Load leveling air pump with pressure clutch

Claim 1

An automatic load leveling mechanism for a vehicle having an unsprung mass, a sprung mass supported from the unsprung mass, and a fluid-receiving device for controlling the relative position of said masses, said masses having a variable average separation depending upon the amount of fluid within said fluid-receiving device and upon the weight of the sprung mass, said load leveling mechanism comprising: a fluid pump for pumping fluid into said fluid-receiving device and powered by the relative movement of said masses in response to motion of said vehicle, said pump comprising a housing connected to one of said masses, a pump piston slidably mounted in said housing and connected to the other of said masses, the feedback means slidably mounted in said housing, said feedback means, said pump piston and said housing cooperating to define a compression chamber therebetween, said pump piston moving relative to said one mass to transfer fluid from said compression chamber to said fluid-receiving device, said feedback means being movable toward said pump piston in response to increasing fluid pressure in the fluid-receiving device; and fluid control means for permitting fluid to escape from the fluid-receiving device upon at least a predetermined separation of said masses; said feedback means comprises a pair of relatively movable feedback pistons slidably and sealingly mounted in said housing, one of said feedback pistons comprising an expandible portion for frictional engagement with said housing, said feedback pistons including relatively engageable portions, said engageable portions being engageable with each other to expand said expandible portion into frictional engagement with said housing to limit movement of said feedback means within said housing as said pump piston moves to compress fluid in said compression chamber.