Abstract: A system for exerting a force, for instance a vertical upward lifting force of a predetermined tension vs. time waveform on a suspended object is useful in training the operators of shoulder-supported rocket launchers. The system includes an actuator for generating a required tensile force, a non-stretchable line or cable for connecting the object to the actuator and an overhead guide supported on an overhead support structure. The cable passes over the guide means defining a portion of the cable directly supporting the object. The position of the guide is controlled, in a response to a deviation from verticality of the portion of the cable with suspended object, before the activation of the actuator so that the verticality of the object lifting force is maintained. In operation, a predetermined force is exerted on the object regardless of whether the object moves as a result of the force.