517 Track-Type Skidder Hydraulic System Caterpillar

Testing and Adjusting

Usage:

517 5WW

Implement Hydraulic System

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Sudden movement of the machine or release of oil under pressure can cause serious injury to persons on or near the machine.

To prevent possible injury, perform the procedure that follows before testing and adjusting the hydraulic system.

Move the machine to a smooth horizontal location. Move away from working machines and personnel. Lower the attachments to the ground.

Allow only one operator on the machine. Keep all other personnel away from the machine or in the view of the operator.

Engage the parking brake.

Stop the engine.

Move the control levers for the hydraulic system to all of the positions in order to release the pressure in the hydraulic system.

Carefully loosen the filler cap on the hydraulic tank in order to release the pressure in the tank.

Make sure that all of the hydraulic pressure is released before any fittings, hoses or components are loosened.

Tighten the filler cap on the hydraulic tank.

Make sure that the oil temperature is within the acceptable limits before removing lines or components.

Release the pressure in the accumulator on the machines with a grapple.

The pressure in the system has now been released and the lines and components can be removed.

Procedure

When you are defining a problem with the hydraulic system, the following procedure should be followed. First do the Visual Checks. If the problem has not been identified after the Visual Checks, then do the Operational Checks. If the problem is not understood still, then do the Instrument Tests. This procedure helps to identify problems in the hydraulic system. When the problem is identified, go to the Troubleshooting section. The Troubleshooting section lists the probable causes of a known problem. There may be more than one cause for a problem. Therefore, the Troubleshooting Section may suggest specific inspections or instrument tests. These procedures help to identify the cause that is the probable source.

During a diagnosis of the hydraulic system, remember that the correct oil flow and pressure are necessary for correct operation. The output of the pump may increase with an increase in engine speed. Oil pressure is caused by a resistance to the output or oil flow.

Use the following tools for the basic measurements of the hydraulic tests that are listed below:

8T-5320 Hydraulic Test Group
4C-4890 Hydraulic Test Group
4C-4892 Hydraulic Test Fitting Gp
Stopwatch
Magnet
Thermometer
Ruler

Measure the drift rates in the attachment circuits. Cylinder drift is caused by leakage past the cylinder pistons, the valve spools, the check valves and/or the makeup valves. Excessive drift can be caused by a problem with any of the components.

Measure cycle times in the attachment circuits. Cycle times that are longer than the values that are shown in the charts are caused by leakage, pump wear and/or pump speed. Line relief settings and pump compensator spool settings can also cause longer cycle times. If the operation checks indicate excessive leakage, pressure tests are needed to identify the components with a problem.

Visual Checks

A visual inspection of the hydraulic system and the corresponding components is the first step in order to identify a problem.

See "Implement Hydraulic System" for the procedure for relieving system pressure prior to performing any inspections.

Make the following inspections.

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Personal injury or death can result from improperly checking for a leak.
Always use a board or cardboard when checking for a leak. Escaping air or fluid under pressure, even a pin-hole size leak, can penetrate body tissue causing serious injury, and possible death.

If fluid is injected into your skin, it must be treated immediately by a doctor familiar with this type of injury.

Check all of the implement oil line connections for damage or leaks.

Trace all of the oil lines from the implement connections to the valve connections. Check the lines and the connections for damage or leaks.

Check the pump and the connections for damage or leaks.

Trace the pump lines to the tank and the valves. Check the lines and the tank for damage or leaks.

Check the oil level in the tank.

Use a clear bottle or a container in order to get an oil sample immediately after the machine is stopped. Check for air bubbles in the oil sample.

Remove the filter element and check for particles that are removed from the oil by the filter. A magnet can be used in order to separate ferrous material from the nonferrous particles in the filter.

Inspect the control linkages for damaged components.

Operation Checks

The operation checks can be used to find leakage in the system. The operation checks can also be used to find a bad valve or a bad pump. When the cylinders move, the speed of the rod movement can be used in order to check the condition of the cylinders and the pump.

The oil in the hydraulic system must be at an operating temperature of 38 to 54 °C (100 to 130 °F).

The control valves have a parallel arrangement. The hydraulic pump and the pump compensator are common to all of the circuits. Each valve section has a check valve in order to prevent cylinder drift when the valve spool is moved.

Relief valves help protect the system components from high pressure. The line relief valves are also makeup valves. Makeup valves supply extra oil to the cylinders when the oil is needed.

Extend the cylinders and retract the cylinders several times.

