type × No .
Delivery
Set pressure
Hydraulic pump
Type × No .
Control method
Control valve
Travel motor
Swing motor
Hydraulic motor
Hydraulic system
Cylinder type
Inside diameter of cylinder
Outside diameter of piston rod
Stroke
Hydraulic cylinder
Max. distance between pins
Min. distance between pins
Hydraulic tank
Hydraulic filter
Hydraulic cooler
l /min
MPa {kg/cm
mm
mm
mm
mm
mm
Assembly-type triple grouser,
45 on each side
HPV190+190, ariable displacement, piston type × 2
2
}
6-spool type + 1-spool type × 1
KMV200ADT-2, Variable displacement, piston type
(with brake valve, parking brake): × 2
KMF230ABE-5, Fixed displacement piston type × 2
(with safety valve, holding brake, reverse rotation preventive valve): × 1
Boom Arm Bucket
Double-acting piston Double-acting piston Double-acting piston
160 185 160
110 130 110
1,570 1,985 1,270
3,830 4,325 3,140
2,260 2,505 1,870
Closed box type
Tank return side
CF40-1 (Air cooled)
Assembly-type triple grouser,
48 on each side
345 × 2
37.8 {380}
Hydraulic
PC400/450(LC)-7
01-7
GENERAL WEIGHT TABLE
WEIGHT TABLE
PC400-7, PC400LC-7
k This weight table is for use when handling components or when transporting the machine.
Unit: kg
Machine model PC400-7 PC400LC-7
Serial Number 50001 and up
Engine assembly
•Engine
• Damper
• Hydraulic pump
Radiator, oil cooler assembly 195 195
Hydraulic tank, filter assembly (excluding hydraulic oil) 198 198
Fuel tank (excluding fuel) 251 251
Revolving frame 3,297 3,297
Operator's cab 279 279
Operator's seat 35 35
Counterweight 9,220 9,500
Swing machinery (including swing motor) 526 526
Control valve (with service valve) 257 257
Swing motor 105 105
Travel motor 208 × 2 208 × 2
Center swivel joint 40 40
Fixed gauge
specification
• Track frame assembly
• Track frame
• • Center frame
• • Crawler frame
•Swing circle
•Idler
•Idler cushion
• Carrier roller
• Track roller
• Final drive (including travel motor)
10,173 11,367 10,965 11,934
5,506 6,766 6,077 7,096
1,500
1,150
14.7
210
Variable gauge
specification
—3,229—3,229
— 1,754 × 2 — 1,921 × 2
605 × 2
230 × 2
338 × 2
32 × 4
72 × 14
722 × 2
Fixed gauge
specification
1,500
1,150
14.7
210
Variable gauge
605 × 2
230 × 2
338 × 2
32 × 4
72 × 16
722 × 2
specification
01-8
PC400/450(LC)-7
GENERAL WEIGHT TABLE
Unit: kg
Machine model PC400-7 PC400LC-7
Serial Number 50001 and up
Track shoe assembly
• Standard triple grouser shoe (600 mm)
• Standard triple grouser shoe (700 mm)
• Wide triple grouser shoe (800 mm)
• Wide triple grouser shoe (900 mm)
Boom assembly 3,290 3,290
Arm assembly 1,374 1,374
Bucket assembly 1,366 1,366
4,470
4,890
5,320
—
4,760
5,210
5,670
6,130
Boom cylinder assembly 355 × 2 355 × 2
Arm cylinder assembly 510 510
Bucket cylinder assembly 280 280
Link assembly 258 258
Boom pin 92 + 20 × 2 + 73 + 27 + 54 92 + 20 × 2 + 73 + 27 + 54
Arm pin 17 + 23 17 + 23
Bucket pin 38 × 2 38 × 2
Link pin 34 × 2 34 × 2
PC400/450(LC)-7
01-9
GENERAL WEIGHT TABLE
PC450-7, PC450LC-7
Unit: kg
Machine model PC450-7 PC450LC-7
Serial Number 20001 and up
Engine assembly
•Engine
• Damper
• Hydraulic pump
Radiator oil cooler assembly 195 195
Hydraulic tank, filter assembly (excluding hydraulic oil) 198 198
Fuel tank (excluding fuel) 251 251
Revolving frame 3,402 3,402
Operator’s cab 279 279
Operator’s seat 35 35
Counterweight 9,220 9,220
Swing machinery 526 526
Control valve 257 257
Swing motor 105 105
Travel motor 208 × 2 208 × 2
Center swivel joint 40 40
Fixed gauge
specification
• Track frame assembly
• Track frame
• • Center frame
• • Crawler frame
•Swing circle
•Idler
•Idler cushion
• Carrier roller
• Track roller
• Final drive (including travel motor)
10,462 11,697 11,269 12,244
5,506 6,766 6,077 7,096
1,500
1,150
14.7
210
Variable gauge
specification
—3,229—3,229
— 1,754 × 2 — 1,921 × 2
605
230 × 2
338 × 2
32 × 4
81 × 6, 72 × 8
722 × 2
Fixed gauge
specification
1,500
1,150
14.7
210
Variable gauge
605
230 × 2
338 × 2
32 × 4
81 × 8, 72 × 8
722 × 2
specification
01-10
PC400/450(LC)-7
GENERAL WEIGHT TABLE
Unit: kg
Machine model PC450-7 PC450LC-7
Serial Number 20001 and up
Track shoe assembly
• Standard triple grouser shoe (600 mm)
• Standard triple grouser shoe (700 mm)
• Wide triple grouser shoe (800 mm)
Boom assembly 3,380 3,380
Arm assembly 1,622 1,622
Bucket assembly 1,941 1,941
Boom cylinder assembly 355 × 2 355 × 2
Arm cylinder assembly 580 580
Bucket cylinder assembly 280 280
4,470
4,890
—
4,760
5,210
—
Link assembly 258 258
Boom pin 92 + 20 × 2 + 73 + 27 + 54 92 + 20 × 2 + 73 + 27 + 54
Arm pin 17 + 23 17 + 23
Bucket pin 38 × 2 38 × 2
Link pin 34 × 2 34 × 2
PC400/450(LC)-7
01-11
GENERAL FUEL, COOLANT AND LUBRICANTS
FUEL, COOLANT AND LUBRICANTS
01-12
PC400/450(LC)-7
10 STRUCTURE, FUNCTION AND
MAINTENANCE STANDARD
ENGINE RELATED PARTS..................... 10- 2
RADIATOR • OIL COOLER •
AFTERCOOLER ................................ 10- 3
POWER TRAIN ....................................... 10- 4
FINAL DRIVE .......................................... 10- 6
SWING MACHINERY .............................. 10- 8
SWING CIRCLE ...................................... 10- 10
TRACK FRAME AND RECOIL SPRING . 10- 12
IDLER ...................................................... 10- 14
CARRIER ROLLER ................................. 10- 16
TRACK ROLLER ..................................... 10- 17
TRACK SHOE ......................................... 10- 18
HYDRAULIC PIPING DRAWING ............ 10- 22
HYDRAULIC TANK.................................. 10- 24
HYDRAULIC PUMP ................................ 10- 26
LS(PC)-EPC VALVE ................................ 10- 44
VARIABLE VOLUME VALVE .................. 10- 47
CONTROL VALVE ................................... 10- 50
MAIN RELIEF VALVE .............................. 10- 64
CLSS ....................................................... 10- 66
SELF PRESSURE REDUCING VALVE... 10- 69
SWING MOTOR ...................................... 10- 72
CENTER SWIVEL JOINT ........................ 10- 80
TRAVEL MOTOR..................................... 10- 82
TRAVEL JUNCTION VALVE .................... 10- 93
VALVE CONTROL ................................... 10- 95
TRAVEL PPC SHUTTLE VALVE ............. 10- 96
WORK EQUIPMENT • SWING PPC
VALVE ................................................ 10-100
TRAVEL PPC VALVE .............................. 10-104
SERVICE PPC VALVE ............................ 10- 111
SOLENOID VALVE .................................. 10-112
PPC ACCUMULATOR............................. 10-114
RETURN OIL FILTER ............................. 10-115
BOOM HYDRAULIC DRIFT
PREVENTION VALVE........................ 10-116
ARM HYDRAULIC DRIFT PREVENTION
VALVE ................................................ 10-121
QUICK RETURN VALVE......................... 10-125
LIFT CHECK VALVE................................ 10-127
ATTACHMENT CIRCUIT SELECTOR
VALVE................................................ 10-128
HOLDING VALVE .................................... 10-130
HYDRAULIC CYLINDER......................... 10-136
WORK EQUIPMENT ............................... 10-138
AIR CONDITIONER ................................ 10-144
ENGINE CONTROL .................................10-145
ELECTRONIC CONTROL SYSTEM........10-151
MONITOR SYSTEM.................................10-178
SENSOR ..................................................10-198
PC400/450(LC)-7
10-1
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD ENGINE RELATED PARTS
ENGINE RELATED PARTS
1. Drive plate 5. Damper assembly
2. Torsion spring 6. Muffler
3. Stopper pin 7. Rear engine mount
4. Friction plate 8. Front engine mount
10-2
Outline
• The damper assembly is a wet type.
