Usage:
Specifications
NOTE: For Specifications with illustrations, make reference to the Specifications for 953C Track-Type Loader Hydraulics, SENR8408. If the Specifications given in SENR8408 are not the same as given in the Systems Operation and Testing and Adjusting, look at the printing date on the cover of each book. Use the Specifications given in the book with the latest date.
Implement Hydraulic System
 |
Sudden movement of the machine or release of oil under pressure can cause injury to persons on or near the machine. To prevent possible injury, do the procedure that follows before testing and adjusting the hydraulic system. |
 |
1. Move the machine to a smooth horizontal location. Move away from working machines and personnel and lower implements to the ground.
2. Permit only one operator on the machine. Keep all other personnel either away from the machine or in view of the operator.
3. Engage the parking brake.
4. Stop the engine.
5. Move the hydraulic control levers to all positions to release the pressure in the hydraulic system.
6 Carefully loosen the filler cap on the hydraulic tank to release the pressure in the tank.
7. Make sure all hydraulic pressure is released before any fitting, hose or components is loosened, tightened, removed or adjusted.
8. Tighten the filler cap on the hydraulic tank.
9. The pressure in the system has now been released and lines or components can be removed.
Procedure
When defining a hydraulic system problem, the following procedure should be followed.
First, do Visual Checks. If the problem has not be identified when Visual Checks are completed, do Operational Checks.
If the problem is still not fully understood, do Instrument Tests. Follow these procedures to help identify hydraulic system problems.
As soon as the problem is defined, proceed to Troubleshooting. The Troubleshooting Section lists the probable causes of a known problem. Since there may be more than one cause for a problem, the Troubleshooting Section may suggest specific inspections or instrument tests be done. These inspections and tests help identify which of the causes is most probable.
During a diagnosis of the hydraulic system, remember that correct oil flow, temperature, and pressure are necessary for correct operation. The output of the pump (oil flow) increases with an increase in engine speed and decreases when engine speed is decreased. Oil pressure is caused by resistance to the flow of oil.
Use the 1U-5481 Pressure Gauge Group, 1U5482 Pressure Adapter Group, 4C-4890 JIC Fitting Group, a stop watch, a magnet, a thermometer and a mm (in) ruler for basic tests to measure:
- 1. DRIFT RATES in the implement circuits: Circuit drift is caused by leakage past cylinder pistons, control valve spools, load check valves, or makeup valves. Excessive drift can be caused by problem with any one or combination of components.
- 2. CYCLE TIMES in the implement circuits: Cycle times that are longer than shown in the charts are the result of leakage, pump wear and/or pump speed. If the basic Operation Checks indicate excessive circuit leakage, then pressure tests are needed to determine which components have a problem.
Visual Checks
A visual inspection of the hydraulic system and its components is the first step when identifying a problem. Stop the engine and lower the implements to the ground. To remove the tank filler cap, slowly turn the filler cap until it is loose. If oil comes out, let the tank pressure lower before the filler cap is removed. Make the following inspections.
|
Personal injury or death can result from improperly checking for a leak. Always use a board or cardboard when checking for a leak. Escaping fluid under pressure, even a pin hole size leak, can penetrate body tissue, causing serious injury, and possible death. If fluid is injected into you skin, it must be treated immediately by doctor familiar with the type of injury. |
|
1. Check all implement oil line connections for damage and leaks.
2. Follow all implement oil lines from the implement connections to the valve connections. Check the lines and connections for damage and leaks.
3. Check the control valves for leaks.
4. Check the pump and connections for damage and leaks.
5. Follow the pump lines to the tank and valves. Check the lines and tank for damage and leaks.
6. Check tank oil level.
NOTE: A vacuum breaker relief valve is installed in the tank. It is set to operate at approximately 172 kPa (25 psi) pressure and 0 to 3.5 kPa (0 to .5 psi) less than atmospheric pressure.
7. Use a clear bottle or container to get an oil sample from the tank immediately after the machine is stopped. Check for air bubbles in the oil sample.
8. Remove the filter element and check for particles removed from the oil by the filter elements. A magnet separates ferrous particles from nonferrous particles (piston rings, O-rings, seals, etc.).
9. Inspect control linkage for bent, broken, or damaged components.
Operational Checks
The Operational Checks can be used to find leakage in the system. They can also be used to find a bad valve or pump. The speed of rod movement when the cylinders move, can be used to check the condition of the cylinders and the pump.
The oil in the hydraulic system must be SAE 10 and at a temperature of 65 ± 3°C (150 ± 5°F).