Watch the cylinder during the range of motion. The movement must be smooth and regular.

Listen for noise from the pump.
Note: The pressure setting of the pump compensator can lower the performance of the machine. A high pressure setting can cause a reduction in the life of the hoses and other parts of the system.

Allow the implement cylinders to travel the full range of motion.

Put each control valve in the HOLD position while the implement is above the ground. Watch for excessive cylinder drift.
Note: Cylinder drift is caused by leakage past the cylinder pistons, the valve spools, the check valves and/or the makeup valves. Excessive drift can be caused by a problem with any of the components.

Lift Cylinder Drift Test

The drift rates change with different conditions of the hydraulic components and the operating conditions.

Before measuring the drift on the cylinder rod, the cylinders must be extended at least five times. Measure the drift by using the following procedure.

Check the temperature of the hydraulic oil.

Raise the bulldozer until the cutting edge is approximately 254 mm (10 inch) above the ground. With the control lever in the HOLD position, stop the engine.

Measure the length of the lift cylinder rods from the lift cylinders and record the measurement.

Refer to Table 1 for allowable drift and the correct time interval.

Note: The drift distances in the charts are for new machines.

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Table 1
Lift Cylinder Drift
Oil Temperature	38 to 49°C (100 to 120°F)	49 to 66°C (120 to 150°F)	66°C (150°F) minimum
Maximum Permissible Drift	32 mm (1.26 inch)	32 mm (1.26 inch)	32 mm (1.26 inch)
Time Interval	5 minutes	2.7 minutes	1.7 minutes

The following conditions can cause too much lift cylinder drift.

Loose oil line connections
Damaged oil line between the control valve and the lift cylinder
Leakage around the piston seals in the lift cylinder
Leakage in the control valve due to a worn valve section and/or spool or a makeup valve that is not seated correctly

Perform the next test if the following conditions are met.

Excessive drift exists.
The hydraulic oil temperature is below 54°C (130°F).
No leaks in the lines to the lift cylinders were found.

Start the engine. Move the control lever to the LOWER position. When the rods are extended and the front of the machine is off of the ground, stop the engine.

Disconnect the oil lines from the rod end of each lift cylinder.

If a small amount of oil escapes through the open connection on the cylinders, the seals on the piston are not the cause of the problem. The problem lies in the control valve.

The leakage in the control valve can be caused by the following conditions.

A check valve that is not seated correctly
A worn valve spool
A worn valve section

Tilt Cylinder Drift Test

The drift rates change with different conditions of the hydraulic components and the operating conditions.

Before measuring the drift on the cylinder rod, the cylinders must be extended at least five times. Measure the drift by using the following procedure.

Check the temperature of the hydraulic oil.

Fully retract the tilt cylinder.

Lower the bulldozer in order to raise the front idlers off the ground. With the control valves in the HOLD position, stop the engine.

Refer to Table 2 for allowable drift and the correct time interval.

Note: The drift distances in the charts are for new machines.

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Table 2
Tilt Cylinder Drift
Oil Temperature	38 to 49°C (100 to 120°F)	49 to 66°C (120 to 150°F)	66°C (150°F) minimum
Maximum Permissible Drift	13 mm (.50 inch)	13 mm (.50 inch)	13 mm (.50 inch)
Time Interval	5 minutes	2.7 minutes	1.7 minutes

The following conditions can cause too much tilt cylinder drift.

Loose oil line connections
Damaged oil line between the control valve and the tilt cylinder
Leakage around the piston seals in the tilt cylinder
Leakage in the control valve due to a worn valve section and/or spool or a makeup valve that is not seated correctly

Drift Test for the Grapple Cylinders

The drift rates change with different conditions of the hydraulic components and the operating conditions.

Before measuring the drift on the cylinder rod, the cylinders must be extended at least five times. Measure the drift by using the following procedure. Check the oil temperature.

In order to check the grapple, extend the cylinders for the grapple arch approximately 100 mm (4 inch) from full extension.

Refer to Table 3 for allowable drift and the correct time interval.

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Table 3
Cylinder Drift for the Grapple Arch
Oil Temperature	Maximum Permissible Drift	Time Interval
40 to 55°C (104 to 130°F)	30.0 mm (1.25 inch)	5.0 minutes

Refer to Service Manual Supplement, SENR5868 for the ESCO grapple for information on the drift distances for the tong and boom cylinders.

If there is excessive cylinder drift, check the following components.

