Usage:
A new type of cartridge for the Vickers vane-type hydraulic pump is now used on some models. The new cartridge has steel-backed bronze plates between the rotor and the end plates. These plates are pressure controlled to keep the correct clearance between the rotor and the plates. The new cartridge operates at a lower noise level. Also, rotor seizure failures are less probable because the bronze surface gives some bearing action for the end of the rotor and because of the pressure and clearance control of the plates.
New vane-type pump.
During normal operation, the bronze plates and the end face of the rotor will show some discoloration (change of color). The former design will have no discoloration under normal conditions. The discoloration is caused by lead oxide in the bronze and is normal. It has no effect on the pump efficiency. In addition to the discoloration, the bronze material is softer than the cast iron end plates which are against the rotor in the former design. This softer material will tolerate minor surface defects such as small amounts of pitting, erosion, fretting and heat checks.
A Guideline for Reusable Parts, Form SEBF8025 is available to assist in analyzing the reusability of the new design parts. Other than the steel-backed bronze plates and the new end plate, the remainder of the pump has not changed. A tee test should be used to determine the pump efficiency in those cases where there is doubt about the reusability of the parts.