Cleaning and Inspection

Steam cleaning assembled drive units after they have been removed from housing is not recommended. It is necessary to completely disassemble drive unit for proper cleaning. Clean all components in suitable solvent and dry immediately afterward. Use soft, clean, lintless paper towels or wiping rags free of abrasive material. Bearings should never be dried by spinning with compressed air.
Inspect all bearings, cups, and cones, including those not removed from parts of drive unit, and replace if rollers or cups are worn, pitted, or damaged in any way. Remove parts needing replacement with suitable puller or in a press with sleeves. Avoid the use of drifts and hammers as they may easily mutilate or distort component parts.
Ring gear and pinion are a matched set and must be replaced as an assembly. Both ring gear and pinion in a replacement set have a matching mark such as ``M29'' or a similar letter/number combination. On the ring gear, matching numbers can be found on the front face of the gear or on the machined outer diameter. On the pinion, matching marks are usually found on the pinion face. However, on pinions with parallel sided splines, the number may be marked on the top flat or one of the splines. Do not install a ring gear and pinion assembly if the matching marks are not the same.

Fig. 6 Pinion Code & Matching Mark Identification:

Fig. 7 Pinion Shim Pack Thickness Chart:

In addition, each pinion has a Pinion Code (P.C.) Variation Number which indicates variations in thousandths of an inch from the nominal pinion depth setting. This number must be used to modify the Nominal Pinion Gauging Number when calculating shim pack thickness to set pinion depth. This variation number is stamped as either a plus (+) or minus (-) value, and is located adjacent to the matching number, Fig. 6.
When a new pinion is installed, shim pack thickness can be determined using the pinion code numbers and chart, Fig. 7.