Abstract: There is described herein methods and system for correcting steady state errors in propeller speed by calculating a leakage flow rate as a function of engine and propeller parameters.

Abstract: A three-dimensional measuring machine (industrial machine) includes an air supplier supplying air; a drive mechanism driven by the air supplied from the air supplier; an electromagnetic valve provided inside an air regulator set to open and close an air supply passage inside the air regulator set, the air regulator set introducing the air from the air supplier to the drive mechanism; and a motion controller controlling the electromagnetic valve to block the air supply passage when a time since the drive mechanism stopped operation reaches a preset time.

Abstract: A method of controlling a float function of a cylinder 25 having a first side and a second side includes connecting the second side of the cylinder to a reservoir 15; connecting the first side of the cylinder to an output of a pump 20 and to the reservoir; and supplying an amount of flow from a pump less than an amount supplied by the pump under loaded conditions. A three-position directional control valve 30 having a pump port, a reservoir port, a first cylinder port, and a second cylinder port may be provided to effectuate aspects of this method.

Abstract: A hydraulic control device includes: a hydraulic pump connected in parallel to steering and boom cylinders; a steering control valve that controls the direction of operating oil flowing through the steering cylinders; a boom control valve that connects the hydraulic pump to a tank when the valve is at a neutral position and controls the direction of the oil flowing through the boom cylinders when the valve is at an offset position; a meter-in pressure compensator that increases flow rate of the oil flowing through a variable restrictor of the steering control valve in accordance with pressure in front of and behind the restrictor; and a bleed-off pressure compensator that decreases flow rate of the oil flowing through the boom control valve in accordance with the increase in pressure of the oil flowing through the steering cylinders to maintain the predetermined pressure of the oil in the steering control circuit.

Abstract: The invention relates to a power cylinder comprising a piston-in-cylinder unit having at least one pressure connection, an integral valve arrangement for controlling the pressure volume flow from the pressure connection into the cylinder space and an integrated control and/or regulation unit for actuating the valve arrangement.

Abstract: The invention relates to a proportional directional control valve for controlling a hydraulic consumer, having a housing with a pressure port, a tank port, and first and second working ports. A control element is movably mounted in the housing. A single actuator is provided for moving the control element, which, in dependence on its position relative to the housing, enables different flow paths between the ports. The control element, starting from a first switching position in which both working ports are connected to the tank port, is movable by the actuator via a second switching position that follows the first switching position, to a third switching position that follows the second switching position. It is possible, by moving the control element from the first switching position into the third switching position, to successively disconnect the two working ports from the tank port and connect them to the pressure port.

Abstract: A hydraulic control system is disclosed for use with a machine. The hydraulic control system may have a tank, a pump, an actuator, and a control valve configured to direct fluid from the pump to the actuator and from the actuator to the tank. The hydraulic control system may also have a pressure sensor to generate a first signal indicative of a pressure differential across the control valve, an operator input device to generate a second signal indicative of a desired movement of the actuator, and a controller. The controller may be configured to make a first determination of an opening amount of the control valve based on the second signal, and to make a second determination based on the first signal of whether the opening amount will result in overspeeding of the actuator. The controller may also be configured to reduce the opening amount based on the second determination.

Abstract: An apparatus for compensating for fluid contraction in a hydraulic powered telescoping boom may include a monitor determining the elevation angle of the telescoping boom, a supply of hydraulic fluid, and a fluid control responsive to the monitor. The fluid control provides the hydraulic fluid from the supply to a hydraulic cylinder controlling extension of the telescoping boom when the elevation angle exceeds a predetermined threshold angle to compensate for thermal contraction of hydraulic fluid and thus prevent uncommanded boom retraction. A method in accordance with the invention is also disclosed.

Abstract: A method for actuating a bypass control valve assembly of a fluid system includes receiving a first input signal at an electronic control unit. The first input signal is related to an active position of a direction control valve that is in fluid communication with a fluid pump and a fluid actuation device. The directional control valve includes a neutral position that provides fluid communication between a fluid inlet port of the directional control valve and a fluid outlet port of the directional control valve. A second input signal is received at the electronic control unit. The second input signal is related to the rotational speed of the fluid pump. The second input signal is compared to a limit. A drain valve of a bypass valve assembly is actuated so that fluid communication between the fluid pump and a fluid reservoir through the bypass valve assembly is blocked.