Oil capacity: 1.3 l
PC400/450(LC)-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD RADIATOR • OIL COOLER • AFTERCOOLER
RADIATOR • OIL COOLER • AFTERCOOLER
1. Oil cooler 10. Condenser
2. Radiator 11. Fuel cooler
3. Radiator cap
4. Reservoir tank
5. Net
6. Shroud
7. Radiator inlet hose
8. Radiator outlet hose
9. Aftercooler
PC400/450(LC)-7
Specifications
Radiator : ALW-4
Oil cooler : CF40-1
10-3
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD POWER TRAIN
POWER TRAIN
1. Idler 7. Hydraulic pump (HPV190+190)
2. Center swivel joint 8. Travel speed solenoid valve
3. Control valve 9. Swing brake solenoid valve
4. Final drive 10. Swing machinery
5. Travel motor (KMV 200ADT-2) 11. Swing motor (KMF230ABE-5)
6. Engine (SAA6D125-3E) 12. Swing circle
10-4
PC400/450(LC)-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD FINAL DRIVE
FINAL DRIVE
10-6
PC400/450(LC)-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD FINAL DRIVE
1. Level plug
2. Drain plug
3. No. 1 planetary gear (No. of teeth: 43)
4. No. 1 sun gear (No. of teeth: 10)
5. No. 2 sun gear (No. of teeth: 18)
6. No. 1 planetary carrier
7. No. 2 planetary carrier
8. Cover
9. Ring gear (No. of teeth: 98)
10. Sprocket
11. Floating seal
12. Travel motor
13. No. 2 planetary gear (No. of teeth: 38)
Specification
Reduction ratio:
10 + 98
– × = –68.600
10
18 + 98
18
Unit: mm
No. Check item Criteria Remedy
Backlash between No. 1 sun
14
gear and No. 1 planetary gear
Backlash between No. 1
15
planetary gear and ring gear
Backlash between No. 2
16
planetary carrier and motor
Backlash between No. 2 sun
17
gear and No. 2 planetary
gear
Backlash between No. 2 plan-
18
etary gear and ring gear
Backlash between No. 2
19
planetary carrier and No. 2
sun gear
Amount of wear on sprocket
20
tooth
21 Width of sprocket tooth
Standard clearance Clearance limit
0.15 – 0.54 1.10
0.18 – 0.66 1.30
0.06 – 0.24 —
0.15 – 0.51 1.00
0.17 – 0.60 1.20
0.15 – 0.54 —
Repair limit: 6
Standard size Repair limit
90 87
Replace
Rebuild or
replace
PC400/450(LC)-7
10-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD SWING MACHINERY
SWING MACHINERY
10-8
PC400/450(LC)-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD SWING MACHINERY
1. Swing pinion (No. of teeth: 13)
2. Cover
3. Case
4. No. 2 planetary gear
5. No. 2 sun gear
6. Ring gear
7. No. 1 sun gear
8. Swing motor
9. Oil level gauge
10. No. 1 planetary gear
11. No. 1 planetary carrier
12. No. 2 planetary carrier
13. Drain plug
Specification
Reduction ratio:
19 + 68
19
16 + 68
× = 24.039
16
Unit: mm
No. Check item Criteria Remedy
Backlash between swing
14
motor shaft and No. 1 sun gear
Backlash between No. 1 sun
15
gear and No. 1 planetary
gear
Backlash between No. 1
16
planetary gear and ring gear
Backlash between No. 1
17
planetary carrier and No. 2
sun gear
Backlash between No. 2 sun
18
gear and No. 2 planetary gear
Backlash between No. 2
19
planetary gear and ring gear
Backlash between coupling
20
and swing pinion
Backlash between swing pin-
21
ion and swing circle
Standard clearance Clearance limit
0.18 – 0.28 —
0.15 – 0.51 1.00
0.17 – 0.60 1.10
0.40 – 0.75 1.20
Replace
0.16 – 0.55 1.00
0.17 – 0.60 1.10
0.08 – 0.25 —
0.00 – 1.21 2.00
Clearance between plate
22
and coupling
Wear of swing pinion surface
23
contacting with oil seal
PC400/450(LC)-7
0.57 – 1.09 —
Standard size Repair limit Apply hard
chrome plat-
150
0
–0.100
—
ing, recondition, or
replace
10-9
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD SWING CIRCLE
SWING CIRCLE
1. Swing circle inner race (No. of teeth: 84)
2. Ball
3. Swing circle outer race
a. Inner race soft zone “S” position
b. Outer race soft zone “S” position
No. Check item Criteria Remedy
Axial clearance of bearing
4
(when mounted on chassis)
Standard clearance Repair limit
0.5 – 1.6 3.2
10-10
Specifications
Reduction ratio: – =
Amount of grease: 33 l (G2-LI)
84
13
6.462
–
Unit: mm
Replace
PC400/450(LC)-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD TRACK FRAME AND RECOIL SPRING
TRACK FRAME AND RECOIL SPRING
1. Idler
2. Track frame
3. Carrier roller
4. Final drive
5. Track roller
6. Track shoe
7. Center guard
8. Recoil spring
9. Front guard
10-12
• The dimensions and the number of track rollers
depend on the model, but the basic structure is
not different.
• Number of track rollers
Model Q’ty
PC400-7, 450-7 7
PC400LC-7, 450LC-7
8
PC400/450(LC)-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD TRACK FRAME AND RECOIL SPRING
Standard shoe
Model
Item
Shoe width 600 mm 700 mm 600 mm 600 mm
Link pitch 228 mm 228 mm 228 mm 228 mm
No. on track (one side) 46 (Pieces) 46 (Pieces) 49 (Pieces) 49 (Pieces)
PC400-7 PC400LC-7 PC450-7 PC450LC-7
Unit: mm
No. Check item Criteria Remedy
10 Vertical width of idler guide
11 Horizontal width of idler guide
12 Recoil spring
Standard
size
Track frame 123 127
Idler support 120 ±0.5 118
Track frame 266 271
Idler support 261 — 259
Standard size Repair limit
Free length
× OD
795 × 241 648
Installation
length
Installation
load
173.3 kN
{17,680 kg}
Tolerance Repair limit
+2
–1
+3
–1
Free length
—
Installation
load
138.56 kN
{14,140 kg}
Rebuild or
replace
Replace
PC400/450(LC)-7
10-13
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD IDLER
IDLER
10-14
PC400/450(LC)-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD
Unit: mm
No. Check item Criteria Remedy
+0.360
+0.220
–0.027
–0.079
Repair limit
Rebuild or
replace
Standard
clearance
0.340 –0.507
Replace bushing
Standard
interference
0.064 –0.149
Outside diameter of protrud-
1
ing
2 Outside diameter of tread 660 648
3 Depth of tread 22 28
4 Total width 202 —
5 Width of tread 48.5 —
Clearance between shaft and
6
bushing
Interference between idler
7
and bushing
Standard size
Standard size
Standard size
95
102.6
704 —
To le ra n c e
Shaft Hole
–0.120
–0.207
To le ra n c e
Shaft Hole
+0.087
+0.037
PC400/450(LC)-7
10-15
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD CARRIER ROLLER
CARRIER ROLLER
Unit: mm
No. Check item Criteria Remedy
1 Outside diameter of flange
2 Outside diameter of tread 148 134
3 Width of tread 50.3 —
4 Thickness of tread 32 25
5 Width of flange 19 —
Standard
Interference between shaft
6
and bushing
Interference between roller
7
and bushing
8 Axial clearance of roller
10-16
Standard size Repair limit
175 —
To le r a nc e
size
50
57
Standard clearance Clearance limit
Shaft Hole
–0.250
–0.270
+0.117
+0.087
0.5 – 0.7 —
+0.099
–0.032
+0.040
0
Standard
interference
0.218 –
0.369
0.047 –
0.177
Interference
limit
—
—
PC400/450(LC)-7
Replace
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD TRACK ROLLER
TRACK ROLLER
Unit: mm
No. Check item Criteria Remedy
Outside diameter of outer
1
flange
Outside diameter of inner flange
2
(double flange)
3 Outside diameter of tread 200 188
4 Thickness of tread 56.2 50.2
5 Overall width 278 —
6 Width of tread
Width of outer
7
flange
Width of inner flange
8
(Double flange)
9 Axial play 0.4 – 1.0 —
Clearance between shaft and
10
bushing
Interference between roller
11
and bushing
Singe flange 54.6 —
Double flange
Singe flange 32.6 —
Double flange
Standard
Standard
Standard size Repair limit
240 —
237 —
51.6 —
32.6 —
23.0 —
size
80
size
87.6
Tolerance
Shaft Hole
–0.250
–0.350
Tolerance
Shaft Hole
+0.108
+0.008
+0.174
+0.029
–0.006
–0.036
Standard
clearance
Standard
interference
0.279 –
0.524
0.014 –
0.144
Clearance
limit
1.5
Interference
limit
—
Rebuild or
replace
Replace
bushing
PC400/450(LC)-7
10-17
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD TRACK SHOE
TRACK SHOE
TRACK SHOE
a P portion shows the link of bushing press-fitting end.