The makeup valves in the arch control valve
The condition of the valve spool in the arch control valve
The piston seals in the cylinders

Cylinder Speed Tests

The oil in the system must be SAE 10W. The oil must be at a temperature of 65° ± 3°C (150° ± 5°F) in order to get the correct results. All speed tests are performed with the engine at HIGH IDLE.

System speeds which correspond with the values in the charts indicate that the circuit operation is normal.

If only one of the cylinder speeds is slow, check that circuit for cylinder drift.

Use a stopwatch or a timer in order to measure the time for the following operations.

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Table 4
	Lift Cylinder Speed Test	Speed in seconds
4P Bulldozer	Raise the blade from the ground to full extension.	2.4 ± 0.1

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Table 5
	Tilt Cylinder Speed Test	Speed in seconds
4P Bulldozer	Fully extend the cylinder from the fully retracted position.	1.7 ± 0.1
4P Bulldozer	Fully retract the cylinder from the fully extended position.	1.4 ± 0.1

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Table 6
	Angle Cylinder Speed Test	Speed in seconds
4P Bulldozer	Angle the blade from the far left to the far right.	3.0

Incorrect cycle times may be caused by the following conditions.

Bad pump efficiency
Leakage in the cylinders
Leakage in the makeup valve
Worn valve spool in the affected circuit
High margin pressure which causes faster cycle times
Low margin pressure which causes slower cycle times
Blockage or leakage in the resolver network

Resolver Network Check

A resolver is a check valve. The resolver compares two pressures. The lower pressure is blocked. The higher pressure goes to the next component in the resolver network.

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Illustration 1	g00481469
Typical control valve (1) Primary resolver (2) Secondary resolver

There are two resolvers per implement control valve. Primary resolver (1) compares the cylinder rod end pressure to the head end pressure.

Secondary resolver (2) compares the highest resolved pressure from the previous control valve to the highest resolved pressure in the next control valve.

The secondary resolvers are arranged in series. The highest resolved pressure from the series is then sent to the pump compensator valve.

The resolvers can be affected by debris, bad seals, bad ball resolver seats or missing balls.

Troubleshooting the Resolver Network

The resolver network can be checked easily. Start the engine and warm up the hydraulic oil. Run the engine at LOW IDLE for this procedure.

Connect a 30000 kPa (4000 psi) pressure gauge to the pressure tap for the signal line. Operate each control lever in the following order:

Bulldozer angle control

Tilt control lever

Lift control lever

Run each implement against a load. Watch the gauge. Maximum system pressure should be seen for all of the circuits. Small leakage problems due to damaged seals can be detected by using the gauge.

Secondary Resolvers (Two or More Valve Sections)

If two or more control valves that are next to each other fail to work normally, the problem may be in a secondary resolver.

The first control valve that is closer to the pump supply which operates properly is the probable source of the problem.

This secondary resolver is allowing signal pressure from any prior control valve to leak to either tank passage in this control valve. This leakage may be caused by a ball that is not correctly seating against the drain port of the resolver.

This is the cause unless one of the following conditions are present.

The ball is missing.
Debris is preventing the ball from seating properly.
A seal is leaking.
A seal is missing.

Operate the malfunctioning valve that is outermost from the pump. At the same time, operate the other valves in the order that is listed above.

The first valve that allows both functions to operate is the cause of the problem. This valve has a bad secondary resolver. The farthest valve is sending a signal and the malfunctioning valve is sending a signal.

When both of the signals intersect at the valve with the bad secondary resolver, the leak does not affect the signal. The signal flows to the pump and there is flow control.

Primary Resolver Versus Secondary Resolver

If only one valve fails to work properly in one direction or both directions, the primary resolver or the secondary resolver in that control valve may be bad. Perform the following procedure in order to determine the secondary resolver that is bad.

Stall an implement control valve that is further than the malfunctioning valve away from the pump supply.

This causes the ball in the secondary resolver to seat away from the drain port in the resolver. This eliminates the possibility of a leak in the drain port of the secondary resolver.

Next, operate the suspect valve while the other implement is in the stall condition. If the suspect valvestill operates in a slow manner in either direction, then the primary resolver may be bad.

If the primary resolver is bad, the pressure loss that is caused by the bad resolver inhibits the ability of the valve spool to shift. The signal pressure and the spring force try to open the valve in order to allow flow to the cylinders. The effective force is insufficient for the load requirements. Therefore, the response of the implement is slow.

Normally, if an implement is slow in both directions, the problem is in the secondary resolver. If an implement is slow in one direction, the cause is typically a bad primary resolver.

