Optimized Cat® Method for Engine Balancing

Optimized Cat^® Method for Engine Balancing

Off-Highway Truck/Tractor:

793C (S/N: ATY1-UP)

793D (S/N: FDB1-UP)

797B (S/N: JSM1-UP; 3TN1-UP)

Introduction

This special instruction describes the method for engine balancing.

Engine Balancing

Tests on Caterpillar engines built with tighter tolerances for cylinder-to-cylinder piston and rod assembly weight variation have shown no significant benefit when compared to normal Reman engine tolerances. Engines that are assembled with Cat^® genuine parts, or with Cat genuine parts that have been salvaged as described by the Reuse and Salvage Guidelines will be within specification from an engine vibration standpoint and no further actions should be required.
Assembly methods may at times appear to improve overall engine balance but there are many factors that can affect engine vibration. If desired, to minimize any effects of mass variation between components Cat recommends individually weighing each piston, rod, piston pin, and assembling the parts to minimize weight variation between the assemblies. Then place the heavier piston and connecting rod assemblies on the left-hand bank of cylinders and the lighter piston and connecting rod assemblies on the right-hand bank. The heaviest assembly will start at cylinder 1 and getting progressively lighter with the lightest assembly at cylinder 2.

Figure 1 Illustrates piston and rod assemblies weight and position in the engine.