PLATE AS 1109216 - Caterpillar

Illustration 1 g00825443
(1) Rocker arm
(2) Valve bridge
(3) Rod
(4) Valve rotator
(5) Valve spring
(6) Gas admission valve
(7) Pushrod
(8) Inlet valve
(9) Valve lifter
(10) Camshaft lobe The crankshaft gear drives the camshaft gears through idler gears. The camshafts must be timed to the crankshaft in order to get the correct relation between the movement of the piston and movement of the valves.The camshafts have three camshaft lobes (10), valve lifters (9), and pushrods (7) for each cylinder. One lobe operates valve bridge (2) that moves two inlet valves (8). One lobe operates the valve bridge that moves the two exhaust valves. The center lobe operates gas admission valve (6). As the camshaft turns, the camshaft lobes cause the valve lifters and pushrods to move up and down.One pushrod moves rod (3) in order to operate gas admission valve (6). The other two pushrods move rocker arms (1). Movement of the rocker arms cause valve bridges (2) to move up and down on a dowel in the cylinder head. This movement operates inlet valves (6) and the exhaust valves. One valve bridge enables one rocker arm to operate two valves simultaneously. There are two inlet valves and two exhaust valves for each cylinder.Valve rotator (4) turns the valve during engine operation. The rotation of the valves keeps the deposit of carbon on the valves to a minimum. This provides longer service life for the valves.When valve lifter (9) moves downward, valve spring (5) closes the valve.