A malfunctioning valve could be caused by one of the following problems:

A misadjusted linkage
A broken spring in the pressure reducing valve
An incorrectly installed flow control spool
A bad line relief/makeup valve

Note: If there is debris in the system, flushing the system is recommended. This is done by removing all of the balls in the secondary resolvers. Then operate the implements. Enough flow is supplied in order to flush the debris to the tank.

Pump Efficiency Check

This test is designed to determine if a pump is operating within the design parameters. A bench test is the only test which is presently available. Perform this test only when all of the cylinder cycle times are too slow and the resolver network check is okay.

For any pump test, the pump flow at 690 kPa (100 psi) will be larger than the pump flow at 6900 kPa (1000 psi) if the pump is operating at the same rpm. The pump flow is measured in L/min (US gpm).

The difference between the pump flow of two operating pressures is the flow loss.

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Table 7
Method for determining flow loss
	Pump flow at 690 kPa (100 psi)
-	Pump flow at 6900 kPa (1000 psi)
	Flow loss

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Table 8
Example of determining flow loss
	217.6 L/min (57.5 US gpm)
-	196.8 L/min (52.0 US gpm)
	20.8 L/min (5.5 US gpm)

Flow loss is used as a measure of pump performance. Flow loss is expressed as a percentage of pump flow.

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Table 9
Method of determining percent of flow loss
Flow loss (L/min or US gpm)	×	100	=	Percent of flow loss
Pump flow at 690 kPa (100 psi)

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Table 10
Example of determining percent of flow loss
20.8 L (5.5 US gal)	×	100	=	9.5%
217.6 L/min (57.5 US gpm)

If the percent of flow loss is greater than 10%, the pump performance is inadequate.

Note: The values in the examples are not set values for any specific pump or for any specific pump condition. Refer to the Hydraulic Specifications, RENR2028 for the pump flow of a new pump at 690 kPa (100 psi) and at 6900 kPa (1000 psi).

Test on the 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 the values in the formula in Table 11.

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Table 11
Method of determining percent of flow loss
Flow loss (L/min or US gpm)	×	100	=	Percent of flow loss
Pump flow at 690 kPa (100 psi)

Test on the Bench

If the test bench can be run at 6900 kPa (1000 psi) and at full pump rpm, determine the percent of flow loss by using the formula in Table 11.

If the test bench can not be run at 6900 kPa (1000 psi) or at full pump rpm, 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 portion of the formula in Table 12.

For the bottom part of the formula in Table 12, run the pump shaft at 2000 rpm. Measure the pump flow at 690 kPa (100 psi).

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Table 12
	Pump flow at 690 kPa (100 psi)
-	Pump flow at 6900 kPa (1000 psi)	×	100	=	Percent of flow loss
	Pump flow at 690 kPa (100 psi) and at 2000 rpm	×	100	=	Percent of flow loss

Instrument Tests

Instrument testing on the hydraulic system and the hydraulic system components is the final step when you are diagnosing a problem. Test results should verify the status of a component. Adjusting procedures are provided if an adjustment may be necessary.

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Sudden movement of the machine or release of oil under pressure can cause serious injury to persons on or near the machine.

To prevent possible injury, perform the procedure that follows before testing and adjusting the hydraulic system.

Move the machine to a smooth horizontal location. Move away from working machines and personnel. Lower the attachments to the ground.

Allow only one operator on the machine. Keep all other personnel away from the machine or in the view of the operator.

Engage the parking brake.

Stop the engine.

Move the control levers for the hydraulic system to all of the positions in order to release the pressure in the hydraulic system.

Carefully loosen the filler cap on the hydraulic tank in order to release the pressure in the tank.

Make sure that all of the hydraulic pressure is released before any fittings, hoses or components are loosened.

Tighten the filler cap on the hydraulic tank.

Make sure that the oil temperature is within the acceptable limits before removing lines or components.

Release the pressure in the accumulator on the machines with a grapple.

The pressure in the system has now been released and the lines and components can be removed.

Location of the Pressure Taps

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Illustration 2	g01743414
Service compartment (1) Signal pressure (2) Pump output pressure (3) Test port for pilot pressure

Remove the plug and install a tee with a test port in order to check signal pressure (1) .

Assemble an elbow with a test port from the following parts:

263-2543 Elbow
6V-3965 Fitting
9S-4191 O-Ring Plug
Two 214-7568 O-Ring Seals

Replace the existing elbow with this elbow assembly in order to check pump output pressure (2) .

