Inspection of locations of hydraulic drift of work equipment TESTING AND ADJUSTING
3. Inspection of PPC valve
Measure the amount of hydraulic drift of the work equipment when the accumulator is charged with pressure and the safety lock lever is put to the LOCK and FREE positions.
• Operate the control lever with the engine starting switch in the ON position.
• If pressure in the accumulator has dropped, run the engine for approx. 10 seconds to charge the accumulator again.
• If there is any difference in the hydraulic drift between LOCK and FREE positions, the PPC valve is defective (some internal fail- ure).
TESTING AND ADJUSTING Release of remaining pressure in hydraulic circuit
Release of remaining pressure in hydraulic circuit
1. Release of residual pressure from hydraulic tank.
The hydraulic tank is enclosed and pressurised.
When removing a hose or a plug connected to the hydraulic tank, release the residual pressure from the hydraulic tank according to the follow- ing procedure.
a. Lower the work equipment to the ground in a stable posture and stop the engine.
b. Slowly loosen oil filler cap of the hydraulic tank to release the air from the tank.
2. Release of residual pressure from hydraulic cylinder circuit.
When disconnecting the piping between a hy- draulic cylinder and the control valve, release the residual pressure from the piping according to the following procedure.
a. Referring to previous step "Release of resid- ual pressure from hydraulic tank"
• Leave the oil filler cap of he hydraulic tank removed.
b. Turn the starting switch to the ON position and set the safety lock lever in the FREE po- sition, and then operate the work equipment control levers on both sides forward back- ward, to the right and to the left.
• The control valve is driven with the pres- sure in the accumulator. If it is operated 2-3 times, the pressure lowers.
c. Start the engine and run it at low idling for 5 seconds to heighten the pressure in the ac- cumulator. Stop the engine.
d. Repeat above steps b and c 2-3 times, and all residual pressure is released from the pip- ing.
3. Release residual pressure from swing motor circuit.
• Release the residual pressure from the swing motor circuit by performing the proce- dure for 2. Release of residual pressure from hydraulic cylinder.
4. Release of residual pressure from travel mo- tor circuit
• Since the control valve spool of the travel motor is open, release the residual pressure from the travel motor circuit by performing the procedure for 1. release of residual pres- sure from hydraulic tank.
Measurement of oil leakage TESTING AND ADJUSTING
Measurement of oil leakage
• Measuring device for oil leakage
• Measure the oil leakage under the following con- dition.
• Hydraulic oil temperature: Within operating range.
1. Measuring leakage from boom cylinder a. Run the engine and raise the boom to the
stroke end.
Referring to RELEASE OF RESIDUAL PRESSURE FROM HYDRAULIC CIRCUIT, release the residual pressure from the piping on the boom cylinder head side (Operate the lever only in the RAISE di- rection, however).
b. Disconnect hoses (1) on the cylinder head side block it with a plug.
Take care not to disconnect the hose on the cyl- inder bottom side.
c. Run the engine at high idling and relieve the boom cylinder by operating the boom control lever in the RAISE direction.
Take care not to operate the boom control lever in the lower direction.
d. Start measuring the oil leakage 30 seconds after the boom cylinder is relieved and meas- ure for 1 minute.
e. After finishing the measurement, make sure that the machine is back to normal condition.
2. Measuring leakage from arm cylinder
a. Run the engine and move the arm to the dig- ging stroke end.
Referring to RELEASE OF RESIDUAL PRESSURE FROM HYDRAULIC CIRCUIT, release the residual pressure from the piping on the arm cylinder head side (Operate the lever only in the digging direction however).
b. Disconnect hose (2) on the cylinder head end and block the hose end with a plug.
Be careful not to disconnect the hose at the cyl- inder bottom end.
c. Run the engine at high idling and relieve the arm cylinder by operating the arm control le- ver in the DIGGING direction.
Take care not to operate the arm control lever in
Symbol Part Number Part Name
R Purchased Measuring Cylinder
1
TESTING AND ADJUSTING Measurement of oil leakage
d. Continue this condition for 30 seconds, then measure the oil leakage amount for one minute.
e. After the measurement, make sure that the machine is back to normal condition.
3. Measuring leakage from bucket cylinder a. Run the engine and curl the bucket to the
stroke end.
Referring to RELEASE OF RESIDUAL PRESSURE FROM HYDRAULIC CIRCUIT, release the residual pressure from the piping on the bucket cylinder head side (Operate the lever only in the CURL di- rection).
b. Disconnect hose (3) at the cylinder head end block the hose end with a plate.
