about this axis in a vertical plane at the extremity opposite cylinder b on the outer link arm 4 is mounted appliance adapter 16 this afixes and supports symbolic load w at this extremity is also located the control release lever 6 with special reference to fig2 amp 4 other items of the invention can be shown item 1 a flexible non elongational cable is rigidly fixed to cylinder a by two clamps 14 then cable 1 continues in clockwise and upward direction to compensating cylinder b then in the clockwise direction over b to and over the guide roller 24 and under a capstan cylinder pulley c then counter clockwise for several revolutions around capstan pulley c back upwards to and under cylinder b it then continues in a clockwise sense up around b then downward to attachment to tension spring 5 the other end of spring 5 is connected to tension adjuster 23 whose other end is connected to cable 1 that is rigidly fixed to cylinder a guide roller 24 revolves about its guide roller axle 25 that is attached to outer link arm 4 by two screws 26 the capstan cylinder revolves around capstan stationary axle 10 that fixes its location to arm 4 by capstan axle locater 22 locking pin 17 prevents axle 10 from rotating relative arm 4 adjacent.