Patent ID: 6408977
Filing Date: 2002-06-25
Classification: B62D

Abstract:
A hydraulic steering system for a mobile working machine, with a steering unit (12) that can be adjusted out of a neutral position by a first steering member (11), which is constructed as a steering wheel, that has a first fluid connection (29), which is connected to a &Parenopenst;left-hand&Parenclosest; pressure chamber (35, 36â€²) of a steering motor (14, 14â€²), said pressure chamber being subjected to pressure for a steering movement to the left, and that has a second fluid connection (30), which is connected to a &Parenopenst;right-hand&Parenclosest; pressure chamber (36, 35â€²) of the steering motor (14, 14â€²), said pressure chamber being subjected to pressure for a steering movement to the right, with a second steering member (55), which is constructed as a joystick and by which a pilot-control means (59, 71) can be adjusted and a pilot-control signal can be produced, and with a control valve (13) that has an axially movable valve spool (50) and can be activated only by the pilot-control signal and has another first fluid connection (43), which is connected to the left-hand pressure chamber (35, 36â€²) of the steering motor (14, 14â€²), and another second fluid connection (44), which is connected to the right-hand pressure chamber (36, 35â€²) of the steering motor (14, 14â€²), wherein the control valve (13) can only be activated when the steering unit (12) is in the neutral position.