2000/09/25 Caterpillar

Telehandler:

TH62 (PIN: 3LN1-UP; 4TM1-UP)

TH82 (PIN: 3JN1-UP; 3KN1-UP)

TH63 (PIN: 3NN1-UP; 5WM1-UP)

TH83 (PIN: 3RN1-UP)

TH103 (PIN: 3PN1-UP)

Reference: Operation and Maintenance Manual, SEBU6865, "TH62, TH63, TH82 and TH83 Telehandlers".

Reference: Operation and Maintenance Manual, SEBU7112, "TH62, TH63, TH82 and TH83 Telehandlers".

Reference: Operation and Maintenance Manual, SEBU7017, "TH103 Telehandlers".

Reference: Operation and Maintenance Manual, SEBU7111, "TH103 Telehandlers".

Reference: Disassembly and Assembly, SENR5846, "TH62, TH63, TH82 and TH83 Telehandlers Machine Systems".

Reference: Disassembly and Assembly, SENR1241, "TH103 Machine Systems Disassembly and Assembly".

Reference: Special Publication, NENG2500, "Tools and Shop Products Guide"

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Cylinders equipped with load control valves can remain pressurized, even with hoses removed. Failure to relieve pressure before removing a load control valve or disassembling a cylinder can result in personal injury or death. Ensure all pressure is relieved before removing a load control valve or disassembling a cylinder.

The information in this article may be used in the following operations:

• Lowering the boom or retracting the boom without hydraulic power

• Maintenance on the Load Control Valves

• Maintenance on the Hydraulic Cylinders

Before you remove any hydraulic components from the machine make sure that all hydraulic pressure in the hydraulic system is relieved.

Care must be taken when you are removing counterbalance valves from load control valves.

Counterbalance valves are installed in the load control valves on the following cylinders:

• Boom Extend Cylinders

• Boom Raise Cylinders

• Stabilizer Cylinders (if equipped)

• Frame Leveling Cylinder (if equipped)

Two types of counterbalance valves are installed in the load control valves on the Telehandlers.

This article will help you to identify the type of counterbalance valve that is installed on your Telehandler.

Before you start any maintenance on the boom, support the boom on a suitable stand. Refer to the "Tools and Shop Products Guide" for information on stands that are available.

Counterbalance Valves

Location

Illustration 1	g00704284
Boom Extend Cylinder TH62 and TH82 The load control valves are an integral part of the boom extend cylinder on these models. The load control valves are not bolted to the boom extend cylinder. The load control valves can therefore not be removed from the cylinder. (I) Load Control Valve (part of the cylinder) (2) Counterbalance Valve (3) Locknut (4) Adjusting Screw

Illustration 2	g00704299
Boom Extend Cylinder TH63, TH83 and TH103 (I) Load Control Valve (2) Counterbalance Valve (3) Locknut (4) Adjusting Screw

Illustration 3	g00704594
Boom Raise Cylinder TH62, TH82, TH63, TH83 and TH103 (I) Load Control Valve (2) Counterbalance Valve (3) Locknut (4) Adjusting Screw

Illustration 4	g00720427
Stabilizer Cylinders (if equipped) TH63,TH83 and TH103 The stabilizer cylinders must be removed from the machine in order to relieve the pressure in the load control valve. (I) Load Control Valve (2) Counterbalance Valve (3) Locknut (4) Adjusting Screw

Illustration 5	g00720625
Frame Leveling Cylinder (if equipped) TH63, TH82, TH83 and TH103 (I) Load Control Valve (2) Counterbalance Valve (3) Locknut (4) Adjusting Screw

Fork Leveling Cylinder

Illustration 6	g00721000
(1) Load Control Valve

The load control valve (1) on the fork leveling cylinder does not have a counterbalance valve. Slowly loosen the mounting bolts for the load control valve in order to release any residual hydraulic pressure in the load control valve. The bolts should be loosened sequentially. Take care to avoid the oil that is being released.

Relieving the Pressure

First Type of Counterbalance Valve

Illustration 7	g00731090

1. Hold adjusting screw (4) in place with a 5/16 inch allen wrench while you use a 9/16 inch spanner wrench with an open end to remove locknut (3). Keep the locknut for reassembly later.

2. Turn the adjusting screw (4) as far as possible in a clockwise direction. Observe the movement of the adjusting screw. The adjusting screw should move into the body of counterbalance valve (2). The pressure in the load control valve will now be relieved. Reset the counterbalance valve after all the pressure has been released. Refer to the "Operation and Maintenance Manual" for your machine.

3. Loosen the counterbalance valve slowly in order to release any pressure that remains in the load control valve. Ensure that all the hydraulic pressure is released from the counterbalance valve before you remove the counterbalance valve from the load control valve. Take care to avoid the oil that is being released from the counterbalance valve. Remove the counterbalance valve from the load control valve.

Note: Follow Steps 1 and 2 when you are lowering the boom or retracting the boom without hydraulic pressure.

Second Type of Counterbalance Valve

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Illustration 8	g00731092

1. Hold adjusting screw (4) in place with a 5/16 inch allen wrench while you use a 9/16 inch spanner wrench with an open end to remove locknut (3). Keep the locknut for reassembly later.

2. Turn the adjusting screw (4) as far as possible in a clockwise direction. Observe the movement of the adjusting screw. The adjusting screw should turn without moving into the body of the counterbalance valve. Tap screw (4) with a hammer in order to ensure that the pressure in the load control valve has been relieved. Reset the counterbalance valve after all the pressure has been released. Refer to the "Operation and Maintenance Manual" for your machine.

3. Loosen the counterbalance valve slowly in order to release any pressure that remains in the load control valve. Ensure that all the hydraulic pressure is released from the counterbalance valve before you remove the counterbalance valve from the load control valve. Take care to avoid the oil that is being released from the counterbalance valve. Remove the counterbalance valve from the load control valve.

Note: Follow Steps 1 and 2 when you are lowering the boom or retracting the boom without hydraulic pressure.

Load Control Valves

Removing the Load Control Valves from the Hydraulic Cylinders

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Personal injury can result from oil under high pressure. DO NOT allow high pressure oil to contact skin. Wear appropriate protective equipment while working with high pressure oil systems.

Before you remove the load control valve from the hydraulic cylinder you must first release the hydraulic pressure. When the hydraulic cylinder has been removed from the machine, use a suitable stand to support the cylinder. Refer to the "Tools and Shop Products Guide" for information on stands that are available. Ensure that the ports on the cylinder are facing away from you before the pressure is relieved.

1. Slowly loosen the mounting bolts for the load control valve in order to release any residual hydraulic pressure in the load control valve. The bolts should be loosened sequentially. Take care to avoid the oil that is being released.

2. When all the residual pressure has been released remove the bolts fully. The load control valve may then be removed from the hydraulic cylinder for maintenance.

3. Reinstall the load control valve when maintenance has been completed. Refer to "Disassembly and Assembly" for your machine.

4. Remove the support for the boom.