Abstract: A fluid-dynamic circuit includes a source of a pressurized fluid; a distributor valve for distributing the pressurized fluid to transport lines; a feeding line for feeding the pressurized fluid, which is interposed between the source and the valve; a main user apparatus, which is reciprocatingly operated by an actuator that includes a slider sealably fitted in a sliding seat of a containing element divided thereby into a first chamber and a second chamber in opposite positions and having variable volumes; and second and third transport lines for the pressurized fluid, which are interposed between the distributor valve and the first and second chamber respectively, a first derived transport line being interposed between the valve and at least one of the second and third transport lines, and having a normally closed quick discharge device mounted thereto, whose opening is designed to be controlled by the actuator.

Abstract: A hydraulic system for an operator controlled machine, the system including at least one actuator for moving a machine component, a source of pressurized fluid for delivering pressurized fluid at a system pressure to a control valve which is operable under operator control, to control the flow of fluid from the source to the actuator at a load pressure, along a load pressure path, a flow control apparatus for controlling the flow of fluid from the source to the control valve, the flow control apparatus including an actuating part which is biased by a resilient device to a condition in which the flow control apparatus provides for a maximum flow of fluid to the control valve, actuating part movement by the resilient device being resisted by system pressure fluid and being supported by fluid at a control pressure, the control pressure being derived from the load pressure, and wherein the system includes a pressure control device to which the load pressure is communicated, the pressure control device being opera

Abstract: A power regeneration device for an operating machine has a hydraulic cylinder and a return line through which fluid returning to a tank flows when the hydraulic cylinder contracts. The return line branches into a plurality of hydraulic lines through a branching part and includes a regeneration line that which leads returning fluid to the tank via a hydraulic motor to which a generator is connected. A control valve line is connected to the branching part and leads the returning fluid to the tank via a control valve. An electricity storage device stores electric power generated by the generator, and an electric amount detector detects the electric amount of the electricity storage device. A flow rate calculator calculates the flow rate of the returning fluid flowing through the regeneration line and the flow rate of the returning fluid flowing through the control valve line depending on an electric amount signal.

Abstract: A method for controlling fluid flow. A valve system may be kept in an open state in response to a fluid being at a selected level of pressure at any of a plurality of ports in a valve. The valve system may be for the valve, and the valve may comprise a housing, the plurality of ports on the housing, and the valve system located inside the housing. The valve system may be configured to be in a closed state when an absence of the selected level of pressure is present at all of the plurality of ports and in the open state when the selected level of pressure is present at any of the plurality of ports. The valve system may be kept in the closed state in response to an absence of the fluid being at the selected level of pressure at all of the plurality of ports.

Abstract: Apparatuses and systems that use a variable displacement motor-pump (VDMP) to control the position of a hose of an aerial refueling system are disclosed. At VDMP displacements greater than required to hold a position of the hose, the VDMP operates in a motor mode to retract the hose. For lesser VDMP displacements, the VDMP operates in a pump mode to control extension of the hose. In accordance with some embodiments, a dual orifice conveys hydraulic fluid at varying rates depending upon the VDMP operational mode.

Abstract: A vehicle steering feel improving apparatus is provided for a vehicle, wherein the vehicle is capable of running with a road wheel driven by a driving force from a power source. The vehicle steering feel improving apparatus includes a steering operation detecting means that detects a condition that steering operation is being performed to steer a steerable wheel of the vehicle. A driving force fluctuating means repeatedly fluctuates the driving force to the road wheel, while the steering operation detecting means is detecting the condition that steering operation is being performed.

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: An orientation-independent hydraulic system comprises a dynamic fluid reservoir defining a first volume substantially equal to the volume of the fluid therein, and a hydraulic cylinder in fluid communication with the dynamic fluid reservoir. The hydraulic cylinder has a second volume of hydraulic fluid and a piston rod configured to extend and retract in response to changes in the second volume. A first hydraulic pump is configured to pump hydraulic fluid between the hydraulic cylinder and the dynamic fluid reservoir, thereby moving the piston rod between the extended and retracted positions.

