Caterpillar Inc.

Valeo Electrical Systems, Inc.

Michael J Mientus

John James Krone

Xiaodong Huang

John Samuel Hill

Rabie E Khalil

Jeffrey J Buschur

Kerry A Machesney

A method of steering a vehicle with a hydraulic steering system is disclosed. A first control signal is sent to a pilot valve. The pilot valve is operated to direct pilot fluid to a main valve in response to the first control signal. The main valve is opened to a first position in response to the pilot fluid. Fluid is directed through the main valve to a first actuator. Resistance to actuation of the first actuator is detected. The detected resistance is compared to a threshold resistance. A second control signal is sent to the pilot valve when the detected resistance exceeds the threshold resistance. The pilot valve is operated to direct pilot fluid to the main valve in response to the second control signal. The main valve is opened to a second position in response to the pilot fluid. Fluid is directed through the main valve to the first actuator and a second actuator.

On-demand electro-hydraulic steering system

A hydraulic steering system for a work machine may include a first steering actuator having a first and a second chamber. In addition, the steering system may include a second steering actuator having a third and a fourth chamber. A multi-position directional valve may include at least one low power position and at least one high power position. The low power position may be configured to direct fluid only to the first chamber during a low power turn to extend the first steering actuator. The high power position may be configured to direct fluid to the first chamber and the third chamber during a high power turn to retract the second steering actuator.

An improved hydraulic motor system, suitable for driving an automotive cooling fan or the like. The system is driven by grade gerotor set and an idle gerotor set which are stacked between a center plate and against a rear wall of a cylindrical cavity in a front face of a manifold. A fluid-tight chamber is established by securing an end frame can around the stacked gerotor sets and against the perimeter of the manifold cavity. Tightness of the seal is controlled by positioning a resilient cover plate against the end frame can from a position opposite the manifold, and adjustably clamping the resilient cover against the manifold until the resilient cover has undergone a predetermined amount of elastic deformation.

Hydraulic motor system

A hydraulic machine of the gerotor type. The machine uses two gerotors which are preferably coplanar, and positioned nearly concentric to each other. This dual arrangement approximately doubles the displacement of hydraulic fluid per revolution, compared with a single gerotor, and thus doubles power transfer. Yet the housing containing the gerotors need only be large enough to contain the larger gerotor.

Hydraulic machine comprising dual gerotors

An accumulator charging valve has a first valve spool determining a cut-in pressure level at which fluid from a pump is directed to an accumulator and a second valve spool determining the cut-out pressure level at which fluid is no longer directed to the accumulator. When the pressure at the accumulator reaches a predetermined high level, the second valve spool moves to a position communicating an inlet port with an intermediate passage. The first spool is normally at a position blocking the intermediate passage from an outlet port so that a flow path is established through a pair of orifices reducing the pressure in the intermediate passage and the inlet port. The reduced pressure is transmitted to an actuating chamber to hold the second valve spool in the above noted position and to a pump displacement controller to destroke the pump to a low standby pressure displacement. When the pressure at the accumulator drops to a predetermined low level, the first valve spool moves to a position communicating the intermediate passage with the outlet port venting the actuating chamber so that the second valve spool moves to a position blocking the inlet port from the intermediate passage. This increases the pressure directed to the displacement controller upstroking the pump to a high pressure displacement. The cycle is repeated when the pressure reaches the predetermined high level.

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Metamora, IL, United States of America

Michael J Mientus