TM 5-3825-226-24
CYLINDER HEAD AND VALVES
CYLINDER HEAD AND VALVES
1. Push rod. 2. Cam follower. 3. Guide support. 4. Rocker arm shaft. 5. Rocker arm. 6. Exhaust valve. 7. Valve
seat insert. 8. Intake valve. 9. Valve spring.
The valves and valve system components control the
flow of inlet air and exhaust gases into and out of the
cylinder during engine operation.
The intake and exhaust valves are opened and closed
by
movement
of
these
components;
crankshaft,
camshaft, cam followers, push rods, rocker arms, and
valve springs. Rotation of the crankshaft causes
rotation of the camshaft. The camshaft gear is driven
by, and timed to, a gear on the front of the crankshaft.
When the camshaft turns, the cams on the camshaft
also turn and cause the cam followers to go up and
down. This movement makes the push rods move the
rocker arms. The movement of the rocker arms will
make the intake and exhaust valves in the cylinder head
open and close according to the firing order (injection
sequence) of the engine. One valve spring for each
valve helps to hold the valves in the closed position.
There is one intake and one exhaust valve for each
cylinder. The valve seat insert for the exhaust valve
can have replacement. The valve seat for the intake
valve is machined in and is a part of the cylinder head.
When the seat for the intake valve has been machined
to the limits given in the SPECIFICATIONS, it can be
bored (machined) for a valve seat insert. The valve
guide bore is machined in and is a part of the cylinder
head.
2-13
