Variable rate spring devices

Claim 1

A VARIABLE RATE SPRING DEVICE COMPRISING A LONGITUDINAL LEAF SPRING ARRANGED TO EXERT A RESILIENT THRUST AT A THRUST POSITION ALONG ITS LENGTH IN A DIRECTION TRANSVERSELY OF ITS LENGTH; FIXING MEANS FOR FIXING THE SPRING AT A FIXING POSITION, SPACED APART ALONG ITS LENGTH FROM THE SAID THRUST POSITION, AGAINST MOVEMENT AT LEAST IN THE SAID TRANSVERSE DIRECTION; AND LOADING MEANS FOR EXERTING A LOADING THRUST ON THE SPRING IN THE SAID TRANSVERSE DIRECTION AT A LOADING POSITION WHICH IS VARIABLE ALONG THE LENGTH OF THE SPRING, WHEREBY VARIATION OF THE LOADING POSITION ALONG THE LENGTH OF THE SPRING CAUSES VARIATION OF THE RATE OF CHANGE OF THRUST AT THE SAID THRUST POSITION WITH CHANGE OF DEFORMATION OF THE SPRING IN THE SAID TRANSVERSE DIRECTION AT THAT POSITION; WHICH SPRING COMPRISES TWO LONGITUDINALLY EXTENDING SPRING PARTS SPACED APART TRANSVERSELY OF THE SAID TRANSVERSE DIRECTION; AND THERE IS PROVIDED MEANS FOR VARYING THE LOADING POSITION AS AFORESAID WHICH MEANS INCLUDES AN ARM MEMBER EXTENDING THROUGH THE SPACE BETWEEN THE TWO SPRING PARTS.