TRANSMISSION SERVICE
THE GEAR BOX
The gear box provides four speeds and has a positive foot change, operated by the right
foot and a kick-starter.
It is retained to the frame by being clamped between the two engine rear plates by two
bolts. The bottom fixing bolt acts as a pivot. The top fixing bolt passes through the
gear box top lug and the rear plates, which are slotted, thereby allowing a swinging fore
and aft movement of the gear box to enable the front driving chain to be adjusted. That
movement is controlled by an adjusting bolt (marked (1) in illustration 16) secured in
an eye bolt (marked (2) in illustration 16) and locked in the required position by a nut
(marked (3) in illustration 16).
Illustration 14 clearly shows the general internal gearbox layout, the simple gear
selection and kickstarter mechanism. It will be seen that movement of the foot change
lever causes movement of the cam barrel through the medium of an ingenious trip fork
to which the lever is attached.
This cam movement actuates the sliding gear striker forks causing movement of the
sliding gears which engage the stationary gears by dogs. As each gear is selected it is
held in engagement by means of a spring loaded conical ended plunger operating in
depressions on the end of the cam barrel.
A
B
C
D
LOW GEAR ON MAINSHAFT
THIRD GEAR ON MAINSHAFT
SECOND GEAR ON MAINSHAFT
MAIN DRIVING GEAR
E
F
G
H
I
LOW GEAR ON LAYSHAFT
THIRD GEAR ON LAYSHAFT
SECOND GEAR ON LAYSHAFT
SMALL PINION ON LAYSHAFT
OIL LEVEL PLUG
Illustration 14
Section through gearbox showing gears and clutch with actuating mechanism
G—S
39
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