An apparatus for the electrohydraulic control of the parallelism of a roller in a bending machine for working metal pieces, has a first and second pumps for supplying with an operating fluid a first and second actuators, position transducers and a first and second proportional valves to adjust the flow of the operating fluid into the first and second actuators according to signals of the position transducers.

A compressed air supply installation for operation of an air spring installation of a vehicle includes an air feed with an air compressor configured to supply a compressed air feed with compressed air, a pneumatic main line with an air dryer and a compressed air connection for supplying the pneumatic installation with compressed air, a purge line branching from the pneumatic main line to the compressed air feed and comprising a purge valve connected in the purge line and a purge connection for releasing air to the environment, wherein the purge valve is part of a controllable valve assembly. The controllable valve assembly with the purge valve can be pneumatically loaded with a control pressure derived from the air compressor.

A linear actuator system includes a linear actuator and at least one integrated pump assembly connected to the linear actuator to provide fluid to operate the linear actuator. The integrated pump assembly includes a pump with at least one fluid driver comprising a prime mover and a fluid displacement assembly to be driven by the prime mover such that fluid is transferred from a first port of the pump to a second port of the pump. The pump assembly also includes two valve assembles to isolate the pump from the system. The linear actuator system also includes a controller that establishes at least one of a speed and a torque of the at least one prime mover to exclusively adjust at least one of a flow and a pressure in the linear actuator system to an operational set point.

A linear actuator system includes a linear actuator and an integrated pump assembly connected to the linear actuator to provide fluid to operate the linear actuator. The integrated pump assembly includes a pump with two fluid drivers, each fluid driver comprising a prime mover and a fluid displacement assembly to be driven by the prime mover such that fluid is transferred from a first port of the pump to a second port of the pump. The pump assembly also includes two valve assembles to isolate the pump from the system. The linear actuator system also includes a controller that establishes the pump in a normal mode of operation in which the prime movers are independently driven and switches to a fail-safe mode of operation in which only one prime mover is operated.

A method for detecting and isolation a leak in a hydraulic system having a supply pump serving at least one control valve is disclosed. In one embodiment, the control valve has multiple work sections. In step of the method, the hydraulic system is activated. In another step, an actuation command for at least one of the work sections is received, for example from a human-to-machine interface. Subsequently, the method may include generating a flow demand for the work sections for which an actuation command has been received. The method also includes the step of implementing at least one of a first, second, third, and fourth leak detection and isolation protocol to detect and isolate a leak between the pump and the control valve assembly, a leak between the reservoir and the control valve assembly and a leak between the at least one work circuit and the control valve assembly.

The hydraulic system includes a reservoir configured to store hydraulic fluid, an actuator, a first conduit coupling the reservoir to the actuator, a second conduit having a first end and a second end, a first valve positioned between the first end of the second conduit and the first conduit, a second valve positioned between the second end of the second conduit and the first conduit, and a pump configured to drive the hydraulic fluid from the reservoir to the actuator. The hydraulic fluid flows through the first conduit to the actuator when the first valve is in a first position. The hydraulic fluid flows partially through the first conduit, through the second conduit, back to the first conduit, and to the actuator when the first valve is in a second position.

A hydraulic system for a rotary implement, including an oil tank, a main pump, a control valve, and a rotary motor is provided. The oil tank is connected to an oil suction port of the main pump; an oil outlet of the main pump is connected to a P port of the control valve; a T port of the control valve is interconnected with the oil tank; and A and B ports of the control valve are connected to both ends of the rotary motor. The control valve includes a compensation valve connected to the P port and the T port, an electric proportional valve connected to the P port and the compensation valve, and an electromagnetic reversing valve connected to the compensation valve, the T port and the B port.

A method of calibrating an electrohydraulic valve is disclosed. The method includes actuating an on-off valve to an open position. A speed of a fixed displacement pump is regulated to establish a desired flow rate at an outlet of the pump. The pump is in fluid communication within a closed loop circuit with the on-off valve and the electrohydraulic valve. A target pressure in the closed loop circuit is determined as a function of the desired flow rate. The method further includes increasing a current to the electrohydraulic valve and monitoring the target pressure in the closed loop circuit. A start of a fluid flow through the electrohydraulic valve is determined based on a drop in the target pressure within the closed loop circuit.

An apparatus for the electrohydraulic control of the parallelism of a roller in a bending machine for working metal pieces, has a first and second pumps for supplying with an operating fluid a first and second actuators, position transducers and a first and second proportional valves to adjust the flow of the operating fluid into the first and second actuators according to signals of the position transducers.

An apparatus and method for recirculating hydraulic fluid includes commanding a fluid switching valve to a first actuating position where pressurized hydraulic fluid moves a piston; detecting when the piston has completed a first stroke; delay commanding the fluid switching valve to a second actuating position, a bypass valve to a bypass position, or a hydraulic pump to stop pressurizing hydraulic fluid, the piston-bypass valve is open such that hydraulic fluid is fluidly communicated into a sub-circuit through an entry port and through the piston-bypass valve wherein a quantity of hydraulic fluid is flushed out of the sub-circuit through an exit port; and command the fluid switching valve to the second actuating position, the bypass valve to the bypass position, or the hydraulic pump to stop pressurizing the hydraulic fluid.