Drive/Propeller Shafts, Bearings and Joints: Description and Operation

PROPELLER SHAFTS

Propeller Shaft:

The basic function of a propeller shaft is to transmit power from one point to another. The shaft is designed to send torque through an angle from the transmission to the axle.

The propeller shaft must operate through constantly changing relative angles between the transmission and axle. It must also be capable of changing length while transmitting torque. The axle rides suspended by springs in a floating motion. This means the propeller shaft must be able to contract, expand and change operating angles. This is accomplished through universal joints. Universal joints permit the propeller shaft to operate at different angles. The slip yokes permit contraction or expansion.

Tubular propeller shafts are balanced by the manufacturer with weights spot welded to the tube.

Before undercoating a vehicle, the propeller shaft and the universal joints should be covered. This will prevent the undercoating from causing an out-of-balance condition and vibration.

CAUTION: Use exact replacement parts for attaching the propeller shafts to ensure safe operation. The specified torque must always be applied when tightening the fasteners.

LUBRICATION
The factory installed universal joints are lubricated for the life of the vehicle. All universal joints should be inspected for leakage and damage each time the vehicle is serviced. If seal leakage or damage exists, the universal joint should be replaced. Refer to Lubrication and Maintenance, for additional information.

PROPELLER SHAFT JOINT ANGLE
When two shafts come together at a common joint, the bend that is formed is called the operating angle. The larger the angle, the larger the amount of angular acceleration and deceleration of the joint. This speeding up and slowing down of the joint must be canceled to produce a smooth power flow. This is done through the phasing of a propeller shaft and ensuring that the proper propeller shaft joint working angles are maintained.

A propeller shaft is properly phased when the yoke ends are in the same plane, or in line. A twisted shaft will make the yokes out of phase and cause a noticeable vibration.

When taking propeller shaft joint angle measurements, or checking the phasing, of two piece shafts, consider each shaft separately.

Ideally the driveline system should have;
- Angles that are equal or opposite within 1 degree of each other.
- Have a 3 degree maximum operating angle.
- Have at least a 1/2 degree continuous operating (propeller shaft) angle.

Maximum Angles And Engine Seed:

Engine speed (rpm) is the main factor in determining the maximum allowable operating angle. As a guide to the maximum normal operating angles refer to image.

PRECAUTIONS
Use the exact replacement parts when installing the propeller shafts. The use of the correct replacement parts helps to ensure safe operation. All fasteners must be torqued to the specified values for safe operation.

Reference Marks On Yoke:

Also make alignment reference marks on the propeller shaft yoke and axle, or transmission, yoke prior to servicing. This helps to eliminate possible vibration.

CAUTION: Do not allow the propeller shaft to drop or hang from any propeller shaft joint during removal. Attach the propeller shaft to the vehicle underside with wire to prevent damage to the joints.

CAUTION: It is very important to protect the external machined surface of the slip yoke from damage during and after propeller shaft removal. If the yoke is damaged, the transmission extension seal may be damaged and therefore cause a leak.