CLIP 1241108 - Caterpillar

The valve system components control the flow of inlet air and of exhaust gases through the cylinder head during engine operation.The crankshaft gear drives the camshaft gears through idler gears. Both camshafts must be timed to the crankshaft in order to get the correct relation between the piston and the valve movement.The camshafts have three lobes for each cylinder. Two lobes operate the valves and one operates the fuel injector.
Illustration 1 g01166681
Valve system components
(1) Rocker arm
(2) Bridge
(3) Rotocoil
(4) Valve spring
(5) Pushrod
(6) Lifter As the camshaft turns, the lobe on the camshaft causes lifter (6) to move up and down. This movement causes the pushrod (5) to move rocker arm (1). The movement of the rocker arm causes bridge (2) to open two valves simultaneously. There are two inlet valves and two exhaust valves for each cylinder.Valve springs (4) close the valves as the lifters move downward.Rotocoils (3) are actuated by the movement of the rocker arm. This causes the valves to turn while the engine is running. The rotation helps to prevent the concentration of carbon deposits on the valves, which provides a longer service life for the valves.