The Piston Locknut for the 155-9255 Bucket Cylinder May Loosen

Usage:

The Piston Locknut for the <a class="catalog_a_num" href="https://avspare.com/caterpillar/cylinder/1559255/">155-9255</a> Bucket Cylinder May Loosen

CONFIDENTIAL

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TECHNICAL INFORMATION BULLETIN	MAY 24, 2000
EXCAVATORS	315B (3AW1200-Up), (1SW1-Up) EXCAVATORS
	COMPONENT CODE: 5457

SUBJECT: THE PISTON LOCKNUT FOR THE 155-9255 BUCKET CYLINDER MAY
LOOSEN

PROBLEM:

Several field reports have identified the problem that the 133-6686 Locknut for the cylinder piston may be loose in the 155-9255 Bucket Cylinder. Failure to identify this problem in time can result in catastrophic damage to the cylinder and the 131-5763 Control Valve.

Reports from dealers into the SIMS reporting system have identified that the majority of the failures appear to occur in the range of 900 to 1200 hours and on the 315B after 3AW1200. However, the reports are showing that the range of affected machines are sporadic and the failures are not isolated to a specific service meter reading.

Failed components that have been returned to Engineering are being analyzed. While Engineering is investigating the root cause of the failures, Caterpillar recommends that all suspected 315B Excavators that are in dealer inventories should be checked in order to insure that the bucket cylinder locknut is tightened to the specified torque of 3100 ? 160 N?m (2280 ? 120 lb ft).

NOTE: Current inventories in the Parts Distribution System are depleted, but Engineering is negotiating to obtain additional bucket cylinders.

SOLUTION:

Inspect the 155-9255 Bucket Cylinders on the suspect machines for the correct torque specification of the piston locknuts. Refer to the Service Manual Module, RENR1131, Disassembly and Assembly Manual for the correct procedure to remove, disassemble, assemble and install the cylinders. The correct specification for the piston locknut in the bucket cylinder is 3100 ? 160 N?m (2280 ? 120 lb ft).

NOTE: Lubricate the threads and the face of the locknut before the locknut is assembled.

If you experience failures or can identify machines with loose locknuts, please contact the Small Excavator Product Support Analyst at Building Construction Products: Jim Bathrick, phone number, (919) 465-2742. The analyst will then submit a parts return request.

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)