Abstract: A hydraulic circuit of an injection cylinder in a die-casting apparatus, which can achieve IN restriction and OUT restriction in a quickly switchable manner with a single circuit and which allows manufacturing of a high-quality molded product. The hydraulic circuit includes: a first pressure oil path supplying pressure oil to the injection cylinder; a second pressure oil path returning the pressure oil from the injection cylinder; a first flow control valve controlling a flow of the pressure oil through the first pressure oil path; a second flow control valve controlling a flow of the pressure oil through the second pressure oil path; a bypass pressure oil path connected to the second pressure oil path for bypassing the second flow control valve; a bypass on-off valve provided on the bypass pressure oil path and opening/closing the bypass pressure oil path with the pressure oil; and a controller controlling each valve.

Abstract: Disclosed is a hydraulic pump control system for minimising flow loss by optimally limiting the discharge flow volume of the hydraulic pump when an upper swivel body is made to swivel abruptly.

Abstract: Inventive embodiments are directed to components, subassemblies, systems, and/or methods for a refrigeration system having a compressor operably coupled to continuously variable accessory drive (CVAD). In one embodiment, the refrigerant is adapted to cool the CVAD. In another embodiment, the refrigerant is configured to actuate a change in operating condition of the CVAD. A change in operating condition of the CVAD can be based at least in part on the thermodynamic state, such as pressure or temperature, of the refrigerant. In one embodiment, a skew-based control system is adapted to facilitate a change in the ratio of a CVAD. In another embodiment, a skew-based control system includes a skew actuator coupled to a carrier member. In some embodiments, the skew actuator is configured to rotate a carrier member of a CVT. Among other things, shift control interfaces for a CVT are disclosed.

Abstract: An exemplary hydraulic system includes a digital valve operable to fluidly connect a hydraulic load to a pressure supply. A digital controller is operably connected to the digital valve. The digital controller stores a target value of a hydraulic system operating parameter and is configured to formulate a pulse width modulated control signal based on the target value. The digital controller transmits the control signal to the digital valve for controlling the operation of the valve.

Abstract: A control system actuates at least two hydraulic consumers that may be supplied with pressure medium via a pump, in the case of which an electrically or electrohydraulically adjustable metering orifice (8) is situated in the pressure medium flow path to each of the consumers. The pressure medium flow to the consumer may be adjusted by the metering orifice. A device may adjust the pump pressure or the pumped quantity once a maximum load pressure in the supply line (22, 24) of a consumer has been reached, depending on the demand for pressure medium by one consumer or the other consumer.

Abstract: A hydraulic driving device for a working machine surely prevents behavior of a single rod double acting cylinder not intended by an operator when discharge pressure of a main pump is raised to raise exhaust gas temperature to temperature required for burning particulate matter. A selector valve 160 interposed between a spool valve 61 and a rod chamber of a single rod double acting cylinder 51 and a section (a filter regeneration time actuation valve 122, a vehicle body controller 150) controlling the selector valve, are provided. A switch control section prevents a flow of oil directed from the rod chamber of the cylinder toward the spool valve by actuating the selector valve by a poppet of the selector valve when a by-pass cut valve 110 is controlled to increase a load of an engine 21 to a degree exhaust gas temperature reaches temperature required for burning particulate matter.

Abstract: A control arrangement for a valve-controlled hydrostatic displacement contains a control unit for controlling the valve-controlled hydrostatic displacement machine, a sensor electronics portion for detecting sensor data of a power electronics portion and of the valve-controlled hydrostatic displacement machine, and the power electronics portion for furnishing a current necessary for operating the valve-controlled hydrostatic displacement machine. The control unit, the sensor electronics portion, and the power electronics portion are connected, as are the sensor electronics portion, the power electronics portion, and the valve-controlled hydrostatic displacement machine, which in turn are each connected to one another via bidirectional communications lines.

Abstract: Construction equipment having an electric control lever is provided, which can intercept a control signal applied to a flow control valve when trouble occurs in the electric control lever or a control unit.

Abstract: A loader includes a hydraulically operated extension arm, a load sensor for monitoring the load condition on the loader and a hydraulic arrangement for actuation of the extension arm and/or an implement attached to the extension arm. The hydraulic arrangement exhibits at least one hydraulic cylinder with one supply line on the piston rod side and one supply line on the piston side. At least one hydraulically switchable control device is coupled between a source of fluid pressure and a hydraulic tank, on the one hand, and the supply lines on the other hand. An actuating device is coupled for routing control pressure to the control device via first and second control pressure lines.

Abstract: A method for reducing a torque load associated with an implement includes determining a speed associated with a power source, wherein the power source is configured to provide power to a hydraulic pump, determining a position associated with an implement system, and limiting a flow associated with the hydraulic pump based on the speed associated with the power source and the position associated with the implement system.

