Hydraulic steering apparatus

Claim 1

Hydraulic steering apparatus comprising a sump, two motors for controlling parts to be steered, said motors including movable motor elements, a steering wheel operated control device having supply and exhaust openings and selectively reversible control ports with each of said control ports alternating as a supply and exhaust port, said control ports each being oppositely connected to one side of one of said motors and to the other side of the other of said motors, a continuously operable pump between said sump and said control device supply opening, a pair of control conduits connected to said control ports and meeting at a junction, a pair of stroke limiting control valves in said control conduits actuatable alternately to open positions by said movable motor elements, and an exhaust conduit from said junction to said sump, a short circuiting path shunting said pump, a pressure operated switching valve in said short circuiting path, a pressure operated pilot valve for controlling said switching valve, a spur connection between said pilot valve and said exhaust conduit, and throttle means in said exhaust conduit downstream from said spur connection to create a pressure at said spur connection to cause concomitant opening of said pilot valve and said switching valve.