1213
Model Code Page
90. Hydraulc system
15. 5. 1993
6000--8750 910 9
15. 6. 1992
Hydraulic system, ---660070
(see figure 2 on previous page)
1. Oil reservoir
2. Suction strainer (125
m)
2a. Pressure---limiting valve 0,2 MP a (lubricating pressure)
3. Twin gear pump
4. Safety valve 23 MPa (high pressure pump).
5. Pressure test point (Valmet HPR)
6. Pressure filter (degree o f separation:
β10=75).
--- by---pass valve 0,35 MPa.
7. Priority valve
8. Non---return valve
9. Steering valve (125 cm
3
/r).
--- steering system pressure---limiting valve 14 MPa
10. Steering cylinder
13. End plate (oil inlet)
--- pressure---limiting valve 19 MP a (high pressure circuit)
19. Control valve for hydraulic lift (Bosch)
--- s h oc k v al v e 20 MPa
20. Lifting cylinders
21. Breather filter for l ifti ng cylinders and transmission hous-
ing (degree of separation:
β10=75).
23. Servo valve block (safety valve 0,4 MPa + pressure---limit-
ing valve 1,8 MP a)
36. Return oil connection for auxiliary hydraulics
37. Oil cooler
Low pressure circuit
(Numbers in text below refer to figure 2).
Low pressure pump supplies oil for:
--- q u i ck --- sh i f t g ea r e n g a g e m e nt
--- 4WD engagement
--- PTO engagement
--- diff. lock engagement
--- transmission lubrication
--- trailer brake valve (optional)
--- oil cooler
The low pressure circuit delivery pipe conducts oil from the
low pressure pump (3) (rearmost) to the servo valve block (23)
on the gearbox LH side. On the servo valve block there are
fitted solenoid valves for 4WD, PTO and diff. lock. The quick---
shift gear solenoid valve is fitted on the quick---shift gear hous-
ing. Clutch pressure to the quick---shift gear is conducted
from the servo valve block via an external pipe.
On the servo valve block there is a pressure---limiting valve
(1,8 MPa) which limits clutch pressures. A pressure test point
for the low pressure circuit is fitted on the servo valve block.
On the servo valve block there are outlet and inlet connections
for the oil cooler. The servovalve block has a safety valve (0,45
MPa) which protects the oil cooler.
Return oil from the oil cooler is conducted to the transmission
lubricating system. Also free---circulation oil from the hy-
draulic lift control valve flows to the lubricating system. A pres-
sure---limiting valve (2a, 0,2 MPa) in the suction strainer hous-
ing rear end limits the lubricating pressure to 0,2 MPa.
From the servo valve block has been drawn a hose to the
priority valve (7). This pressure from the low pressure circuit
to the priority valve reduces the high pressure pump free---cir-
culation pressure
Note! An optional brake valve for trailer brakes also uses oil
from the low pressure circuit.
Note! See also transmission, servo and lubricating system in
section 42 on pages 420/17---420/22.
High pressure circuit
(Numbers in text below refer to figure 2).
High pressure pump supplies oil for:
--- steering system (priority)
--- hydraulic power lift
--- auxiliary hydraulics
In the high pressure pump there is fitted a safety valve (23
MPa), which protects the pump in cold weather when the hy-
draulic oil is thick.
High pressure pump (3) (foremost) delivery pipe conducts oil
from the pump to the pressure filter (6) ,and then to the priority
valve (7).
Note! Priority valve and steering system, see section 61.
From the priority valve oil flows to the auxiliary hydraulic valve
set end plate (inlet side). The high pressure circuit pressure---
limiting valve (19 MPa) is fitted on the underside of the end
plate.
Then oil flows through the auxiliary hydraulic valves to the hy-
draulic lift control valve (19) and then to the lifting cylinders.
The control valve free---circulating oil flows to the lubricating
system for transmission and oil pressure over 0,2 MPa flows
direct to the hydraulic pump suction side.
The hydrauliclift control valve (19)has an in---built shockvalve
(20 MPa), which protects the system against pressure shocks
from the lifting cylinders.
On the pressure filter bracket there is a pressure test point (5)
for measuring working hydraulic pressure and also the steer-
ing system pressure (see steering system in sectio n 61).
Pump
The pump drive shaft front end is engaged to the engine fly-
wheel by means of the drive flange. The drive shaft goes
through the gearbox input shaft to the rear end where it is
fitted to the pump drive mechanism.
The twin gear pump is placed in the gearbox housing and is
attached to the rear side of the wall between the gearbox and
differential housings.
The twin pump capacity per revolution and the drive mechan-
ism gear ratio:
--- 23,5+6,4 cm
3
/r, i =1,32 (---658899).
--- 2 5 + 8 c m
3
/r, i=1,32 (658900---)
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