Abstract: An anti-saturation valve assembly (51) for use in a hydraulic system having priority (17) and auxiliary (25) load circuits, the priority circuit providing a priority load signal (19). The anti-saturation valve assembly includes a pressure sensor portion (61) which senses a decrease between pump pressure (23) and the priority load signal (19), and generates a force on a pressure reducing portion (63) to reduce, correspondingly, a pilot pressure (59): The reduced pilot pressure to a pilot valve (35) results in reduced flow to a pilot-operated main control valve (27) in the auxiliary load circuit (25), thus providing anti-saturation protection for the circuit, without throttling a main flow path and wasting substantial hydraulic power.

Abstract: An apparatus for controllably actuating a hydraulic actuator is provided. The apparatus is connected between a source of pressurized hydraulic fluid and the hydraulic actuator. The apparatus controllably provides pressurized hydraulic fluid to the hydraulic actuator. The apparatus includes a controller for receiving an operating signal and a load pressure signal and responsively actuating the hydraulic actuator.

Abstract: A hydraulic control system for controlling the motion of a double acting hydraulic actuator determines the flow to and from the actuator in accordance with1. the desired movement of the actuator2. the measured hydraulic pressures on opposite sides of the piston of the actuator3. a selected, predefined model of the system of which the actuator forms a partand sets the valves controlling the flows accordingly.

Abstract: A stroke control device having a servomotor, a hydraulic cylinder having a piston, a ball-thread mechanism coupling the servomotor with the piston, and a hydraulic circuit including pressure control valves for driving the hydraulic cylinder. Further it has a numerical control unit for driving the servomotor based on the numerical input data representative of the movement and moving speed of the piston, for detecting signals representative of the load on the servomotor and for producing control signals to control the pressure control valves in the hydraulic circuit in response to the load signals to move the piston so that the load on the servomotor will approach zero.

Abstract: A power steering system for a wheeled vehicle comprising a fluid motor connected to dirigible wheels of the vehicle, a power steering pump and a steering valve structure situated in flow delivery and flow return passages that connect the pump with the fluid motor, the valve structure including a pilot-operated solenoid valve means that controls the bypass flow between the supply and return sides of the pump wherein a solenoid actuator is adapted to apply a vehicle speed sensitive force on a pilot valve portion of the valve which develops valve actuating forces on a flow control portion of the valve wherein the latter is speed conscious only and does not depend upon flow to and from the pump nor upon the steering pressure for the fluid motor.

Abstract: A control system for the hydraulic operating circuit associated with a vehicle lifting device in which the circuit is provided with pressure fluid control valves and flow sensors which are operative on the vehicle lowering cycle to establish substantial evenness of the lowering mechanism and protection against malfunction of an operating component to arrest the travel of the vehicle lifting device in its lowering cycle.

Abstract: A pilot hydraulic system comprises a directional control valve having at least one pilot chamber for controlling the operation of a hydraulic actuator; and a pilot valve connected through a pilot line to the pilot chamber of the directional control valve for operation thereof. The pilot line includes a flow control valve which allows a free flow of hydraulic fluid from the pilot valve to the directional control valve while limiting a flow of hydraulic fluid from the directional control valve to the pilot valve.

Abstract: An improved power steering apparatus includes a pressure modulation assembly which modulates the fluid pressure transmitted from a power steering control valve to a power steering motor. The modulation assembly varies the fluid pressure output from the steering control valve as a direct function of vehicle speed. This results in relatively easy steering for parking and low speed maneuvers and a firmer feel for maneuvers at higher speeds. The pressure modulation assembly is connected in series fluid communication with and between the power steering control valve and the power steering motor and includes a pair of pressure modulation valves. Fluid for actuating the power steering motor flows from the power steering control valve through the pressure modulation valves to the power steering motor. The pressure modulation valves are biased closed by the output pressure from an auxiliary pump which is driven at a speed which varies as a function of vehicle speed.

Abstract: A rotary regenerator is provided with a hydraulic drive system to vary the rotational speed in relation to the temperature scanned. The hydraulic control system provides accurate operation at low rotational speeds.

Abstract: The invention is concerned with an improvement in a hydraulic steering system for an articulated vehicle of the type which comprises a main steering valve system which directs fluid introduced thereto from a fluid source to a steering motor system responsive to an output of a steering pump apparatus. The improvement comprises an articulation angle pump and an associated conduit system connecting the articulation angle pump parallel to the steering pump system to make the steering valve system responsive to a difference in flow between the steering pump system and the articulation angle pump. Alternately or additionally the improvement can comprise a hydraulic accelerometer and associated accelerometer conduit system in parallel to the steering pump system to make the steering valve system responsive to the output of the steering pump system plus a signal determined by the hydraulic accelerometer.