housing 11 of the thermostatic operating element 10 facing away from the work piston 12 is inserted the interior of the cap like guide 31 is sealed against the area containing coolant by means of a seal ring 32 inserted into an annular groove of the housing 11 the cap like guide 31 is connected with the exterior of the housing element 28 by means of at least one strip which leaves a sufficiently large flow cross section towards a hose connector 33 the electrical supply lines for the heating element of the thermostatic operating element 10 are conducted from the outside through the strip in a manner not represented in detail to the housing 11 of the thermostatic operating element 10 furthermore the housing element 29 is also connected with the base plate 17 in the area of its circumferential edge the base plate 17 is provided with several cutouts 34 which are also visible in fig2 shoulders 35 of the housing element 28 protrude through these cutouts which are either designed as clip connectors or which have been reshaped in a rivet like manner by heating it will therefore be readily understood by those persons skilled in the art that the present invention is susceptible of broad utility and application many embodiments and adaptations of the present invention other than those herein described as well as many variations modifications and equivalent arrangements will be apparent from or reasonably suggested by the present invention and the foregoing description thereof without departing from the substance or scope of the.