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Illustration 3	g01743534
View from floor of cab (4) Pressure compensator valve

Pump Discharge Pressure Tests

Pump discharge pressures are known values that can be tested during two specific conditions. The two conditions are listed below:

Low pressure standby
High pressure stall

Low Pressure Standby Test Procedure

Attach a 0 to 4000 kPa (0 to 580 psi) pressure gauge to the test port for signal pressure (1) .

Start the engine and run the engine at high idle.

Leave all control levers in the HOLD position.

The pressure reading must be approximately 3200 kPa (465 psi). Low pressure standby pressure is approximately 1500 kPa (190 psi) additionally higher than margin pressure. Margin pressure is 1700 ± 200 kPa (245 ± 30 psi).

Adjustments to the pump output should not be based only on the results of this test. Instead, if the results are not acceptable, the "Margin Pressure Test" should be performed also.

High Pressure Stall Test Procedure

You will need one of the following test groups:

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Table 13
Tools Needed
Part Number	Description	Qty
5S-5123	Hydraulic Testing Group	1
5P-5224	Hydraulic Testing Group	1
6V-4161	Hydraulic Testing Group	1

Lower all of the implements to the ground.

Shut off the engine and move the control levers to all positions in order to release system pressure.

Carefully loosen the filler cap on the hydraulic tank in order to release any pressure in the tank. Tighten the cap.

Attach a 0 to 28000 kPa (0 to 4000 psi) pressure gauge to the test port for pump output pressure (2) .

Start the engine and run the engine at high idle.

Move the control levers individually in both directions in order to initiate a stall condition. Do not maintain the stall condition for more than 10 seconds. If you need additional time, wait for 30 seconds and then return to the stall condition.

All pressure readings must be 20700 ± 350 kPa (3000 ± 50 psi).
Note: If the pressure readings are too low or too high, the pressure compensator valve needs to be adjusted. See the "Compensator Valve Adjustment" procedure.

Margin Pressure Test

Lower all of the implements to the ground.

Shut off the engine and move the control levers to all positions in order to release system pressure.

Carefully loosen the filler cap on the hydraulic tank in order to release any pressure in the tank. Tighten the cap.

Open the cover for the service compartment.

Attach a pressure gauge to the test port for signal pressure (1) .

Attach a pressure gauge to the test port for pump output pressure (2) .

Start the engine and run the engine at low idle. Check for leaks.

Warm up the hydraulic oil. Check for leaks.

Bring the engine speed up to high idle.

Move the bulldozer control lever to a position between the HOLD and the FULL RAISE positions. Read the pressure on the gauges. Subtract the signal pressure from the pump output pressure in order to determine the margin pressure.
The margin pressure should be 1700 ± 200 kPa (245 ± 30 psi).

If the margin pressure is not correct, see the "Flow Compensator Spool Adjustment" procedure.
Note: After performing the "Flow Compensator Spool Adjustment" procedure, recheck the margin pressure.

Compensator Valve Adjustment

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Illustration 4	g00487211
Compensator valve (7) Adjustment screw for the flow compensator (8) Locknut (9) Flow compensator spool (10) Pressure compensator spool (11) Locknut (12) Adjustment screw for the pressure compensator

The high pressure stall test indicates if the pressure compensator needs to be adjusted. The margin pressure test and/or the low pressure standby test also indicates if the flow compensator needs to be adjusted.

Adjustment of the Pressure Compensator Spool

Adjustments to the pressure compensator valve can be made on the machine. If the high pressure stall test indicates that an adjustment is needed, use the following procedure.

Lower all of the implements to the ground.

Shut off the engine and move the control levers to all positions in order to release system pressure.

Loosen locknut (11) .

Turn adjustment screw (12) clockwise in order to increase the pressure setting. Turn the screw counterclockwise in order to decrease the pressure setting.
Note: When you decrease the pressure setting, make sure that you turn adjustment screw (12) counterclockwise past the desired setting. Then, turn the screw clockwise to the correct setting. This method of adjusting the pressure setting will eliminate any free play from the threads in the adjustment screw.

Repeat the high pressure stall test in order to make sure that the pressure settings are 20700 ± 350 kPa (3000 ± 50 psi).

When the pressure is correctly adjusted, tighten locknut (11) .

Flow Compensator Spool Adjustment

Adjustments to the flow compensator valve can be made on the machine. If the margin pressure test indicates that an adjustment is needed, use the following procedure.

Lower all implements to the ground.

Shut off the engine and move the control levers to all positions in order to release system pressure.

