Description and operation

Propeller shaft

DESCRIPTION

A propeller shaft (Fig. 2), (Fig. 3), and (Fig. 4) is the shaft which connects the transmission/transfer case to the axle differential. This is the link through which the engine power is transmitted to the axle.

The propeller shaft is designed and built with the yoke lugs in line with each other which is called zero phasing. This design produces the smoothest running condition, an out-of-phase shaft can cause a vibration.

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

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.

Also make alignment reference marks (Fig. 1) 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.

Fig. 1 Reference Marks on Yokes Fig. 1 Reference Marks on Yokes

1 - REFERENCE MARKS

OPERATION

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. The propeller shaft must be able to change operating angles when going over various road surfaces. This is accomplished through universal joints, which permit the propeller shaft to operate at different angles. The slip joints (or yokes) permit contraction or expansion (Fig.

2), (Fig. 3), and (Fig. 4).

Before undercoating a vehicle, the propeller shaft and the U-joints should be covered to prevent an out-of-balance condition and driveline vibration.

CAUTION: Use original equipment replacement parts for attaching the propeller shafts. The specified torque must always be applied when tightening the fasteners.

Center bearing

DESCRIPTION

Vehicles equipped with a two-piece propeller shaft uses a rubber insulated center bearing. The bearing is used to support the shafts where they are joined together.

Fig. 2 Front Propeller Shaft Fig. 2 Front Propeller Shaft

1 - REAR AXLE

2 - COMPANION FLANGE

3 - TRANSFER CASE

4 - FRONT PROPELLER SHAFT

5 - COMPANION YOKE

6 - FRONT AXLE

7 - COMPANION FLANGE

8 - REAR PROPELLER SHAFT

9 - COMPANION YOKE

OPERATION

The propeller shaft center bearing serves to divide the required propeller shaft length into two smaller shafts, which has several inherent advantages. Having two short propeller shafts instead of one long shaft decreases the chance of unwanted noise and vibrations. The shorter shafts are easier to balance and serve to increase ground clearance while maintaining acceptable driveline angles.

Fig. 3 Rear Propeller Shaft with Center Bearing Fig. 3 Rear Propeller Shaft with Center Bearing

1 - REAR AXLE

2 - REAR PROPELLER SHAFT

3 - TRANSMISSION EXTENSION HOUSING

4 - CENTER BEARING

Fig. 4 Rear Propeller Shaft Fig. 4 Rear Propeller Shaft

1 - REAR AXLE

2 - REAR PROPELLER SHAFT

3 - TRANSMISSION EXTENSION HOUSING

Propeller shaft joints

DESCRIPTION

Two different types of propeller shaft joints are used in AN vehicles (Fig. 5) and (Fig. 6). None of the joints are serviceable. If worn or damaged, they must be replaced as a complete assembly.

Fig. 5 Single Cardan U-Joint Fig. 5 Single Cardan U-Joint

1 - CROSS

2 - SEAL

3 - CAP AND NEEDLE BEARINGS

LUBRICATION

The factory installed universal joints are lubricated for the life of the vehicle and do not need lubrication.

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.

Propeller shaft joint angle

DESCRIPTION

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 cancelled to produce a smooth power flow.

OPERATION

This cancellation 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.

Fig. 6 Double Cardan U-Joint Fig. 6 Double Cardan U-Joint

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.

Propeller shaft speed (rpm) is the main factor in determining the maximum allowable operating angle.

As a guide to the maximum normal operating angles refer to (Fig. 7).

 Fig. 7 Maximum Angles And Propeller Shaft Speed Fig. 7 Maximum Angles And Propeller Shaft Speed

    Dodge Durango (DN) 1998-2003 Service Manual

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