In an embodiment a locking device for a first transport carriage includes a gripping arm configured to lock a key of a second transport carriage, a slide, an electric motor and/or an actuator configured to drive an eccentric disc for initiating a release movement of the slide, a receiver configured to receive a Bluetooth, Near Field Communication or WLAN signal from a transmitter, wherein the receiver is configured to control the motor or the actuator via an electrical or electromagnetic signal, wherein the slide is configured to release the key based on the initiated release movement when the electric motor and/or the actuator receives the electrical or electromagnetic signal.

A method for operating a deposit-operated lock system for a borrowed object, in particular for a transport trolley which can be moved by hand. There is also described a suitable deposit-operated lock system. A key that is held in a deposit lock is released when an electric drive drives a carriage that is displaceably mounted on a blocking element in an initial position.