Abstract: A production-line robot comprising an operative arm provided at its outer, pivoted end with a support mechanism is coupled via the latter to one of a plurality of tools associated with the robot, the tools being supported in their inoperative position by lock plates or bolts operable by the tool holder of the robot arm. The lock plates may comprise a tool receiving support provided with centering members with which a tool bearing plate is adapted to co-operate in the inoperative tool position, the bearing plate and the end support of the robot comprising mutual centering mechanisms, at least one of them being provided with controlled coupling and uncoupling members so that the robot can pick up and become coupled with one tool automatically and, after using this tool, deposit same upon the corresponding receiving support for subsequently picking up and becoming coupled with another tool waiting on its relevant receiving support.