Connection device associated with an arm of an articulated three-dimensional measuring appliance

A connection device associated with an arm of an articulated three-dimensional measuring appliance, the device comprising a moving assembly rigidly secured to a jointed end of the arm and mounted in the tubular body of a arm to turn about the longitudinal axis of said arm, and a fixed assembly mounted at the other end of the arm, together with connection means for providing an electrical link between these two assemblies, wherein the moving assembly comprises first and second adjacent components on a common axis, each presenting a central passage for passing electrical connection wires, the first component being constrained to rotate with the jointed end of the arm and being connected to the second component by a coupling system having successive dogs so that said second component is not entrained in rotation until said first component has been entrained in rotation through significantly more than one complete revolution, and wherein the connection means include facing contact members carried respectively by the fixed assembly and by the second component of the moving assembly, said contact members being arranged to provide a continuous electrical link in normal operation without the second component being entrained in rotation, and an electrical link that is limited to a short angular range of rotation when said second component is entrained in rotation by the first component.