RESISTOR 4723611 - Caterpillar

(67M),
637 (65M) and 637 PP (79P) TractorsReference: Service Magazine, June 28, 1976, Pages 6 and 7. The article "Hydraulic Pump Will Engage Completely In New Gear Assembly" tells about the use of a new gear assembly. This gear assembly was needed to permit clearance for the seal surface on the pump drive shafts that have two seals. The article tells how to machine the former gear assembly so the pumps can be used. The article does not include information about the above tractors.On some 631C, 637 and 637 (PP) Tractors, it is possible that there is not enough clearance between the end of the gear and the end of the shaft seal area. To make sure the pump will fit correctly, remove the seal from the pump flange. Install the pump and check for a gap between the pump flange and the bearing cage. If there is no gap, the be removed from the gear.
If the engine is in the tractor, it will be easier to grind a chamfer on the inside bore of the gear. The chamfer must be approximately 3.0 mm (.12") × 45° or enough to provide clearance so that there is no gap when the pump is installed. Shop towels can be put in the bore of the gear to keep out debris when the chamfer is machined. Make sure no debris gets into the system.
If the engine is out of the tractor, 4.8 mm (.19") of material can be machined off the hub of the gear.
When the pump is installed, make sure it fits completely against the bearing cage. The mounting bolts must not be used to force the pump against the bearing cage.