HYDRAULISK STYREINDRETNING MED EN INDSTILLELIG DROSSEL

摘要

The invention relates to a hydrostatic steering control unit of the type having valving for an open center neutral position which bypasses pressurized fluid from the pump to the tank when in neutral. During a turning operation with a steering wheel the open center valving is caused to close and the pressurized fluid is directed to one side or the other of a servomotor which is connected to wheels to be steered. The open center valving includes orifices in relatively rotatable elements which are aligned in the neutral position and closed to effect the turning operation. Open center valving can be the cause of noise and cavitation and such valving herein is provided with slot shaped orifices and flat generally wedge shaped throttle passages to minimize the noise and cavitation problems. The throttle passages are defined by curved bounding surfaces having rectangularly shaped outlines. A characteristic of the curved surfaces is that they are formed with exponentially shaped sections.