10-18
PC400/450(LC)-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD TRACK SHOE
Unit: mm
No. Check item Criteria Remedy
1Link pitch
2 Bushing outside diameter
3 Thickness of bushing metal 12 7
4Link height
Thickness of link metal
5
(bushing press-fitting portion)
6
Shoe bolt pitch
876.2
Inside
width
Overall
width
Tread
width
10
11
9
Link
Standard size Repair limit
228.9 231.9
Standard size When turned
71.5 66.5
Standard size Repair limit
129 119
34.5 24.5
184
106
51.6
44.8
Reverse or
replace
Adjust or
replace
Repair or
replace
Replace7 144
Repair or
replace
12 Protrusion of pin 4.4
13 Protrusion of regular bushing 5.25
14 Overall length of pin 252
15 Overall length of bushing 164.5
16 Thickness of spacer —
17
Press-fitting
force
19
Bushing 118 – 304 kN {12 – 31 ton}
Regular
pin
Master
pin
176 – 451 kN {18 – 46 ton}
137 – 284 kN {14 – 29 ton}
: Dry type track link
PC400/450(LC)-7
Adjust or
replace
—18
10-19
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD TRACK SHOE
Unit: mm
No. Check item Criteria Remedy
Shoe bolt
20
No. of shoes (each side)
Interference between
21
bushing and link
Interference between regular
22
pin and link
Clearance between regular
23
pin and bushing
a. Regular
link
b. Master
link
Tightening torque
(Nm {kgm})
Triple shoe 393±39 {40±4} 120±10
Tightening torque
(Nm {kgm})
———
Standard size
71
47
Standard size
47
Additinal tightening
angle (deg.)
PC400-7, PC450-7: 46
PC400LC-7, PC450LC-7: 49
Tolerance
Shaft Hole
+0.494
+0.454
+0.235
+0.085
Tolerance
Shaft Hole
+0.235
+0.085
Additinal tightening
angle (deg.)
Lower limit torque
(Nm {kgm})
+0.074
0
–0.218
–0.280
+0.915
+0.415
0.380 – 0.494
0.303 – 0.515
0.180 – 0.830
Retighten
—
Standard
interference
Standard
clearance
Adjust or
replace
24
25
10-20
Interference between master
pin and bushing
Clearance between master
pin and bushing
Standard size
47
Standard size
47
Tolerance
Shaft Hole
+0.03
0
Tolerance
Shaft Hole
–0.2
–0.4
–0.218
–0.280
+0.915
+0.415
Standard
interference
0.218 – 0.310
Standard
clearance
0.615 – 1.315
PC400/450(LC)-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD TRACK SHOE
TRIPLE GROUSER SHOE
Unit: mm
No. Check item Criteria Remedy
1Height
2 Thickness 13
3
Length at of base
427
5
Length at tip
617.5
723.5
PC400/450(LC)-7
Standard size Repair limit
37 22
33
25.5
Rebuild or
replace
10-21
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD HYDRAULIC PIPING DRAWING
HYDRAULIC PIPING DRAWING
1. Bucket cylinder
2. Arm cylinder
3. Boom cylinder
4. Swing motor
5. Control valve
6. Oil cooler
7. Hydraulic filter
8. Hydraulic pump
9. L.H. travel motor
10. Hydraulic tank
11. Multi-pattern selector valve
12. L.H. PPC valve
13. Safety lever (electric type)
14. Center swivel joint
15. R.H. PPC valve
16. Travel PPC valve
17. Attachment circuit selector valve
18. Holding valve
19. Accumulator
20. Solenoid valve assembly 20A. PPC lock solenoid 20B. Travel junction solenoid 20C. Pump merge/divider solenoid 20D. Travel speed solenoid 20E. Swing brake solenoid 20F. Machine push-up solenoid 20G. 2-stage relief solenoid
10-22
PC400/450(LC)-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD HYDRAULIC PIPING DRAWING
PC400/450(LC)-7
10-23
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD HYDRAULIC TANK
HYDRAULIC TANK
1. Oil filler cap
2. Breather
3. Hydraulic tank
4. Sight gauge
5. Strainer
6. Filter element
7. Strainer
8. Bypass valve
10-24
Specifications
Tank capacity: 335 l
Amount of oil inside tank: 248 l
Pressure valve
• Relief cracking pressure: 16.7 ± 6.9 kPa
{0.17 ± 0.07 kg/cm
• Suction cracking pressure: 0 – 0.49 kPa
{0 – 0.005 kg/cm
• Bypass valve set pressure: 150 ± 30 kPa
{1.5 ± 0.3 kg/cm
Breather
• Intake valve set pressure: 2.0 ± 0.3 kPa
{0.02 ± 0.003 kg/cm
• Exhaust valve set pressure: 98 ± 14.7 kPa
{1.0 ± 0.15 kg/cm
PC400/450(LC)-7
2
}
2
}
2
}
2
}
2
}
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD HYDRAULIC PUMP
HYDRAULIC PUMP
HPV160+160(190)
1. Front main pump
2. Rear main pump
3. LS valve
4. PC valve
5. LS-EPC valve
6. PC-EPC valve
7. Variable volume valve
IM : PC mode selector current
ISIG : LS set selector current
PAF : Front pump delivery
PFC : Front pump delivery
pressure detection
PAR : Rear pump delivery
PRC : Rear pump delivery
pressure detection
PBF : Front pump pressure input
PD1F : Case drain port
PENF : Front pump control
pressure detection
PBR : Rear pump pressure input
PD2F : Drain plug
PD2R : Drain plug
PENR : Rear pump control
pressure detection port
PLSF : Front load pressure input
PLSFC: Front load pressure
detection port
PLSR : Rear load pressure input
PLSRC: Rear load pressure
detection port
PS : Pump suction
PLSCR: LS set selector pressure
detection port
PM : PC set selector pressure
detection port
PEPC : EPC basic pressure input
PDIR : Air bleeder
PEPB : EPC basic pressure
detection port
Outline
• This pump consists of 2 variable capacity swash plate piston pumps, PC valve, LS valve, and EPC valve.
10-26
PC400/450(LC)-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD HYDRAULIC PUMP
1. Shaft (Front) 7. Cylinder block
2. Cradle 8. Valve plate
3. Case (Front) 9. End cap
4. Rocker cam 10. Shaft (Rear)
5. Shoe 11. Case (Rear)
6. Piston 12. Servo piston
PC400/450(LC)-7
10-27
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD HYDRAULIC PUMP
Function
• The rotation and torque transmitted to the pump
shaft are converted into hydraulic energy, and
pressurized oil is discharged according to the
load.
• It is possible to change the discharge amount by
changing the swash plate angle.
Structure
• Cylinder block (7) is supported to shaft (1) by a
spline, and shaft (1) is supported by the front and
rear bearings.
• The tip of piston (6) is a concave ball, and shoe
(5) is caulked to it to form one unit. Piston (6) and
shoe (5) form a spherical bearing.
• Rocker cam (4) has flat surface A, and shoe (5) is
always pressed against this surface while sliding
in a circular movement.
Rocker cam (4) brings high pressure oil at cylinder surface B with cradle (2), which is secured to
the case, and forms a static pressure bearing
when it slides.
• Piston (6) carries out relative movement in the axial direction inside each cylinder chamber of cylinder block (7).
• The cylinder block seals the pressure oil to valve
plate (8) and carries out relative rotation. This surface is designed so that the oil pressure balance is
maintained at a suitable level. The oil inside each
cylinder chamber of cylinder block (7) is sucked in
and discharged through valve plate (8).
10-28
PC400/450(LC)-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD HYDRAULIC PUMP
Operation
1) Operation of pump
i Cylinder block (7) rotates together with shaft
(1), and shoe (5) slides on flat surface A.
When this happens, rocker cam (4) moves
along cylindrical surface B, so angle a
between center line X of rocker cam (4) and
the axial direction of cylinder block (7)
changes. (Angle is called the swash plate
angle.)
ii Center line X of rocker cam (4) maintains
swash plate angle in relation to the axial
direction of cylinder block (7), and flat surface
moves as a cam in relation to shoe (5).
A
In this way, piston (6) slides on the inside of
cylinder block (7), so a difference between
volumes E and F is created inside cylinder
block (7). The suction and discharge is carried out by this difference F – E.
In other words, when cylinder block (7)
rotates and the volume of chamber
becomes smaller, the oil is discharged during
that stroke. On the other hand, the volume of
chamber F becomes larger, and as the volume becomes bigger, the oil is sucked in.
iii If center line X of rocker cam (4) is in line with
the axial direction of cylinder block (7) (swash
plate angle = 0), the difference between volumes E and F inside cylinder block (7)
becomes 0, so the pump does not carry out
any suction or discharge of oil.
