Ball splines and rotary ball splines are devices for transmitting both linear and rotary motion. They are widely used in assembly automation for SCARA robots, pick-and-place devices, and tool changers.
A ball spline consists of three components: a grooved shaft, a spline nut and ball bearings. The grooves on the shaft are linear rather than helical like those of a ballscrew. The balls travel along the grooves, recirculating inside the spline nut. This prevents the nut from rotating on the shaft, enabling transfer of torque through the shaft to the nut or vice versa.