Loosen locknut (8) .

Turn adjustment screw (7) clockwise in order to increase the pressure setting. Turn the screw counterclockwise in order to decrease the pressure setting.
Note: When you decrease the pressure setting, make sure that you turn adjustment screw (7) counterclockwise past the desired setting. Then, turn the screw clockwise to the correct setting. This method of adjusting the pressure setting will eliminate any free play from the threads in the adjustment screw.

Repeat the margin pressure test and the low pressure standby test.
1. Margin pressure should be 1700 ± 140 kPa (246 ± 20 psi).
1. Low pressure standby should be 3200 kPa (464 psi).

When the pressure is correctly adjusted, tighten locknut (8) .

Relief Valves

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Sudden movement of the machine or release of oil under pressure can cause serious injury to persons on or near the machine.

To prevent possible injury, perform the procedure that follows before testing and adjusting the hydraulic system.

Move the machine to a smooth horizontal location. Move away from working machines and personnel. Lower the attachments to the ground.

Allow only one operator on the machine. Keep all other personnel away from the machine or in the view of the operator.

Engage the parking brake.

Stop the engine.

Move the control levers for the hydraulic system to all of the positions in order to release the pressure in the hydraulic system.

Carefully loosen the filler cap on the hydraulic tank in order to release the pressure in the tank.

Make sure that all of the hydraulic pressure is released before any fittings, hoses or components are loosened.

Tighten the filler cap on the hydraulic tank.

Make sure that the oil temperature is within the acceptable limits before removing lines or components.

Release the pressure in the accumulator on the machines with a grapple.

The pressure in the system has now been released and the lines and components can be removed.

There is no main relief valve in the system. The pressure compensator valve acts as a main relief valve. The pressure compensator valve limits the system pressure to 20700 ± 350 kPa (3000 ± 50 psi).

The pressure compensator can be checked on the machine by running the high pressure stall test.

The lift cylinder rod end (power angle tilt blade) has combination line relief and makeup valves. The rod end and the head end of the blade angle cylinder have combination line relief and makeup valves. The relief valves are set higher than the system pressure from the pump. In order to check the relief valves, supplemental pump pressure is required.

The correct pressure setting for the relief valve for the angle circuit is 34460 ± 350 kPa (5000 ± 50 psi).

The correct setting for the relief valve for the raise circuit is 24200 ± 350 kPa (3500 ± 50 psi).

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Table 14
Tools Needed
Part Number	Description	Qty
3S-6224	Electric Hydraulic Pump	1
1U-5216	Manifold	1

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Illustration 5	g00487215
Implement control valve bank (1) Rod end of the left angle cylinder and the head end of the right angle cylinder (relief valve) (2) Relief valve for rod end of the lift cylinder (machines that are equipped with a straight blade only) (3) Rod end of the right angle cylinder and the head end of the left angle cylinder (relief valve) (A) Bulldozer angle control valve (B) Bulldozer tilt control valve (C) Bulldozer lift control valve

Bench Test

Lower all of the implements to the ground.

Shut off the engine and move the control levers to all positions in order to release system pressure.

Carefully loosen the filler cap on the hydraulic tank in order to release any pressure in the tank. Tighten the cap.

Remove the desired relief valve for testing.

Install the relief valve in the 1U-5216 Manifold .

Connect the manifold to the hydraulic test bench.

Slowly increase pressure. Note the pressure reading when the relief valve opens. Adjust the relief valve, if necessary.

Relief Valve Adjustments

Note: See the topic "Relief Valves" when you test the relief valves.

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Illustration 6	g00487217
Typical line relief/makeup valve (4) Cap (5) Adjustment screw (6) Locknut

Remove protective cap (4) .

Loosen locknut (6) .

Turn adjustment screw (5) clockwise in order to increase the pressure setting. Turn adjustment screw (5) counterclockwise in order to decrease the pressure setting of the relief valve.

After the adjustment has been made, tighten locknut (6) and retest the adjustment.

Install cap (4) after the adjustment has been made.

Testing and Adjusting the Relief Valves

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Table 15
Tools Needed
Part Number	Description	Qty
8T-5320	Hydraulic Test Group	1

Increase the temperature of the oil to the normal operating temperature.

Lower all of the implements to the ground.

