Method For Releasing Internal Pressure In Hydraulic Circuit - Komatsu PC1250-7 Operation & Maintenance Manual

MAINTENANCE PROCEDURE

METHOD FOR RELEASING INTERNAL PRESSURE IN HYDRAULIC CIRCUIT

RELEASING PRESSURE FROM WORK EQUIPMENT CIRCUIT, SWING CIRCUIT, TRAVEL CIRCUIT
The hydraulic system is always under internal pressure, so when inspecting or replacing the piping or hoses, always release
the pressure in the circuit before starting. If the pressure is not released, high pressure oil may spurt out and cause serious
personal injury.
The parts and oil are at high temperature after the engine is stopped, and may cause serious burns. Wait for the temperature
to go down before starting the operation.
When the oil filler cap is removed, oil may spurt out, so turn the cap slowly to release the pressure before removing the cap.
1. Stop the machine on firm horizontal ground, lower the work
equipment to the ground as shown in the diagram on the right,
then stop the engine.
Set the lock lever at the FREE position.
2. Operate each work equipment control lever to the full stroke
within 5 - 6 seconds after stopping the engine.
Leave the starting switch at the ON position.
3. Remove the cap of the hydraulic tank.
4. Start the engine, run for approx. 10 seconds, then stop the
engine again.
Do not run the engine at more than 1000 rpm.
Set the work equipment control levers to the HOLD position.
5. Operate each work equipment control lever to the full stroke
within 5 - 6 seconds after stopping the engine.
Repeat Steps 4 - 5 three times.
RELEASING PRESSURE IN ACCUMULATOR CIRCUIT
After stopping the engine, set lock lever (1) to the FREE position,
then operate each work equipment control lever 3 - 4 times to the
end of the stroke. After 1 minute, the internal pressure will be
relieved.
Do not loosen any piping until at least 1 minute has passed after
relieving the internal pressure.
4 - 40
WARNING
MAINTENANCE