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 hydraulic system (600) and method for reducing boom dynamics of a boom (30), while providing counter-balance valve protection, includes a hydraulic actuator (110), first and second counter-balance valves (300, 400), first and second control valves (700, 800), and first and second blocking valves (350, 450). A net load (90) is supported by a first chamber (116, 118) of the hydraulic actuator, and a second chamber (118, 116) of the hydraulic actuator may receive fluctuating hydraulic fluid flow from the second control valve to produce a vibratory response (950) that counters environmental vibrations (960) on the boom. The first blocking valve prevents the fluctuating hydraulic fluid flow from opening the first counter-balance valve. The first blocking valve may drain leakage from the first counter-balance valve.

The present disclosure relates to a blended or hybrid power system with increased operating efficiency. The blended power system combines the advantages of electrical power with the advantages of hydraulic power when delivering power to a hydraulic actuator. The hydraulic power provides higher power density and the electrical power provides high efficiency and control accuracy in the blended power system. In a blended power system, a control system may be configured to select different modes of operation based on the loads encountered in the combined hydraulic and electrohydrostatic system. The blended power system also allows for smooth and uninterrupted transitions between the different modes of operation within the blended power system. Thus, jerkiness in the blended power system may be minimized or eliminated.

A valve arrangement includes a housing arrangement (12), (18), a first spool valve (1a, 1b) having a first spool (3a, 3b) and a second spool valve (2a, 2b) having a second spool (4a, 4b), wherein the first spool valve (1a, 1b) and the second spool valve (2a, 2b) each includes a supply channel arrangement having a pump channel (5) and a tank channel (6), and a working port arrangement having two working ports (8, 9), wherein the spools (3a, 3b; 4a, 4b) control a flow path between the supply channel arrangement (5, 6) and the working port arrangements (7, 8). In such a valve arrangement, it should be possible to simply adapt the control behaviour to different purposes. To this end, the working port arrangement (7, 8) is arranged in a flange (16a, 16b) connected to the housing arrangement (13, 14; 19, 20).

Disclosed herein are embodiments of a servo-control system comprising at least one pneumatic actuator comprising a movable member, at least one proportional pneumatic valve configured to control fluid flow between the at least one pneumatic actuator and a pressurized fluid supply or a vent, a plurality of pressure sensors each configured to independently measure pressure in a respective supply line to the at least one pneumatic actuator, at least one position sensor configured to measure a position of the moveable member, and a controller. The controller is configured to determine a control signal based at least in part on pressure measurements of the plurality of pressure sensors and a position measurement of the at least one position sensor, and apply the control signal to at least one proportional pneumatic valve to move the movable member to a target position.

Provided is an arrangement and a method to detect an oil leakage between a first section and a second section of a hydraulic cylinder. A movable piston is arranged between the first and second section in a way that the piston changes position between the sections. The change in position is done in dependency of a difference between a first force, which acts at the first section on a first cross sectional area of the piston, and a second force, which acts at the second section on a second cross sectional area of the piston. The first section comprises hydraulic oil with a predefined first pressure, while the first force is calculated based on this pressure and based on the first area. The second section comprises hydraulic oil with a predefined second pressure, while the second force is calculated based on this pressure and based on the second area.

This invention relates to an automatic vehicle wash apparatus employing one or more rotary cloth or foam rubber brushes, and more particularly to the way how the rotary brush to vehicle surface contact is managed using one or more encoders connected to the rotating shaft of each brush and one or more programmable logic controllers (PLC). The encoders, recording the revolutions per minute (RPM) of each brush shaft, provide input to the programmable logic controller. If the RPM value is at or above the high RPM limit, the pivoted boom will move the brush toward the vehicle to achieve a desired brush-to-washable surface contact. If, on the other hand, the RPM value is at or below the low RPM limit, the pivoted boom will move the brush away from the vehicle to achieve a desired brush-to-washable surface contact.

A method is for controlling an actuation force exerted by an actuating device having a first working chamber and a second working chamber supplied with pressurized air from a source of pressurized air by a first pressure regulator and a second pressure regulator. The method includes calculating, by an optimization algorithm based on a dynamic model of the actuating device and of the first and second pressure regulators, desired values for control signals for the first and second pressure regulators to generate an actuation force equal to a desired value for the actuation force. An estimated value for the actuation force, estimated values for pressures inside the first and second working chambers and for first derivatives of the pressures, are determined by a state observer based on a measured value for the actuation force and on measured values for the pressures in the first and second working chambers.

A motor creep control system includes at least one motor and a manifold fluidically coupled to the at least one motor and configured to control flow of a fluid through the at least one motor. The manifold includes an input port, an output port, at least one fluid control valve to control the at least one motor, and a motor creep control valve. A first state of the motor creep control directs the fluid from the input port, through the at least one fluid control and motor, and to the at least one output port. Meanwhile, a second state of the motor creep control in conjunction with the at least one fluid control valve being deactivated directs the fluid from the input port that leaks past the deactivated at least one fluid control valve to the at least one output port, while bypassing the at least one motor.

A servo valve comprises a first spool extending along a first spool axis, a second spool extending along a second spool axis, a first piezoelectric actuator, and a second piezoelectric actuator. The first piezoelectric actuator is operatively connected to the first spool for translating the first spool in response to a voltage applied thereto. The second piezoelectric actuator is operatively connected to the second spool for translating the second spool in response to a voltage applied thereto.