3.2 General


3.2.1 Mated and matched assemblies

The hydraulic head and rotor should be separated and examined; they should be re-mated immediately after examination and immersed in a covered bath of clean test oil until required for reassembly into the pump.

The following groups are matched and must be kept in their sets:

  1. Rollers and shoes
  2. Delivery valves and seats
  3. Advance housing, piston(s) and servo valve
  4. Latch valve and body
  5. Rotor vent switch valve and body
  6. Cam ring and scroll plates
  7. Stop solenoid plunger and body
  8. Cold idle advance body and piston

If any part is considered to be unfit for further service, the whole assembly must be replaced.

The pump housing drive shaft bush is not a service repair item; if the bearing is worn, the housing must be replaced.

3.2.2 Examination and replacement

Check all components for corrosion, wear, or damage. Under service workshop conditions it is not feasible to test individual parts or subassemblies to determine their suitability for further service. Close examination of the areas vulnerable to damage, and interpretation of pre-test results, should indicate the condition of parts.

A) Corrosion

Check for signs of corrosion or water ingress (rust or staining) damage to machined surfaces. These include the pump housing, drive shaft. rear bearing, hydraulic head bore, cam ring, scroll plates, end plate, valves and auto advance device.

B) Wear

Inspect drive shaft splines and associated parts for wear or damage. If excessive end-float or radial play was detected prior to pump strip down, examine the drive shaft thrust washer and housing bearing thrust face for wear.

C) Damage

Inspect all parts for damage or bending due to abuse, especially external levers and controls.

3.2.3 Seals

Replace all gaskets i.e. the governor cover, advance device and inspection cover, as well as all seals. Note that overhaul kits may not include drive shaft seals, which are stocked as separate items.

When fitting new O-rings and oil seals, care must be taken to use protection caps to avoid damage to the seals.

Internal seals must be dipped in clean test oil prior to being assembled. External seals must be lightly coated with grease. Where possible, inspect seals for small cuts after assembly.

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