The circuits comprise a first part located at a control station where the trolley lies when not operated, and a second part located on the trolley. The first part comprises a three phase power circuit and a control circuit for the trolley. The connection between two parts is effected by only three active conductors, although the power supply is of the three phase type, the control signals being transferred to the second part when only two of the three phase conductors are coupled to the second part. To this end, a time lag contact controlled by a relay of said control circuit is inserted in the coupling of one of the three conductors and the circuit of the second part includes a memory relay which is energized by means of the two other conductors and which is no longer energized when the third phase is applied to the second part.
展开▼