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Illustration 7	g00487218
Relief Valve (1) Locknut (2) Cap (3) Adjustment screw

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Illustration 8	g00487219
Control valves (grapple) (4) Relief valve for head end of tong cylinder (5) Relief valve for rod end of boom cylinder (6) Relief valve for head end of arch cylinder (7) Relief valve for rod end of arch cylinder (8) Relief valve for head end of boom cylinder (A) Port (B) Port (C) Port (D) Port (E) Port

Release the steering and hydraulic system pressure.

Carefully loosen the filler cap on the hydraulic tank in order to release any pressure in the tank. Tighten the cap.
Note: The relief valves have a pressure setting that is higher than the pump compensator pressure. The valves must be removed in order to properly set the valves. Set the valves on a test bench or use supplemental pump pressure to set the valves.

Remove the hydraulic line from the appropriate port for the relief valve that is being tested. Refer to Table 16 and Illustration 8 in order to determine the appropriate port. Install a plug in the line.

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Table 16
Relief Valve		Port
Arch Cylinder	Head End	E
Arch Cylinder	Rod End	D
Boom Cylinder	Head End	B
Boom Cylinder	Rod End	C
Tong Cylinder	Head End	A

Assemble fittings and attach a 3S-6224 Pump to the appropriate port for the relief valve that is being tested. Attach a pressure gauge to the pump.
Note: The 3S-6224 Pump reservoir only contains 7.58 L (2 US gal) of oil. Make sure that the pump does not run out of oil.

Start the pump and slowly increase the pump pressure.

The pressure setting of the relief valve should be 24200 ± 350 kPa (3510 ± 50 psi).

If the pressure setting of the relief valve is not at the specified setting it will be necessary to adjust the valve.

Stop the pump.

Remove cap (2) . Loosen locknut (1) and turn adjustment screw (3) clockwise in order to increase the pressure. Turn the adjustment screw counterclockwise in order to decrease the pressure.

After adjustment screw (3) is turned for an adjustment, tighten locknut (1) to a torque of 20 ± 3 N·m (177 ± 26 lb in).

Repeat Steps 7 and Step 8.

If the pressure setting is correct, stop the pump.

If the pressure setting is not correct, repeat Step 10 through Step 13.

When the pressure setting is correct, stop the pump. Install cap (2) .

Remove the test equipment. Remove the plug from the line and reinstall the hydraulic line to the port.

Troubleshooting

Hydraulic Pump and Hydraulic System

The temperature of the oil is too hot.

Probable causes

The viscosity of the oil is wrong. Refer to the Operation and Maintenance Manual, SEBU7156, "Lubricant Viscosities and Refill Capacities".

Excessive wear of the pump

There is a restriction in an oil passage.

The load on the system is too high.

Oil aeration

Low oil level in the hydraulic tank

The flow compensator valve is set incorrectly.
1. Margin pressure is too high.

The outside air temperature is too hot.

The pump makes unusual noises.

a. The cylinder rods do not move smoothly.

b. Air bubbles in the oil

Probable causes

The viscosity of the oil is wrong. Refer to the Operation and Maintenance Manual, SEBU7156, "Lubricant Viscosities and Refill Capacities".

There is a loose connection of the oil line on the inlet side of the pump. Oil aeration

Excessive wear of the pump

Low oil level in the hydraulic tank

A large amount of air in the oil

Probable causes

A leak in the oil line between the tank and pump

Low oil level in the hydraulic tank

There is leakage in the cylinder seals or around the cylinder seals.

Low pressure standby is too low.

Probable causes

The flow compensator valve is set incorrectly.

The spring in the flow compensator valve is broken.

The pump is not upstroking. The swashplate is blocked or the actuator spring is broken.

A low setting of the pressure compensator valve or a broken spring

Low pressure standby is too high.

Probable causes

The flow compensator valve is set incorrectly.

Signal pressure from the implements has not bled off.

Margin pressure is too low.

Probable causes

The flow compensator valve is set incorrectly.

Leak in the signal network

Margin pressure is too high.

Probable causes

The flow compensator valve is set incorrectly.

The pump discharge pressure is too high.

a. High pressure stall

Probable causes

The pressure compensator valve is set incorrectly.

The pressure compensator valve is stuck.

The pump is not destroking. The swashplate is blocked or the actuator piston is stuck.

The pump discharge pressure is too low.

a. High pressure stall

Probable causes

The pressure compensator valve is set incorrectly.

Spring in the pressure compensating valve that is broken or fatigued

Line relief valves are set too low.

The signal network is leaking.

There is a pause before pressure is reached in all circuits.

Probable causes

Air in the signal network

Dirt or debris in the oil could cause a resolver to be held open momentarily.

