Drive Axles, Bearings and Joints: Description and Operation

GENERAL DESCRIPTION

PROPELLER SHAFT
Torque is transmitted from the transmission to the front axle through one propeller shaft and universal joint assembles. All propeller shafts are the balanced tubular type. A splined slip joint is provided in some drivelines.
- Since the propeller shaft is total balanced carefully, welding or any other modification are not permitted.
- Alignment marks should be applied to each propeller shaft before removal.
- Be sure vehicle is stopped, engine is not running, brake is secured and vehicle is secured to prevent injury.
- Be careful not to grip the propeller shaft tube too tightly in the vise as this will be cause deformation.

PHASING
The propeller shaft is designed and built with the yoke lugs (ears) in, line with each other. This design produces the smoothest running shaft possible, called phasing. Vibration can be caused by an out-of-phase propeller shaft. The propeller shaft will absorb vibrations from speeding up and slowing down each time the universal joint goes around. This vibration would be the same as a person snapping rope and watching the "wave" reaction flow to the end. A propeller shaft working in phase would be similar to two persons snapping a rope at the same time, and watching the "waves" meet and cancel each other out. In comparison, this would be the same as the universal joints on a propeller shaft. A total cancellation of vibration produces a smooth flow of power in the driveline. It is very important to apply a reference mark to the propeller shaft before removal, to assure installation alignment.





UNIVERSAL JOINT
A universal joint consists of two Y-shaped yokes connected by a crossmember called a spider. The spider is shaped like a cross. Universal joints are designed to handle the effects of various loadings and front or rear axle windup during acceleration. Within the designed angle variations, the universal joint will operate efficiently and safely. When the design angle is changed or exceeded the operational life of the joint may decrease. The bearings used in universal joints are of the needle roller type. The needle rollers are held in place on the trunnions by round bearing cups. The bearing cups are held in the yokes by snap rings.