Vehicles (e.g. trams, underground trains, etc.) which, in the event of derailment, are impossible to lift and/or move from outside the derailed vehicle (e.g. when in tunnels) are recovered using so-called "internal jacks". Internal jacks are understood to mean lifting devices which are fitted permanently or temporarily in the floor area in the interior of the vehicle and by means of which recovery measures can be carried out from outside even where accessibility is extremely restricted. Known internal jacks are designed as single-acting hydraulic cylinders or telescopic cylinders which are generally attached in the floor of the vehicle. Therefore, a floor sleeve provided for this purpose is arranged on the vehicle. The cylinder is installed head-first in this floor sleeve. In operation, the piston rod, when actuated, extends downwards and lifts the vehicle body so that it can then be moved.
In low-floor vehicles, which are now being used to an increasing extent, suitable installation of the internal jacks is becoming more and more difficult due to the restricted space available.