(In actual fact, the swash plate angle never
becomes 0.)
E
PC400/450(LC)-7
10-29
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD HYDRAULIC PUMP
2) Control of discharge amount
• If the swash plate angle becomes larger,
the difference between volumes E and F becomes larger and discharge amount Q increases.
• Swash plate angle is changed by servo
piston (12).
• Servo piston (12) moves in a reciprocal
movement ( ) according to the signal pressure from the PC and LS valves. This
straight line movement is transmitted
through rod (13) to rocker cam (4), and rocker cam (4), which is supported by the cylindrical surface to cradle (2), slides in a
rotating movement in direction of arrow.
• With servo piston (12), the area receiving the
pressure is different on the left and the right,
so main pump discharge pressure (self pressure) PP is always brought to the chamber
receiving the pressure at the small diameter
piston end.
• Output pressure
brought to the chamber receiving the pressure at the large diameter end. The relationship in the size of pressure PP at the small
diameter piston end and pressure
large diameter end, and the ratio between
the area receiving the pressure of the small
diameter piston and the large diameter piston controls the movement of servo piston
(12).
of the LS valve is
Pen
Pen
at the
10-30
PC400/450(LC)-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD HYDRAULIC PUMP
LS VALVE
1. Plug
2. Locknut
3. Sleeve
4. Spring
5. Seat
6. Spool
7. Piston
8. Sleeve
PC VALVE
: Pump port
PA
PP
PDP
PLP
PLS
PPL
PSIG
Pump port
:
: Drain port
: LS control pressure output port
: LS pressure input port
: PC control pressure input port
: LS mode selection pilot port
1. Servo piston assembly
2. Plug
3. Pin
4. Spool
5. Retainer
6. Seat
7. Cover
8. Wiring
PC400/450(LC)-7
: Pump port
PA
PA2 : Pump pressure pilot port
: Drain port
PDP
: PC mode selector pressure pilot port
PM
: PC control pressure output port
PPL
10-31
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD HYDRAULIC PUMP
Function
(1) LS valve
The LS valve detects the load and controls the
discharge amount.
This valve controls main pump discharge
amount Q according to differential pressure
PLS
(=PP –
) [called the LS differential
PLS
pressure] (the difference between main pump
pressure PP and control valve outlet port pressure
Main pump pressure PP, pressure
PLS
).
{called
PLS
the LS pressure} coming from the control valve
output, and pressure
{called the LS selec-
Psig
tor pressure} from the proportional solenoid
valve enter this valve. The relationship between
discharge amount Q and differential pressure
, (the difference between main pump
PLS
pressure PP and LS pressure
) changes as shown in the diagram at the
PLS
PLS
) (= PP –
right according to LS pressure selector current
of the LS-EPC valve.
isig
When isig changes between 0 and 1A, the set
pressure of the spring changes according to this,
and the selector point for the pump discharge
amount changes at the rated central valve
between 1.2 2.6 MPa {12 27 kg/cm
2
}.
(2) PC valve
When the pump discharge pressure
pressure) and
(other pump pressure) are
PP2
PP1
high, the PC valve controls the pump so that no
more oil than the constant flow (in accordance
with the discharge pressure) flows even if the
stroke of the control valve becomes larger. In
this way, it carries out equal horsepower control
so that the horsepower absorbed by the pump
does not exceed the engine horsepower.
In other words, If the load during the operation
becomes larger and the pump discharge pressure rises, it reduces the discharge amount from
the pump; and if the pump discharge pressure
drops, it increases the discharge amount from
the pump. The relationship between the average
of the front and rear pump discharge pressures
(average discharge amount of F, R pumps (
+ PP2)/2
) and pump discharge amount Q is
shown on the right, with the current given to the
PC-EPC valve solenoid shown as a parameter.
The controller senses the actual speed of the
engine, and if the speed drops because of an
increase in the load, it reduces the pump discharge amount to allow the speed to recover. In
other words, when the load increases and the
engine speed drops below
the set value, the command current to the PCEPC valve solenoid from the controller
increases according to the drop in the engine
speed to reduce the pump swash plate angle.
(self-
PP1
10-32
PC400/450(LC)-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD HYDRAULIC PUMP
OPERATION
(1) LS valve
1) When control valve is at neutral position
• The LS valve is a three-way selector valve, with
pressure
(LS pressure) from the inlet port of
PLS
the control valve brought to spring chamber B,
and main pump discharge pressure PP brought
to port H of sleeve (8). The size of this LS pressure
+ force Z of spring (4) and the main
PLS
pump pressure (self pressure) PP determines
the position of spool (6). However, the size of the
output pressure
(the LS selection pres-
PSIG
sure) of the EPC valve for the LS valve entering
port G also changes the position of spool (6).
(The set pressure of the spring changes).
• Before the engine is started, servo piston (12) is
pushed to the right. (See the diagram on the
right)
• When the engine is started and the control lever
is at the neutral position, LS pressure
MPa {0 kg/cm
2
}. (It is interconnected with the
PLS
is 0
drain circuit through the control valve spool.)
At this point, spool (6) is pushed to the right, and
port C and port D are connected. Pump pressure PP enters the large diameter end of the
piston from port K and the same pump pressure
also enters port J at the small diameter end
PP
of the piston, so the swash plate is moved to the
minimum angle by the difference in the area of
the piston (12).
PC400/450(LC)-7
10-33
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD HYDRAULIC PUMP
2) Operation in increase direction for pump discharge amount
• When the difference between the main pump
pressure PP and LS pressure
words, LS differential pressure
smaller (for example, when the area of opening
of the control valve becomes larger and pump
drops), spool (6) is pushed to the left by the
PP
combined force of LS pressure
force of spring (4).
• When spool (6) moves, port D and port E are
joined and connected to the PC valve. When this
happens, the PC valve is connected to the drain
port, so circuit D – K becomes drain pressure PT.
(The operation of the PC valve is explained later).
PLS
, becomes
PLS
PLS
, in other
and the
10-34
• For this reason, the pressure at the large diameter end of servo piston (12) becomes drain pressure PT, and pump pressure PP enters port J at
the small diameter end, so servo piston (12) is
pushed to the right. Therefore, the swash plate
moves in the direction to make the discharge
amount larger. If the output pressure of the EPC
valve for the LS valve enters port G, this pressure creates a force to move piston (7) to the
right. If piston (7) is pushed to the right, it acts to
make the set pressure of spring (4) weaker, and
the difference between
when ports D and E of spool (6) are connected.
and PP changes
PLS
PC400/450(LC)-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD HYDRAULIC PUMP
3) Operation in decrease direction for pump discharge amount
• The following explains the situation if the servo
piston (12) moves to the right (the discharge
amount becomes smaller). When LS differential
pressure
when the area of opening of the control valve becomes smaller and pump pressure PP rises),
pump pressure PP pushes spool (6) to the right.
• When spool (6) moves, main port pressure
flows from port C and port D and from port K, it
enters the large diameter end of the piston.
• Main pump pressure PP also enters port J at the
small diameter end of the piston, but because of
the difference in area between the large diameter
end and the small diameter end of servo piston
(12), servo piston (12) is pushed to the right.
PC400/450(LC)-7
becomes larger (for example,
PLS
PP
• As a result, the swash plate moves in the direction to make angle smaller.
• If LS selection pressure
acts to make the set pressure of spring (4) weaker.
enters port G, it
PSIG
10-35
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD HYDRAULIC PUMP
4) When servo piston is balanced
• Let us take the area receiving the pressure at the
large diameter end of the piston as A1, the area
receiving the pressure at the small diameter end
as A0, and the pressure flowing into the large diameter end of the piston as
. If the main
Pen
pump pressure PP of the LS valve and the combined force of force Z of spring (4) and LS pressure
A0
are balanced, and the relationship is
PLS
PP = A1 ×
×
, servo piston (11) will stop
Pen
in that position, and the swash plate will be kept
at an intermediate position. (It will stop at a position where the opening of the throttle from port
to port E and from port C to port D of spool (6) is
approximately the same.)
10-36
• At this point, the relationship between the area
receiving the pressure at both ends of piston (12)
is A0 : A1 = 1:2, so the pressure applied to both
ends of the piston when it is balanced becomes
:
Pen
= 2:1.
PP
• The position where spool (6) is balanced and
stopped is the standard center, and the force of
spring (4) is adjusted so that it is determined when
PP
–
PLS
= 2.6 MPa {27 kg/cm
2
}. However, if
PSIG (the output pressure of 0 2.9 MPa {0
30 kg/cm
D
plied to port G, the balance stop position will
change in proportion to pressure
PP
2
} of the EPC valve of the LS valve) is ap-
PLS
–
= 2.6 1.2 MPa {27 12 kg/cm
PSIG
between
2
}.
PC400/450(LC)-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD HYDRAULIC PUMP
(2) PC Valve
1) When pump controller is normal a. When the load on the actuator is small
and pump pressures PP1 and PP2 are
low
i) Movement of PC-EPC solenoid (1)
• The command current from the pump controller flows to PC-EPC solenoid (1).This
command current acts on the PC-EPC valve
and outputs the signal pressure. When this
signal pressure is received, the force pushing piston (2) is changed.
