The support for offset socket keys, each key comprising a first arm and a second arm which extend in a plane Q, comprises a body which is provided with a series of openings which extend in a plane P and a retention unit for retaining the series of keys relative to the body, the keys being offset vertically relative to each other. The traction current converter includes at least one pulse current converter on the engine side, and the clamps of the permanent-field synchronous motor are connected to a change-over switch such that the permanent-field synchronous motor can be connected to a load circuit forming a load, to drive the pulse current converter or for generative braking. The portable device transmits periodically encrypted location information as well as status information across the wireless network to the monitoring system. A capturing arrangement is carried by the sheet conveyor for capturing at least a part of the topmost sheet and for facilitating conveyance of the topmost sheet by the sheet conveyor to the printing station. Patients not in close proximity to the unit will be alerted remotely via a pager. A moving mechanism moves at least one of the object and the bottom part of the process chamber so that the object can be heated with less influence by the cooling arrangement being positioned away from the target object while the target object can be efficiently cooled by the cooling arrangement being positioned close to the target object.