Abstract: A pneumatic unit for a hydropneumatic pressure booster has a system line that leads from a compressed air inlet to a compressed air outlet. A bypass line runs parallel to the system line and it is connected to the system line via first and second compressed air switches. A compressed air reservoir is connected in the bypass line, and a pressure intensifier is connected in the region between the first compressed air switch and the compressed air reservoir. The pneumatic unit makes available to the pressure booster a sufficiently high pneumatic pressure for carrying out at least one operational step of a connected hydraulic tool, even in the case of a pressure decrease or pressure failure in the supplying pneumatic line. For that purpose, the second compressed air switch is configured for switching the compressed air flow between the system line and the bypass line.

Abstract: A hydraulic arrangement for lifting and/or lowering at least one implement carrying arm on an agricultural machine. The arrangement comprises an inlet hydraulic line and an outlet hydraulic line connecting a fluid pump and a fluid reservoir respectively to a first valve means, said arrangement comprising at least one dual acting hydraulic cylinder for lifting/and or lowering the implement carrying arm. The at least one cylinder is connected to the first valve means allowing the cylinder to be switched between a single acting mode wherein the arm can be lifted and a double acting mode wherein the arm can be lifted and lowered.

Abstract: A method of combining outputs of a plurality of fluid pumps includes receiving an input signal from an input device. The input signal is adapted to control a function of a work vehicle. An actuation signal is sent to a first direction control device of a first actuator assembly. The first actuator assembly is in selective fluid communication with a first pump assembly. A position of a second direction control valve of a second actuator assembly is received. The second actuator assembly is in selective fluid communication with a second pump assembly. A selector valve that is in fluid communication with a cavity of a poppet valve assembly is actuated so that the second pump assembly is in fluid communication with the first actuator assembly when the second direction control valve is in a neutral position.

Abstract: The present disclosure relates to a hydraulic system for construction machinery, which is applied to construction machinery provided with a steering unit for controlling steering of equipment, and a main control valve for controlling operating of a work tool, and includes: a main pump for discharging working fluid supplied to the steering unit and the main control valve; a load sensing pressure sensor for sensing a load sensing pressure of the steering unit; a priority valve installed in a supply passage for the working fluid discharged from the main pump, for dividing and supplying the working fluid discharged from the main pump to the steering unit and the main control valve, to correspond to the load sensing pressure; an auxiliary pump for supplementing working fluid to the supply passage supplying the working fluid divided by the priority valve to the steering unit; an electric motor for operating the auxiliary pump; and a controller for operating the electric motor when the load sensing pressure is great

Abstract: The present invention relates to devices and systems that alter intracranial compliance, cerebral blood flow and/or intracranial pressure pulsatility/waveform by oscillating the contraction and expansion of a compressible composition within the cranial or spinal cavities such that they increase intracranial capacity. The contraction and expansion of the compressible composition in the oscillating compliance devices can be due to an individual's intracranial pressure, the result of the expansion and compression of a reservoir which is mediated by the contractility of the heart or driven by a pump gaited to a biorhythm. The invention also relates to methods for protecting an individual's brain from abnormal arterial pulsations and for altering an individual's cerebral blood flow using the devices and systems of the invention.

Abstract: A pneumatic system controlling a bath crust breaker includes a cylinder defining a piston chamber. A piston is slideably displaced within the cylinder by pressurized fluid directed to either a piston chamber first portion with respect to the piston or a piston chamber second portion oppositely positioned about the piston. A pneumatic valve system includes a first control valve aligned between first control valve first and second positions, the first control valve first position aligned with the first portion, and in the first control valve second position is aligned with the second portion. A second control valve is aligned between second control valve first and second positions. An orifice between a pressure source and first control valve is sized to control fluid flow rate so a pressure reached in either the first or second portion during a crust breaking cycle is less than a pressure source maximum pressure.

Abstract: An efficient use of discharged energy of a boom cylinder is provided. A control unit has a function of receiving an output signal from a sensor provided in a boom operated valve and determining a manipulated direction and a manipulated variable of the boom operated valve, and a function of, in accordance with the manipulated direction and the manipulated variable, controlling the degree of opening of a proportional solenoid valve and operating the tilt-angle control units to control the tilt angles of a sub pump and an assist motor. An output of the assist motor is used to assist in an output of the sub pump and an output of the electric motor.

