Kinematics of Universal Joints
If two shafts bent at angles to each other are connected with a universal joint (fig.1 ) and the drive shaft moves at constant angular velocity, the driven shaft runs with uneven angular velocity. i.e. the twist angle of the driven shaft does not at any point agree with the twist angle of the drive shaft. The difference angle and hence the degree of unevenness depends on the deflection angle of the joint.
The correlations are shown in the following figures 2 -5.
Fig 3. Difference in Twist Angle (cardan fault)
Fig 4. Max. difference in twist angle.
Fig 5. Degree of unevenness