CYLINDER GP-COUPLER 2743404 - Caterpillar

TECHNICAL INFORMATION BULLETIN April 23, 2003
OFF-HIGHWAY TRUCKS ALL
Component Codes 7200, 7201, 7213SUBJECT: Additions to Service Maintenance Interval for Suspension Cylinders on Off-Highway Trucks
PROBLEM:
Damage can occur to a suspension cylinder that operates at low pre-charge or low hydraulic oil levels. Front and rear suspension cylinder service intervals will be added to the machine maintenance manual to provide the correct information to the field regarding proper operating conditions and proper servicing of suspension cylinders.
When properly maintained, the suspension cylinder will operate on a nitrogen and oil volume. The cylinder will provide excellent service for a long period of time when the nitrogen and oil volume is maintained at the recommended levels. When nitrogen and oil levels are below the recommended levels, the cylinder piston can impact the cylinder head or barrel as the rod extends or retracts. This will transfer the load of the truck to the cylinder head or barrel, resulting in damage to components in the suspension cylinder.
SOLUTION:
The following additions to the service manual maintenance intervals and component servicing should be adhered to in order to prevent damage to suspension cylinders.
Daily:
Visually inspect the front and rear suspension cylinders for oil leaking. If oil leaking is present, remove the cylinder and repair the leaking condition before continued operation of the truck or as soon as practical.
Visually inspect the front suspension cylinder grease relief valve to verify that grease does come out of the relief valve. Do not attempt to remove a grease relief valve or a grease inlet passage plug when there is pressure in the cylinder.
Visually inspect the front suspension cylinders for a condition that can occur where grease will be forced into the gas cavity inside of the cylinder. This condition will limit the travel of the cylinder rod and cause the truck ride to become harsh. If reduced cylinder rod travel is found, remove the cylinder and repair the problem before continued operation or as soon as practical.
Visually inspect the front and rear suspension cylinders for any unusual conditions that might affect the operation of the cylinder or the ride of the truck, i.e.: collapsed cylinder, excessive rod extension, and cylinder rod chrome damage.
Every 500 hours:
Measure and record ride height dimensions and compare these measurements with measurements in the previous service interval. If the measurement is not within the limits specified in the Operation and Maintenance Manual, stop operation of the truck until the necessary suspension cylinder repair is completed.
Annually:
Purge the nitrogen charge from the suspension cylinders. (See Service Manual - Testing and Adjusting).
Replace front suspension cylinder grease relief valves and make sure all grease ports are clear.
Re-charge the suspension cylinders with nitrogen charge. (See Service Manual - Testing and Adjusting).
Personal injury or death can result from sudden suspension cylinder movement.
Sudden movement, up or down, can cause the clearance above your head to change rapidly.
Read all warning labels on the suspension cylinders before servicing. Do not check the oil in the suspension cylinder until all the nitrogen pressure has been released.
Do not, under any condition, remove valves, cover