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IMPORTANT: Test ports on the transaxle are painted
closed. Opening the ports will loosen the paint.
Make sure dirt or paint particles do not fall into the
open port.
Charge Pressure Test
NOTE: See Sauer–Sundstrand IHT Service Manual for
more information.
Use a 500 or 1,000 PSI (35 or 70 Bar) test gauge.
Specification: 80 to 130 PSI (5.5 to 9 Bar)
1. Make sure hydraulic oil is at normal operating temper-
ature by operating the machine for approximately 10
minutes.
2. Lower cutting unit, engage parking brake and stop the
engine.
3. Remove the plug from the charge pressure port and
install a 500 or 1,000 PSI (35 or 70 Bar) pressure gauge
with extension hose.
4. Start the engine and move the throttle control all the
way forward. Take pressure reading with machine sta-
tionary. Also take a pressure reading while operating the
machine in forward and reverse. To test in forward and
reverse, engage the brakes and push the traction pedal
forward, then reverse.
NOTE: When you move the traction pedal to create
pressure, move it a short distance first and wait for a
change in sound before moving the pedal further. The
change in sound indicates that the easy ride valves have
closed.
If pressure is good under no load, but drops below speci-
fication when under traction load, the piston pump and
motor should be suspected of wear and inefficiency.
When the pump and/or motor is worn or damaged the
charge pump is not able to supply enough oil to keep up
with internal leakage in the closed loop circuit.
Charge Pressure Priority Valve Test
While checking charge pressure, check the the opera-
tion of the charge priority valve. Rotate the steering
wheel to create back–pressure while observing the
gauge. The gauge should not have a significant pres-
sure increase during steering operation.
1
Figure 11
1. Charge pressure port
Hydraulic System
Page 5 – 12
Groundsmaster 3000/3000–D