Steering stabilizer with valved accumulator

An apparatus for holding at a center position at least one steerable member mounted on a frame means for movement to either side of the center position, said apparatus 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, and accumulator means for holding a supply of fluid and means for pressurizing the fluid held in said accumulator means;

• wherein said linkage means comprises resistance means for providing a resistance force resisting steering forces tending to move said steerable member to either side of the center position, and trim means for transmitting said steering forces to said resistance means;
• wherein said trim means comprises:
• a trim piston,
• trim cylinder means providing a portion of said linkage means and cooperating with said trim piston to form first and second trim chambers one on each side of said trim piston,
• and trim fluid means for providing a flow of trim fluid between said accumulator means and each of said trim chambers and comprising trim valve means operable between a closed position for preventing said trim fluid flow so that said trim piston is held in a locked position, and an open position for allowing said trim fluid flow so that said trim piston is free to move away from said locked position in said trim cylinder, said trim piston movement causing trim fluid flow to one of said trim chambers and trim fluid flow from the other of said trim chambers to permit trimming movement of said steerable member to another center position by changing the length of said linkage means in response to said steering forces;
• wherein said resistance means comprises:
• resistance cylinder means providing a portion of said linkage means,
• resistance piston means cooperating with said resistance cylinder means to form first and second resistance chambers, and being arranged for movement in a first direction for compressing a fluid within said first resistance chamber and for movement in a second direction for compressing a fluid within said second resistance chamber,
• resistance rod means providing a portion of said linkage means and arranged for movement with said resistance piston means to either side of a neutral position corresponding to said center position,
• and resistance fluid means for providing a pressurized resistance fluid in each of said first and second resistance chambers so that fluid pressure provides said resistance force by causing said resistance piston means to be biased toward said neutral position, said bias opposing movement of said steerable member toward either side of said center position;
• and wherein said trim valve means comprises:
• a first conduit for communicating with said accumulator means to supply trim fluid to said first trim chamber,
• a second conduit for communicating with said accumulator means to supply trim fluid to said second trim chamber,
• a first port for providing fluid communication between said accumulator means and said first conduit,
• a second port for providing fluid communication between said accumulator means and said second conduit,
• and a valve member arranged for reciprocating movement between a closing position for causing simultaneously closure of said first and second ports and an opening position for causing simultaneously opening of said first and second ports.