1243
Model Code Page
90. Hydraulic system
1. 11. 1998
6000--8750 911 3
1. 8. 1998
IMPORTANT! On the HiTech tractors, there are fitted V almet
HPR test points to measure theDPS clutchpressures (see pic-
ture on page 440/ 25). Under code 370 (AC V) there are
shown calibrations of the DPS clutches.
NOTE! Under code 370 there are also shown calibrations and
resettings of HiTech Shuttle clutches F--- an d R.Concerning
pressure test points, see page 440/25.
HiTech shuttle
Mechanical shuttle
2. High pressure circuit
A. Measuring free circulation pressure
(0 --- 40 ba r )
The free circulation pressure can be measured by connecting
a pressure gauge to the pressure---test point at the pressure
filter bracket. When measuring this pressure, the steering
wheel must not be turned. The auxiliary hydraulic valve levers
should be in the neutral positions. In addition, the power lift
position control potentiometer must not be in the lowest posi-
tion.
Pressure values at engine revs of 1500 r/min:
--- ~1,5MPa(+50˚...+65˚C)
--- ~1,7MPa(+30˚...+32˚C)
--- ~2,0MPa(+20˚...+25˚C)
Note! Possible extra hydraulic equipment raise the free circu-
lation pressure value. For instance, on tractor that has three
valve blocks and a front loader,the pressure value is about 2,1
MPa (+50...+65˚ C).
Note! Pressure measuring equipment above are included in
the test kit 31965000.
B. Working pressure
1. Connect a pressur e gauge (pressure measuring equip-
ment, se page 910/5) to the pressure---test point at the pres-
sure filter.
2. Adjust engine revs to 1500 r/min. Warm the hydraulic oil to
50---65˚C.
3. Move an auxiliary hydraulic valve lever to the pressure posi-
tion and read off the gauge reading which should be
19,0 ---19,8 MPa.
Pressure---limiting valve
Shims
Note! The pressure is maintained by the pressure limiting
valve on the underside of the front plate of the auxiliary
hydraulic valve set.
4. If the pressure reading deviates much from the correct
value, change pressure limiting valve spring or adjust it with
shims. Shims thickness of 0,2 mm raises the pressure value
about 0,4 MPa.
Note! Possible deviation can also be caused by a dirty or
faulty safety valve (23 MPa)in the hydraulic pump or the pump
can be rundown.
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