Subject: Automobile Engineering

Topic: Transmission Systems, Live Axle & Differential

Difficulty: Medium

When the center of gravity of propeller shaft does not coincide with axis of propeller shaft during rotation, the shaft is subjected to centrifugal force. This will cause bend the propeller shaft & further increase the C. G (center of gravity) from rotational axis & shaft occur. The bending depends upon rotational speed & length of propeller shaft. The speed at which shaft run with additional deflection of the shaft from axis of rotation became infinite, known as critical or whirling speed. Hence, the operating speed of shaft is less than critical speed to avoid failure & violent vibrations. The propeller shaft connects the transmission shaft to the bevel þinion shaft of differential at the wheel axle. It is also called as drive shaft. Function of Propeller Staft: i) It transmits rotary motion of gear box output shaft to differential & then to wheel through the axle shaft. ii) It transmits motion at an angle which is varying frequently iii) It adjusts the change in length between gearbox & rear axle.

Fig 14.1 shows a propeller shaft, with two universal joints at the ends & a slip or sliding joint.