• On the opposite side to the force pushing this
piston (2) is the spring set pressure of
springs (4) and (6) and pump pressure
(self pressure) and
sure) pushing spool (3). Piston (2) stops at a
position where the combined force pushing
spool (3) is balanced, and the pressure
(pressure of port C) output from the PC valve
changes according to this position.
PC400/450(LC)-7
(other pump pres-
PP2
PP1
• The size of command current X is determined by the nature of the operation (lever
operation), the selection of the working
mode, and the set value and actual value for
the engine speed.
a Other pump pressure
This is the pressure of the pump at the opposite end.
For the F pump, it is the R pump pressure
For the R pump, it is the F pump pressure
10-37
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD HYDRAULIC PUMP
ii) Action of spring
• The spring load of springs (4) and (6) in the
PC valve is determined by the swash plate
position.
• If piston (9) moves to the right, spring (6) is
compressed, and if it moves further to the
right, spring (6) contacts seat (5) and is fixed
in position. In other words, the spring load is
changed by piston (9) extending or compressing springs (4) and (6).
10-38
• If the command circuit input to PC-EPC
valve solenoid (1) changes further, the force
pushing piston (2) changes, and the spring
load of springs (4) and (6) also changes according to the valve of the PC-EPC valve solenoid command current.
PC400/450(LC)-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD HYDRAULIC PUMP
•Port C of the PC valve is connected to port
of the LS valve (see (1) LS valve). Self pressure
ter end of servo piston (9), and other pump
pressure
• When pump pressures
small, spool (3) is on the left. At this point,
port C and D are connected, and the pressure entering the LS valve becomes drain
pressure PT. If port E and port G of the LS
valve are connected (see (1) LS valve), the
pressure entering the large diameter end of
the piston from port J becomes drain pressure PT, and servo piston (9) moves to the
left. In this way, the pump discharge amount
moves in the direction of increase.
• As servo piston (9) moves further, springs
(4) and (6) expand and the spring force becomes weaker. When the spring force becomes weaker, spool (3) moves to the right,
so the connection between port C and port
is cut, and the pump discharge pressure
ports B and C are connected. As a result, the
pressure at port C rises, and the pressure at
the large diameter end of the piston also rises, so the movement of piston (9) to the left
is stopped.
• In other words, the stop position for piston (9)
(= pump discharge amount) is decided at the
point where the force of springs (4) and (6)
and the pushing force from the PC-EPC
valve solenoid and the pushing force created
by the pressures
spool (3) are in balance.
enters port B and the small diame-
PP1
enters port A.
PP2
and
PP1
PP1
and
acting on the
PP2
PP2
are
E
D
PC400/450(LC)-7
10-39
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD HYDRAULIC PUMP
b. When load on actuator is large and pump
discharge pressure is high
• When the load is large and pump discharge
pressures
pushing spool (3) to the right becomes larger
and spool (3) moves to the position in the diagram above. When this happens, as shown
in the diagram above, part of the pressurized
oil from port B flows out through port
where the LS valve is actuated to port D, and
the pressurized oil flowing from port C to the
LS valve becomes approximately half of
main pump pressure PP.
• When port E and port G of the LS valve are
connected (see (1) LS valve), the pressure
from port J enters the large diameter end of
servo piston (9), and servo piston (9) stops.
PP1
and
are high, the force
PP2
10-40
• If pump discharge pressure PP and
creases further and spool (3) moves further
to the right, main pump pressure
to port C and acts to make the discharge
amount the minimum. When piston (9)
moves to the right, springs (4) and (6) are
C
compressed and push back spool (3). When
spool (3) moves to the left, port C and port
are disconnected and port C and port D are
interconnected. As a result, the pressure at
port C (= J) drops, and piston (9) stops moving to the right.
• The position in which piston (9) stops when
this happens is further to the right than the
position when pump pressures
are low.
PC400/450(LC)-7
PP1
PP1
PP2
and
in-
flows
B
PP2
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD HYDRAULIC PUMP
• The relation of average pump pressure
+ PP2)/2
forms a bent line because of the doublespring effect of springs (4) and (6). The relationship between average pump pressure
(PP1 + PP2)/2
is shown in the figure at the right.
Q
• If command voltage X sent to PC-EPC valve
solenoid (1) increases further, the relationship between average pump pressure
+ PP2)/2
proportional to the pushing force of the PCEPC valve solenoid and moves in parallel. In
other words, the pushing force of PC-EPC
solenoid (1) is added to the force pushing to
the left because of the pump pressure applied to the spool (3), so the relationship between the average pump pressure
PP2)/2
ance with the increase in X.
and the position of servo piston (9)
and pump discharge amount
, and pump discharge amount Q is
and Q moves from to in accord-
(PP1
(PP1
(PP1 +
PC400/450(LC)-7
10-41
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD HYDRAULIC PUMP
2) When pump controller is abnormal and emergency pump drive switch is ON
a. When load on main pump is light
• If there is a failure in the pump controller, turn
emergency pump drive switch ON to switch
to the resistor side. In this case, the power
source is taken directly from the battery. But
if the current is used as it is, it is too large, so
use the resistor to control the current flowing
to PC-EPC valve solenoid (1).
• When this is done, the current becomes con-
stant, so the force pushing piston (2) is also
constant.
• If the main pump pressure
low, the combined force of the pump pressure and the force of PC-EPC valve solenoid
(1) is weaker than the spring set force, so
spool (3) is balanced at a position to the left.
PP1
and
PP2
10-42
• At this point, port C is connected to the drain
pressure of port D, and the large diameter
end of the piston of servo piston (9) also becomes the drain pressure PT through the LS
valve. When this happens, the pressure at
the small diameter end of the piston is large,
so servo piston (9) moves in the direction to
make the discharge amount larger.
are
PC400/450(LC)-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD HYDRAULIC PUMP
b. When main pump load is heavy
• In the same way as in the previous item,
when the emergency pump drive switch is
, the command current sent to PC-EPC
ON
valve solenoid (1) becomes constant. For
this reason, the force of piston (2) pushing
spool (3) is constant.
• If main pump pressures
crease, spool (3) moves further to the right
than when the main pump load is light, and is
balanced at the position in the diagram
above (See Fig. P).
• In this case, the pressure from port B flows
to port C, so servo piston (9) moves to the
right (to make the discharge amount smaller)
by the same mechanism as explained in item
2)-b, and stops at a position to the right of the
position when the load on the pump is light
(See Fig. Q). In other words, even when the
emergency pump drive switch is ON, the
curve for the pump pressure PP and discharge amount Q is determined as shown in
PC400/450(LC)-7
PP1
and
PP2
in-
the diagram for the valve of the current sent
to the PC-EPC valve solenoid through the
resistor.
The curve when the emergency pump drive
switch is ON is curve , which is to the left
of curve for when the pump controller is
normal.
10-43
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD LS(PC)-EPC VALVE
LS(PC)-EPC VALVE
1. Body 5. Coil
2. Spool 6. Plunger
3. Spring 7. Connector
10-44
:To LS(PC) valve
PSIG
: To tank
PT
:From self-reducing pressure
PEPC
valve4. Rod
PC400/450(LC)-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD LS(PC)-EPC VALVE
Function
• The EPC valve consists of the proportional solenoid portion and the hydraulic valve portion.
• When it receives signal current i from the pump
controller, it generates the EPC output pressure
in proportion to the size of the signal, and outputs
it to the LS valve.
Operation
1. When signal current is 0 (coil de-energized)
• When there is no signal current flowing from the
controller to coil (5), coil (5) is de-energized.
• For this reason, spool (2) is pushed to the left in
the direction of the arrow by spring (3).
• As a result, port
rized oil from the main pump does not flow to the
LS valve.
At the same time, the pressurized oil from the LS
valve passes from port
and is drained to the tank.
PT
closes and the pressu-
PEPC
PSIG(PM)
through port
PC400/450(LC)-7
10-45
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD LS(PC)-EPC VALVE
2. When signal current is very small (coil energized)
• When a very small signal current flows to coil (5),
coil (5) is energized, and a propulsion force is
generated which pushes plunger (6) to the left.
• Push pin (4) pushes spool (2) to the left, and
pressurized oil flows from port
PSIG(PM)
• When the pressure at port
the load of spring (3) + the force acting on surface a of spool (2) becomes greater than the propulsion force of plunger (6), spool (2) is pushed
to the right. The circuit between port
port
port
• As a result, spool (2) is moved up or down until
the propulsion force of plunger (6) is balanced
with the load of spring (3) + pressure of port
PSIG(PM)
• Therefore, the circuit pressure between the EPC
valve and the LS valve is controlled in proportion
to the size of the signal current.
.
PSIG(PM)
PSIG(PM)
.
PSIG(PM)
is shut off, and at the same time,
and port PT are connected.