The lift and tilt circuits are connected in a series circuit that interrupted (not completely continuous). The hydraulic pump and the main relief valve are common to all circuits. Each circuit has a load check valve to help prevent cylinder drift when the valve spool is first moved.
Relief valves help give protection to system components from too much pressure. The main relief valve is also a makeup valve. Makeup valves let extra oil flow to the cylinders when needed.
Extend and retract each implement cylinder several times.
1. Watch the implement cylinders as they extended and retracted. Movement must be smooth and regular.
2. Listen for noise from the pump.
3. Listen for the sound of the relief valves. When the bucket is empty, the relief valves must no open except when the implement cylinders are fully extended or retracted.
The pressure setting of the relief valve can lower the performance of the machine. A high pressure setting causes a reduction in the life of hoses and other parts of the system.
4. Allow the implement cylinders to travel full stroke in each direction.
5. Put each control valve in HOLD while implement is off the ground. Watch for excessive cylinder rod drift.
Implement cylinder drift is caused by leakage past cylinder piston seals, control valve seals, check or makeup valves, and/or much spool to valve body clearance.
Measure lift cylinder rod drift using the following procedure:
1. Check hydraulic oil temperature.
2. Lift the bucket to maximum height. With the lift control lever in HOLD position, stop the engine.
3. Measure the distance (and check the time) that the cylinders retract with the chart.
NOTE: The drift distances in the chart are for new machines.
Too much lift cylinder rod drift is caused by:
1. Loose oil line connections and condition of the oil hoses between the control valve and the rod ends of the lift cylinders.
2. Leakage around the piston seals in the lift cylinders.
3. Leakage in the control valve (worn valve section and spool valve and/or makeup valve not on its seat).
4. Lift cylinder head end relief valve needs adjustment, dirty or worn.
Tilt Cylinder Rod Drift Test
Measure tilt cylinder rod drift using the following procedure:
1. Check hydraulic oil temperature.
2. Lift the bucket to maximum height and move the lift control lever to the HOLD position
3. Measure the distance (and check the time) that the tilt cylinder retracts with the chart.
NOTE: The drift distances in the chart are for new machines.
Too much tilt cylinder rod drift is caused by:
1. Loose oil line connections and condition of the oil hoses between the control valve and the rod end of the tilt cylinders.
2. Leakage around the piston seals in the tilt cylinders.
3. Leakage in the control valve (worn valve section and spool valve).
4. Tilt cylinder head end relief valve needs adjustment, dirty or worn.
Ripper Cylinder Rod Drift Test
Measure ripper cylinder rod drift using the following procedure:
1. Check hydraulic oil temperature.
2. Lift the ripper to maximum height, and move the ripper control lever to the HOLD position. With the ripper control valve in HOLD, stop the engine
3. Measure the distance (and check the time) that the cylinder extends with the chart.
NOTE: The drift distances in the chart are for new machines.
Too much ripper cylinder and rod drift is caused by:
1. Loose oil line connections or damaged oil lines with oil leaks.
2. Leakage around the piston seals in the cylinder.
Too much ripper cylinder and rod drift is caused by:
1. Loose oil line connections or damaged oil lines with oil leaks.
2. Leakage around the piston seals in the cylinder.
3. Leakage in the control valve (worn valve section and spool valve and/or makeup not on its seat).
4. Ripper cylinder rod end relief valve needs adjustment, dirty or worn.
Multi-Purpose Bucket Cylinder Rod Drift Test
Measure multi-purpose cylinder rod drift using the following procedure:
1. Check hydraulic oil temperature.
2. Activate the tilt circuit until the bucket is at FULL TILT BACK position.
3. Move the tilt control lever to the HOLD position.
4. Move the third control lever to the OPEN position until the bucket is open approximately 609 mm (24 in) between the bulldozer assembly and the bowl assembly. Stop the engine.
5. Measure the distance (and check the time) that the cylinder extends with the chart.
NOTE: The drift distances in the chart are for new machines.
Too much multi-purpose bucket cylinder and rod drift is caused by:
1. Loose oil line connections or damaged oil lines with oil leaks.
2. Leakage around the piston seals in the cylinder.
3. Leakage in the control valve (worn valve section and spool valve and/or makeup valve not on its seat).
4. Multi-purpose bucket cylinder rod end relief valve needs adjustment, dirty or worn.
Cylinder Speed Tests
The oil in the system must be SAE 10 and at a temperature of 65 ± 3°C (150 ± 5°F) to get correct results. All speed tests are made with the engine speed at HIGH IDLE.
