Vehicle steering compensator with air actuated trim mechanism

An apparatus for positioning at least one steerable member mounted on a frame means for movement to either side of a selected center position, said apparatus comprising:

• resistance means for providing a resistance force resisting steering forces tending to move said steerable member to either side of said center position, said resistance means comprising linkage means of variable length extending between said steerable member and said frame means, the length of said linkage means defining said center position;
• trim means operable for varying said center position of said steerable member, said trim means comprising a trim piston, trim cylinder means for providing first and second trim chambers one on each side of said trim piston, and trim passage means for providing a flow of a liquid to and from each of said trim chambers, said trim piston being movable relative to said trim cylinder means to cause said flow and vary said center position by changing the length of said linkage means;
• and,
• actuator means for operating said trim means so as to controllably vary said center position of said steerable member from a location remote from said trim means and said steerable member, said actuator means comprising:
• a source of said liquid,
• trim conduit means for providing a flow of said liquid between said source and said trim passage means,
• trim valve means operable between a closed position for preventing said liquid flow from each of said trim chambers and an open position for allowing said trim piston to move relative to said cylinder, said piston movement causing said liquid flow to one of said trim chambers and said liquid flow from the other of said trim chambers,
• and operating means activatable from said remote location for operating said trim valve means between said closed and open positions, said operating means comprising a piston head arranged for reciprocal movement in an actuator chamber between a rest position and a depressed position, actuator fluid means for pressurizing said actuator chamber to cause movement of said piston head from said rest position to said depressed position and for depressurizing said actuator chamber for return movement of said piston head to said rest position, and push means connected to said piston head for movement between an extended position in which a push element of said push means moves at least one stem of said valve means to cause said valve means to be in its open position and a retracted position in which said push element moves said at least one stem to cause said valve means to be in its closed position, said valve open and closed positions corresponding respectively to the depressed and rest positions of said piston head.