PEPC
rises and
PEPC
to port
and
3. When signal current is maximum (coil energized)
• When the signal current flows to coil (5), coil (5)
is energized.
• When this happens, the signal current is at its
maximum, so the propulsion force of plunger (6)
is also at its maximum.
• For this reason, spool (2) is pushed fully to the
left by push pin (4).
• As a result, the maximum flow of pressurized oil
from port
circuit pressure between the EPC valve and LS
valve becomes the maximum.
At the same time, port PT closes and stops the
oil from flowing to the tank.
PEPC
flows to port
PSIG(PM)
, and the
10-46
PC400/450(LC)-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD VARIABLE VOLUME VALVE
VARIABLE VOLUME VALVE
1. Block
2. Plug
3. Spring
4. Piston
:To PC valve
PM
:To tank
PT
:From self-reducing pressure valve
PEPC
PC400/450(LC)-7
10-47
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD VARIABLE VOLUME VALVE
Function
• This stabilizes the EPC output pressure.
Operation
• The output pressure from EPC flows to port PM,
and when the propulsion force of piston (4) becomes larger than the load of spring (3), piston
(4) is pushed to the left and the volume at port
increases.
PM
When the propulsion force of piston (4) becomes
less than the load on spring (3), piston (4) is
pushed to the right and the volume at port
goes down.
PM
10-48
PC400/450(LC)-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD CONTROL VALVE
CONTROL VALVE
Outline
1. 6-spool valve
2. Cover 1
3. Cover 2
4. Pump merge-divider valve
5. Back pressure valve
6. Boom lock valve
7. Boom, arm Hi valve
8. Quick return valve
9. Boom Hi check valve
• This control valve consists of a 7-spool valve (6
spool valve + boom • arm Hi valve). A merge-divider valve, back-pressure valve, boom hydraulic
drift prevention valve, quick return valve, and Hi
valve check valve are installed to it.
• Since all the valves are assembled together with
connecting bolts and their passes are connected
to each other inside the assembly, the assembly
is small in size and easy to maintain.
• Since one spool of this control valve is used for
one work equipment unit, its structure is simple.
A1
A2
A3
A4
A5
A6
A-1
A-2
B1
B3
B4
B5
B6
B-1
P1
P2
P3
P4
P5
P6
P7
P8
P9
P10
: To bucket cylinder bottom
: o left travel motor
: To boom cylinder bottom
: To swing motor
: To right travel motor
: To arm cylinder head
: To boom cylinder bottom
: To attachment
: To bucket cylinder head
: To bottom cylinder head
: To swing motor
: To right travel motor
: To arm cylinder bottom
: To arm cylinder bottom
: From bucket PPC valve
: From bucket PPC valve
: From left travel PPC valve
: From left travel PPC valve
: From boom PPC valve
: From boom PPC valve
: From swing PPC valve
: From swing PPC valve
: From right travel PPC valve
: From right travel PPC valve
P11
P12
BP1
PB5
PLS1
PLS2
PP1
PP2
PPS1
PPS2
PR
PS
PST
PX1
PX2
SA
SB
T
T1
TS
TSW
:From arm PPC valve
:From arm PPC valve
: Boom RAISE PPC output pressure
: From 2-stage safety valve solenoid valve
: To rear pump control
: To front pump control
: To rear pump control
: To front pump control
: From rear main pump
: From front main pump
: To solenoid valve, PPC valve, EPC valve
: From pump merge-divider solenoid valve
: From travel junction valve
: From 2-stage solenoid valve
: From 2-stage solenoid valve
: Pressure sensor fitting port
: Pressure sensor fitting port
: To tank
: To tank
: To tank
: To swing motor
10-50
PC400/450(LC)-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD CONTROL VALVE
7-spool valve
(1/9)
PC400/450(LC)-7
10-51
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD CONTROL VALVE
(2/9)
10-52
PC400/450(LC)-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD CONTROL VALVE
(3/9)
1. Unload valve 9. Pressure compensation valve (Arm IN)
2. Pressure compensation valve (Arm OUT) 10. Pressure compensation valve (Bucket DUMP)
3. Pressure compensation valve (Right travel reverse)
4. Pressure compensation valve (Left swing) 13. Pressure compensation valve (Right swing)
5. Pressure compensation valve (Boom RAISE) 14. Pressure compensation valve (Right travel for-
7. Pressure compensation valve (Bucket CURL) 15. Pressure compensation valve (Arm IN)
8. Pressure compensation valve (Boom RAISE) 16. Main relief valve
PC400/450(LC)-7
11. Pressure compensation valve (Left travel forward)
12. Pressure compensation valve (Boom LOWER)
ward)6. Pressure compensation valve (Left travel reverse)
10-53
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD CONTROL VALVE
(4/9)
1. Spool (Arm) 6. Spool (Bucket)
2. Spool (Right travel) 7. Spool (Boom Hi)
3. Spool (Swing) 8. Spool (Arm Hi)
4. Spool (Boom) 9. Unload valve
5. Spool (Left travel) 10. Main relief valve
No. Check item
Standard size Repair limit
Free length
OD
11 Spool return spring
12 Spool return spring 54.6 × 34.8 51.2
13 Spool return spring 54.5 × 34.8 51.2
14 Spool return spring 54.9 × 24.2 51.2
15 Spool return spring 57.2 × 32.8 51
×
54.2 × 34.8 51.2
Installed
length
Criteria
Installed
load
416.5 N
{42.5 kg}
429.9 N
{42.9 kg}
393 N
{40.1 kg}
251 N
{25.1 kg}
416 N
{42.5 kg}
Free
length
—
—
—
—
—
Installed
load
333.2 N
{34 kg}
336.1 N
{34.3 kg}
314.6 N
{32.1 kg}
201.0 N
{20.5 kg}
333.2 N
{34.0 kg}
Unit: mm
Remedy
If damaged or
deformed,
replace spring
10-54
PC400/450(LC)-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD CONTROL VALVE
(5/9)
1. Safety-suction valve (Arm OUT) 9. Safety-suction valve (2-stage) (Boom LOWER)
2. Suction valve (Right travel reverse) 10. Suction valve (Right travel forward)
3. Suction valve (Boom RAISE) 11. Safety-suction valve (Arm IN)
4. Suction valve (Left travel reverse) 12. LS shuttle valve (Arm, right travel)
5. Safety-suction valve (Boom Hi) 13. LS select valve
6. Safety-suction valve (Arm IN) 14. LS shuttle valve (Boom, left travel, bucket)
7. Safety-suction valve (Bucket DUMP) 15. LS check valve
8. Suction valve (Left travel forward) 16. Pressure relief plug
No. Check item
17 Check valve spring
Standard size Repair limit
Free length
OD
×
11.5 × 4.6 8.5
Installed
length
Criteria
Installed
load
1.5 N
{0.15 kg}
Free
length
—
Installed
load
1.2 N
{0.12 kg}
Remedy
If damaged or
deformed,
replace spring
PC400/450(LC)-7
Unit: mm
10-55
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD CONTROL VALVE
(6/9)
ARM CONTROL VALVE R. H. TRAVEL CONTROL VALVE
1. Unload valve 5. Safety-suction valve 12. Suction valve
2. Main relief valve 6. Spool 13. Spool
3. Safety valve (Boom RAISE) 7. Pressure compensation valve (OUT)
8. LS shuttle valve 15. LS shuttle valve
9. Pressure compensation valve (IN)
10. Safety-suction valve 17. Suction valve
11. Check valve for regeneration circuit
14. Pressure compensation valve (Reverse)4. Lift check valve
16. Pressure compensation valve (Forward)
10-56
PC400/450(LC)-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD CONTROL VALVE
Unit: mm
No. Check item
Standard size Repair limit
Free length
OD
18 Regeneration valve spring
19 Piston return spring 36.9 × 11.1 28
20 Piston return spring 36.9 × 11.1 28
×
31.5 × 10.3 19.5
Installed
length
Criteria
Installed
load
6.2 N
{0.6 kg}
29.4 N
{3 kg}
29.4 N
{3 kg}
Free
length
—
—
—
Installed
load
4.9 N
{0.5 kg}
23.5 N
{2.4 kg}
23.5 N
{2.4 kg}
Remedy
If damaged or
deformed,
replace spring
PC400/450(LC)-7
10-57
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD CONTROL VALVE
(7/9)
SWING CONTROL VALVE
1. Spool
2. Pressure compensation valve (Left)
3. LS select valve
4. Pressure compensation valve (Right)
10-58
ARM CONTROL VALVE
5. Suction valve
6. Spool
7. Pressure compensation valve (RAISE)
8. Hydraulic drift prevention valve
9. LS shuttle valve
10. Pressure compensation valve (Lower)
11. Safety-suction valve
12. Check valve for regeneration circuit
L. H. TRAVEL CONTROL VALVE
13. Pump merge-divider valve (Travel junction valve)
14. Return spring
15. Suction valve
16. Spool
17. Pressure compensation valve (Reverse)
18. LS shuttle valve
19. Pressure compensation valve (Forward)
20. Suction valve
PC400/450(LC)-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD CONTROL VALVE
Unit: mm
No. Check item
Standard size Repair limit
Free length
OD
21 Regeneration valve spring
22 Piston return spring 48.1 × 10.8 28
23 Piston return spring 36.9 × 11.1 28
24 Spool return spring 30.7 × 20.5 23
×
31.5 × 10.3 19.5
