Caterpillar Inc.

Rabie E Khalil

John James Krone

Xiaodong Huang

Michael J Mientus

Sivaprasad Akasam

Brian Douglas Hoff

Bryan D Brown

A hydraulic cylinder is disclosed. The hydraulic cylinder may have a tube, and a piston disposed within the tube and having a bore passing through the piston. The hydraulic cylinder may also have a valve element disposed within the bore and having a length shorter than a length of the bore. The valve element may be mechanically movable to allow fluid flow through the bore, and hydraulically movable to inhibit fluid flow through the bore.

Hydraulic cylinder having piston-mounted bypass valve

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 transformer is disclosed. The hydraulic transformer may have a housing, and a first pumping mechanism disposed within the housing and rotated in a first direction by fluid pressure. The hydraulic transformer may also have a second pumping mechanism disposed within the housing and rotated by the first pumping mechanism in the first direction to increase the fluid pressure. The hydraulic transformer may further have a common shaft connecting the first and second reversible pumping mechanisms. One of the first and second pumping mechanisms may also be rotated in a second direction opposite the first by fluid pressure. The other of the first and second pumping mechanisms may also be rotated by the one of the first and second pumping mechanisms in the second direction to increase the fluid pressure.

Bidirectional hydraulic transformer

A method of operating an electrically propelled machine includes the steps of, operating an electrical power source for the machine, and limiting an output torque of an electrical propulsion motor system of the machine based upon the occurrence of a crowd force condition of the machine. An electrically propelled machine is further provided, including an electronic controller having means for limiting motor output torque based at least in part on a crowd force condition of the machine.

Crowd force control in electrically propelled machine

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 electro-hydraulic system for a machine may include a brake charging system including at least one accumulator. A fan drive system may include a fan and a fan motor. A fluid source may be in communication with the brake charging system and the fan drive system. The fluid source may be configured to provide pressurized fluid to the brake charging system and the fan drive system to charge at least one accumulator and to drive a fan motor. A priority valve may be configured to provide pressure from the fluid source to the brake charging system, such that the fluid pressure at the accumulator is maintained at a substantially constant level during normal operating conditions.

Electro-hydraulic system for fan driving and brake charging

An electro-hydraulic steering control system for directing fluid to steering actuators on a work machine may include a main valve configured to control fluid flow to the steering actuators. Left and right primary steering valves may be in communication with and configured to affect the main valve to control fluid flow to the steering actuators. Left and right redundant steering valves may be in communication with and configured to affect the main valve to control fluid flow to the steering actuators. A shuttle valve may be operably disposed between one of the right primary and the right redundant steering valves and the left primary and left redundant steering valves. The shuttle valve may be operable to selectively control fluid from the one of the right primary and the right redundant steering valves and the left primary and left redundant steering valves to the main valve to control the main valve.

Growing community of inventors

Dunlap, IL, United States of America

Rabie E Khalil