Rotation Of Coupler Pins Causes Difficulty Coupling Work Tools Caterpillar

Problem:

Rotation of the quick coupler pins causes difficulty connecting work tools to the machine because the pins may not enter the engagement window of the worktool. This rotation occurs when the setscrew designed to prevent rotation of the pins does not contact the pin. During the heat treat process the tapped hole for the setscrew becomes distorted and prevents the setscrew from engaging the pin.

Solution:

On the above machines, perform the following Quick Coupler Pins Inspection Procedure:

1. Without any tool on the coupler, extend the Quick Coupler Pins.

2. Shutoff the engine.

3. Try to rotate the Quick Coupler Pins. If the Setscrew is properly installed, the Coupler Pins will only rotate approximately 5 degrees in either direction. Otherwise, if the pins can be rotated, perform the rework procedure.

Rework Procedure. See Illustration 1.

1. Remove 138-1232 Plate (4) and 138-1234 Plate (5).

2. Remove the 4B-3566 Setscrew (2) from each coupler.

3. Retap setscrew holes using 4C-4971 Bottom Tap 1/4-20. Note:

NOTE: Do not force the tap hard against the quick coupler pin.

4. Place 154-9731 Thread Lock Compound (10 mL) or 155-0695 Thread Lock Compound (50mL) on the two 4B-3566 Setscrews (2). Install the the two 4B-3566 Setscrews (2). Tighten the Setscrews to a torque of 12 N·m (106 lb in).

5. Install the 138-1232 Plate (4) and 138-1234 Plate (5). Tighten the four bolts (3) to a torque of 12 N·m (106 lb in).

Illustration 1.

View of the Quick Coupler for 902 or 906 Compact Wheel Loaders.

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