Friction welding apparatus

Apparatus for use in friction welding comprising mechanism comprising driven means operative in use to cause reciprocation of a first workpiece relative to a second workpiece such as will lead to the generation of frictional heat between the workpieces, characterised in that the mechanism comprises a first drive operative to generate reciprocatory motion and a second drive operative to generate reciprocatory motion of the same frequency as that of the first drive, adjustment means operative to enable the relative phase of the first and second drives to be adjusted while said drives are in use, and integrating means operative to produce reciprocatory motion of said driven means which is a function of the reciprocatory motions of the first and second drives and of which the amplitude can be reduced to zero by appropriate adjustment of the adjustment means, the integrating means comprising a rockable linking body, first coupling means coupling the first drive to a first part of the linking body, and second coupling means coupling the second drive to a second part of the linking body, spaced from said first part, and said driven means being coupled to a third part of the linking body, spaced from said first and second parts thereof.