the form of a double helix these are also compressed axially in the same manner described above relative to fig1 the characteristic of this particular structure is that there is more surface contact between chamber wall 27 39 and the abutting portions of elastomeric members 20 39 in fig5 a still further embodiment ot the present invention is shown wherein there is a triple helix consisting of three elastomeric strands 20 39 confined under compression within chamber wall 27 34 in both of these embodiments the amount of axial contact between the elastomeric members and the chamber walls will depend on the respective diameters and lengths as discussed above relative to fig1 and 2 while the elongated elastomeric members 20 20 39 and 20 34 have been depicted as cylindrical prior to being distorted into their undulating shape by the preloading action of piston 19 it will be appreciated that these elastomeric members may be of any other columnar shape furthermore in situations where very little or no preload is required the elastomeric member 20 can be preformed into an undulating shape rather than being of original cylindrical shape before it was preloaded to the condition shown in fig1 an embodiment of the latter type can be visualized from fig1 if it is assumed that member 20 was preformed to the shape shown so that it would exert only a small force or no force on.