System speeds that are the same as those given in the chart is an indications that the circuit operation is normal.
If only one of the cylinder speeds is slow, check that circuit for cylinder drift.
Use a stop watch or timer to measure the time for the lift arms to raise and the time for the bucket to tilt in each direction.
Pump Efficiency Test
A pump efficiency test is designed to tell if a pump is operating within design parameters. An efficiency test should be run only if all cylinder cycle times are too slow.
For any pump test, the pump flow measured in liter/min (U.S. gpm) at 690 kPa (100 psi) is larger than the pump flow at 6900 kPa (1000 psi) at the same speed.
The difference between the pump flow of two operating pressures is the flow loss.
Method of finding flow loss:
Flow loss when expressed as a percent of pump flow is used as a measure of pump performance.
Example of finding percent of flow loss:
If the percent of flow loss is more than 10 percent, pump performance is not good enough.
*Numbers in examples are for illustration and are not values for any specific pump or pump condition. Refer to Specifications for 953C Track-Type Loader Hydraulics, SENR8408, for pump flow of a new pump at 690 kPa (100 psi) and 6900 kPa (1000 psi).
Test on Machine
Install a Flow Meter. Run the engine at HIGH IDLE. Measure the pump flow at 690 kPa (100 psi) and at 6900 kPa (1000 psi). Use these values in Formula I.
Formula I:
Test on Bench
If the test bench can be run at 6900 kPa (1000 psi) and at full pump speed, find the percent of flow loss using Formula I.
If the test bench can not be run at 6900 kPa (1000 psi) at full pump speed, run the pump shaft at 1000 rpm. Measure the pump flow at 690 kPa (100 psi) and at 6900 kPa (1000 psi). Use these values in the top part of Formula II. For the bottom part of the formula, run the pump shaft at 2000 rpm. Measure the pump flow at 690 kPa (100) psi.
Formula II:
Instrument Tests
|
Make reference to the WARNING on the first page of Testing and Adjusting Section. |
|
Instrument testing on the hydraulic system and its components is the final step when diagnosing a problem. Test results should verify the status of a component. Adjusting procedures are provided where needed.
If the basic test give an indication of circuit leakage, install a flow meter and do an instrument test to find the source of the leakage.
Location of Pressure Taps
Relief Valve for Tilt Cylinder Head End
|
Make reference to the WARNING on the first page of Testing and Adjusting Section. |
|
Tools Needed:4C-4890 JIC Fitting Group
Relief Valve
Head End Tilt Relief Valve
1. At tilt cylinder (8), disconnect hose (9) from elbow (10) and install a swivel tee and connector in the line.
2. Connect a 50 000 kPa (7500 psi) pressure gauge and hose to the connector. Make sure that all connections are tight.
3. Start the engine and raise the lift arms to maximum height.
4. Tilt the bucket back completely.
5. Lower the lift arms to the ground and record the highest pressure reading on the gauge. The correct pressure setting for the head end tilt cylinder relief valve is 32 600 ± 700 kPa (4728 ± 100 psi) at a flow of 38 ± 2 liter/min (10 ± .5 U.S. gpm).
6. If the pressure setting is not correct, lower the bucket to the ground and stop the engine. Make a separation of the hydraulic tank. Loosen nut (4) and turn adjustment screw (7) clockwise to increase or counterclockwise to decrease the pressure.
7. When the pressure setting is correct, tighten nut (4) and remove the test equipment.
Relief Valve for Tilt Cylinder Rod End
NOTE: The relief valve has a dual pressure setting and can only be tested on a test bench. Use a 1U-9357 Valve Test manifold to test the valve.
The correct low pressure setting for the tilt cylinder rod end relief valve is 26 000 ± 700 kPa (3770 ± 100 psi) (10 ± 1 U.S. gpm).
The correct high pressure setting for the tilt cylinder rod end relief valve is 34 500 ± 700 kPa (5000 ± 100 psi) at a flow of 2.0 ± 0.5 liter/min (.53 ± .13 U.S. gpm).
Relief Valve for Lift Cylinder Head End
NOTE: The relief valve can only be tested on a test bench. Use a 136-1903 Valve Test Manifold to test the valve.
The correct pressure setting for the head end tilt cylinder relief valve is 32 600 ± 700 kPa (4728 ± 100 psi) at a flow of 38 ± 2 liter/min (10 ± .5 U.S. gpm).