Be careful not to disconnect the hose at the cyl- inder bottom end.
c. Run the engine at high idling and relieve the bucket cylinder by operating the bucket con- trol lever in the CURL direction.
Take care not to operate the bucket control lever in the DUMP direction.
d. Continue this condition for 30 seconds, then measure the oil leakage amount for one minute.
e. After the measurement, make sure that the machine is back to normal condition.
4. Measuring leakage from swing motor
a. Disconnect drain hose (4) and fit a blind plug in the hose.
b. Turn the swing lock switch to the ON posi- tion.
c. Run the engine at high idle and relieve the swing circuit and measure the oil leakage.
• Start measuring the oil leakage 30 sec- onds after the swing motor circuit is re- lieved and measure for 1 minute.
• After the first measurement, turn the up- per structure by 180 degrees and take measurement again in the same way.
2
3
4
Measurement of oil leakage TESTING AND ADJUSTING
d. After finishing the measurement, make sure that the machine is back to normal condition.
5. Measuring leakage from travel motor
a. With the safety lock lever in the ENGAGED position the PPC switch in the OFF position, the engine running at high idle and the serv- ice brake locked in the ON position. Raise the hydraulic oil temperature to be in the range 40~50°C.
b. Disconnect flushing hose (1) of the travel motor and fit a blind plug in the hose end.
c. Using the travel pedal, put the travel circuit into relief.
d. Port A or B are set under pressure above the setting of relief valves (i.e. 380 bar)
• Since any incorrect operation of the con- trols may lead to a serious accident. On- ly do this test in a secure area marked with adequate warning signs.
• Start measuring the oil leakage 30 sec- onds after the travel motor circuit is re- lieved and measure for 1 minute.
• Measure the oil leakage several times, moving the motor little by little (changing the positions of the valve plate, cylinder, those of the cylinder and piston).
e. After the measurement, make sure that the machine is back to normal conditon.
Leakage - 4 ~ 6 litres / min Normal Leakage > 10 litres / min Abnormal
Repair or replace travel if motor is found to have an abnormal level of oil leakage.
TESTING AND ADJUSTING Air bleeding of various parts
Air bleeding of various parts
NOTE
Bleed air from the swing motor and travel motor only when oil in the casing is drained.
1. Bleeding air from hydraulic pump
a. Loosen air bleeder (1) by 4 turns and remove the oil filler cap of the hydraulic tank.
• Leave the machine under the above condition for 10 minutes.
b. After oil flows out of bleeder (1) run the en- gine at low idle.
• If the engine water temperature is low and the automatic warm up operation is started, stop the engine temporarily and reset the automatic warm up operation with fuel control dial (Set the starting switch in the ON position and hold the fuel control dial in MAX position for 3 seconds and the automatic warm up op- eration is reset.)
• Set the safety lock lever in the DISEN- GAGED position so that you will not op- erate a lever by mistake.
c. After clear oil flows out of bleeder (1) tighten the bleeder.
Bleeder: 7.8–9.8 Nm {0.8–1.0 kgm}
Air bleeding item
Contents of Work
Steps for air bleeding
1 2 3 4 5 6
Bleeding air from hydrau-
lic pump
Starting engine
Bleeding air from cylinder
Bleeding air from swing motor
Bleeding air from
travel motor
Checking oil level and
starting work Replacement of hydraulic oil
Cleaning of strainer (See note) (See note)
Replacement of return filter element Replacement or repair of hydraulic pump Removing suction piping
Replacement or repair of control valve Removal of control valve piping Replacement or repair of cylinder Removal of cylinder piping
Replacement or repair of swing motor Removal of swing motor piping Replacement or repair of travel motor Removing travel motor piping Replacement or repair of swivel joint Removal of swivel joint
1
Air bleeding of various parts TESTING AND ADJUSTING
2. Starting engine
When running the engine after the engine after per- forming step 1, keep its speed at low idle for 10 min- utes.
3. Bleeding air from cylinder
• If a cylinder was replaced, bleed air from it before connecting the work equipment. In particular, the boom cylinder does not move to the lowering stroke end, if it is installed to the work equipment.
a. Run the engine at low idle for about 5 min- utes.
b. Running the engine at low idle, raise and lower the boom 4-5 times.
• Stop the piston rod about 100mm before each stroke end. Do not relieve the oil.
c. Running the engine at high idle, perform step 2.
d. Running the engine at low idle, move the pis- ton rod to the stroke end and relieve the oil.
e. Bleed air from the arm cylinder and bucket cylinder according to steps 2-d.
4. Bleeding air from swing motor a. Motor unit
• Bleed air from the motor unit according to the following procedure.