plate 45 up or down on lead screw 44 drive nut and plate 45 is a plate which has secured to each end stainless steel aircraft cables 46 which pass over pullies 47 and are then attached to platform 49 platform 49 supports a pneumatic cylinder 50 which receives air from a supply 50s via a pressure regulator model 10 motorized 6 fpm 120 vac 60 hz 50r regulator 50r controlled by overload relay 245 fig1 as lead screw 44 rotates the nut and drive plate 45 moves up or down causing the cables 46 to be shortened thus raising the pneumatic cylinder 50 as the motor is driven in the desired direction this causes the entire body weight assembly and ankle assembly 14 to move upward this permits the adjustment of the offset in the ankle assembly 14 without effecting any of the body weight control motion so that shorter or larger specimens may be accepted this motion is automatically controlled by the maximum range by limit switches not shown to prevent damaging lead screw 44 and nut plate assembly 45 the simulation of body weight is controlled by pneumatic cylinder 50 and the regulator assembly 50r the pneumatic regulator 50r is controlled from one of the front panel switches and applies an increasing air pressure from a supply 50s.