ENGINE AR-COMPLETE 3389076 - Caterpillar

Illustration 1 g00816510
Typical camshaft assembly
The engine has a camshaft assembly for each bank.The camshafts are assembled with identical segments, journals, spacers, and a drive end. Each segment has three lobes. Individual segments can be replaced for each cylinder through access holes in the cylinder block. The camshaft assembly is supported by bearings. A thrust plate at the rear of each camshaft controls end play.As the camshaft turns, each lobe moves a lifter assembly. There are three lifter assemblies for each cylinder. Each outer lifter assembly moves a pushrod for two inlet valves or for two exhaust valves. The center lifter assembly moves a pushrod that operates the gas admission valve.The relation of the camshaft to the crankshaft position cause the valves to operate at the correct time. The camshaft must be in time with the crankshaft.