Universal joint

A universal joint, universal coupling, U-joint, Cardan joint, Hardy-Spicer joint, or Hooke's joint is a joint or coupling in a rigid rod that allows the rod to 'bend' in any direction, and is commonly used in shafts that transmit rotary motion. It consists of a pair of hinges located close together, oriented at 90° to each other, connected by a cross shaft

Universal joint

Diagram of variables for the universal joint. Axle 1 is perpendicular to the red plane and axle 2 is perpendicular to the blue plane at all times. These planes are at an angle β with respect to each other. The angular displacement (rotational position) of each axle is given by   and  respectively, which are the angles of the unit vectors   and   with respect to their initial positions along the x and y axes. The   and  vectors are fixed by the gimbal connecting the two axles and so are constrained to remain perpendicular to each other at all times.

Angle selectionThe capacity of a universal joint is the torque which the joint can transmit. For a given joint, this is a function of speed, operating angle and service conditions. Table 2 shows use factors based on speed and operating angle for two service conditions: intermittent operation (say, operational or less than 15 minutes, usually governed by necessity for heat dissipation) and continuous operation. The torque capacity of a single Cardan joint of standard steel construction is determined as follows:

There are many types of u joints, they are used for various purposes based on their requirement.If we connect two shafts with a u joint then there will be relative speed between them to avoidThat we use two u joints with an intermediate shaft which is called constant velocity joint or cv joint.There are many types of c v joints or equivalent types they are rzeppa, tracta, weiss, tripod,Double carton, thompson, malpezzi joints.Out of these rzeppa joint is widely used

Rzeppa jointDouble carton joint