Before removing unit or parts of unit to be serviced, be certain the unit is not
subject to hydraulic pressure.
A puller must be used to remove pulley or gear from shaft. Otherwise bearing and shaft damage may result.
During disassembly, special attention should be given to identification of parts for proper reassembly.
Clean all parts except O-ring seals in a clean mineral solvent. Blow the parts dry with filtered compressed air.
After drying thoroughly, lay the parts on a clean, lint-free surface. All internal oil passages of the pump cover,
housing, and body must be thoroughly cleaned.
All O-rings, and the shaft seal should be replaced at reassembly. All seals should be soaked in hydraulic fluid
before being used. Refer to Fig. 7 and proceed with disassembly.
Reservoir and Manifold
1. VTM40 and VTM41 Reservoir-The VTM40 and VTM41 pumps are tank enclosed units. To remove
the reservoir from the pump, simply remove the discharge fitting, backup washer, and O-ring and free the
reservoir from the pump.
2. VTM27, VTM28, and VTM42 Reservoir-Begin disassembly of VTM27, VTM28, and VTM42 pumps
equipped with externally mounted reservoirs as follows:
Clamp pump mounting flange in a machinist's vise, being certain to use protective jaws. Remove wing nut,
washer, cover, and gasket. Remove cotter pin
from reservoir stud. Lift flat washer, retainer spring, filter retainer, and filter element from stud. Remove
reservoir stud and nut assembly. Remove the two capscrews, lockwashers, and baffle. Separate reservoir
from pump and remove the O-rings from their seats in the cover.
3. VTM27, VTM28, and VTM42 Manifold-Begin disassembly of the VTM27, VTM28, and VTM42 units
equipped with manifolds by removing the capscrews, copper washer, manifold, and O-rings from the pump
Cover and Cartridge-Clamp pump mount- ing flange in a machinist's vise, being certain to use protective jaws.
Remove cover mounting capscrews. Separate the cover from the pump body. Remove pressure plate spring
and pressure plate. Remove adapter plate and O-rings (VTM40 and VTM41 units only). Remove pump ring,
locating pins, rotor and vanes, and the two O-rings.
Mount the cover in a vise. Drive out retaining pin with pin punch. Protect the relief valve plug and
subassembly against falling from bore. Work the plug, control valve, and spring from the bore.
Access to the relief valve plug and subassembly may be gained through the large
chamfered hole which leads to relief valve bore from inside the cover.
Wash all parts in clean solvent. Inspect relief valve and bore for wear and scoring.