HANGZHOU BANYAN CO
Universal joints allow drive shafts to move up and down with the suspension while the shaft is moving so power can be transmitted when the drive shaft isn’t in a straight line between the transmission and drive wheels.
A universal joint is considered the oldest of all flexible couplings. It is commonly known for its application in automobiles and trucks. A universal joint is located where two shafts are to be joined at an angle to transmit torque.
In the transmission system of a vehicle, the output shaft of the gearbox. The propeller shaft and the differential pinion shaft are not in one line, and hence the connection between them is made by a universal joint.
Thus, the universal joint permits the torque transmission at an angle, and also while this angle is changing constantly while the vehicle is moving on the road. It is a simple and most common type of joint and is known as a Cardan joint or hook joint. Universal joints have a number of unique features that make them perfect for a range of applications.
Purpose of Universal Joint
When a car is running on an uneven road, the differential rises and falls. Thus the propeller shaft also changes its angle due to the rise and fall of the differential.
At the same time propeller shaft is rotating. Under such conditions, the universal joint allows the changes of angle of the propeller shaft without the transmission.
If the differential is directly connected from the gearbox without a universal joint during the rise and fall of the rear axle the connection fails because it is not flexible due to the absence of a universal joint.
Working of Universal Joint
The figure shows the construction of a universal joint. It consists of a driving yoke on one side. This is connected to the main shaft of the gearbox, and there is a driven yoke is connected to the ropeller shaft. These two yokes are connected by means of a crossed spider. The four arms of the spider are known as trunnions.
When the driving shaft is rotating the driven shaft also rotates, and at the same time, the universal joint allows angular motion. Hence the power is transmitted from the gearbox to the propeller shaft at an angle.
Thus, the universal joints are used to make a flexible connection between two rigid shafts at an angle with each other. They permit the transmission of the power not only at an angle but also while this angle is being varied constantly.
