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Hydraulic oil that is hot, and under pressures that can be higher than 4000 psi (275 bar) can remain in the hydraulic systems on this machine after the engine and pump have been stopped. Serious injury or death can be caused if this pressure is not released before any service is done on the hydraulic systems. To prevent possible injury, refer to section, RELEASING PRESSURE IN THE HYDRAULIC SYSTEM, before any fitting, hose or component is loosened, tightened, removed or adjusted. When possible, the bucket must always be lowered to the ground before service is started. When it is necessary for the boom to be raised while tests or adjustments are done, be sure that boom and stick have correct support and the bucket is in the full open position. Always move the machine to a location away from the travel of other machines. Be sure that other personnel are not near the machine when the engine is running and tests or adjustments are being made. |
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NOTE: The engine rpm information given is to be used as a guide only, the actual rpm may vary between machines.
In an analysis of machine performance, comparison of engine rpms under different conditions of loading is of very little value. There are conditions, however, when a change in engine rpm can be an indication of the cause of a problem.
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Serious injury or death by electrocution can result if the machine or attachments are not kept a safe distance from electrical power lines. Keep the distance at least 3.05 m (10 feet) plus an additional 10 mm (.4 in.) for each 1,000 volts over 50,000 volts. For safety, local or state codes or jobsite operating directives, may require a greater distance. Never swing a load over a truck cab or workers. |
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Release of Pressure In The Pilot System
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To prevent personal injury, release the pressure in the implement hydraulic circuits (boom, stick and bucket) before any hydraulic lines or components are disconnected or removed. Be careful of hot oil. Follow this procedure: |
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1. Fully retract the rod in the stick cylinder.
2. Adjust the position of the bucket so that it will be flat on the ground when the boom is lowered.
3. Lower the boom until the bucket is flat on the ground.
4. Shut off the engine and put the lever for the lock valve in the locked position.
5. Move the control levers for boom, bucket, stick and swing to all positions. This will relieve any pressure that might be present in the pilot system.
6. Slowly loosen the filler cap on the hydraulic tank and release the pressure.
7. Tighten the filler cap back on the hydraulic tank.
8. The pressure in the system should now have been released and lines and components can be removed.
NOTE: There are no bleed valves in the circuits. Normally, any pressure that might be trapped in these lines, will bleed off through the motors or through tank.
Instructions For Testing And Adjusting
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Make reference to WARNING on first page of the TESTING AND ADJUSTING Section. |
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NOTE: Make these tests when the hydraulic oil is at normal temperature of operation. (1 Bar is equal to 100 kPa; 6.9 kPa is equal to 1 psi; 1 Bar is equal to 14.5 psi).
LEFT VALVE BANK COMPONENTS (Typical Example)
1. Supply line for retracting bucket. 2. Series (crossover) connection. 3. Series (crossover) connection. 4. Control valve for forward-left and reverse-left travel. 5. Control valve for stick cylinder extension and optional hydraulic function. 6. Return line. 7. Control valve for bucket cylinder. 8. Main relief valve for left valve bank. 9. Control valve for boom cylinders. 10. Pressure tap for left valve bank. 11. Line relief valve for stick cylinder. 12. Line relief valve for bucket cylinder. 13. Line relief valve for boom cylinders. 14. Line relief valve for forward-left and reverse-left travel.
Main Relief Valve On Left Valve Bank
Connect a pressure gauge to gauge connection (quick disconnect) (10) of left valve bank. Run engine at normal operating speed. Retract bucket cylinder up to the limit stop. Then the pressure should be 300 bar (30 000 kPa). Adjust the pressure by turning the adjustment screw (8) on the main relief valve on the left valve bank.
Line Relief Valve On Left Valve Bank
(a) Connect a pressure gauge to gauge connection (quick disconnect) (10) of left valve bank. Run engine at a 1200 rpm speed. Retract stick cylinder all the way against its stop.
NOTE: In order to check the line relief pressure, the main relief valve will have to be set higher than the line relief setting each time. Be sure to reset the main relief back to its correct setting each time.
1. Check line relief valve (12) for bucket cylinder extension = 325 bar (32 500 kPa)
Extend the bucket cylinder fully against its stop.
(b) Turn the adjustment screw on main relief valve (8) of left valve bank until the pressure gauge indicator stops rising. The indicator should now show the specified pressure. The pressure is corrected by means of shims located between the cap and spring of the line relief valve (12). Now reset the main relief valve (8) at 300 bar (30 000 kPa).
2. Check the line relief valve (12) for bucket cylinder retraction = 325 bar (32 500 kPa)
Carry out instruction (a), retract the bucket cylinder with shutoff valve closed (from operator's compartment) and carry out instruction (b).
NOTE: In order to check the line relief pressure, the main relief valve will have to be set higher than the line relief setting each time. Be sure to reset the main relief back to its correct setting each time.