Installed
length
Criteria
Installed
load
6.2 N
{0.6 kg}
17.5 N
{1.8 kg}
29.4 N
{3 kg}
50.0 N
{5.1 kg}
Free
length
—
—
—
—
Installed
load
4.9 N
{0.5 kg}
14.0 N
{1.4 kg}
23.5 N
{2.4 kg}
40.0 N
{4.1 kg}
Remedy
If damaged or
deformed,
replace spring
PC400/450(LC)-7
10-59
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD CONTROL VALVE
(8/9)
BUCKET CONTROL VALVE
1. Safety-suction valve
2. Spool
3. Pressure compensation valve (CURL)
4. LS shuttle valve
5. Pressure compensation valve (DUMP)
6. Safety-suction valve
No. Check item
Standard size Repair limit
Free length
OD
14 Piston return spring
15 Piston return spring 36.9 × 11.1 28
×
48.1 × 10.8 28
10-60
BOOM, ARM HI VALVE
7. Boom Hi spool
8. Pressure compensation valve (Boom RAISE)
9. Boom Hi check valve
10. Quick-return valve
11. Pressure compensation valve (Arm IN)
12. Arm Hi spool
13. Safety-suction valve
Criteria
Installed
length
Installed
load
17.5 N
{1.8 kg}
29.4 N
{3 kg}
Free
length
—
—
Installed
load
14.0 N
{1.4 kg}
23.5 N
{2.4 kg}
Unit: mm
Remedy
If damaged or
deformed,
replace spring
PC400/450(LC)-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD CONTROL VALVE
(9/9)
1. Unload valve 9. LS bypass plug
2. Main relief valve 10. Screw
3. Pump merge-divider valve (Main) 11. Poppet
4. Return spring 12. Spring (Pressure reducing valve pilot)
5. Pump merge-divider valve (For LS) 13. Spring (Pressure reducing valve main)
6. Return spring 14. Valve (Pressure reducing valve)
7. Valve (Sequence valve) 15. Spring (Safety valve)
8. Spring (Sequence valve) 16. Ball
10-62
PC400/450(LC)-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD CONTROL VALVE
Unit: mm
No. Check item
Standard size Repair limit
Free length
OD
17 Check valve spring
18 Spool return spring 46.6 × 21.8 3.3
19 Spool return spring 64.5 × 32.3 63
20 Sequence valve spring 70.9 × 18.0 59
×
11.5 × 4.6 8.5
Installed
length
Criteria
Installed
load
1.5 N
{0.15 kg}
156.8 N
{16.0 kg}
177.5 N
{18.1 kg}
199.8 N
{20.4 kg}
Free
length
—
—
—
—
Installed
load
1.2 N
{0.12 kg}
125.5 N
{12.8 kg}
142.0 N
{14.5 kg}
160.0 N
{16.3 kg}
Remedy
If damaged or
deformed,
replace spring
PC400/450(LC)-7
10-63
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD MAIN RELIEF VALVE
MAIN RELIEF VALVE
1. Spring
2. Poppet
Function
• The relief valve set pressure is set to 2 stages.
When power is needed, pilot pressure P is turned
ON and the pressure is set to high pressure.
Operation
• The relief valve set pressure is determined by the
installed load of spring (1). (First stage)
• It is unnecessary to set the first and second
stage individually.
The second stage is set when the first stage is
set.
1. When pilot pressure P is OFF: Low-pressure
setting
The set pressure is determined by the installed
load of spring (1).
2. When pilot pressure P is ON: High-pressure setting
In addition to the installed load of spring (1), pilot
pressure P is applied to poppet diameter d1, so
the set pressure becomes higher.
10-64
PC400/450(LC)-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD CLSS
CLSS
OUTLINE OF CLSS
Features
• CLSS stands for Closed center Load Sensing
System, and has the following features.
1) Fine control not influenced by load
2) Control enabling digging even with fine control
3) Ease of compound operation ensured by flow
divider function using area of opening of spool
during compound operations
4) Energy saving using variable pump control
10-66
Structure
• The CLSS consists of a main pump (2 pumps),
control valve, and actuators for the work equipment.
• The main pump body consists of the pump itself,
the PC valve and LS valve.
PC400/450(LC)-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD CLSS
Basic principle
1) Control of pump swash plate
• The pump swash plate angle (pump discharge
amount) is controlled so that LS differential pressure
sure PP and control valve outlet port LS pressure
PLS) (load pressure of actuator) is constant.
(LS pressure
– LS pressure
PP
(the difference between pump pres-
PLS
= Pump discharge pressure
PLS
)
PLS
• If LS differential pressure
than the set pressure of the LS valve (when the
actuator load pressure is high), the pump swash
plate moves towards the maximum position; if it
becomes higher than the set pressure of the LS
valve (when the actuator load pressure is low),
the pump swash plate moves towards the minimum position.
PC400/450(LC)-7
becomes lower
PLS
10-67
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD CLSS
2) Pressure compensation
• A pressure compensation valve is installed to the
outlet port side of the control valve to balance the
load.
• When two actuators are operated together, this
valve acts to make pressure difference P between the upstream (inlet port) and downstream
(outlet port) of the spool of each valve the same
regardless of the size of the load (pressure).
In this way, the flow of oil from the pump is divided (compensated) in proportion to the area of
opening S1 and S2 of each valve.
10-68
PC400/450(LC)-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD SELF PRESSURE REDUCING VALVE
SELF PRESSURE REDUCING VALVE
Function
• This value reduces the discharge pressure of the
main pump and supplies it as control pressure for
the solenoid valves, PPC valves, etc.
Operation
1. When engine is stopped
• Poppet (11) is pressed by spring (12) against the
seat and port PR is not connected to TS.
• Valve (14) is pressed by spring (13) against the
left side and port P2 is connected to PR.
• Valve (7) is pressed by spring (8) against the left
side and port P2 is not connected to A2.
PC400/450(LC)-7
10-69
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD SELF PRESSURE REDUCING VALVE
2. When in neutral or load pressure P2 is low
(When boom is lowered and arm is in IN position
and they are moving down under own weight)
Note:
When load pressure A2 is lower than selfpressure reducing valve output pressure
PR.
• Valve (7) receives the force of spring (8) and PR
pressure (which is 0 MPa {0 kg/cm
2
} when the
engine is stopped) in the direction to close the
circuit between ports P2 and A2. If the hydraulic
oil flows in port P2, the fdx P2 pressure becomes
equal to the total of the force of spring (8) and the
value of area of ød
PR pressure, then the area
×
of the pass between ports P2 and A2 is so adjusted that the P2 pressure will be kept constant
above the PR pressure.
• If the PR pressure rises above the set level, puppet (11) opens and the hydraulic oil flows from
the PR port through orifice “a” in spool (14) and
open part of poppet (11) to seal drain port TS.
Accordingly, differential pressure is generated
between before and after orifice “a” in spool (14)
and then spool (14) moves to close the pass between port P2 and PR. The P2 pressure is controlled constant (at the set pressure) by the area
of the oil pass at this time and supplied as the PR
pressure.
3. When load pressure P2 is high
• If load pressure A2 rises and the pump discharge
increases because of operation of the work
equipment, the fdx P2 pressure rises higher than
the total of the force of spring (8) and the value of
ød
PR pressure, and then valve (7) moves to
×
the right stroke end.
• As a result, the area of the pass between ports
P2 and A2 increases and the pass resistance
lowers and the loss of the engine power is reduced.
• If the PR pressure rises above the set pressure,
poppet (11) opens and the hydraulic oil flows
from the PR port through orifice “a” in spool (14)
and open part of poppet (11) to seal drain port
TS.
Accordingly, differential pressure is generated
between before and after orifice “a” in spool (14)
and then spool (14) moves to close the pass between port P2 and PR. The P2 pressure is controlled constant (at the set pressure) by the area
of the oil pass at this time and supplied as the PR
pressure.
10-70
PC400/450(LC)-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD SELF PRESSURE REDUCING VALVE
4. When abnormally high pressure is generated
• If the PR pressure on the self-pressure reducing
valve rises high abnormally, ball (16) separates
from the seat against the force of spring (15) and
the hydraulic oil flows from output port PR to TS.
Accordingly, the PR pressure lowers. By this operation, the hydraulic devices (PPC valves, solenoid valves, etc.) are protected from abnormal
pressure.
