Releasing Remaining Pressure In Hydraulic Circuit; Testing Oil Leakage Amount - Komatsu ecot3 PC300LC-8 Shop Manual

SEN02625-06
Releasing remaining pressure in
hydraulic circuit
k
When disconnecting the piping routed from
the hydraulic cylinder and the hydraulic mo-
tor to the control valve, release the residual
pressure in the circuit according to the fol-
lowing procedure.
a The swing motor circuit and travel motor circuit
are free from residual pressure. However, since
these circuits are affected by the pressure inside
the hydraulic tank, the operation up to opening of
the hydraulic tank cap must be implemented.
1. Stop the engine and then gradually loosen the oil
filler cap of the hydraulic tank to release the
pressure in the tank.
2. Turn the engine starting switch to the ON posi-
tion and operate the control levers several times.
a Power must be conducted to PPC lock valve,
thus the starting switch must be set to ON po-
sition prior to the lever operation.
a When the levers are operated 2 - 3 times, the
pressure stored in the accumulator is re-
moved.
3. Start the engine, run at low idle for approx. 10
seconds to accumulate pressure in the accumu-
lator, then stop the engine.
4. Repeat the steps in Item 2 to 3 above several
times.
56

Testing oil leakage amount

1. Measurement of oil leakage amount from
boom cylinder
1) Start the engine and keep it running until the
hydraulic oil temperature rises to the oper-
ating range. Then extend the boom cylinder
to the stroke end.
k
Release the pressure remaining in the
piping referring to "Releasing remain-
ing pressure in hydraulic circuit".
2) Disconnect hose (1) on the cylinder head end
and block the hose end with a plate.
k
Be careful not to disconnect the hose
at the cylinder bottom end.
3) Run the engine at high idle and relieve the
boom circuit by raising the boom.
4) Continue this condition for 30 seconds, then
measure the oil leakage amount for 1 minute.
5) Remove the measurement tools after the
measurement, and make sure that the
machine is back to normal condition.
2. Measurement of oil leakage amount from arm
cylinder
1) Start the engine and keep it running until the
hydraulic oil temperature rises to the oper-
ating range. Then extend the arm cylinder to
the IN stroke end.
k
Release the pressure remaining in the
piping referring to "Releasing remain-
ing pressure in hydraulic circuit".
2) Disconnect hose (2) on the cylinder head end
and block the hose end with a plate.
k
Be careful not to disconnect the hose
at the cylinder bottom end.
3) Run the engine at high idle and relieve the
arm circuit by moving the arm IN.
30 Testing and adjusting
PC300, 350-8