A trolley (1), for a beam-mounted supply unit, for fastening medical devices to a ceiling. The trolley has a chassis (2) which can be meshed with a rail track of the beam-mounted supply unit for moving the trolley (1) along the rail track. A medical device can be fastened to the trolley (1). The trolley has a brake unit (3) with at least one braking element (7), which exerts a braking force on the rail track and/or on the chassis in the activated state of the brake unit (3), so that a movement of the chassis along the rail track is at least made difficult compared to an operating state with the brake unit (3) deactivated. In the activated state of the brake unit (3), the braking force exerted by the braking element (7) on the rail track and/or on the chassis is generated without the aid of electric energy.