A machine for fusing polyolefin pipes of selected outside radius end-to-end, the machine comprises: an upper half jaw having an inner radius substantially equal to the selected outside radius of the pipes being fixed; lower left and right complemental jaws each having an inner radius substantially equal to said inner radius of said upper half jaw; left and right pivots connecting said lower left and right complemental jaws to left and right portions of said half jaw, respectively; and comprising at least one actuator comprising left and right actuators connected between said lower left and right complemental jaws and said left and right portions of said half jaw, respectively, one direction of operation of said actuators causing said lower left and right complemental jaws to simultaneously rotate to an opened condition in which said upper half jaw can be lowered onto and lifted from the pipe and another direction of operation of said actuators causing said lower left and right complemental jaws to rotate to a closed condition in which the pipe is gripped so substantially around a circumference thereof as to resist deformation thereof from round during manipulation by the machine; each of said left and right actuators comprising a cylinder and a linkage serially connected between said lower left and right complemental jaws and said left and right portions of said half jaw, respectively; and characterised in that each of said linkages comprises a toggle and a link, said toggle being pivoted at a first axis on said upper half jaw and pivotally connected at a second axis to a piston of its respective said cylinder and at a third axis to a first arm of said link, said link being pivoted at a fourth axis on said upper half jaw and a second arm of said link being fixed to its respective said lower complemental jaw (63, 65), said axes (125, 127, 129, 131, 133) being parallel, to provide a mechanical advantage between its respective said cylinder and complemental jaws. an upper half jaw having an inner radius substantially equal to the selected outside radius of the pipes being fixed; lower left and right complemental jaws each having an inner radius substantially equal to said inner radius of said upper half jaw; left and right pivots connecting said lower left and right complemental jaws to left and right portions of said half jaw, respectively; and comprising at least one actuator comprising left and right actuators connected between said lower left and right complemental jaws and said left and right portions of said half jaw, respectively, one direction of operation of said actuators causing said lower left and right complemental jaws to simultaneously rotate to an opened condition in which said upper half jaw can be lowered onto and lifted from the pipe and another direction of operation of said actuators causing said lower left and right complemental jaws to rotate to a closed condition in which the pipe is gripped so substantially around a circumference thereof as to resist deformation thereof from round during manipulation by the machine; each of said left and right actuators comprising a cylinder and a linkage serially connected between said lower left and right complemental jaws and said left and right portions of said half jaw, respectively; and characterised in that each of said linkages comprises a toggle and a link, said toggle being pivoted at a first axis on said upper half jaw and pivotally connected at a second axis to a piston of its respective said cylinder and at a third axis to a first arm of said link, said link being pivoted at a fourth axis on said upper half jaw and a second arm of said link being fixed to its respective said lower complemental jaw (63, 65), said axes (125, 127, 129, 131, 133) being parallel, to provide a mechanical advantage between its respective said cylinder and complemental jaws.