Abstract: There is provided a hydraulic system, including an oil tank storing operating oil, a hydraulic actuator, and a hydraulic pump which draws the operating oil from the oil tank and supplies the operating oil to the hydraulic actuator. The hydraulic system is provided with an operating oil separating unit which is located at a midway point of a main tube sending the operating oil from the hydraulic pump to the hydraulic actuator and which separates a part of the operating oil supplied from the hydraulic pump to return the part of the operating oil to the oil tank. A universal testing machine including the hydraulic system is also provided.

Abstract: A hydraulic system (10) includes an electronically-controlled counter-pressure valve (60) that enables backpressure in a return line (36) of the system to be varied by a control unit (64). The system allows active control of the pressure in the return line to produce different return pressures for different situations. A higher return line pressure may be set to improve make-up or recirculating flow through an anti-cavitation valve (50). This may improve controllability of functions that benefit from backpressure, such as lowering loads (12). The control unit that controls the counter-pressure valve may take into account any of a wide variety of possible inputs when setting the counter-pressure valve.

Abstract: In a hydraulic control device H comprising a pressure source P which can be switched on and switched off, a reservoir R and a pressure switch W located in a discharge path 13 from a valve assembly V to the reservoir R, which pressure switch W either connects the valve assembly V with the reservoir R or blocks the valve assembly V versus the reservoir R, the pressure switch W contains a displaceable control member 16 which is actuated in a first switching direction by a spring 17 and a pilot pressure originating from the pressure P1 acting at the valve assembly V and in a second switching direction to a control position blocking the discharge path 13 by a pilot pressure originating from the supply pressure of the pressure source, the pressure switch W is designed as a 2/2-multi-way seat valve 16 operating with a blocking position without leakage. A valve member 24 forms the control member 16 and co-operates with a valve seat 25 arranged in the discharge path 13.

Abstract: A hydraulic control circuit includes a hydraulic cylinder, a control valve, a recovery oil passage, a hydraulic pump, an engine rotation speed setting unit, a recovery control valve, and a controller that reduces an engine rotation speed to not more than a preset reduction control engine rotation speed when the load is lowered; and adjusts an increase or decrease in an opening amount of the recovery control valve in accordance with a level of the target rotation speed set by the engine rotation speed setting unit.

Abstract: A dump truck includes: an oil-cooling center brake; a first hydraulic pump supplying cooling oil to the center brake; a second hydraulic pump supplying cooling oil to the center brake in addition to the cooling oil from the first hydraulic pump; a hydraulic motor driving the second hydraulic pump; a third hydraulic pump supplying hydraulic oil to the hydraulic motor; an open/close valve letting the hydraulic oil bypass the hydraulic motor; and a controller controlling a bypass flow amount at the open/close valve. A capacity of the first hydraulic pump corresponds to a flow amount of the cooling oil required to lubricate a transmission. A capacity of the second hydraulic pump corresponds to a flow amount for compensating the cooling oil from the first hydraulic pump when a brake is off. A capacity of the third hydraulic pump is smaller than the capacity of the second hydraulic pump.

Abstract: A bypass pin for a hydrostatic transmission is disclosed. The hydrostatic transmission has a hydraulic pump. The bypass pin has a head positioned at one end of a shaft. The bypass pin also has a tip positioned at an opposite end of the shaft. The bypass pin is configured to receive a linear force exerted against the head in a first direction which causes the bypass pin to move in the first direction. The shaft of the bypass pin is configured to be positioned through a casing containing the hydrostatic transmission. The tip is configured to contact a rotating member in the hydraulic pump when the rotating member is in contact with a fluid directional member, the tip pushing the rotating member away from a fluid directional member in the first direction when the linear force is applied.

