A universal joint consists of two Y-shaped yokes attached to a spider. The spider is shaped like a cross having arms of equal length called trunnions.

Universal joints handle the effects of various loads and axle windup during acceleration. Within the designed angle variations the universal joint operates efficiently and safely. When the design angle changes or is exceeded, the operational life of the joint may decrease.

Needle roller bearings are used in universal joints. Round bearing cups hold the needle rollers in place on the trunnions. Either snap rings or injected plastic, depending on the manufacturer of the joint, hold the bearing cups in the yokes.