Abstract: The invention relates to an hydrostatic hybrid drive system for road vehicles, said system comprising a pump/motor unit (1) which is or can be connected to the powertrain of the vehicle, can be controlled by means of a control unit (5) in a pump or motor operation and can be connected to a high-pressure hydraulic accumulator via a first working line (7) that can be closed by means of a control valve (45) and to a low-pressure hydraulic accumulator via a second working line (9). The high-pressure hydraulic accumulator and low-pressure hydraulic accumulator are formed by a double-piston accumulator (11), in which a high-pressure side and a low-pressure side having respective accumulator pistons (15, 17) are formed in an accumulator housing (13), wherein the fluid chambers (23 and 25) of the high-pressure side and the low-pressure side are separated by a central housing part (21) through which the common piston rod for both accumulator pistons (15, 17)extends.

Abstract: A flow control apparatus for a fluid cylinder for a workpiece holder includes a flow restricting member and a flexible sealing member. The flow restricting member defines a first passageway and a sealing surface. The flexible sealing member is positioned around the sealing surface. A second passageway is defined between the sealing member and a sealing surface of the flow restricting member when the sealing member is pushed away from the sealing surface in response to fluid flow in a first direction. When fluid flow is applied in the opposite direction, the sealing member moves to engage the sealing surface to substantially limit or preclude fluid flow between the sealing member and the sealing surface in the second direction. The fluid flow in the second direction is thus restricted to flow through the first passageway, thereby slowing or controlling the flow in the second direction.

Abstract: An improved method and apparatus utilizing regenerative hydraulic control principles are disclosed. A regenerative valve is operatively connected in a hydraulic control circuit with a primary hydraulic cylinder for controlling the speed at which the piston and attached rod of the hydraulic cylinder operatively move. The regenerative valve and control apparatus and method control speed of operation of the primary hydraulic cylinder when moving in both its power and its return strokes, to significantly reduce the cylinder's cycle time. A unique regenerative valve configuration enables significantly enhanced volumes of hydraulic fluid to be transferred during a regeneration cycle between the rod and blind sides of the hydraulic cylinder.

Abstract: A hydraulic axial pump/motor comprises a plurality of revolving as well as reciprocating pistons, operatively associated with a stationary port plate. The port plate comprises at least a first, elongated, arcuate suction port and at least a second elongated, arcuate discharge port, divided by a bringing portion extending between the downstream side of the suction port and the upstream side of the discharge port. A tortuous passage of a non-uniform cross-section is formed in the bridging portion, allowing the by-passing of the fluid first in a direction towards the downstream side of the suction port and then towards and into the upstream side of the discharge port.

Abstract: A hydraulic actuator includes three cylinder spaces: a first cylinder space (6) located between a ring piston and a cylinder; a second cylinder space (7) between the ring piston and an auxiliary piston inside a hollow piston rod connected to the ring piston; and the third cylinder space (8) formed between the ring piston, the cylinder and the hollow piston rod.

Abstract: A flow reinforcement directional control valve that is capable of reinforcing a pressure fluid to two actuators, can be formed as compact and yet is capable of flowing a return fluid out of a single actuator into a tank is provided, wherein a valve block 20 has a spool bore 21 in which a first spool (22) and a second spool (23) are slidably inserted; in which the first spool (22) is adapted to be held at a neutral position thereof by a first spring (36) and to be displaced by a pressure fluid in a second pressure receiving chamber (47) to a position thereof for supplying the fluid to an actuator; and in which the above mentioned second spool (23) is adapted to be held at a neutral position thereof by a second spring (41) and to be displaced by a pressure fluid in a first pressure receiving chamber (42) to a position thereof for flowing a return fluid into a tank and to be displaced by a pressure fluid in a third pressure receiving chamber (52) to a position thereof for supplying a pressure fluid to an actuato

Abstract: A motor cavitation prevention device for hydraulic systems is disclosed. The device exerts no influence upon return fluid of any actuators other than the hydraulic motor thereby preventing undesired pressure loss of the return line. The device has valve means installed in a given position of the return line such that the return fluid of the motor necessarily passes the check valve prior to returning to a return tank but the return fluid of the other actuators does not pass the check valve, and a feedback line for feeding the return fluid of the motor back to the motor in the ease of generation of the pressure above tank in the return line, one end of which feedback line is connected to the return line at the front of the check valve but the other end of which feedback line is connected to the motor.