Abstract: A system has a variable displacement pump that supplies pressurized fluid to power a plurality of hydraulic functions. Each hydraulic function has a control valve with a variable source orifice controlling fluid flow between the pump and a flow summation node, and a variable metering orifice controlling fluid flow between the flow summation node and a hydraulic actuator. Variable bypass orifices in the control valves are connected in series between the flow summation node and a tank. As the metering orifice in a control valve enlarges, the source orifice enlarges and the bypass orifice shrinks. This alters pressure at the flow summation node, which is used to control the output of the pump. Components are provided to give selected hydraulic functions different levels of priority with respect to consuming fluid flow from the pump.

Abstract: A hydrostatic drive includes a hydraulic pump configured to drive at least two hydraulic motors. The hydraulic motors each include an inlet side and an outlet side. The hydraulic motors are each connected on the inlet side to a respective outlet of a flow divider, which is arranged downstream of the hydraulic pump. The hydraulic motors are each connected on the outlet side to a respective inlet of a flow divider, which is arranged upstream of the hydraulic pump.

Abstract: A backup system is provided that has a local electric motor and pump for some or all of hydraulic actuators. A local backup hydraulic actuator has two power sources, hydraulic as primary and electrical as backup. During normal operation, the hydraulic actuator receives pressurized fluid from a hydraulic system and the fluid flow to the chambers is controlled by a servo valve. If the hydraulic system fails, the electronic controller detects the failure by observing the signal indicative of the pressure from the pressure sensor, and the controller powers the local hydraulic pump to provide high pressure hydraulic fluid to the hydraulic actuator via the servo valve.

Abstract: A hydraulic transmission system for a zero-turn vehicle, comprises first and second transaxles each of which includes an axle, a casing supporting the axle, a fluid sump provided in the casing, first and second ports provided on the casing and opened outward from the casing, an HST circuit, a charge pump disposed in the casing, and a charge passage disposed in the casing to supply the HST circuit with fluid delivered from the charge pump. A first pipe connects the first ports of the transaxles, thereby making the flow of fluid from the charge pump of the first transaxle to the fluid sump of the second transaxle. A second pipe connects the second ports of the transaxles, whereby overflowing fluid of the fluid sump of the second transaxle is released to the fluid sump of the first transaxle via the second pipe.

Abstract: A relief valve assembly limits the maximum torque of a gear motor of a hydraulically driven tool. The relief valve assembly dumps flow to a return channel to return hydraulic fluid to the supply when the relief valve assembly is activated. The relief valve assembly is placed in the channel of a directional valve spool, and varies its pressure setting depending upon spool position. This is useful to vary the pressure settings of a hydraulic motor in different directions.

Abstract: A lubrication system is provided that includes a pump operatively connected to one or more supply lines for delivery of a lubricant, the system including a first pressure sensor associated with the supply line at a first position, and a second pressure sensor associated with the supply line at a second position downstream of the first position and pump, a controller configured to receive pressure signals and control operation of the pump based upon the pressure differential between the pressures at the first position and second position. The pressure differential may be employed to determine when a pressure at a third position downstream of the second position has been achieved. At least one of the pressure sensors may be positioned adjacent to the pump, the controller further being operable to deactivate the pump in the event that a maximum pump pressure has been met.

Abstract: A hydraulic system is disclosed. The hydraulic system may have a pump, a hydraulic actuator, and first and second passages fluidly connecting the pump to the hydraulic actuator in a closed-loop. The hydraulic system may also have a control valve, and a load-holding valve configured to selectively lock movement of the hydraulic actuator. The load-holding valve may include a valve block at least partially defining a pump passage, an actuator passage, a control passage, a restricted passage connecting the actuator passage and the control passage, and a bypass passage connecting the actuator passage and the control passage. The load-holding valve may also include a valve element movable between a first position at which flow between the pump and the hydraulic actuator is blocked, and a second position at which fluid is allowed to flow between the pump and the hydraulic actuator, the valve element being spring-biased toward the first position.

