pair of the plate like elements 11 in a pressurization of the pressure space 15 a deformation of the h shaped housing part 5 is produced in particular in the area of the middle crosslink of the h and the transition areas between the crosslink and the lateral legs of the h in this way the rigidly constructed lower legs of the h are moved inwards in the direction of the intermediately placed object 17 and transfer corresponding braking or clamping forces to the object in this respect it is possible to provide clamping and or brake shoes 23 on the insides of the lower legs of the h if instead of an h shaped housing part 5 a u shaped housing is used in which one or more for example rectangular plate like elements are provided between the legs of the u with these elements pressing the legs of the u toward the outside with a pressurization then an u201c active loosening u201d of an object for example with a linear guide can be realized of course this can also be attained with an h shaped housing in that the brake shoes are located on the outsides of the lower legs of the h and they apply pressure on the object for example in a groove conversely an u201c active clamping or braking u201d can also be produced with a u shaped housing if the brake shoes are located on the outsides of the legs of the u and correspondingly apply pressure on the object finally it should be pointed out that of course individual features which are described in the preceding only in connection with a specific embodiment can also be combined if.