SECTION 2 STRUCTURE AND FUNCTIONSECTION 2 STRUCTURE AND FUNCTION
Group 1 Pump Device
2-1
Group 2 Main Control Valve
2-20
Group 3 Swing Device
2-47
Group 4 Travel Motor
2-58
Group 5 RCV Lever
2-65
Group 6 Accelerator Pedal
2-72
Group 7 Brake Pedal
2-73
Group 8 Transmission
2-75
Group 9 Travel Control Valve
2-82
Group 10 Steering Valve
2-84
2-1
1. STRUCTURE1. STRUCTURE
The pump device consists of main pump, regulator and gear pump.
SECTION 2 STRUCTURE AND FUNCTIONSECTION 2 STRUCTURE AND FUNCTION
GROUP 1 PUMP DEVICEGROUP 1 PUMP DEVICE
Pi1
a4
Dr3
B3
A3
A1 A2
Pi1
Pi2
B1
Qmax adjusting screw
EPPR valve
Front regulator
Rear regulator
Front pump Valve block
Rear pump
Gear pump
Qmin adjusting screw
Qmin adjusting screw
P1
Dr2
a3
Pi2
Hydraulic circuit
Dr1
A
VIEW A
A2
A1
a1
a2
B1
a1
a2
A1
A2
Pi2
Pi1
B3
a3
A3
P1
FRONT REAR
Dr2
B1
Dr1
a4
Dr3
Dr2
KR38-9N37
KR38-9N35
17W92MP01
Port Port name Port size
A1,2 Delivery port SAE6000psi 3/4"
B1 Suction port SAE2500psi 2 1/2"
Dr1 Drain port PF 3/4 - 20
Dr2 Drain port PF 1/2 - 19
Dr3 Drain port PF 3/8 - 15
Pi1, i2 Pilot port PF 1/4 - 15
P1 EPPR valve primary port PF 1/4 - 15
a1,2,3 Gauge port PF 1/4 - 15
a4 Gauge port PF 1/4 - 14
A3 Gear pump delivery port PF 1/2 - 19
B3 Gear pump suction port PF 3/4 - 20.5
2-2
MAIN PUMP (1/2)
The main pump consists of two piston pumps(front & rear) and valve block.
1)1)
111 Drive shaft (F)
113 Drive shaft (R)
116 Gear
123 Roller bearing
124 Needle bearing
127 Bearing spacer
141 Cylinder block
151 Piston
152 Shoe
153 Push-plate
156 Bushing
157 Cylinder spring
211 Shoe plate
212 Swash plate
214 Bushing
251 Support
261 Seal cover (F)
262 Seal cover (R)
271 Pump casing
312 Valve block
313 Valve plate (R)
314 Valve plate (L)
401 Hexagon socket bolt
406 Hexagon socket bolt
466 VP Plug
467 VP Plug
468 VP Plug
490 Plug
531 Tilting pin
532 Servo piston
534 Stopper (L)
535 Stopper (S)
548 Pin
702 O-ring
710 O-ring
711 O-ring
717 O-ring
719 O-ring
724 O-ring
725 O-ring
727 O-ring
728 O-ring
732 O-ring
774 Oil seal
789 Back up ring
792 Back up ring
808 Hexagon head nut
824 Snap ring
885 Pin
886 Spring pin
901 Eye bolt
953 Set screw
954 Set screw
981 Plate
983 Pin
710
406113152151124719312711901
954
724
534
792702214
548
531
532732789535
808
953
886
717
406
774
111
261
127
123
710
824
251
490
212 211 153 156 157 467
728
468
727
466
725
313 116 885 314 141 981
983
271 401
406
262
808
14W72SF02
2-3
MAIN PUMP (2/2)MAIN PUMP (2/2)
04 Gear pump
115 Shaft
117 Gear No. 2
118 Gear No. 3
125 Ball bearing
126 Roller bearing
128 Bearing spacer
262 Cover
284 Plate
326 Gear case
414 Screw