Abstract: A low noise hydraulic pump is disclosed which can be an piston pump or a vane pump, including a flow generation assembly with at least one pumping chamber for creating positive displacement of hydraulic fluid into a hydraulic system. The pump also includes a valve plate in fluid communication with the flow generation assembly, wherein the valve plate defines an inlet for admitting hydraulic fluid and also an outlet for receiving discharged hydraulic fluid. A check valve assembly is received within the valve plate for establishing a fluid passageway between the flow generation assembly and the outlet, wherein the check valve assembly reduces the pressure overshoot between the flow generation assembly and the outlet. The check valve assembly further comprises a check valve having a plurality of apertures, the apertures being sized so as to permit a predetermined flow of fluid through the check valve assembly, whereby the check valve assembly reduces noise generated by the pump.

Abstract: A service valve circuit of a hydraulic excavator connected beforehand for use in controlling a special attachment in addition to a prescribed actuator control valve. The service valve circuit comprises a confluence valve 17 for performing electromagnetic proportional flow rate control, disposed in a confluence circuit 16 in communication with the section between inflow circuits 3F and 3R of two variable pumps 2F and 2R, an electrical switch 21 for switching the confluence valve 17 on or off according to a required flow rate and a volume 22 for adjusting the quantity of flow after passing through a confluence valve 17 in a range of flow for a maximum of one to two pumps. Since the requirement of confluence with respect to a required quantity of flow for a special attachment e and the quantity of confluence are set in advance, there will be no excess or shortage of the quantity of confluence.

Abstract: A prioritizing method and arrangement for a hydraulic system including two independent hydraulic fluid supply units (4, 5) adapted to jointly and severally supply hydraulic fluid to at least two hydraulic components (2, 3). A cross-communication between the at lest two hydraulic components (2, 3) is controlled, with a flow of hydraulic fluid from one of the two hydraulic fluid supply units (5) being diverted to one of the at least two hydraulic components (3) to a substantial exclusion of the other of the at least two hydraulic components (2) in dependence upon an operating condition of the other of the two hydraulic fluid supplying units (5). A biasing force (F) acts upon the prioritizing arrangement so as to define an operating stage at which the respective hydraulic fluid supplying units (4, 5) exclusively supply hydraulic fluid to the respective ones of the at least two hydraulic units (2, 3).

Abstract: The invention is directed to a hydraulic control mechanism for a work vehicle. The work vehicle is provided with a work implement that is operated by a hydraulic actuator. The positioning of the work actuator is controlled by a pilot control system that supplies a pilot control signal to the end caps of a main hydraulic control valve. The mechanism comprises two pressure sensing valves which control the flow of hydraulic fluid from a fixed displacement pump to move the hydraulic actuator, and the flow of hydraulic fluid from a variable displacement pump to hold the hydraulic actuator.

Abstract: The hydraulic piston cylinder assembly which operates the governor of a turbine which powers a hydropower generator has a servo valve capable of flowing only a portion of its flow requirements during normal low power fluctuation conditions of the turbine's operation. During high power fluctuation conditions of the turbine's operation, such as during start-up, hydraulic fluid also flows to and from the piston and cylinder assemblies through high flow pressure and return conduits that bypass the servo valve. Control of fluid flow in the high flow conduits is accomplished by a proportional throttling valve located in the high flow return line. The servo valve and proportional throttling valve together have a flow capacity which is equal to the flow requirements of the piston and cylinder assembly and they are both actuated by the same electronic controller.

Abstract: A hydraulic actuator control circuit capable of increasing the flow rate of the working fluid supplied to hydraulic actuators when the load on the hydraulic actuators increases beyond predetermined values includes a first valve group having a plurality of pilot controlled selector valves connected, respectively, to hydraulic actuators, a second valve group having a plurality of pilot controlled selector valves connected, respectively, to lines connecting the hydraulic actuators to the pilot controlled selector valves of the first valve group, two hydraulic pumps connected, respectively, to the first and second valve groups, and a tank for containing working fluid.