Abstract: The invention relates to a hydrostatic drive having one hydraulic pump unit (3) and at least one first hydraulic motor unit (14) and a second hydraulic motor unit (15). The first hydraulic motor unit (14) and the second hydraulic motor unit (15) are connected in parallel with the hydraulic pump unit (3) in a hydraulic circuit. A flow divider (80) is provided between the two hydraulic motor units (14, 15) and the hydraulic pump unit (3). The first working line (7) connecting the flow divider (80) with the hydraulic pump unit (3) is connected to a pressure control valve (23).

Abstract: The present disclosure relates to an apparatus for controlling a swing brake for construction machinery, comprising: a lower travel body; an upper swinging body supported at the lower travel body such that the upper swing body is capable of being swung; a swing motor for driving the upper swing body; a swing brake for braking the swing motor; a swing brake valve which operates to control the braking and releasing operations of the swing brake; a solenoid valve mounted on the swing brake valve to control the operation of the swing brake valve; an operation sensor which applies a first reference signal and a second reference signal in accordance with the motion of a swing operation control unit for controlling the operation of the upper swinging body, wherein said second reference signal is generated when an amount of displacement of the swing operation control unit is larger than the first reference signal; and a control unit, which operates the swing brake valve to release the swing brake when the first refer

Abstract: The present invention provides a method of controlling a fluid working machine (12) having a plurality of working cylinders (14) having pistons (16) therein and arranged to drive a shaft (18), in which said cylinders are supplied with pressurized working fluid via a manifold (24), the contents of which may be 5 purged by a de-pressurizer taking one of a number for forms such as to allow re-activation of said machine (10).

Abstract: A stability valve assembly includes a centrifugal pump and a valve downstream of the centrifugal pump. The valve includes a valve member that is movable along a valve axis within a valve body to control a fluid flow from the centrifugal pump. The valve member has a first orifice connecting a valve input to a valve chamber, and has at least one second orifice connecting a valve outlet to the valve chamber. A reference pressure upstream of the centrifugal pump applies pressure to a stepped portion of the valve member such that an amount of negative feedback provided by the valve assembly is proportional to a rotational speed of the centrifugal pump.

Abstract: A bypass/flushing valve for a hydrostatic system includes a valve body including a central bore, a shuttle valve located in the central bore, and a valve spindle disposed within the central bore. The valve body includes four ports each in communication with the central bore. The shuttle valve blocks flow through the central bore between a first port and a second port. When pressure at the second port is higher than at the first port, the shuttle valve moves to allow flow passage between the first port and the third port. When pressure at the first port is higher than at the second port, the shuttle valve moves to allow flow passages between the second port and a third port. The spindle is movable between a first position to block communication between the second port and the fourth port and a second position to allow for communication between the second port and the fourth port.

Abstract: A dump truck includes: an oil-cooling center brake; a first hydraulic pump supplying cooling oil to the center brake; a second hydraulic pump supplying cooling oil to the center brake in addition to the cooling oil from the first hydraulic pump; a hydraulic motor driving the second hydraulic pump; a third hydraulic pump supplying hydraulic oil to the hydraulic motor; an open/close valve letting the hydraulic oil bypass the hydraulic motor; and a controller controlling a bypass flow amount at the open/close valve. A capacity of the first hydraulic pump corresponds to a flow amount of the cooling oil required to lubricate a transmission. A capacity of the second hydraulic pump corresponds to a flow amount for compensating the cooling oil from the first hydraulic pump when a brake is off. A capacity of the third hydraulic pump is smaller than the capacity of the second hydraulic pump.

Abstract: Disclosed is a hydraulic control device for a continuously variable transmission which changes the transmission gear ratio by changing the hydraulic pressure (Pin, Pout) supplied to hydraulic pressure chambers (134, 154) for pulleys in the continuously variable transmission via control valves (217, 218) is changed. In this hydraulic control device, line pressure regulation hydraulic pressure (Psrv) which corresponds to the magnitudes of the oil pressure (Pin, Pout) supplied to the hydraulic pressure chambers (134, 154) is introduced into a regulator valve (212), and line pressure (P1) which is input into the control valves (217, 218) according to the magnitudes of the oil pressure (Pin, Pout) is subjected to feedback regulation.

