of the piston cylinder unit 35 39 is connected to the control valve 31 39 through a loose coupling element 38 and a dead center catch 39 furthermore the extension of the piston 36 39 supports a second plate 40 which can be moved back and forth with a second regenerator 41 between two heat exchangers 42 and 43 in a second gas chamber 44 consequently both plates 4 and 40 are moved by only one drive 14 39 in synchronism but phase shifted with respect to each other with the movement of the pistons controlling the controller in another variation which is not shown here the outlets 45 and 46 and 45 39 and 46 39 respectively are connected to the sniffing valve 37 and 37 39 respectively via a low pressure reservoir in this way a closed system is attained in fig7 there is shown a modification of the device of the invention wherein the drive 2 is connected to a refrigerating machine 13 34 by a connecting conduit 47 the auxiliary drive 48 of drive 2 is connected to the plate 40 39 of the refrigerating machine 13 34 via a beam balance 49 herein the auxiliary drive 48 is supplied from the drive 2 with compressed air which.