A supply device for supplying a device that can be moved on a driving surface with a material supplied through a supply line. The supply device has a plug with an electric plug contact element that extends along a plug axis and is coupled to a plug receptacle of the mobile device by a linear joining movement, and a supply line with a valve, and detects a coupled state of the plug with the plug receptacle by an electric plug contact element. In the coupled state the valve is actuated. The supply device has a nozzle arranged on the supply line and is coupled to an inlet port of the mobile device. A feeding holder keeps the nozzle and the plug in a defined position and orientation relative to each other so that when coupling the plug to the plug receptacle the nozzle couples to the inlet port. The movement device makes the feeding holder with the plug and nozzle at least height adjustable and movable in the direction of the joining movement along a joining axis. The detection system determines a position of the plug receptacle. The supply device couples the plug to the plug receptacle and thereby the nozzle to the inlet port by a linear joining movement along the joining axis based on the determined position.