A servo actuator is provided which may comprise a controller configured to control a plurality of solenoid valves based upon an output signal. The plurality of solenoid valves may be used to control the position of the object. For example, a set of solenoid valves, of the plurality of solenoid valves, may be configured to conduct fluid from a tank into a first chamber of the cylinder, conduct fluid from the tank into a second chamber of the cylinder, conduct fluid from the second chamber of the cylinder into a first solenoid valve and/or conduct fluid from the first chamber of the cylinder into the first solenoid valve. The first solenoid valve, of the plurality of solenoid valves, may be configured to conduct fluid from the set of solenoid valves into a vent valve based upon a pulse width modulation (PWM) signal received from the controller.

A control system and method for controlling the positioning of an adjustable deflector plate employed in a harvesting combine to adjust a side-to-side flow of crop residue to spreaders associated with the combine and the distribution thereby. The deflector plate is operably extendable into the flow of crop residue to redirect crop residue impinging the deflector plate. The deflector plate is adjusted based upon a comparison between the open/closed states of valves associated with the control system.

The energy recovery system includes an inertial fluid container, a low pressure container, a high pressure container, a low pressure valve, and a high pressure valve, a valve flow conduit, and a valve controller. The valve controller switches, in response to a decrease in volume of the fluid chamber, the inertial fluid container between communicating with the low pressure container and the high pressure container, thereby generating inertial forces of the working fluid flowing toward the low pressure container in the inertial fluid container, and causing the working fluid to flow into the high pressure container by the inertial forces. The valve controller sets a switching frequency for the valves to a frequency close to an Nth-order (where N is a natural number) anti-resonance frequency of a flow conduit for the working fluid.

Electrically controllable hydraulic system for a vehicle transmission and method for controlling the same An electrically controllable hydraulic system (1) for a vehicle transmission comprises a pressure pump system (4a, 4b) and a subsystem (1A) comprising a transmission element (2) and an electrically controlled hydraulic pressure controlling module (1B) including a hydraulic valve element (15) for controlling a hydraulic pressure for actuating the transmission element (2) and an electromagnetically controllable operating element (21) for operating the hydraulic valve element (15). The subsystem (1A) and the pressure controlling module (1B) have a first and a second cut-off frequency (f1, f2) with f2>f1. The hydraulic system includes a driver circuit (32) for driving the pressure controlling module (1B) that comprises a full bridge circuit and a control circuit (42) for simultaneously controlling both switching elements of the driver circuit with a duty cycle according to an input value of the input signal (Iset) dithered with a frequency (f.sub.dith) in the range (f1, f2).

A system and method for the controlled lowering and lifting of a load are disclosed. The system and method may include operating a work machine having a hydraulic system including a hydraulic actuator for supporting a load, a first control valve in fluid communication with the actuator, and a controller for operating the first control valve. In one embodiment, the controller includes a first algorithm for operating the first control valve in a load lowering operation. When an operational fault within the hydraulic system is detected, the controller can be configured to enter into a safe lowering mode. In the safe lowering mode, the first algorithm is disabled and a pulse width modulation (PWM) current is sent from the controller to the first control valve. A user interface is provided to allow an operator to control the PWM current duty ratio to allow the load supported by the actuator to be lowered.

A solenoid valve system includes a supply solenoid valve, a plurality of exhaust solenoid valves, and a valve control section controlling opening and closing operation of the supply solenoid valve and the plurality of exhaust solenoid valves using PWM or PFM. The plurality of exhaust solenoid valves are disposed in parallel with each other. The supply solenoid valve and the plurality of exhaust solenoid valves have substantially identical flow rate characteristics. The number of the plurality of the exhaust solenoid valves is twice the number of the supply solenoid valve.

A control system includes a variable displacement hydraulic pump, the pump having an inlet for receiving fluid, an outlet for discharging fluid under pressure, and a pump displacement input, a hydraulic motor having an inlet and an outlet, a fluid circuit including a supply conduit for conducting fluid discharged by the pump to the motor and a return conduit for returning fluid discharged by the motor to the pump, a pump displacement control cooperating with the pump displacement input in order to vary a displacement of the pump, a control circuit in communication with the pump displacement control for controlling the pump output such that the motor is driven at a constant rotational speed, and a system controller in communication with the control circuit and a remote location to transmit and receive information to and from the remote location.

A system and method for the controlled lowering and lifting of a load are disclosed. The system and method may include operating a work machine having a hydraulic system including a hydraulic actuator for supporting a load, a first control valve in fluid communication with the actuator, and a controller for operating the first control valve. In one embodiment, the controller includes a first algorithm for operating the first control valve in a load lowering operation. When an operational fault within the hydraulic system is detected, the controller can be configured to enter into a safe lowering mode. In the safe lowering mode, the first algorithm is disabled and a pulse width modulation (PWM) current is sent from the controller to the first control valve. A user interface is provided to allow an operator to control the PWM current duty ratio to allow the load supported by the actuator to be lowered.

A fluid system has a fluid actuator that receives a fluid to cause movement of a component. A valve selectively controls the flow of fluid to the fluid actuator. A motor for the valve is provided with an electric voltage or current. A control applies a pulse width modulation variation to the supplied voltage or current. The control is operable to vary the pulse width modulation of the voltage or the current based upon conditions of the system. A mechanical system and a method are also disclosed.

An emergency braking method for aircraft, comprising using a progressing parking brake controlled by a lever (10) that can be actuated by the pilot between a 0% position in which the brakes are connected to the return pressure of the aircraft, and a 100% position in which the brakes are connected to the feed pressure of the aircraft, the lever being blockable in the 100% position in order to provide parking braking when the aircraft is stationary. According to the invention, the emergency braking method being characterized in that it comprises: using a valve having an outlet port connected to the brakes, a return port, and a feed port, the valve presenting a state connecting the outlet port to the return port and a state connecting the outlet port to the feed port; and controlling the valve to occupy one or other of those states by pulse width modulation (PWM) having a duty ratio (R) that is a function of the position of the lever in order to deliver the brakes with pressure lying in the range return pressure to feed pressure, depending on the position of the lever.