Yuchai YC310LC-8, Operation Manual

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4. Discharging the air in the hydraulic system
A. Discharging the air in the pump
1) Release the air exhaust plug installed at the drain vent, and check if the oil flow out, completing the
exhaust.
2) Tighten the bolt after the exhaust completion.
Note: If run the pump when it is not full of oil, the pump will become abnormally hot, leading to
the premature failure of it.
B. Discharging the air between the hydraulic pimp and the tank
1) Start the engine and keep it running at low or middle speed.
2) Operate the working device slowly to discharge the air.
Note: If you keep the engine running rapidly before exhausting the air between the pump and
tank, the pump will also have an abnormally high temperature, thereby damaging the pump.
C. Discharging the air in the cylinder
1) When the engine is running at low speed, extend and retract the cylinder to the position about
100mm from the end of its trip four or five times.( remember not to the end of its trip)
2) Then, operate the cylinder to the end of its trip three or four times.
3) At last, operate the cylinder to the end of its trip four or five times, completing the air discharge,
Note: If you let the engine running at high speed or operate it to the end of its trip the time the
motor is just started, the air in the cylinder will cause damage to the piston seal, thereby
damaging the cylinder.
D. Discharging the air in the rotating motor (when the oil in the rotating motor has been
discharged)
Note: During the discharge, the machine cannot be rotated in any case.
1) Idle the engine and release the exhaust plug, to check if the oil flows out from the exhaust plug.
2) If there is no oil flowing out, open the exhaust plug, then inject the hydraulic fluid into the motor
housing.
3) After completing the exhaust, tighten the exhaust plug.
4) Finally, run the engine at low idle and slowly rotate the upper body of the machine to left and to
right, twice respectively, to make the exhaust complete and full.
Note: If the air within the motor is not discharged, the bearings of the rotating motor may be
damaged.
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