Repair of the CAT SBS80 Pump – Typical Failures, Service Process, and Tests
Hydraulic pumps in construction machines, such as the excavator CAT 318D, are responsible for the proper functioning of the entire working system. One of the most common problems in the SBS80 model is a drop in performance after the oil has warmed up. Below, we discuss the causes of failures, the repair process, and the final tests.
Most Common Symptoms of CAT SBS80 Pump Failure
Operators primarily report a loss of power and slower machine operation after the oil has warmed up. This is a classic signal that the pump is not maintaining its parameters. The most common reasons are:
- Worn Regulators – lack of tightness, oil leakage, and unstable regulation,
- Worn Pistons and Cylinders – causing a drop in working pressure,
- System Leaks – especially at higher oil temperatures.
Verification and Diagnosis
Disassembly of Regulators
In the CAT SBS80 pump, the control piston is located in the regulator, allowing for its replacement without interfering with the housing. This significantly reduces repair costs compared to pumps where the piston is located in the main housing.
Assessment of the Rotating Group
During verification, we check the tightness of the pistons. If oil is leaking from the sides, it means that the components are worn and do not ensure proper operation at higher temperatures. In this instance, it was necessary to replace the complete set of pistons, cylinders, and sliding bearings.
Repair – Step by Step
After thorough cleaning and preparation of the components, we carried out a comprehensive regeneration. Worn parts were replaced with new ones, and the tilting plates were ground. When assembling, we pay special attention to:
- the correct working direction of the tilting plates (left/right),
- seating and securing of the shafts,
- lubrication and proper fitting of the components,
- installation of control coils responsible for regulating the pump's performance.
Tests on the Test Bench
The assembled pump goes to the test station. The most important aspect is comparing performance on cold and warmed-up oil. A well-regenerated pump maintains stable pressure, and the difference between operation at 20°C and 70°C is minimal. In the case of this SBS80, tests confirmed full functionality.
Why Is It Worth Entrusting Repairs to Specialists?
Self-diagnosing hydraulic pumps is difficult, and the symptoms often lead to confusion. In our service, we offer free verification of hydraulic pumps on the same day they arrive. This allows the customer to quickly learn the actual condition of the pump and the scope of repairs needed.
Summary
The CAT SBS80 pump has its typical weaknesses, but after professional regeneration, it returns to full functionality. Regular inspection and a quick response to the first signs of performance drop can help avoid serious failures and costly downtimes.
