HEAD 9T6347 - Caterpillar

The valve system components control the flow of the inlet air and the exhaust gases into the cylinders and out of the cylinders during engine operation.The crankshaft gear drives the camshaft gears through idlers. Both camshafts must be timed to the crankshaft in order to get the correct relation between the piston and the valve movement.
Illustration 1 g00322585
Valve system components that illustrate the adjustable valve bridge
(1) Rocker arm
(2) Bridge
(3) Rotocoil
(4) Valve spring
(5) Pushrod
(6) Lifter
Illustration 2 g01042301
Valve system components that illustrate the nonadjustable valve bridge
(1) Rocker arm
(2) Bridge
(3) Rotocoil
(4) Valve spring
(5) Pushrod
(6) Lifter The camshafts have three lobes for each cylinder. Two lobes operate the valves and the other lobe operates the fuel injector.As each camshaft turns, the lobes on the camshaft cause lifters (6) to move up and down. This movement causes pushrods (5) to move rocker arms (1). The movement of the rocker arm causes bridges (2) to move up and down on the dowels in the cylinder head. The bridges allow one rocker arm to open two valves. When the lifters move downward the action of valve springs (4) closes the valves. The valves can be either inlet valves or exhaust valves. There are two inlet valves and two exhaust valves for each cylinder.Rotocoils (3) cause the valves to turn while the engine is running. The rotation of the valves keeps the carbon deposits on the valves to a minimum which gives the valves a longer service life.