435 Hexagon socket bolt
468 Plug
710 O-ring
711 O-ring
728 O-ring
825 Retainer ring
826 Retainer ring
885 Spring pin
886 Pin
04
826
115
128
262
885
126
326
414
125
711
284 710 825
435
468 728
118
117
FRONT SIDE REAR SIDE
886
14W92MP03
2-4
REGULATOR (1/2)REGULATOR (1/2)
2)2)
412
876
874
A
B
755
858
614
615
613
611
A
B
VIEW C (FRONT)
897
612
641
730
643
708
644
645
646
SECTION B-B
728
924
801
438
P2
KR38-9N37 (FRONT)
KR38-9N35 (REAR)
A
B
413
438
496
724
725
436
D
D
VIEW C (REAR)
413
438
656
438
722
496
724
725
436
079
735
722
466
755496753
SECTION D-D(REAR)
P1
a
875
P1
a
405
699
Pi
735
Pi
Pi
C
753
Pi
14W92MP04
Port Port name Port size
A Delivery port 3/4"
B Suction port 2 1/2"
Pi Pilot port PF 1/4-15
P1
EPPR valve primary port
PF 1/4-15
P2 Companion delivery port Internal
a
Gauge port
PF 1/4-15
2-5
REGULATOR (2/2)REGULATOR (2/2)
079 EPPR valve assembly
405 Hexagon socket screw
412 Hexagon socket screw
413 Hexagon socket screw
436 Hexagon socket screw
438 Hexagon socket screw
466 Plug
496 Plug
601 Casing
611 Feed back lever
612 Lever (1)
613 Lever (2)
614 Fulcrum plug
615 Adjust plug
621 Compensator piston
622 Piston case
623 Compensator rod
624 Spring seat (C)
625 Outer spring
626 Inner spring
627 Adjust stem (C)
628 Adjust screw (C)
629 Cover (C)
630 Lock nut
631 Sleeve, Pf
641 Pilot cover
643 Pilot piston
644 Spring seat (Q)
645 Adjust stem (Q)
646 Pilot spring
651 Sleeve
652 Spool
653 Spring seat
654 Return spring
655 Set spring
656 Block cover
699 Valve casing
708 O-ring
722 O-ring
724 O-ring
725 O-ring
728 O-ring
730 O-ring
732 O-ring
733 O-ring
734 O-ring
735 O-ring
753 O-ring
754 O-ring
755 O-ring
756 O-ring
763 O-ring
801 Nut
802 Nut
814 Snap ring
836 Snap ring
858 Snap ring
874 Pin
875 Pin
876 Pin
887 Pin
897 Pin
898 Pin
924 Set screw
734
653
654
836
651
652
601
624
629
630
655
641
814
898
631
732
628
756
763
887
626
625
733
622
621
623
754
802
627
SECTION A-A
14W92MP05
2-6
GEAR PUMPGEAR PUMP
3)3)
307 Poppet
308 Seat
309 Spring seat
310 Spring
311 Screw
312 Nut
351 Gear case
353 Drive gear
354 Driven gear
355 Filter
361 Front case
433 Flange socket
434 Flange socket
435 Flange socket
466 Plug
700 Ring
709 O-ring
725 O-ring
732 O-ring
850 Snap ring
887 Pin
434 466,725
435
700 353 351
354
709 361
433
434
311
312
732
310
307 309308
355
850
Dr3 Dr3
a3
B3
887
A3
14W7A2MP06
2-7
Rotary groupRotary group
The rotary group consists of drive shaft
(F) (111), cylinder block (141), piston
shoes (151,152), set plate (153),
spherical bushing (156) and cylinder
spring (157).
The drive shaft is supported by bearing
(123,124) at its both ends.
