Propeller Shaft Description and Operation

The propeller shaft is a tube with propeller shaft universal joints or constant velocity joints at both ends which do not require periodic maintenance, that transmit power from the transfer case or transmission output shaft to the differential. Front Axle Propeller Shaft Description The front axle propeller shaft transmits rotating force from the transfer case to the front differential when the transfer case is engaged. The front axle propeller shaft consists of a tube with constant velocity joints on both ends, connecting to the transfer case using an internally splined slip joint. Propeller Shaft Description A propeller shaft uses either an internally or externally splined slip joint and two propeller shaft universal joints with a propeller shaft flange to connect the driveline to the transmission or transfer case. Propeller Shaft Phasing Description The propeller shaft is designed and built with the yoke lugs (ears) in line with each other. This produces the smoothest running shaft possible. A propeller shaft designed with built in yoke lugs in line is known as in - phase. An out of phase propeller shaft often causes vibration. The propeller shaft generates vibration from speeding up and slowing down each time the universal joint goes around. The vibration is the same as a person snapping a rope and watching the wave reaction flow to the end. An in phase propeller shaft is similar to 2 persons snapping a rope at the same time and watching the waves meet and cancel each other out. A total cancellation of vibration produces a smooth flow of power in the drive line. All splined shaft slip yokes are keyed in order to ensure proper phasing. Propeller Shaft Universal Joint Description The propeller shaft universal joint is connected to the propeller shaft. The propeller shaft universal joint consist of four caps with needle bearings and grease seals mounted on the trunnions of a cross or spider. These bearings and caps are greased at the factory and no periodic maintenance is required. There are two propeller shaft universal joints used in a propeller shaft and three used in a front and rear propeller shaft. The bearings and caps are pressed into the propeller shaft slip yokes or propeller shaft flange and held in place with snap rings. Propeller shaft universal joints are designed to handle the effects of various loads and rear axle windup conditions during acceleration and braking. The propeller shaft universal joint operates efficiently and safely within the designed angle variations. When the design angles are exceeded or out of specification, the operational life of the propeller shaft universal joint decreases.