Types of Universal Joints

Constant Velocity Universal Joint Necessity:


• Angle of drive between gearbox and differential is never constant and goes on changing

• Hooke’s joint is capable of transmitting power up to 20° angle without causing vibration or 

  strain

• What happens when the angle of drive is more than 20°?

• What happens when the angle of drive is varying from     0 degrees to 60 degrees ?

• To know this consider the following 

 

Driving and Driven Shaft Speeds:

• Let us assume that there is one universal joint between driving and driven shafts 

• When the driving shaft is revolving at an absolute constant speed, the driven shaft will not

  revolve at a constant speed  

• During two parts of each revolution, the speed of driven shaft will be slightly greater than 

  the constant

• During the other two parts of the revolution the speed will be slightly lesser than the 

  constant speed 

• The number of turns made by the driven shaft will be the same, but its velocity or speed of 

  rotation will fluctuate

• The fluctuation is found to be zero when the inclination is zero and considerable when the 

   inclination is large

 

 How to Obtain Constant Velocity ?

 • The above mentioned irregularity in the vehicle transmission is overcome by using two

   separate universal joints connected to the propeller shaft 

 • The variation in the second joint is found to be equal and opposite to that to that which

   occurs at the first joint

 

 Use of two universal joints to obtain constant velocity:

 • The angle of the driving and driven shaft to the intermediate connecting propeller shaft are

   equal

 • The variation caused by one joint is then cancelled out by the second joint 

 • Constant velocity joints are used when the angle is more than 30°and up to 40°

 

 Other Constant Velocity Universal Joints:

 • Special constant velocity universal joints where the fluctuations in the speed of the driven 

   shaft at very large angles are completely absent 

 • These types of joints are being used in front engine, front wheel drive and four wheel 

   drive vehicles