The shoe is caulked to the piston to from
a spherical coupling. It has a pocket to
relieve thrust force generated by loading
pressure and the take hydraulic balance
so that it slides lightly over the shoe plate
(211). The sub group composed by a
piston and a shoe is pressed against the
shoe plate by the action of the cylinder
spring via a retainer and a spherical
bush.
Similarly, the cylinder block is pressed
against valve plate (313) by the action of
the cylinder spring.
Swash plate groupSwash plate group
The swash plate group consists of swash
plate (212), shoe plate (211), swash plate
support (251), tilting bushing (214), tilting
pin (531) and servo piston (532).
The swash plate is a cylindrical part
formed on the opposite side of the sliding
surface of the shoe and is supported by
the swash support.
If the servo piston moves to the right or
left as hydraulic force controlled by the
regulator is admitted to hydraulic
chamber located on both sides of the
servo piston, the swash plate slides over
the swash plate support via the spherical
part of the tilting pin to change the tilting
angle (α)
2. FUNCTION2. FUNCTION
MAIN PUMPMAIN PUMP
The pumps may classified roughly into the rotary group performing a rotary motion and working as
the major part of the whole pump function: the swash plate group that varies the delivery rates: and
the valve cover group that changes over oil suction and discharge.
1)1)
(1) (1)
(2)(2)
151
152
157
111
123
153
156
141
313
124
211
531
211
548
214
212
532
251
α
α
21092MP06
2507A2MP14
2-8
Valve block groupValve block group
The valve block group consists of valve
block (312), valve plate (313) and valve
plate pin (885).
The valve plate having two melon-
shaped ports is fixed to the valve block
and feeds and collects oil to and from the
cylinder block.
The oil changed over by the valve plate is
connected to an external pipeline by way
of the valve block.
Now, if the drive shaft is driven by a
prime mover (electric motor, engine, etc),
it rotates the cylinder block via a spline
linkage at the same time. If the swash
plate is tilted as in Fig (previous page)
the pistons arranged in the cylinder block
make a reciprocating motion with respect
to the cylinder block, while they revolve
with the cylinder block.
If you pay attention to a single piston, it
performs a motion away from the valve
plate (oil sucking process) within 180
degrees, and makes a motion towards
the valve plate (or oil discharging
process) in the rest of 180 degrees.
When the swash plate has a tilting angle
of zero, the piston makes no stroke and
discharges no oil.
(3)(3)
885
313
312
21092MP07
2-9
Negative flow controlNegative flow control
By changing the pilot pressure Pi, the
pump tilting angle (delivery flow) is
regulated arbitrarily, as shown in the
figure.
This regulator is of the negative flow
control in which the delivery flow Q
decreases as the pilot pressure Pi rises.
With this mechanism, when the pilot
pressure corresponding to the flow
required for the work is commanded, the
pump discharges the required flow only,
and so it does not consume the power
uselessly.
REGULATORREGULATOR
Regulator consists of the negative flow control, total horse power control and power shift control
function.
2)2)
(1) (1)
Pilot pressure, P
i
Delivery flow, Q
2-10
Flow reducing functionFlow reducing function
①
As the pilot pressure Pi rises, the pilot piston (643) moves to the right to a position where the
force of the pilot spring (646) balances with the hydraulic force.
The groove (A) in the pilot piston is fitted with the pin (875) that is fixed to lever 2 (613).
Therefore, when the pilot piston moves, lever 2 rotates around the fulcrum of point B [fixed by
the fulcrum plug (614) and pin (875)]. Since the large hole section (C) of lever 2 contains a
protruding pin (897) fixed to the feedback lever (611), the pin (897) moves to the right as lever 2
rotates. Since the opposing-flat section (D) of the feedback lever is fitted with the pin (548) fixed
by the tilting pin (531) that swings the swash plate, the feedback lever rotates around the fulcrum
of point D, as the pin (897) moves.
Since the feedback lever is connected with the spool (652) via the pin (874), the spool moves to
the right.
