Section V. CAMSHAFT AND GOVERNOR

f. Check that the crankshaft rotates freely

without any binding or catching. Correct any

difficulties.

g. Lubricate the lips of the oil seals (8 and 11)

with grease. Slide the seals on the ends of the

crankshaft, taking care to prevent damage to the

sealing lips. Position the seals on the shaft so that

the lips face inward. Turn the engine on its side and

drive the seals squarely into the seats on the engine

cylinder block and on the bearing plate.

h. Install the magneto and flywheel (TM 5-

4320-259-12).

i. Install the piston and connecting rod (para 4-

10).

j. Install the centrifugal pump on the engine

(para 3-4).

k. Install the carburetor, fuel tank and lines,

muffler, and air cleaner on the engine and service

the engine (TM 5-4320-259-12).

Figure 4-10. Crankshaft end play measuring point.

Section V. CAMSHAFT AND

GOVERNOR

cause the engine to slow down momentarily. This

4-15. Description

change will be sensed by the governor and a

a. The camshaft is gear driven by the geared

resulting adjustment of the carburetor throttle lever

portion of the crankshaft. It rotates in a 1:2 ratio

will restore the engine to the governed speed almost

with the crankshaft. The camshaft rides on a pin

immediately.

which extends through the cylinder block, parallel

4-16. Removal and Disassembly

with the crankshaft. The camshaft has one exhaust

a. Remove the air cleaner, muffler, fuel tank and

valve cam, one intake valve cam, and one breaker

lines, carburetor, and breaker points (TM 5-4320-

point cam. The valve cams operate the valve

159-12).

tappets to open and close the valves at the required

b. Remove the centrifugal pump from the engine

time of the engine cycle. The breaker point cam

(para 3-2).

engages the breaker point pin which operates the

c. Remove the cylinder head and valves (para 4-

ignition breaker point.

4).

b. The governor is driven by the camshaft to

d. Remove the piston and connecting rod (para

maintain control of the engine speed. The governor

4-8 ).

is a flyball type in which a driver forces four captive

e. Remove the flywheel and magneto (TM 5-

steel balls to rotate. As the balls rotate, centrifugal

4320-259-12).

force throws them outward against a dished race.

f. Remove the main bearings and crankshaft

This causes the dished race to move axially. The

(para 4-12).

axial movement of the race is transferred to an

g. Invert the cylinder block. Using a small

externally mounted lever through a cross shaft. The

punch, drive out the camshaft pin (13, fig. 4-7),

cross shaft extends through the wall of the crank-

applying pressure from the power takeoff side of

case and is perpendicular to the camshaft. The

the engine. After the pin clears the rear end of the

externally mounted lever is linked to the throttle

crankcase, it will slide out easily.

lever on the carburetor. As engine speed increases,

h. Lift the assembled camshaft and governor

the movement of the governor parts causes the

from the cylinder block.

throttle lever to close to decrease engine speed. As

i. Remove the valve tappets (20) from the

the engine speed decreases, the governor parts

cylinder block.

cause the throttle lever to open. In this manner, a

state of equilibrium is reached and the engine speed

remains constant. An increased engine load will

4-9