Abstract: A hydrostatic transmission including a main pump, two main ducts serving respectfully as feed and as discharge for first and second hydraulic motors that serve to drive disposed one after the other. A bypass valve can take up a reduced-speed position in which the feed main orifices are connected to the discharge main duct, and an increased-speed position in which one of the motors is bypassed, the feed main orifice of the motor being connected to the discharge main duct via a bypass link, while the other main orifices continue to have their respective links. The apparatus further includes a constriction suitable for being activated to restrict the flow of fluid through the bypass link.

Abstract: A control device for the position control of a hydraulic cylinder unit has a controller which receives a set and an actual piston position and determines a preliminary manipulated variable based on the difference of the set and actual positions. A linearization unit multiplies the variable with a linearization factor and outputs it to the valve control unit so that the piston is adjusted at an adjustment speed. The linearization unit determines the factor dynamically as a function of the actual piston position and of working pressures that prevail at both piston sides. The linearization factor is determined such that a ratio of the adjustment speed to the difference of the set and actual positions is independent of the actual position and the working pressures. In the specific case where the controller is configured as a P controller, the order of the controller and the linearization unit can be reversed.

Abstract: A hydraulic control assembly, in particular for controlling hydraulic consumers of a mobile machine, includes a load reporting line (26) that can be subjected to the highest load pressure of a plurality of hydraulic consumers, triggered simultaneously each via a respective main control valve (38, 57), and that is connectable by an end portion (26a) to a pump regulator (25). A pressure limiting valve (50) limits the control pressure in the end portion (26a) of the load reporting line (26). The pressure limiting valve (50) is adjustable as a function of the magnitude of a pilot control signal serving to trigger a main control valve (38, 57).

Abstract: A valve assembly has a flow summation node coupled to a displacement control port of the first pump. Each valve in the assembly has a variable metering orifice controlling flow from an inlet to a hydraulic actuator and has a variable source orifice conveying fluid from a supply conduit to a flow summation node. The source orifice enlarges as the metering orifice shrinks. Each valve includes a variable bypass orifice and the bypass orifices of all the control valves are connected in series forming a bypass passage between a bypass node and a tank. The bypass node is coupled to the flow summation node and receives fluid from a second pump. At each valve, a source check valve conveys fluid from the supply conduit to the inlet and a bypass supply check valve conveys fluid from the bypass passage to the inlet.

Abstract: An axle driving apparatus includes a first housing having a plurality of cooling fins, an axle rotatably mounted in the first housing, a hydraulic stepless speed change assembly disposed within the first housing. The axle driving apparatus also includes a second housing having a plurality of cooling fins, an axle rotatably mounted in the second housing, a hydraulic stepless speed change assembly disposed within the second housing. A connecting means, such as a bar and/or plate connects the first and second housings. The plurality of cooling fins on the first housing has a different configuration that the plurality of cooling fins on the second housing.

Abstract: A power pack unit includes a first hydraulic pump including a first pump enclosure accommodating a first pump cartridge. A second hydraulic pump includes a second pump enclosure accommodating a second pump cartridge. A hydraulic fluid reservoir is positioned between the first and second hydraulic pumps. A first end of the reservoir is secured to the first pump enclosure and a second end of the reservoir is secured to the second pump enclosure. The first and second hydraulic pumps and the reservoir can extend along a common axis. First and second motors can be connected to the first and second pumps. The entire structure can extend along a common axis.

Abstract: A drive unit and a method for the operation thereof. The drive unit has an internal combustion engine in operative connection with a driven shaft and a reciprocating piston expansion engine in an operative connection with a crankshaft. The driven shaft is mechanically connected to the crankshaft by a clutch in such a way that torque is transmitted from the crankshaft to the driveshaft. The reciprocating piston expansion engine has at least one cylinder, and a fluid is guided from a fluid supply into an interior of the at least one cylinder at least occasionally via an inlet valve and a bypass valve which is arranged in parallel with the inlet valve.

