PROPELLER SHAFT ASSEMBLIES

The propeller shaft assembly consists of a propeller shaft, a slip joint, and one or more universal joints. This assembly provides a flexible connection through which power is transmitted from the transmission to the live axle.

The propeller shaft may be solid or tubular. A solid shaft is stronger than a hollow or tubular shaft of the same diameter, but a hollow shaft is stronger than a solid shaft of the same weight. Solid shafts are used inside a shaft housing that encloses the entire propeller shaft assembly. These are called torque tube drives.

A slip joint is put at one end of the propeller shaft to take care of end play. The driving axle, attached to the springs, is free to move up and down, while the transmission is attached to the frame and cannot move. Any

upward or downward movement of the axle, as the springs flex, shortens or lengthens the distance between the axle assembly and the transmission. This changing distance is compensated for by a slip joint placed at one end of the propeller shaft.

The usual type of slip joint consists of a splined stub shaft, welded to the propeller shaft, that fits into a splined sleeve in the universal joint. A slip joint and universal joint are shown in figure 13-16.

Universal joints are double-hinged with the pins of the hinges set at right angles. They are made in many different designs, but they all work on the same principle. (See chapter 11.)