An assembly of devices designed to be attached to a table for the application of constant horizontal traction forces to the cervical or lumbar vertebrae by means of attached harnesses whilst the patient typically lies in a supine position on the table during treatment. The assembly usually consists of several specialized harnesses, a combination of pulleys and cords, and a set of weights that hang from the cords as the source of the traction force (the patient's own weight or pneumatic devices may also be used). Adjustable spreader bars may be used to vary the angle at which the cord applies the traction. The assembly is used in orthopaedic and/or physical therapy procedures.