Abstract: Parallel, pulse-width-modulation controlled three-way valves each both supply and exhaust a pressure chamber of a fluid actuator. The phase difference of the oscillator carrier waves of the pulse width modulation input circuit effectively increases the frequency of a net actuator carrier wave so as to quicken the response of the actuator.

Abstract: A hydraulic brake system for automotive vehicles with a master brake cylinder (51) and with a hydraulic power booster (49) connected upstream of the master brake cylinder, in which a pressure medium pump (18) which may be driven by an electric motor (17) is used for providing an auxiliary hydraulic energy, the drive of which may be switched on by a pressure accumulator (1), on the one hand, and by a brake pedal contact (58), on the other hand, in the unbraked operation of the automotive vehicle the pressure accumulator (1) permanently being kept on a pressure level sufficient for an initial actuation of the brake and the charge of the pressure accumulator (1) being monitored by a pressure control valve (19).

Abstract: A multiple compensating unloading valve circuit including multiple fixed displacement pumps and corresponding compensator unloading valves which are phased so that one pump supplies the fluid demand for the circuit until the demand exceeds that pump's capacity and then another pump adds to the flow to supplier larger flow demands. Thus, a primary pump delivers its output to satisfy low flow requirements while a secondary pump's output is vented to a reservoir. When the primary pump cannot supply the demand, the secondary pump automatically adds to the flow to satisfy larger demands. The compensator unloading valves are closed center and are operated in response to a differential pressure which is created between the primary pump's outlet pressure and the load pressure. The primary pump unloading valve has a differential pressure setting which is greater than the differential pressure setting for the secondary pump unloading valve.

Abstract: A safety drive for an artificial heart, if the right drive should fail it is simply put out of operation, while if the left drive fails, the right drive, which is still functioning, is switched over to the left circulatory pump and thus serves as a system-internal backup drive.

Abstract: An improved brake control apparatus for a brake system having redundant brake application fluid circuits 30, 32 and a brake retraction fluid circuit 62. A valve assembly 34, including a slidable two position valve element 60 communicates one brake application fluid circuit 30 with the retraction circuit 62, during normal brake actuation. The valve element 60 is biased towards one position by the combination of pressure in the other brake application circuit 32 and a resilient biasing arrangement 68, and biased towards the second position by pressure in the one application circuit 30. In the event of failure in the other application 32 circuit, the loss of biasing fluid pressure causes the valve element to shift to the second position, interrupting fluid communication from the one application circuit to the retraction circuit and drains fluid pressure in the retraction circuit into the failed circuit.

Abstract: All but the circle drive motor of the implement actuators of a motor grader are divided into two groups each consisting of those which need not be operated simultaneously. The power system has three fixed displacement pumps for driving the circle drive motor via a circle control valve and the two implement actuator groups via respective implement control valve arrangements of carry-over parallel configurations. One of the pumps is connected to the two implement control valve arrangements via a restriction and a flow divider. A first demand valve controls communication between the other two pumps and the implement control valve arrangements in response to the pressure differential across the restriction, maintaining constant fluid flow to the valve arrangements regardless of engine speed or the loads on the implement actuators.

Abstract: A hydrostatic drive system consisting of at least two component systems is provided, each component consisting of an adjustable pump, where the loading of the pump adjusting cylinder is regulated by a hydraulically controlled servo control valve, one side of which is acted upon by the delivery pressure of the associated pump and the other side is acted upon through a control pressure line by pressure beyond the metering restrictor, the improvement comprising a coupling valve to which all delivery lines and all the control pressure lines are connected, each through a branch connection line wherein the said valve in the closed position shuts off all the branch connection lines and in the open position connects all the delivery lines together and all the control pressure lines together and is hydraulically controlled, a first pressure chamber on one side of said valve to which each delivery line is connected, a valve element in said pressure chamber being loaded with a pretensioned spring on said first chamber,

Abstract: A fluid motor (10) having a housing (12) with first (14), second (16) and third (18) chambers therein. A first partition (22) separates the first chamber (14) from the second chamber (16). A second partition (24) separates the second chamber (16) from the third chamber (18). The third chamber (18) is connected to a source of fluid under pressure. A valve mechanism (91) controls the communication of the source of fluid between the second (16) and third (18) chambers. A poppet valve (42) allows the fluid to flow into the first chamber (14) from the second chamber (16). The first chamber (14) is connected to the third chamber (18) through a check valve (118). The valve mechanism (91) responds to an operator input signal by terminating fluid communication between the second (16) and third (18) chambers and initiating communicationof the second chamber (16) with the atmosphere to allow fluid to escape and create a pressure differential across the first (22) and second (24) partitions.