PC400/450(LC)-7
10-71
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD SWING MOTOR
SWING MOTOR
KMF230ABE-5
: From swing lock solenoid valve
B
: From control valve
S
: To tank
T
: From control valve
MA
: From control valve
MB
10-72
Specifications
Model KMF230ABE-5
Theoretical displacement
Safety valve set
pressure
Rated revolving
speed
Brake release
pressure
229.4 cm³/rev
+0.5
27.9 MPa
+0
+0.5
{285 kg/cm
+0
1,413 rpm
1.9 ± 0.4 MPa {19 ± 4 kg/cm2}
2
}
PC400/450(LC)-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD SWING MOTOR
1. Brake spring 8. Housing 15. Safety valve
2. Drive shaft 9. Piston 16. Check valve
3. Spacer 10. Cylinder block 17. Shuttle valve
4. Case 11. Valve plate
5. Disc 12. Reverse prevention valve
6. Plate 13. Center shaft
7. Brake piston 14. Center spring
10-74
PC400/450(LC)-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD SWING MOTOR
Unit: mm
No. Check item Criteria Remedy
Standard size Repair limit
Free length
18 Check valve spring
19 Shuttle valve spring 24.5 × 11.6 14.5
× OD
66.5 × 25.6 45
Installed
length
Installed
load
6.96 N
{0.71 kg}
7.45 N
{0.76 kg}
Free length
—
—
Installed
load
5.59 N
{0.57 kg}
5.98 N
{0.61 kg}
If damaged or
deformed,
replace spring
PC400/450(LC)-7
10-75
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD SWING MOTOR
RELIEF VALVE
1. Outline
The relief portion consists of check valves (2)
and (3), shuttle valves (4) and (5), and relief
valve (1).
2. Function
When the swing is stopped, the outlet port circuit
of the motor from the control valve is closed, but
the motor continues to rotate under inertia, so
the pressure at the output side of the motor
becomes abnormally high, and this may damage the motor.
To prevent this, the abnormally high pressure oil
is relieved to port S from the outlet port of the
motor (high-pressure side) to prevent any damage.
3. Operation
1) When starting swing
• When the swing control lever is operated to
swing right, the pressure oil from the pump passes through the control valve and is supplied to
port MA. As a result, the pressure at port MA rises, the starting torque is generated in the motor,
and the motor starts to rotate. The oil from the
outlet port of the motor passes from port MA
through the control valve and returns to the tank.
(Fig. 1)
2) When stopping swing
• When the swing control lever is returned to neutral, the supply of pressure oil from the pump to
port MA is stopped. With the oil from the outlet
port of the motor, the return circuit to the tank is
closed by the control valve, so the pressure at
port MB rises. As a result, rotation resistance is
generated in the motor, so the braking effect
starts.
• If the pressure at port MB becomes higher than
the pressure at port MA, it pushes shuttle valve
A (4) and chamber C becomes the same pressure as port MB. The oil pressure rises further
until it reaches the set pressure of relief valve (1).
As a result, a high braking torque acts on the motor and stops the motor. (Fig.2)
• When relief valve (1) is being actuated, the relief
oil and oil from port S passes through check
valve B (3) and is supplied to port MA. This prevents cavitation at port MA.
10-76
PC400/450(LC)-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD SWING MOTOR
Operation of swing lock
1. When swing lock solenoid valve is deactivated
When the swing lock solenoid valve is deactivated, the pressurized oil from the main pump is
shut off and port B is connected to the tank circuit.
As a result, brake piston (7) is pushed down by
brake spring (1), discs (5) and plates (6) are
pushed together, and the brake is applied.
2. When swing lock solenoid valve is excited
When the swing lock solenoid valve is excited,
the valve is switched and the pressure oil from
the main pump enters port B and flows to brake
chamber a.
The pressure oil entering chamber a overcomes
brake spring (1) and pushes brake piston (7) up.
As a result, discs (5) and plates (6) are separated and the brake is released.
PC400/450(LC)-7
10-77
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD SWING MOTOR
REVERSAL PREVENTION VALVE
Outline diagram
1. Valve body
2. Spool (MA side)
3. Spring (MA side)
4. Plug
5. Spool (MB side)
6. Spring (MB side)
7. Plug
Explanation of effect
10-78
PC400/450(LC)-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD SWING MOTOR
Outline
This valve reduces the swing back generation in
the swing body by the inertia of the swing body,
the backlash and rigidity of the machinery system, and the compression of the hydraulic oil
when the swing is stopped. This is effective in
preventing spillage of the load and reducing the
cycle time when stopping the swing (the positioning ability is good and it is possible to move
swiftly to the next job.
Operation
1. When brake pressure is being generated at port MB
• Pressure MB passes through the notch and goes
to chamber d, spool (5) pushes spring (6) according to the difference in area D1 > D2, moves
to the left, and MB is connected to e.
When this happens, pressure MA is below the
set pressure of spring (3), so spool (2) does not
move. For this reason, the pressure oil is closed
by spool (2), and the braking force is ensured.
2. After motor stops
• The motor is reversed by the closing pressure
generated at port MB. (1st reversal)
When this happens, reversal pressure is generated at port MA. Pressure MA goes to chamber
a, so spool (2) pushes spring (3) and moves to
the right, and MA is connected to B. At the same
time, b is connected to f through the drill hole in
spool (5), so the reversal pressure at port MA is
bypassed to port T to prevent the 2nd reversal.
PC400/450(LC)-7
10-79
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD CENTER SWIVEL JOINT
CENTER SWIVEL JOINT
1. Cover
2. Body
4. O-ring
5. Shaft
No. Check item Criteria Remedy
Clearance between rotor and
6
shaft
10-80
: To L.H. travel motor port PB
A1
: From control valve port A2
A2
: To R.H. travel motor port PA
C1
: From control valve port B2
B2
: To R.H. travel motor port PB
D1
: To L.H. and R.H. travel
E
motors port P
Standard Size Standard clearance Repair limit If damaged or
80 — —
: To tank
T2
: From L.H. and R.H. travel
T1
motors port T3. Slipper seal
: From control valve port B5
D2
: To L.H. travel motor port PA
B1
: From control valve port A5
C2
PC400/450(LC)-7
Unit: mm
deformed,
replace spring
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD TRAVEL MOTOR
TRAVEL MOTOR
KMV280ADT
Port T (to tank)
Specifications
Port PA (from control valve)
Port PB (from control valve) Model: KMV200ADT
Port PI (from travel speed solenoid valve) Theoretical delivery
Min 130 cm
Max 200 cm
Brake releasing pressure: 1.0 ± 0.4 MPa
{10 ± 4 kg/cm
Travel speed switching pressure:
+0.4
0.8 MPa {8 kg/cm
–0.1
(Differentical pressure)
10-82
3
/rpm
3
/rpm
2
}
+4
–1
2
}
PC400/450(LC)-7
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD TRAVEL MOTOR
1. Output shaft 8. Regulator piston 15. Safety valve
2. Motor case 9. Plate 16. Rgegulator valve
3. Piston 10. Disc 17. Spring
4. Cylinder 11. Check valve spring 18. Brake spring
5. Valve plate 12. Check valve 19. Brake piston
6. End cover 13. Counterbalance valve 20. Check valve
7. Slow return valve 14. Spool return spring
PC400/450(LC)-7
10-83
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD TRAVEL MOTOR
Unit: mm
No. Check item Criteria Remedy
Standard size Repair limit
Free leng th
21 Spool return spring
22 Check valve spring 62.5 × 20.0 39.0
23 Regulator piston spring 55.0× 9.0 50.0
× OD
62.52 × 32.0
10-84
Installed
length
42.0
Installed
load
426.6N
{43.5 kg}
3.04 N
{0.31 kg}
98.1 N
{10 kg}
Free length
—
—
—
Installed
load
341.3 N
{32.2 kg}
2.45 N
{0.25 kg}
78.5 N
{8 kg}
PC400/450(LC)-7
Replace
spring if damaged or
deformed
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD TRAVEL MOTOR
Operation of moter
1) At low speed (motor swash plate angle at maximumu)
• The solenoid valve is de-energized, so the pilot
pressure oil from the main pump does not flow to
port
P
For this reason, regulator valve (16) is pushed
down by spring (17).
• The main pressure oil from the control valve pushes check valve (20), goes to end cover (6), in regulator valve (16) and acts also on chamber b.
• When this happens, the propulsion force of regulator piston (8) acts in a downward direction.
PC400/450(LC)-7
• As a result, valve plate (5) and cylinder block (4)
move in the maximum swash plate angle direction, the motor capacity becomes maximum, and
the system is set to low speed.
10-85
STRUCTURE, FUNCTION AND MAINTENANCE STANDARD TRAVEL MOTOR
2) At high speed (motor swash plate angle at minimum)
• When the solenoid valve is energized, the pilot
pressure oil from the main pump flows to port P,
and pushes regulator valve (16) up.
• As a result, the oil in chamber b is drained inside
the case, and acts on chamber a via regulator
valve (16).
• Because of this, the propulsion force of the pressure oil at chamber a of regulator piston (8) acts
in a upward direction.
• As a result, valve plate (5) and cylinder block (4)
move in the minimum swash plate angle direction, the motor capacity becomes minimum, and
the system is set to hign travel speed.
10-86
PC400/450(LC)-7
Loading...