3. Check line relief valve (13) for boom cylinder extension = 350 bar (35 000 kPa).
Carry out instruction (a), extend the boom cylinders against their stop and carry out instruction (b).
4. Check line relief valve (13) for boom cylinder retraction = 350 bar (35 000 kPa).
Carry out instruction (a), retract boom cylinder against the stop and carry out instruction (b).
Line Relief Valve On Right Hand Valve Bank
5. Check the line relief valve (14) for forward-left travel = 325 bar (32 500 kPa).
Do instruction (a). Secure the machine with the brakes, shift the direction control to run hydraulic motor in reverse-left against the stop. Run the machine with brakes engaged and carry out instruction (b). If necessary, pressure can be corrected by means of shims between the cap and the spring of the line relief valve (14).
6. Check the line relief valve (14) for forward-left travel = 325 bar (32 500 kPa). Do the same test as in Step 5, only use forward-left instead of reverse-left.
7. Check the line relief valve (11) (series connection) for stick cylinder extension = 350 bar (35 00 kPa).
NOTE: Do this test as described in Step 9 with no optional hydraulic function or instructions (c) and (d).
8. Line relief valve = 325 bar (32 500 kPa).
NOTE: If the machine is not equipped with optional hydraulic function, the line relief valve does not need to be checked. If the machine is equipped with optional hydraulic function, check whether the actuator is equipped with its own line relief valve, which could have a lower pressure setting, or whether line relief is adjusted to meet the needs of actuator. The adjustment procedure can be different according to the application.
RIGHT VALVE BANK COMPONENTS (Typical Example)
1. Shutoff valve for stick circuit. 2. Oil supply line for right valve bank. 3. Main relief valve for right valve bank. 4. Control valve for swing motor. 5. Control valve for stick cylinder. 6. Control valve for forward-right and reverse-right travel. 7. Bucket and boom crossover valve. 8. Return line from right valve bank. 9. Pressure tap for right valve bank. 10. Line relief valve for stick cylinder. 11. Line relief valve for forward-right and reverse-right travel.
Main Relief Valve On Right Valve Bank
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Make reference to WARNING on first page of the TESTING AND ADJUSTING Section. Connect a pressure gauge to pressure tap (9) of the right valve bank. Run the engine at operating speed. Retract the stick cylinder against the stop. the indication should be 300 bar (30 000 kPa). Adjust the pressure by turning the adjustment screw on the main relief valve (3) of the right valve bank. |
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Line Relief Valve On Right Valve Bank
(c) Connect a pressure gauge to pressure tap (9) on the right valve bank. Run the engine at 1200 rpm. Retract bucket cylinder against its stop.
NOTE: In order to check the line relief pressure, the main relief valve will have to be set higher than the line relief setting each time. Be sure to reset the main relief valve back to its correct setting each time. 9. Check line relief valve (10) for stick cylinder extension and retraction = 350 bar (35 000 kPa). Extend and retract the stick cylinder against its stop.
NOTE: If the pressure reading differs from the indicated value, both the line relief on the right valve bank and the line relief on the left valve bank require checking, since both of them are actuated by the series (crossover) connection. The machine is equipped with a shutoff valve (1) in the series connection line for optional hydraulic function. When doing this test, the shutoff valve (1) must be turned so that it is clear the line relief on the right valve bank is being checked.
(d) Turn the adjustment screw on the main relief valve (3) of the right valve bank until the pressure indication stops increasing. the pressure gauge should now be showing the specified pressure. If not, the pressure is corrected by shims between the cap and the spring of the line relief valve (10). Now reset the main relief valve at 300 bar (30 000 kPa).
10. Check the line relief valve (11) for forward-right travel = 325 bar (32 500 kPa).
Do instruction (c). Secure the machine with the brakes, shift the direction control to run hydraulic motor in forward-right against the stop. Run the machine with brakes engaged and carry out instruction (d).
Check the line relief valve (11) also for reverse-right travel = 325 bar (32 500 kPa). Do the same test as above, only use reverse-right instead of forward-right.
Relief Valve On Swing Gear Hydraulic Motor
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Make reference to WARNING on first page of the TESTING AND ADJUSTING Section. |
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11. Check the line relief valve for swing gear hydraulic motor, clockwise and counterclockwise swing = 200 bar (20 000 kPa).
Lock the upper carriage to the undercarriage with the swing lock pin. Be sure it is in its correct locked position.
Rotate in a clockwise and a counterclockwise direction and run the swing motor against the stops. The pressure gauge should now indicate the specified pressure. Pressure can be corrected by means of an adjustment screw.
NOTE: The line relief valves for clockwise and counterclockwise swing operate like main relief valves. When checking pressure, run the engine at maximum speed against the stop with no jerky motion and the upper carriage locked with the swing pin. In this case, instruction (c) does not apply, except with respect to the pressure gauge connection.
