Abstract: According to the invention, a car, for a transporter system, is provided, as means for detecting the close proximity of another car, with a device operated alternately as a signal transmitter and as a receiver and a plurality of plates at sides of the car, at least one plate, for example that of the leading side, being connected to the said device to serve as a receiving plate when the device is operating as a receiver and at least one plate being so connected to serve as a transmitting plate when the said device is operating as transmitter. Advantageously, switch means automatically changes over the connections of the plates to the said device in dependence upon the direction of travel. The output of the device when operating as a receiver may interrupt the driving of the car upon the detection of another car within a predetermined proximity.