Relief Valves for Attachment (Third) Cylinders
NOTE: These relief valves can only be tested on a test bench. Use a 136-1903 Valve Test Manifold to test the valves.
The correct pressure setting for the rod and head end relief valves is 32 600 ± 700 kPa (4728 ± 100 psi) at a flow of 38 ± 2 liter/min (10 ± .5 U.S. gpm).
Main Relief Valve (Dual Pressure)
Main Relief Valve (Dual Pressure) With Solenoid
Pressure Taps
NOTE: Always adjust the HIGH setting before adjusting the LOW setting.
1. Connect 50 000 (7500 psi) pressure gauge at implement pump pressure port (F).
2. With engine at HIGH IDLE, raise the bucket to it's highest height.
3. Hold the lift control lever in RAISE position and look at the reading of the relief valve on the pressure gauge.
4. With the tilt control lever in neutral (HOLD) position, the main relief valve should be at HIGH setting.
5. With the tilt control lever in TILT BACK position, the main relief valve should be at LOW setting.
6. The correct HIGH pressure setting of the main relief valve is 24 000 ± 350 kPa (3485 ± 50 psi) at a flow of 124 ± 6 liter/min (33 ± 1.6 U.S. Gpm).
7. The correct LOW pressure setting of the main relief valve is 21 400 ± 350 kPa (3100 ± 50 psi) 124 ± 6 liter/min (33 ± 1.6 U.S. Gpm).
8. If an adjustment is needed, the HIGH setting should always be adjusted first. After adjusting the HIGH setting the LOW setting can be adjusted.
9. HIGH setting is controlled by large adjusting screw (B). One quarter turn of screw (B) changes pressure 1512 kPa (220 psi).
10. LOW setting is controlled by smaller adjusting screw (C). One quarter turn of screw (C) changes pressure 755 kPa (110 psi).
Both screws turn clockwise to increase the setting and counterclockwise to decrease the setting.
Hydraulic Implement Tank Fill and Air Removal Procedure
NOTE: Do the following procedure any time the hydraulic system has been completely drained. The procedure is necessary to remove air from the hydraulic system. Damage to the hydraulic pump can be the result if the procedure is not done.
1. Fill the hydraulic tank to the top of the fill screen with oil as recommended in Operation and Maintenance Manual SEBU6935.
2. use a 4C-4890 JIC Fitting Group to connect an air regulator and valve to the test fitting on the hydraulic tank. Connect a hose and needle valve from the kit to the test fitting on the hydraulic pump outlet line.
| NOTICE |
|---|
Do not use more that 105 kPa (15 psi) of air pressure in the hydraulic tank. Do not disconnect any of the quick disconnect fittings until all pressure in them is released. |
3. Move the tilt control lever to the FULL TILT BACK position. Put 50 to 105 kPa (7 to 15 psi) of air pressure in the hydraulic tank. Open the needle valve to let oil drain out of the hose on the pump outlet line until it is free of air bubbles. Close the needle valve.
4. Move the tilt control lever to the HOLD position.
5. Close the valve on the air regulator. Loosen the filler cap on the hydraulic tank a small amount, to release all the pressure in the system. When all pressure is released, disconnect the hose from the test fitting on the pump outlet line and the air regulator from the test fitting on tank.
6. Fill the hydraulic tank again to the top of the fill screen.
7. Connect the air regulator and valve to the test fitting on the tank again. Put 50 to 105 kPa (7 to 15 psi) of air pressure in the hydraulic tank.
8. Crank (turn) the engine in 10 second intervals. DO NOT start the engine.
9. Add oil as needed to keep it at the ADD mark or above. Always close the valve on the air regulator and slowly loosen the cap on the hydraulic tank to release all the pressure in the tank when oil is added.
10. Crank the engine in 10 second intervals until the oil level in the hydraulic tank does not change a large amount.
11. Close the valve on the air regulator and slowly loosen the cap on the hydraulic tank to release all the pressure in the tank. Remove the air regulator and valve from the test fitting on the hydraulic tank.
12. Start the engine. Let the engine speed come up for a short period of time (briefly) then move the governor control lever to 1/4 of HIGH IDLE.
13. Keep the oil level in the hydraulic tank at or above the ADD mark on the oil level gauge at all times.
14. Move the control lever to FULL TILT BACK position for one second. Move the control lever to the HOLD position for two seconds. Repeat the cycle for 15 seconds to be sure of implement pressure and cylinder rod movement.