Abstract: A hydraulic power unit is disclosed that is selectively connectable to a hydraulic tool. The hydraulic power unit automatically detects the attached or detached state of the tool and/or operates an unloading valve during activation of the tool.

Abstract: A work vehicle includes a telescoping boom extending outwardly from the vehicle. An attachment is operably connected to the boom, the attachment including opposed forks configured to be both urgable toward each other and urgable away from each other. The attachment is configured to be positionable over and substantially laterally surround at least one pair of round bales arranged substantially side by side and having corresponding diameters in close proximity of each other. The opposed forks are urgable toward each other with sufficient compressive force applied to opposed portions of the diameters of the at least one pair of round bales, at least elastically deforming the cylindrical profile of at least one of the at least one pair of round bales, so that the at least one pair of round bales can be vertically lifted and manipulated by at least the boom to a predetermined destination.

Abstract: A control method and system for controlling a hydraulically actuated mechanical arm to perform a task, the mechanical arm optionally being a hydraulically actuated excavator arm. The method can include determining a dynamic model of the motion of the hydraulic arm for each hydraulic arm link by relating the input signal vector for each respective link to the output signal vector for the same link. Also the method can include determining an error signal for each link as the weighted sum of the differences between a measured position and a reference position and between the time derivatives of the measured position and the time derivatives of the reference position for each respective link. The weights used in the determination of the error signal can be determined from the constant coefficients of the dynamic model. The error signal can be applied in a closed negative feedback control loop to diminish or eliminate the error signal for each respective link.

Abstract: The present disclosure relates to a vehicle transmission with jet pump. The jet pump includes a hydraulic control system that has a nozzle fitted between a first and second housing. The nozzle is separable from the first and second housing. The hydraulic control system is configured to produce a jet stream of fluid through a center section of the nozzle.

Abstract: A hydrostatic drive system (1) has a load-sensing pump (2) with an adjustable discharge volume and at least one consumer connected to the pump (2). The discharge volume of the pump (2) can be set by a discharge volume control device (6) that sets the delivery pressure of the pump available in a delivery line (4) of the pump (2) so that it is higher by a pilot control pressure difference than the load pressure of the consumer. The discharge volume control device (6) can be actuated by an electronic control device (7) functionally connected with a sensor device (9) for measuring the load pressure of the consumer and with a sensor device (8) for measuring the delivery pressure available in the delivery line (4). A circulation device (15) is associated with the delivery line (4) to control the connection of the delivery line (4) with a reservoir (3).

Abstract: A motor having two series of distribution ducts each having two groups of ducts. The displacement selector is able to occupy a large displacement position in which the first groups of distribution ducts of the first series are connected to a main duct while the second groups are connected to the other main duct, and a small displacement configuration in which the first group of distribution ducts of the first series is connected to a main duct, the second group of distribution ducts of the first series is connected to the other main duct and a bypass connection exists between the first and the second group of distribution ducts of the second series. The device has a restriction in order, in the small displacement configuration, to restrict this bypass connection.

Abstract: A method of gradually relieving pressure in a hydraulic system of a work machine, wherein a pump in fluid communication with the hydraulic system and a fluid reservoir, is operable for pressurizing fluid from the reservoir and pumping the pressurized fluid into the hydraulic system, wherein the pump is restrictive to fluid flow therethrough when not operating, and the hydraulic system includes at least one valve in fluid communication with the work element configured for receiving the pressurized fluid. The valve is controllably operable in at least two operating modes, including a first mode wherein the pressurized fluid can pass therethrough between the pump and the work element or elements, and a second mode wherein the fluid is prevented from passing between the pump and the work element.

