Abstract: A push-pull coupling for coupling a valve spool to a coaxial cable includes a lost-motion connection which operatively disconnects the coaxial cable from the valve spool when in a first mode and positively connects the coaxial cable to the valve spool when in a second mode. Switching from the first mode to the second mode is accomplished by energizing an electromagnetic actuator within the coupling which locks components to one another to transmit push and pull motion. When the actuator is deenergized, the components move relative to one another, disconnecting the coaxial cable from the valve spool. The push-pull coupling is used in hydraulic machines to prevent operation of hydraulic cylinders when a driver is not seated on the machine so as to close a seat operated switch which energizes the electromagnetic actuator.