15. Tilt cylinder air removal:
a. Extend tilt cylinder 1/3of rod length, retract.
b. Extend tilt cylinder 2/3of rod length, retract.
c. Extend tilt cylinder to full rod length, retract.
NOTE: Use FULL TILT BACK and FULL DUMP positions to extend and retract the rod. Do not move the control lever part way. Do not make the relief valve open. Keep the oil level in the hydraulic tank at or above the ADD mark on oil level gauge at all times. Keep the engine at LOW IDLE.
16. Do Step 15 again for the lift cylinders, ripper cylinders, and multi-purpose bucket cylinders.
17. Install the cap on the hydraulic tank after the cylinders are completely full and the oil level in the hydraulic tank does not change a large amount.
Troubleshooting
Problem List
1. Slow RAISE or TILT BACK speed.
2. Bucket drift in LOWER direction. (Lift circuit)
3. Can not keep down pressure with lift control valve in HOLD position.
4. Bucket drift in DUMP direction. (Tilt circuit)
5. Bucket drift in TILT BACK direction. (Tilt circuit)
6. Implement drifting in DOWN or CLOSE direction. (Third circuit)
7. Can not keep down pressure in CLOSE direction. (Third circuit)
8. Bucket drift in DUMP position as tilt lever is slowly moved from HOLD to TILT BACK with engine at LOW IDLE.
9. Bucket drift in LOWER direction as lift lever is slowly moved from HOLD to RAISE with engine at LOW IDLE.
10. Control lever detent does not operate correctly.
Problem 1: Slow RAISE or TILT BACK speed.
Probable Cause:
1. Main relief valve needs adjustment, cleaned, or replaced.
2. Cylinder packing. Replace if necessary.
3. Pump needs repaired or replaced.
4. Pump suction line leakage. Repair leaks.
5. Cylinder relief valve needs adjustment, cleaned, or replaced.
6. Internal seal leakage. Replace seal.
Problem 2: Bucket drift in LOWER direction (Lift circuit)
Probable Cause:
1. Lift cylinder packing. Replace if necessary.
2. Lift and tilt control valve (spool to body fit). Replace.
3. Internal seal leakage. Replace seal.
4. Head end lift cylinder relief valve needs adjustment, cleaned, or replaced.
Problem 3: Can not keep down pressure with lift control valve in HOLD position.
Probable Cause:
1. Rod end lift cylinder makeup valve needs adjustment, cleaned, or replaced.
2. Lift cylinder packing. Replace if necessary.
3. Internal seal leakage. Replace seal.
Problem 4: Bucket drift in DUMP direction (Tilt circuit)
Probable Cause:
1. Tilt cylinder packing. Replace if necessary.
2. Lift and tilt control valve (spool to body fit). Replace.
3. Head end lift cylinder relief valve needs adjustment, cleaned, or replaced.
4. Internal seal leakage. Replace seal.
Problem 5: Bucket drift in TILT BACK direction (Tilt circuit)
Probable Cause:
1. Rod end tilt cylinder makeup valve needs cleaned.
2. Rod end tilt relief valve needs adjustment, cleaned, or replaced.
3. Internal seal leakage. Replace seal.
4. Tilt cylinder packing. Replace if necessary.
Problem 6: Implement drifting in DOWN or CLOSE direction (Third circuit)
Probable Cause:
1. Rod end tilt cylinder relief valve needs adjustment, cleaned, or replaced.
2. Cylinder packing. Replace if necessary.
3. Third control valve (spool to body fit). Replace.
4. Internal seal leakage. Replace seal.
Problem 7: Can not keep down pressure in CLOSE direction. (Third circuit)
Probable Cause:
1. Head and cylinder relief valve needs adjustment, cleaned, or replaced.
2. Cylinder packing. Replace if necessary.
3. Third control valve (spool to body fit). Replace.
4. Internal seal leakage. Replace seal.
Problem 8: Bucket drift in DUMP position as tilt lever is slowly moved from HOLD to TILT BACK with engine at LOW IDLE.
Probable Cause:
1. Load check valve needs cleaned or replaced.
Problem 9: Bucket drift in LOWER direction as lift lever is slowly moved from HOLD to RAISE with engine at LOW IDLE.
Probable Cause:
1. Load check valve needs cleaned or replaced.
Problem 10: Control lever detent does not operate correctly.
Probable Cause:
1. Incorrect adjustment of detents. Adjust set screws behind detents on control valve in tank. Refer to Disassembly and Assembly module for correct adjustment of detents.