Preparation For Disassembly
Overhaul motor only in a clean, dust-free location, using clean tools and equipment. Dirt or grit will damage the highly machined surfaces and will result in leakage or premature failure of the motor.
Before beginning disassembly, scribe match marks at the junction of the body and cover to ensure that the motor will be reassembled in the same manner as it was when shipped from the factory. If the body or rear cover is replaced during overhaul, scribe a match mark on the new part in the same location as on the part it replaced.
All reference numbers refer to items illustrated in the exploded view provided with the parts list section of this publication.
Clean outside of motor with a good grade solvent and dry thoroughly.
On models with splined drive shaft, proceed to next step. On models with keyed drive shaft, remove woodruff key (10) and snap ring (11) from drive shaft. Using a file or stone, remove any burrs or sharp edges from shaft end and keyway, grease keyway before removing rear.
Secure unit in vise (use light clamping pressure) with shaft end down; remove cap screws (1) and washers (2).
To ensure maximum efficiency after overhaul, serviceable worn parts should be returned to the same position from which they were removed. Take special note of the wear pattern on wear plate (5) and thrust plate* (4). Wear pattern can be symmetrical on a reversible motor. Also note that the long journal of driven gear (13) is toward the drive end of the motor.
Separate rear cover (12) from body (15) by supporting motor, shaft end up, on mounting flanges and pressing on drive shaft end in arbor press.
Use one hand to support rear cover from underneath, since cover and internal parts will drop suddenly when dowels are disengaged.
An alternate method of removing the rear cover is to hold the motor with the drive end up and tap the end of the drive gear shaft with a plastic head mallet. Do not use a metal hammer.
Remove dowel pins (7) from either rear cover or body.
Square cut ring (3) and thrust plate *(4) may or may not remain with rear cover. Should they remain with body, remove square cut ring and lift out thrust plate before proceeding.
Lift out driven gear (13), drive gear (14), and wear plate (5) with pressure seal (6). On "MC" Series invert body and ball bearings (16) will drop out.
On "MC" Series do not remove plug (17) from body (15).
Invert motor body with shaft seal up. Remove retainer (8); then remove shaft seal (9) by prying it out with a large screwdriver.
Care should be taken not to damage the shaft seal bore as this would result in seal leakage.
*May be of 2 wear plate design (3), no thrust plate, M30.
Wash all parts with a high-grade solvent and dry thoroughly.
Inspect wear plate (5) and thrust plate (4). Replace if scoring or uneven wear is observed.
Remove pressure loading seal (6) from wear plate. This seal may be of two-piece or one-piece design. In either case, discard old seal or seals. All replacement seals should be two-piece design and should be installed into groove with Nylatron, flat surface out. The seal should extend a minimum of .127 mm (.005 in.) above surface of wear plate. Do not push seal to flush or below wear plate surface at any point.
Inspect needle bearings in body and cover. Replace cover or body if bearings are damaged, skewed or broken.
Inspect gear journals and faces. Replace if faces or journals are scored or worn, or if shaft journal wear exceeds .025 mm (.001 in.) differential between a worn and unworn diameter.
Inspect body for wear and scoring. If gear contact wear on low pressure (outlet) side exceeds .127 mm (.005 in.) depth, replace body. If the body is usable, remove wipe burr with suitable burring tool.