PL72 Pipelayer Caterpillar

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Personal injury or death can result from grease under pressure. Grease coming out of the relief valve under pressure can penetrate the body causing injury or death. Do not watch the relief valve to see if grease is escaping. Watch the track or track adjustment cylinder to see if the track is being loosened. Loosen the relief valve one turn only. If track does not loosen, close the relief valve and contact your Caterpillar dealer.

1. Move the machine forward. Allow the machine to coast to a stop without the use of the service brakes. Adjust the tracks while you are located in typical operating conditions for the machine. If packing conditions prevail on the workplace, the tracks should be adjusted without removing the packed material.
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   Illustration 1	g03746430

2. To measure the sag in the track, stretch a string over the grousers that are between the drive sprocket and the front idler. Record the measurement from the string to the top of the grouser at the maximum dimension for point (A) and the maximum dimension for point (B).

Calculate the average of dimension (A) and dimension (B). The correct average value is 55 ± 10 mm (2.2 ± 0.4 inch).

Loose Track Adjustment

Use the following procedure if the tracks are loose.

Illustration 2	g03746469

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Illustration 3	g03746500
(1) Access cover (2) Relief valve (3) Adjustment valve

1. Remove access cover (1).

2. Add multipurpose grease (MPGM) through track adjustment valve (3). Add the MPGM until the average value of dimension (A) and dimension (B) is correct.

3. Operate the machine back and forth in order to equalize the pressure. Allow the machine to coast to a complete stop. Do not use the brakes.

4. Remeasure dimension (C).

Tight Track Adjustment

Use the following procedure if the tracks are too tight.

1. Loosen relief valve (2) by one turn of 360 degrees. Allow the grease to escape.

2. Close the valve. Tighten the valve to a torque of 34 ± 7 N·m (25 ± 5 lb ft).

3. Install the access cover.

Bolt Torque for Track Shoes

The track shoe bolts are 19.0 mm (0.75 inch). The torque requirement for track shoe bolts is 400 ± 70 N·m (300 ± 50 lb ft). Tighten the bolts by an additional turn of 120 degrees. If you are using bolts with a master link, tighten the bolts to a torque of 400 ± 70 N·m (300 ± 50 lb ft). Then, tighten the bolts by an additional turn of 120 degrees.