Deere + Company

Hilmar S Ortlepp

Manfred A Becker

Volker D Huckler

Vasile A Benedek

A hydraulic system includes a hydraulic pump, a reservoir, a hydraulic function, such as a cylinder, and a power beyond valve for controlling communication between the pump, the reservoir and the cylinder. The pump provides pressurized fluid at a pump output as a function of the pressure in a load sensing port. For generating a pump controlling load sensing signal in case that the cylinder does not generate such a signal, it is proposed to provide a valve which blocks in a first position or opens in a second position communication between the feed line of the cylinder and the load sensing port of the pump. The valve functions in dependence of control pressures acting on each side of a valve member. A spring is provided biased to urge the valve member to its first closed position. Further, shift valve means are provided to supply selectively different pressures to both sides of the valve member. In an open-center hydraulic system, the valve means the shift valve means connects the first side of the valve member to the reservoir and the second side of the valve member to the feed line. In a closed-center system, the shift valve means will be changed over to connect the first side of the valve member to the feed line and the second side of the valve member to the pump outlet.

Hydraulic system for open or closed-centered systems

A valve includes a valve housing having a valve bore with a first valve member movable therein to control fluid communication between a pump, a reservoir and a hydraulic function. The first valve member includes annular grooves which receive pressure controlled seals. A second valve member is movable in the valve bore and is connected to an actuator. The first and second valve members cooperate to form a pre-control valve which controls pressurization of the pressure controlled seals. The second valve member also connects the actuator with the first valve member so that the seals are relieved of pressure before the first valve member is moved.

Control valve

Disclosed herein is a support for supporting the load sensing bar of a draft control system. The support includes an L-shaped bracket which is adapted to have one leg attached to a vehicle and the other extending outwardly therefrom. The attached leg has a through opening with a spherical bearing therein through which the load sensing bar passes. A stop is carried on the other end of the outwardly projecting leg to limit bending of the bar. A clip is also carried by the outwardly extending leg and extends to a position where it will prevent the bar from sliding out of the bearing in the attached leg in the event the bar breaks.

Draft vehicle with load sensor and removable support

An improved hydraulic control valve is disclosed for providing the metering of fluid to a steering arrangement such as that normally employed on a motorized vehicle. The steering arrangement includes a piston-cylinder assembly, a main pump for supplying pressurized fluid from a fluid reservoir to the control valve and a control pump connected to the control valve which is actuated by a manually operated steering mechanism. The improved control valve includes a housing having an elongated bore formed therein. Movably positioned within the bore is a valve spool which has at least three annular grooves formed thereon separated by a pair of lands. The valve spool also contains a longitudinal bore formed therein which intersects a transverse bore which opens into the centrally positioned annular groove. The valve spool cooperates with the elongated bore to form control pressure chambers at each end thereof. Also positioned at each end of the valve spool are check valves which are closed when the valve spool is in a neutral position and which open when the valve spool is subjected to pressure loading. Fluid flow through the valve is directed by a plurality of passages formed in the housing. One of the passages connects the main pump to the elongated bore, while two working passages connect opposite ends of the piston-cylinder assembly to the elongated bore approximate the outer two annular grooves which are formed in the valve spool. There are also two control passages connecting the opposite ends of the control pump to the elongated bore approximate the pair of lands formed on the valve spool and at least one reservoir passage connecting the reservoir to the elongated bore approximately between an outer end of the valve spool and the outer annular groove formed thereon. This improved hydraulic control valve can be used for any constant pressure system.

Growing community of inventors

Mannheim, Germany

Hilmar S Ortlepp