You set whether a joint behaves as a hinge, a drawer slide, or another type of joint by setting for each object in the kinematic chain. Joints control the rotation and position of an object with respect to its parent.
You set whether an object can move or rotate about a given axis by using the Active check box in the joint rollouts. Joints have a maximum of six possible axes: three for rotation and three for position. You constrain the motion of a joint by setting which axes are active.
Most joints are limited in their range of motion along an active axis. For example: a hinge might open only to 120 degrees; a piston slides only within the length of its cylinder. To limit the range of motion allowed on an active axis, you turn on Limited and set values for the From and To fields on the joint rollouts.