Tilt Cylinders May Form A Void During Some Applications Caterpillar

THIS TIB REPLACES THE AUGUST 6, 1997 BACKHOE LOADER TIB, COMPONENT CODE 5124, TILT CYLINDERS MAY FORM A VOID DURING SOME APPLICATIONS, DESTROY THE AUGUST 6, 1997 TIB. IT WILL NOT APPEAR IN THE QUARTERLY INDEX.

Problem:

The following applications may cause a void to form in the tilt cylinder: metered tilting of the bucket; back dragging (leveling) with the loader bucket; lifting or holding the machine on the cutting edge while operating the backhoe. Voiding is caused by the pump not receiving the proper signal when performing one of the above tasks. Low resistance to hydraulic flow in the tank lines will not allow the make-up valve to open.

Solution:

An orificed check valve may be inserted in the hydraulic return line to tank to reduce voiding. This check valve provides a small amount of back pressure which will assist the make up portion of the line relief valve to open. After the make-up valve opens, return oil will flow to the opposite end of the cylinder to prevent or reduce voiding.

The Parts listed below need to be installed at the port on the loader valves where the return line to the hydraulic filter is attached.Required Parts for C-Series Backhoe Loaders

Required Parts for B-Series Backhoe Loaders

Procedure to Install Check Valve for the C-Series Backhoe Loader

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To prevent personal injury, move the control levers backward and forward to release the pressure in the hydraulic system. Slowly loosen the cap of the hydraulic tank. Be cautious of hot hydraulic oil when any lines are disconnected in the hydraulic system.

1. Disconnect the return hose and remove the 6V-9007 Elbow currently in the outlet port of the Loader Valve. (See Illustration 2)

2. Install the 8T-6451 Elbow into the Loader Valve outlet port.

3. Install the 9X-6643 Adapter into the 8T-6451 Elbow.

4. Install the 129-1555 Check Valve Group.

5. Install the 6V-8946 Reducer Assembly on the 129-1555 Check Valve Group.

6. Reinstall the return hose to the Reducer Assembly.

Procedure to Install Check Valve for the B-Series Backhoe Loader

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To prevent personal injury, move the control levers backward and forward to release the pressure in the hydraulic system. Slowly loosen the cap of the hydraulic tank. Be cautious of hot hydraulic oil when any lines are disconnected in the hydraulic system.

1. Disconnect the hydraulic lines from the 8T-1685 Tee and remove the tee from the Loader Valve. (See Illustration 3)

2. Add 129-1555 Check Valve Group to Loader Valve.

3. Install 6V-8946 Reducer Assembly into 129-1555 Check Valve Group.

4. Install 6V-9839 Tee into the into the 6V-8946 Reducer.

5. Reassemble the hydraulic lines to 6V-9839 Tee.

Illustration 1. C-Series Components.

The front of the machine is indicated by the pointer.

NOTE: It is optional to remove the 6V-8946 Reducer Assembly and change hose coupling from 45° to 90°.

Illustration 2. C-Series. Loader Valve (1). Location of 6V-9007 Elbow.

Illustration 3. B-Series. Remove 8T-1685 Tee (1) first.

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