Abstract: A hydraulic transmission system for a vehicle, the system including: a main pump serving to feed with fluid at least one hydraulic motor for driving a vehicle mover member; an auxiliary pump, the main pump and the auxiliary pump being suitable for being actuated jointly by drive means; and a “bypass” connection between a delivery orifice of the auxiliary pump and an unpressurized reservoir. First constriction means, arranged on the bypass connection, maintain a pump protection pressure in a pump protection portion of the bypass connection; this pressure is applied to the main orifices of the main pump when said pump is actuated but is not delivering, thereby ensuring that the pump is protected.

Abstract: An apparatus for preventing noise from occurring due to cavitation in a power steering pump during low temperature start-up includes the addition of a multi-passage orifice element for adding wetted surface resistance to high viscous fluid flow downstream from a single passage outlet orifice element of a fluid flow control device and upstream of an associated steering gear or steering assist valve.

Abstract: A hydraulic transmission comprises a hydraulic pump and a hydraulic motor, which are mounted onto a center section to be fluidly connected to each other through a closed fluid circuit formed in the center section. A neutral valve is connected to the closed fluid circuit. The neutral valve is fitted into an outward opened end of a vertical slanted oil hole of the closed fluid circuit. Alternatively, the neutral valve is fitted into an outward opened end of a straight oil hole having an opposite outward opened end into which a charge check valve is fitted.

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 stability valve assembly includes a centrifugal pump and a valve downstream of the centrifugal pump. The valve includes a valve member that is movable along a valve axis within a valve body to control a fluid flow from the centrifugal pump. The valve member has a first orifice connecting a valve input to a valve chamber, and has at least one second orifice connecting a valve outlet to the valve chamber. A reference pressure upstream of the centrifugal pump applies pressure to a stepped portion of the valve member such that an amount of negative feedback provided by the valve assembly is proportional to a rotational speed of the centrifugal pump.

Abstract: A hydrostatic stepless transmission comprises: a hydraulic pump; a hydraulic motor, wherein at least one of the hydraulic pump and motor is variable in displacement, and is provided with a movable swash plate; a closed circuit connecting the hydraulic pump and motor to each other through a pair of main fluid passages, wherein one main fluid passage is higher-pressurized during forward traveling, and wherein the other main fluid passage is higher-pressurized during backward traveling; a hydraulic servomechanism for controlling a tilt angle of the movable swash plate of the at least one of the hydraulic pump and motor; a speed-controlling motive member attached to the hydraulic servomechanism, wherein the speed-controlling motive member interlocks with the movable swash plate and is moved by operating a speed control operation lever; and a load controlling system attached to the hydraulic servomechanism.

Abstract: A machine includes a hydraulic fan system for circulating cooling air through an engine compartment. Periodically, the fan rotation direction is briefly reversed in order to dislodge any material debris that may have accumulated at the inlet to the engine compartment. When a fan reversal event is initiated, the fan motor will continue to rotate due to angular momentum even after the pump output flow has been switched from a first motor port to a second motor port. During this continued rotation as the fan decelerates to zero speed, vacuum pressure levels can arise at the first motor port, and a pressure spike can develop at the second motor port. In order to alleviate these conditions, a pressure transfer valve briefly opens to facilitate fluid flow directly from the second motor port to the first motor port as the fan motor decelerates towards zero speed before reversing direction, simultaneously alleviating vacuum and pressure spike conditions.

Abstract: A transmission for use with a machine is disclosed. The transmission may have a pump, a motor fluidly connected to receive pressurized fluid from the pump and propel the machine, and an operator input device configured to generate a signal indicative of an operator desired gear ratio of the transmission. The transmission may also have a controller in communication with the pump, the motor, and the operator input device. The controller may be configured to determine an desired gear ratio of the transmission as a function of the signal, and determine an efficiency loss of the transmission at the desired gear ratio. The controller may also be configured to select a known setting of at least one of the pump and motor that provides the desired gear ratio and accounts for the efficiency loss.