TH220B, TH330B and TH340B Telehandlers Boom Wear Pad Clearance - Inspect/Adjust Caterpillar

The clearance between the wear pads and the boom section should be checked at more frequent intervals when the machine is operated in severe conditions.

Note: Sand or grit particles can cause accelerated wear to the wear pads.

1. Park the machine in a clear area on level ground and chock the wheels.
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   The boom can fall if a control is moved or if a hydraulic component fails. This can cause personal injury or death. Support the boom with stands. Do not rely on the cylinder to hold the boom up.

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   Illustration 1	g00857782

2. Raise the boom to the horizontal position and fully extend the boom. Install a suitable stand under the first section in order to prevent the boom from falling unexpectedly. Do not support the second and third sections. To properly support the boom, use the following tools:
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   Table 1

   Required Tools
   Part Number	Description	Quantity
   8S-7641	Tube	1
   4C-6486	Stand	1
   8S-7615	Pin	1
   8S-7625	Collar	1
   8S-8048	Saddle	1

3. Stop the engine.
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   Illustration 2	g00857783

4. Measure clearances (1) between the wear pads and the side of the boom sections at each side.

5. Measure clearances (2) between the wear pads and the top of the boom sections.
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   Illustration 3	g00857785

6. Raise the boom and remove the stand. Fully retract the boom and support the boom in the horizontal position. In order to support the boom, install the stand under the third section or install cribbing under the quick coupler.
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   Illustration 4	g00857804

7. Remove the cover from the rear of the chassis and measure clearances (3) between the rear wear pads and the side of the boom sections at each side.

8. Measure clearances (4) between the rear wear pads and the top of the boom sections.

9. The clearance at each location must not exceed 1.5 mm (0.06 inch). If the clearances are excessive, adjustments must be made.

Adjustment

Note: The bolts that secure different wear pads are not identical lengths. Do not mix the bolts. Clean all used bolts. Before installation, apply thread lock compound to bolts that secure wear pads.

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Illustration 5	g00858058

1. Loosen bolts (5) that secure the rear top wear pads. Install sufficient shims in order to reduce the clearance to 0.75 mm (0.030 inch). Tighten the bolts to a torque of 75 ± 5 N·m (55 ± 4 lb ft).

2. Remove bolts (6) that secure the rear side wear pads. Install sufficient shims in order to reduce the clearance to 0.75 mm (0.030 inch) at each side. Install sufficient shims in order to produce an equal clearance between the boom sections at each side. It may be necessary to install more shims at one side than the other side. Tighten the bolts to a torque of 75 ± 5 N·m (55 ± 4 lb ft).
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   Illustration 6	g00857793

3. Raise the boom sufficiently above the stand. Fully extend the boom and lower the boom to the horizontal position. Support the boom under the third section.
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   Illustration 7	g00865469

4. Remove bolts (7) that secure the bottom wear pads. Install sufficient shims in order to reduce the clearance to 0.75 mm (0.030 inch). Tighten the bolts to a torque of 75 ± 5 N·m (55 ± 4 lb ft).
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   Illustration 8	g00865472

5. Remove bolts (8) that secure the side wear pads. Install sufficient shims in order to reduce the clearance to 0.75 mm (0.030 inch) at each side. Install sufficient shims in order to produce an equal clearance between the wear pads and the boom sections at each side. It may be necessary to install more shims at one side than the other side. Tighten the bolts to a torque of 75 ± 5 N·m (55 ± 4 lb ft).

6. Fully extend and retract the boom at angles of 0 degrees, 45 degrees and 70 degrees. The boom operation must be smooth. If the boom operation is not smooth, operate the boom with a load of 500 kg (1100 lb) on the attachment. Fully extend the boom and retract the boom at an angle of 45 degrees. Repeat ten times.
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   Illustration 9	g00858059

7. Extend the boom and lower the work tool to the ground. Lower the boom to the ground and fully extend the boom. Check the temperature of the top surfaces of number 1 boom section and number 2 boom section. Check the temperature of the wear pads at opposite locations at positions (A) and at positions (B). Both sides of each section should feel the same temperature. If necessary, increase the thickness of the shims under the rear wear pad which is in contact with the cool side of the boom section. Alternatively, decrease the thickness of the shims under the front wear pad which is in contact with the hot side of the boom section.

8. Install the cover on the rear of the boom.