Abstract: A method of friction welding comprising causing relative rotation between a pair of workpieces by actuating first and second drive means, the first drive means being coupled to a primary source of energy, and the second drive means being adapted to store auxiliary energy; bringing the workpieces into contact with one another under pressure, whereby the first and second drive means are adapted together to supply sufficient rotational energy to overcome the effects of resistive torque between the workpieces on initial contact between the workpieces; and thereafter continuing actuation of the first drive means to maintain relative rotation between the workpieces.

Abstract: Friction welding apparatus comprises a housing (1, 2) and a workpiece support (20', 24) rotatably and axially movably mounted in the housing. An air driven motor (20) is coupled to the workpiece support (20', 24) to cause the workpiece support to rotate relatively to the housing. A compression spring (33) urges the workpiece support in a first axial direction relatively to the housing while a piston (7) responsive to air pressure is provided to move the workpiece support (20', 24) relatively to the housing (1, 2) in a second axial direction opposite to the first direction. Air under pressure is communicated through a common inlet (6) in the housing (1, 2) to a valve arrangement (8, 9, 13, 14) so that air is conveyed along a first path to the drive motor (20) and along a second path to the piston (7). The valve arrangement is such that axial movement of the piston (7) relatively to the housing (1, 2) causes the valve gradually to close thereby gradually stopping rotation of the motor (20).