CONFIDENTIAL TIBU3697

Building Construction Products Service has received several reports for loose piston locknuts on the stick cylinders or the bucket cylinders. Reports from Dealers indicate that initial customer complaints identify excessive cylinder drift and/or noise from the affected cylinder. Failure to identify this problem in a timely manner can result in catastrophic damage to the hydraulic cylinder and the main control valve.

Caterpillar recommends that a stick cylinder or a bucket cylinder with a customer complaint of cylinder noise or cylinder drift should be removed from the machine. Perform an inspection of the piston locknut for the correct torque.

Inspect the stick cylinder or the bucket cylinder on suspect machines for the correct torque of the piston locknut. Refer to the appropriate Disassemble and Assemble Manual for the correct procedure to remove, disassemble, assemble and install the cylinders. See the following instructions for the cylinder torque specifications and the procedure to check the piston locknut torque.

INSPECTION PROCEDURE FOR CYLINDER PISTON LOCKNUT

1. Remove the appropriate cylinder from the machine and remove the rod assembly from the barrel. See the appropriate D&A module.
2. Mark the current location of the piston locknut in relation to the rod.
3. Place the torque tool in position and mark the socket location to match the piston locknut and rod mark.

NOTE: This depends upon the torque tool that is being used.

4. Loosen the piston locknut by turning the locknut 90 degrees counterclockwise from the locknut?s current position.
5. Increase the torque and stop when the marks are lined up. Record the torque value that is registered on the tool. Contact either Jim Bathrick, phone 919-465-2742, or Don Allen, phone 919-465-2743 with the results.
6. Tighten the cylinder piston locknut to the correct torque specification that is identified in the table below. Assemble the cylinder and install the cylinder on the machine.

If you experience failures or identify machines with loose piston locknuts, please contact the Small Excavator Product Support Group at Building Construction Products: Jim Bathrick, phone number, (919) 465-2742, or Don Allen, phone number (919) 465-2743.

Please provide the following information:

• Product Identification Number (PIN)
• Machine Service Hours
• Machine Configuration
• Machine Application
• Piston Retaining Locknut Torque (if found prior to failure)
• Extent Of Damage (if failure has occurred)
• Work Order Number (if failure has occurred)
  

COPYRIGHT 2002 CATERPILLAR
ALL RIGHTS RESERVED