Shibaura ST330, Workshop Manual

Page: 114 / 250

104
6. INSPECTION AND ADJUSTMENT
1 ） High pressure relief valve inspection
①
Jack up the front and rear wheels off of the ground
and jack stands under the axles.
Make sure all four wheels are clear of the ground.
② Set the auxiliary speed change lever at H position
(after starting the engine).
③
Remove the plug (PT 1/8) on the clutch case.
NOTE
：
Either one of the 2 plugs may be removed but the HST
pedal depressing direction at the time of measurement
varies depending on the plug.
When pressure gauge is set on the tractor left side HST
pedal depressed front-wards.
When pressure gauge is set on the tractor right side,
HST pedal depressed rearwards.
④ Install a pressure gauge 0 ～ 50 MPa (0 － 500 kg/c
㎡
) to test port.
⑤
Securely lock the parking brake
⑥ Disengage the clutch and start the engine. Set
throttle speed to 2800 rpm.
⑦ Be sure the HST foot pedal is in neutral position
and then release the clutch.
⑧
Slowly move the foot pedal in the forward position
to obtain a reading on the pressure gauge. Read the
maximum pressure on the gauge. Pressure reading
should be 27.5MPa{280 kgf/c
㎡
}.
NOTE: Read pressure in minimum time to prevent
overheating and possible damage to the HST.
NOTE: If low hydrostatic power is a concern, test HST
pressure when oil is cold. Then test pressure
at operating temperature. If pressure is within
specification when cold and low when at
operating temperature, suspect internal wear
of pump or motor rotating group or valve
plates.
NOTE：
Measure the relief pressure within 2 － 3 seconds.
The relief valve is non adjustable type, then replace the
relief valve as an ass’y, if necessary.
⑨ Continued to low pressure relief valve test as
follows.
392Y
393Y
394Y
Relief set pressure
27.5 MPa
｛
280 kg/c
㎡｝