The movement of the spool causes the delivery pressure P1 to connect to port CL through the
spool and to be admitted to the large diameter section of the servo piston. The delivery pressure
P1 that is constantly admitted to the small diameter section of the servo piston moves the servo
piston to the right due to the area difference, resulting in decrease of the tilting angle.
When the servo piston moves to the right, point D also moves to the right. The spool is fitted
with the return spring (654) and is tensioned to the left at all times, and so the pin (897) is
pressed against the large hole section (C) of lever 2.
Therefore, as point D moves, the feedback lever rotates around the fulcrum of point C, and the
spool is shifted to the left. This causes the opening between the sleeve (651) and spool (652) to
close slowly, and the servo piston comes to a complete stop when it closes completely.
D
Large diameter
chamber
Servo piston
Small diameter
chamber
A
C
P1 CL
643 654 651 652
611
875
548
531
646613
B(E)
897
Pi(From MCV)
874
14W92MP12
2-11
Flow increasing functionFlow increasing function
②
As the pilot pressure Pi decreases, the pilot piston (643) moves to the left by the action of the
pilot spring (646) and causes lever 2 (613) to rotate around the fulcrum of point B. Since the pin
(897) is pressed against the large hole section (C) of lever 2 by the action of the return spring
(654) via the spool (652), pin (874), and feedback lever (611), the feedback lever rotates around
the fulcrum of point D as lever 2 rotates, and shifts the spool to the left. Port CL opens a way to
the tank port as the spool moves. This deprives the large diameter section of the servo piston of
pressure, and shifts the servo piston to the left by the discharge pressure P1 in the small
diameter section, resulting in an increase in the flow rate.
As the servo piston moves, point D also moves to the left, the feedback lever rotates around the
fulcrum of point C, and the spool moves to the right till the opening between the spool and sleeve
is closed.
D
Large diameter
chamber
Servo piston
Small diameter
chamber
A
C
P1
CL
643 654 651 652
611
875
548
531
646613
B(E)
897
Pi(From MCV)
874
14W92MP13
2-12
Adjustment of flow control characteristicAdjustment of flow control characteristic
The flow control characteristic can be
adjusted with the adjusting screw.
Adjust it by loosening the hexagon nut
(801) and by tightening (or loosening)
the hexagonal socket head screw (924).
Tightening the screw shifts the control
chart to the right as shown in the figure.
Adjusting valueAdjusting value
③
※
Pilot pressure, P
i
Delivery flow, Q
801
924
2-12 (140-7)
Speed
Adjustment of flow control
characteristic
Tightening
amount of
adjusting
screw (924)
Flow control
starting
pressure
change
amount
Flow change
amount
(min
-1
) (Turn)
(kgf/cm
2
)
(ℓ/min)
2100 +1/4 +1.53 +10
2-13
Total horsepower controlTotal horsepower control
The regulator decreases the pump tilting
angle (delivery flow) automatically to limit
the input torque within a certain value with
a rise in the delivery pressure P1 of the
self pump and the delivery pressure P2 of
the companion pump.
(The input horsepower is constant when
the speed is constant.)
Since the regulator is of the simultaneous
total horsepower type that operates by the
sum of load pressures of the two pumps
in the tandem double-pump system, the
prime mover is automatically prevented
from being overloaded, irrespective of the
load condition of the two pumps, when
horsepower control is under way.
Since this regulator is of the simultaneous
total horsepower type, it controls the tilting
angles (displacement volumes) of the two
pumps to the same value as represented
by the following equation :
Tin = P1×q/2Л + P2×q/2Л
= (P1+P2)×q/2Л
The horsepower control function is the
same as the flow control function and is
summarized in the following. (For detailed
behaviors of respective parts, refer to the
section of flow control).
(2)(2)
Delivery pressure, (P
1
+P
2
)
Delivery flow, Q
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