TM 5-3805-290-23-1
THEORY OF OPERATION - CONTINUED
0003 00
ENGINE - CONTINUED
427-B1503
9.
Camshaft.
a.
Engine has a single camshaft. Camshaft is made of cast iron. Camshaft lobes are chill hardened.
b.
Camshaft is driven at front end. As camshaft turns, camshaft lobes move valve system components. Valve system
components move cylinder valves.
c.
Camshaft gear must be timed to crankshaft gear. Relationship between lobes and camshaft gear causes valves in
each cylinder to open at correct time. Relationship between lobes and camshaft gear also causes valves in each cyl-
inder to close at correct time.
10.
Valve System.
a.
Valve system components control flow of inlet air into cylinders during engine operation. Valve system compo-
nents also control flow of exhaust gases out of cylinders during engine operation.
b.
Crankshaft gear drives camshaft gear through an idler gear. Camshaft must be timed to crankshaft in order to
obtain correct relation between piston movement and valve movement.
c.
Camshaft has two camshaft lobes for each cylinder. Lobes operate inlet and exhaust valves. As camshaft turns,
lobes on camshaft cause lifter to move pushrod up and down. Upward movement of pushrod against rocker arm
results in downward movement (opening) of valve.
d.
Each cylinder has one inlet valve and one exhaust valve. Valve spring closes valve when lifter moves down.
0003 00-3
