1928 Cadillac - GM Heritage Center

96 C A DILL A COPER A TOR'S MANUAL
GENERAL INFORMATION 97
Transmission
The purpose of the transmission is to provide a means for varying the ratio
and direction of the rear axle speed in relation to the engine speed. Three
things are accomplished by doing this: First, the engine is enabled to drive
The Cadillac transmission is known as the selective, sliding gear type. It
has three speeds forward, of which one is direct drive, and one speed in
reverse. Selection of the various speeds is accomplished by movement of
two shifter gears (Fig. 50), which are controlled by the transmission control
lever. The positions of the gears corresponding to the five positions of the
control lever, as illustrated in Fig. 7, are as follow:
Neutral—When the control lever is in neutral position, the shifter gears
are in the positions shown in Fig. 50, that is, they are not in mesh with any
of the other gears.
Low—When the control lever is moved from neutral to low, the low and
reverse shifter gear is moved forward into mesh with the low gear on the
jack-shaft. The ratio of engine speed to propeller shaft speed in low is
approximately 3 to 1.
Intermediate—When the control lever is moved from low to intermediate,
the low and reverse shifter gear is first returned to its neutral position and
the high and intermediate shifter gear is then moved back into mesh with
the intermediate gear on the jackshaft. The ratio of engine speed to propeller
shaft speed in intermediate is approximately 1.7 to 1.
High—When the control lever is moved from intermediate to high, the
high and intermediate gear is first moved forward out of mesh with the
intermediate gear on the jackshaft, and then farther forward until teeth,
cut internally in a recess in the high and intermediate shifter gear, engage
teeth on the extreme end of the gear on the clutch shaft. The drive is then
direct from the clutch shaft to the transmission main shaft without reduction.
Reverse—When the control lever is moved from neutral to reverse, the low
and reverse shifter gear is moved back into mesh with an idler gear, which
is at all times in mesh with the reverse gear on the jackshaft. The interposi •
tion of the idler gear reverses the direction of rotation. The ratio of engine
speed to propeller shaft speed in reverse is approximately 3-7 to 1.
Fiptrt 50.
Sectional view of clutch, transmission and universal joint.
the car backwards. Second, the engine is permitted to revolve fast enough
to develop the power necessary for starting and for driving the car at extremely
low speeds. Third, the turning effort of the engine is multiplied, so that
it may be sufficient for climbing steep hills and pulling through deep sand
and mud.