Testing And Adjusting Hst Oil Pressure - Komatsu WA250-6 Shop Manual

120 Testing and adjusting, Part 2

Testing and adjusting HST oil pressure

Testing and adjusting HST oil
pressure
Necessary tools
Symbol Part No.
799-101-5002
L
790-261-1204
k
Loosen the oil filler cap slowly to release
the pressure inside the hydraulic tank.
a HST oil temperature when measuring: Within
operating range
a The high-pressure relief pressure is the same
as the safety pressure of the main circuit, so it
cannot be measured. (Normally, the cut-off
valve is actuated first, so it does not rise to the
safety valve set pressure)
Testing
Testing high-pressure cut-off oil pressure
[Testing with monitoring function]
1. Referring to "Special functions of machine
monitor (EMMS)", select the real-time monitor-
ing function in the service mode.
2. Display "HST PRESS" among the monitoring
items of the machine monitor.
a Monitoring item
Code No. 32600: HST PRESS (HST oil
pressure)
[Testing with tools]
1. Open the engine hood side cover.
2. Install oil pressure gauge L (60 MPa {600 kg/
cm }) to pressure measurement nipple (1).
2
Nipple (1): For FORWARD circuit
q
(port: MA)
Nipple (2): For REVERSE circuit
q
(port: MB)
a Install the oil pressure gauge L to nip-
ple (1) of the forward circuit.
WA250, 250PZ-6
Part Name
Analog type hydraulic tester
Digital type hydraulic tester
1
3. Measure the high-pressure cut-off oil pressure
under the following conditions.
1) Lower the bucket to near the ground, then
drive the machine forward and thrust the
bucket into the stockpile of soil or rock
(portion a).
a Set the directional lever to FOR-
WARD and the speed selector switch
to 2nd and traction control switch to
ON.
2) Run the engine at full throttle and press
the bucket into part "a" until the machine
does not move forward.
k
Carry out the measurement on
hard ground where it is difficult for
the tires to slip.
3) Keep the engine running at full throttle,
check that the tires are not turning, then
measure the oil pressure.
4) After finishing the work, remove the mea-
s u r i n g i n s t r u m e n t s a n d r e t u r n t h e
removed parts.
SEN03837-01
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