Abstract: A vehicle hydraulic system wherein there is provided a primary pump coupled to a steering control valve through which steering of the vehicle is effected. A main priority valve is used to meter the flow of pressurized hydraulic fluid from the primary pump to either the steering control valve or an implement valve which is utilized to effect operation of auxiliary equipment, in accordance with the priority demands of the steering system. An auxiliary ground-drive pump provides a source of pressurized hydraulic fluid at all times the vehicle is in motion and is coupled to the steering control valve to provide a source of pressurized fluid when necessary or circulates the pressurized fluid to sump. The application of the output from the ground-drive pump is controlled by a secondary priority valve coupled to the output from the ground-drive pump to direct the output to the steering control valve or to sump.

Abstract: Hydraulic apparatus (7), for use where a hydraulic actuator (42) is powered by a first hydraulic supply (40) or selectively and alternatively by a second hydraulic supply (41) independent of the first, which, when a fault occurs, will establish whether the actuator or the first hydraulic supply is at fault, and if it is the first hydraulic supply will isolate that supply and select the second hydraulic supply, but if it is the actuator will ensure that both supplies are isolated. Moreover, the apparatus will establish whether the actuator fault is tolerable and if it is, will select the second supply. By the arrangement described a second hydraulic supply is selected when the first fails, but if the actuator is at fault the second supply will only be selected if that fault is tolerable; if the second supply were to be selected if the actuator was intolerably faulty, failure of the second supply would follow in rapid succession.

Abstract: A closed center programmed valve system having a load sense fluid source for control of the raising and lowering of load means by a raise and a lower normally closed two stage valve assembly. Each of the second stages of the valve assemblies has a poppet with a parabolic contour which is dimensioned to provide substantially linear flow rate change for minimized shock when the respective valve is actuated to the valve closed state. The load sense for the load means is taken from the outlet of the raise second stage without the requirement of a separate actuated valve or land with a load sense signal being applied to the fluid source during the time the raise valve assembly is actuated to the valve open state.

Abstract: A relief valve mechanism for a hydraulic booster provides in an open position a by-pass passage leading to a power steering and relieves excess pressure on the upstream side of the hydraulic booster. The relief valve in the open position forms a second throttle besides a normal fixed orifice to decrease through flow rate to the drain to thereby supply sufficient quantity of oil to the power steering when steering is steeply operated.

Abstract: A hydraulic fluid power system includes an accumulator which stores a reserve of pressure fluid at pump standby pressure. The charging and discharging of the accumulator is controlled by an emergency steering valve which is operable in response to a predetermined minimum fluid pressure outputted by the steering pump to discharge the stored fluid for emergency steering. The emergency steering valve also has components which serve as a pressure switch which is actuated to complete a circuit through an indicator light whenever the emergency steering valve moves to effect the discharge of the accumulator. The steering valve components are arranged so that premature actuation of the indicator light during pressure drops of short duration are avoided.

Abstract: A hydraulic fluid power steering system includes an accumulator which stores a reserve of pressure fluid at pump standby pressure. The charging and discharging of the accumulator is controlled by an emergency steering valve which is operable in response to a predetermined minimum fluid pressure outputted by the steering pump to discharge the stored fluid for emergency steering. The emergency steering valve also has components which serve as a pressure switch which is actuated to complete a circuit through an indicator light whenever the emergency steering valve moves to effect the discharge of the accumulator.

Abstract: The standby supply for delivering pressure fluid to a user component includes a fluid pump as a primary fluid source coupled to the user component by a first check valve, an accumulator as a secondary fluid source coupled to the pump by a second check valve for charging the accumulator and a valve arrangement coupled to the pump, the accumulator and the user component responsive to pressure from the pump to control a connection from the accumulator to the user component.

Abstract: Hydraulic control.The unit is characterized in that it is provided, between an inlet well and an outlet well for pressurized fluid, with an obturator urged in the closed position by a resilient member arranged to act against the pressurized fluid in the inlet well in a chamber communicating with a conduit issued from the outlet well and separated from a return conduit by a relief valve which is urged in the closed position by a spring and by the fluid pressure prevailing in the inlet well.Application to transfer-machines with one single hydraulic station.

