Hydraulic System Cleanup Recommendations Following Catastrophic Component Failures on Wheel Loader Hydraulic Systems {0645, 0680, 0738, 0768, 5050, 5056, 5095} Caterpillar

Integrated Toolcarrier

All

Landfill Compactor

All

Soil Compactor

All

Wheel Dozer

All

Wheel Loader

All Large Wheel Loaders

All Medium Wheel Loaders

Introduction

This document describes basic cleanup procedures and recommendations following a catastrophic component failure on Caterpillar Large and Medium Wheel Loaders. The primary focus of this document is piston pump failures. The principles can be applied to any catastrophic failure in which debris is present in the hydraulic system.

Cleanup Recommendations

Note: This document lists standard recommendations only. Not every failure can be anticipated. Dealer discretion should be used to determine the level of cleanup that is necessary following a failure.

Following a catastrophic pump failure, the entire hydraulic system should be cleaned by kidney loop filtration. Service also recommends that all hydraulic lines are cleaned by shooting projectiles through the lines. The preferred practice is to replace hydraulic hoses that are near the failed components. Shards of debris may have become lodged in the hoses. The debris can later dislodge due to cycles in system pressure and flow, which may cause subsequent failures. All cylinders that are in the same circuit as the failed component should be disassembled, cleaned, and resealed. If the cylinders are not cleaned and resealed, contaminants could remain in the cylinders. These contaminants could then cycle back and forth as the cylinders are stroked.

Any hydraulic circuit that has been activated after the pump failure could contain debris. For example, if the lift circuit was activated, contamination has likely traveled to the control valve, cylinders, lines, and so on. Thoroughly inspect and clean all such components.

Thoroughly clean all hydraulic reservoirs. Make sure that there are no loose parts in the tank. During operation of the machine, parts that have not been removed could travel through the hydraulic system. This process can result in repeat failures of the various hydraulic components.

Inspect all oil coolers, cooler bypass components, and related items. Heat exchanger tubes may trap debris. Heat exchanger cores should be replaced following any catastrophic failure. If the cooler bypass is blocked open, this issue could cause the pump to cavitate. Any solenoid controlled valves in the system should be replaced, as any ferrous debris will be attracted to the coil magnets.

After catastrophic component failure, the standard cleanliness recommendations must be applied. The following documents contain cleanup recommendations and reference information.

Reference: Special Publication, SEBF8279, "Procedure for Operating Caterpillar Filter Carts"

Reference: Special Publication, SEBF8493, "Procedure for Filtering Wheel Loader, Landfill Compactor, Soil Compactor, and Integrated Toolcarrier Hydraulic Oil"

Reference: Special Publication, SEBF9199, "Filtration Times for Caterpillar Machine Fluid Compartments"

Reference: Special Publication, SEBF8485, "Cleaning Fluid-Carrying Hose and Tube Assemblies In Shop and Field Applications"

Reference: Special Publication, SEBF8482, "Obtaining Oil Samples for Analysis"

Reference: Special Instruction, REHS1656, "Flushing Contaminated Wheel Loader Hydraulic Systems"

Referring to the above documents, determine effective cleanup of the hydraulic system based on the following steps.

1. Establish a baseline particle count by collecting an oil sample while the machine is at low idle. DO NOT operate the Implements or the steering.

2. If the baseline particle count is above ISO 18/15, connect the appropriate Caterpillar Filter Cart. Perform a Kidney Loop filtration of the main hydraulic tank until a particle count of ISO 18/15 is obtained.

3. After the particle count has reached ISO 18/15 or better while at low idle, cycle the implements. Cycle the Rack-Back, Dump, Raise Boom, Lower Boom, Steer Right, and Steer Left two to three times (still at low engine idle speed).

4. Obtain another particle count in order to make sure operating the implements did not introduce additional contaminants into the hydraulic system. If a particle count above ISO 18/15 is measured, repeat the process until satisfactory results are obtained.

5. After a stable ISO Particle Count of 18/15 or better is obtained, the machine can be placed back into service.

6. Revisiting the machine at 250 and 500 SMU Service Hours is recommended to obtain a follow-up SOS Particle Count.

Note: Refer to the Hydraulic Schematic for the machine. Consider the potential flow paths on the schematic in order to predict the possible locations where contamination or debris may be found.

Note: High-Efficiency filters can be used to clean out the system. Caution should be exercised in regard to "blind" components that could be harboring contaminants.