An assembly of devices designed to apply and relieve pre-set traction forces from a motor through harnesses typically attached to the cervical or lumbar vertebrae. It usually consists of a mains electricity (AC-powered) motor with a control unit to generate and regulate various intermittent mechanical forces (regular, progressive/regressive, cyclic), and a cord clamped to harnesses to transmit the force. Adjustable spreader bars attached to the control unit may be used to vary the angle at which the cord applies traction. The assembly may be table/wall-mounted for horizontal cervical and lumbar traction, or vertical cervical traction. It is used primarily to widen intervertebral spaces.