Abstract: An anti-skid brake control device includes a servo mechanism for controlling pressure reducing operation of the device. The servo mechanism includes a constant pressure chamber connected to an engine intake manifold, a variable pressure chamber alternately connected to atmospheric pressure and vacuum in the engine intake manifold, and a vacuum pressure responsive valve including a flow restriction passage wherein, when the engine vacuum rises above a predetermined level due to engine brake operation, the restriction passage is actuated to restrict the vacuum flow to the variable pressure chamber to gradually carry out the pressure recovering operation of the anti-skid brake applied with the engine brake operation.

Abstract: A hydraulic brake booster mechanism for use with an open or circulating fluid pressure system includes a divider valve for the fluid flow interposed between a source of continuously circulating fluid pressure and a power steering mechanism, a control valve operatively associated with a brake pedal for applying the brakes, and a change-over valve actuated by means of the displacement of the divider valve upon the failure of the source to deliver the fluid pressure from an accumulator to the control valve for assuring an emergency application of the brakes.

Abstract: A shifting apparatus for the indirect changing of the mechanical brake pedal transmission ratio in case of failure of the servo-assist of a motor vehicle brake force booster system, in which the shifting apparatus can be installed at any suitable place of the motor vehicle as well as in the lines extending between the master brake cylinder and the wheel cylinders; the control piston which is arranged in the shifting apparatus is actuated by the medium put under pressure by the pump of the servo-installation, and undertakes the shifting control of the pressure medium coming from the master cylinder to attain a shifting action in case of failure of the servo-installation.

Abstract: A concentrating vortex shaker for the simultaneous shaking and concentration of a multiplicity of liquid samples comprises a heat-conductive block having a plurality of openings for receiving laboratory vessels containing sample liquids and removably mounted on a base provided with an adjustable eccentric drive for displacing the block in a gyrating motion. An airtight cover is removably mounted on the block and forms a chamber above the samples which can be controllably evacuated. The samples can be heated or cooled by a temperature-controlled liquid which is fed through a channel formed in the block or heated by an adjustable electrical heater provided in the block mounting or cooled by a cooling plate, upon which the block mounts.

Abstract: A hydraulic boosting apparatus in a braking system, which apparatus has an accumulator which provides an oil pressure accumulated in a high pressure circuit, the oil pressure being supplementarily used in addition to an oil pressure from the usual hydraulic circuit for a braking operation. A booster cylinder has a booster piston, a free spool and an operating spool which are arranged coaxially with each other. There is provided a pressure chamber between the booster piston and the free spool, which chamber communicates with a first working chamber defined in and serving to close an on-off valve which is, in turn, in communication with the accumulator. There is also provided a closed chamber between the free spool and the operating spool, which chamber communicates with a second working chamber defined in and serving to open the on-off valve.

Abstract: A motor vehicle fluid power circuit is disclosed which includes a primary pump, a closed center brake booster, and an open center steering valve. These components are hydraulically connected in series with the fluid flowing from the pump to the closed center brake booster and then to the open center steering valve. The brake booster includes valve means throttling fluid flow from the pump to the steering valve and maintaining the outlet pressure of the pump at at least a predetermined pressure differential above the working pressure of the brake booster under normal operating conditions in order to conserve output load requirements of the pump while assuring adequate pump pressure for brake booster actuation. In a second embodiment, a back-up pump is also provided in the circuit, and a pilot valve hydraulically disconnects the primary pump and hydraulically connects the back-up pump to the brake booster in response to a fluid pressure failure in the primary pump.

Abstract: A hydraulic brake booster is disclosed which is normally actuated by a primary pressure source, but which may be actuated by a secondary pressure source during failure of the primary pressure source. The booster includes a spool valve which controls communication between the primary pressure source and the booster pressure chamber. The spool valve is actuated by a control pressure which is generated by the vehicle operator when a brake application is effected. The control pressure shifts the spool valve to cause the latter to communicate fluid pressure from the primary pressure source into the pressure chamber. A pressure differential responsive piston is responsive to a pressure differential between the control pressure and the pressure communicated into the booster pressure chamber.