Signal pressure and/or tank pressure is not at zero when all of the valves are in the HOLD position.

Probable causes

All controls are not in HOLD.

The signal network is not vented.

Implement System Problems

Any implement moves with the control lever in HOLD position.

Probable causes

The control valve and the valve spool have a large amount of wear.

A piston seal in a cylinder is damaged or the seal has a large amount of wear.

A leak in the connection between the control valve and the cylinders

The control stem on the valve does not shift into the valve body.

Probable causes

Dirt or water in the end housing

Too much implement drift

Probable causes

There is leakage in the cylinder seals or around the cylinder seals of the affected cylinder.

There is a leakage past a makeup valve for the affected circuit . This relates only to the bulldozer lift.

The spool in the main control valve is not correctly centered. This problem can be caused by a broken spring or a sticky valve spool.

The control valve or the spool has a large amount of wear.

The implement droops when you go from a partially raised position to a raised position.

Probable causes

Air in the signal network

The resolver is not closing because of dirt or debris between the ball and the seat. See the "Resolver Network Check".

Springs in the flow compensator valve may be broken or fatigued.

The flow compensator valve is incorrectly set. The margin pressure is too low.

All implement cycle times are too slow.

Probable causes

Blockage or leakage in the signal network

Margin pressure setting is incorrect.

The pump is not at full stroke. This can be caused by one of the following problems.
1. The actuator piston is stuck.
1. The swashplate is blocked.

All implement cycle times are too fast.

Probable causes

Margin pressure is too high.

The bulldozer blade moves upward when you are dozing with the control lever in HOLD position (float).

Probable causes

The makeup valve is not closing.

The makeup valve is not opening when the blade is being lowered.

The pause at ground level is too long before the machine starts to raise.

Probable causes

The restrictor spool in the inlet manifold for the implement valve stays open. This can be caused by one of the following problems.
1. Broken spring for the restrictor spool
1. The restrictor spool is stuck.

Line relief valves are too noisy.

Probable causes

The affected relief valve is set too low.

Springs in the affected relief valve are broken or fatigued.

The pressure compensator valve is set too high.

The decking blade or the grapple moves with the control lever in the HOLD position.

Probable causes

The control valve and the valve spool have a large amount of wear.

A piston seal in a cylinder has a large amount of wear.

There is a leak in a connection between the control valve and the cylinders.

The line relief/makeup valves are open.

The spool in the main control valve is not correctly centered. This problem can be caused by a broken spring or a sticky valve spool.

If a valve spool is pilot operated, residual pilot pressure may be the cause.

If a valve spool is electrically operated, residual voltage in the wiring harness may be the cause.

Too much drift in the decking blade or the grapple.

Probable causes

There is leakage in the cylinder seals or around the cylinder seals of the affected cylinder or cylinders.

The line relief setting is low.

Leakage past a line relief valve or a makeup valve for the affected circuit

The spool in the main control valve is not correctly centered. This problem can be caused by a broken spring or a sticky valve spool.

If the drift problem is in the arch cylinders, the cause could be one that is listed above. In addition, the selector and pressure control valve could be leaking excessively.

The decking blade or the grapple droops when you go from a partially raised position to a raised position.

Probable causes

Air in the signal network

Advanced signal passages in the main spool of the control valve are blocked in the affected circuit.

The control valve compensator spool spring or springs may be broken or fatigued.

Hydraulic cycle times are too slow.

Probable causes

Blockage or leakage in the signal network

Margin pressure setting is incorrect.

The pump is not at full stroke. This can be caused by one of the following problems.
1. The actuator piston is stuck.
1. The swashplate is blocked.

A malfunction in the pump

Excessive leakage from the pump output to the hydraulic oil tank

Plugged hydraulic oil filters

The engine high idle setting is too low.

The cycle times for the arch, the boom, the tong, the swing and the grapple rotate are too slow.

Probable causes

The main spool for the control valve is not fully shifted for the affected circuit.

The load signal that is going to the pump compensator valve is blocked or partially blocked or there is leakage in the signal network.

The line relief setting is too low on the affected circuit.

The line relief/makeup valve is leaking for the affected circuit.

There is leakage in the piston seals or around the piston seals of the affected cylinder or cylinders.

The pump is not at full stroke. This can be caused by one of the following problems.
1. The actuator piston is stuck.
1. The swashplate is blocked.

The pump margin pressure setting is too low.

If the cycle time for raising the arch is too slow, the cause could be one that is listed above. In addition, the selector and pressure control valve could be leaking excessively.