SPRING 1175913 - Caterpillar

The engine has a camshaft assembly for each side of the engine.The camshafts are made from identical camshaft segments, journals, spacers and a drive end. Each camshaft segment has three lobes. The camshaft segments are replaceable at each cylinder through access holes in the cylinder block. A thrust plate at the rear of each camshaft controls end play. Each camshaft for the 3612 Engine is supported by seven bearings. Each camshaft for the 3616 Engine is supported by nine bearings.As the camshaft turns, each lobe moves a lifter assembly. There are three lifter assemblies for each cylinder. Each of the lifter assemblies that are on the ends of the lifter guide move a pushrod and a set of valves (inlet or exhaust). The center lifter assembly moves a pushrod that operates the unit injector.The camshaft must be in time with the crankshaft and with each other. The relation of the camshaft lobes to the crankshaft position will cause the valves (inlet and exhaust) and the unit injector in each cylinder to operate at the correct time. The crankshaft/camshaft timing is established by the No. 1 cylinder when the No. 1 cylinder is in the top center position (TC). Timing pins are provided for the camshaft and the crankshaft in order to establish No. 1 top center position (TC).