PUMP GP-GEAR 1265013 - Caterpillar

There is one two-piece camshaft per side. The 3512B camshaft is supported by seven bearings. The 3516B camshaft is supported by nine bearings. Each camshaft is driven by the gears at the rear of the engine.As the camshaft turns, each lobe moves a lifter assembly. There are three lifter assemblies for each cylinder. Each outside lifter assembly moves a pushrod and two valves. The valves can be inlet valves or exhaust valves. The center lifter assembly moves a pushrod that operates the fuel injector. The camshafts must be in time with the crankshaft. The relation of the camshaft lobes to the crankshaft position causes the valves and fuel injectors in each cylinder to operate at the correct time.