the weight member 62 the rate of retardation depending upon the viscosity of the selected fluid 64 the fluid 64 likewise affects the rate of return which can also be important in some installations inasmuch as it is planned that a fluid 64 will be employed in most instances the use of the flexible bellows 66 along with the o ring 40 assures that the lower portion of compartment of the casing 12 will be sealed from the upper portion containing the disc 42 and that no fluid can pass therebetween while the bellows 66 prevents any transfer of the fluid 64 it will be observed that the downwardly extending skirt or flange 44 provides a concave configuration as far as the disc 42 is concerned the use of a flat disc at least a disc having a flat lower surface could cause a sticky condition to develop by reason of two flat surfaces the upper surface of the platform 34 being the second such flat surface confronting each other in other words the surface tension particularly if there is a film of oil existing could adversely influence or affect the operation however the rounded knife edge shape imparted to the lower edge of the flange or skirt 44 obviates any possibility of a sticky condition arising which could adversely affect the operation of my device 6 hence it should be obvious that the device 6 is indeed quite versatile and can be employed in a number of situations without modification where modification to meet certain criteria is needed the user has the option of changing the disc 42 and or the weight member 62.