Abstract: A travelling apparatus having a high travelling performance with a simple structure is provided. A travelling apparatus according to an embodiment includes: a frame; front wheels disposed in a front of the frame; first links configured to be extendable and retractable and coupled between the front wheels and an oscillation axis located in a rear of the front wheels; and first linear motion mechanisms that are coupled between the frame and the first links and are extended and retracted so as to rotate the first links about the oscillation axis.

Abstract: A hydraulic circuit for use on a construction machine includes a first valve, a second valve, and at least a third valve. The second and third valve each includes at least one inlet port connected to a first outlet port of the first valve. The first outlet port of each of the second and third valves are configured to reduce a first pressure to a second pressure and/or a third pressure downstream of the second valve and the third valve, respectively. The second valve and the third valve also include at least a second outlet port connected to a reservoir tank. A hydraulic motor is connected to the first outlet port of the second valve, which operates the hydraulic motor in a first direction. The hydraulic motor also is connected to the first outlet port of the third valve, which operates the hydraulic motor in a second direction.

Abstract: The present invention provides a hydraulic drive train including a check valve provided in a return oil passage disposed between a branching position of a first branching oil passage and a branching position of a second branching oil passage, wherein at the time of starting of startup of the hydraulic drive train, the switching valve is closed, the opening degree of the flow rate adjusting valve is set to the initial opening degree, the on-off valve is opened, the boost pump is driven by the drive motor, and the hydraulic oil is supplied to the hydraulic pump, thereby assisting the rotational speed of the vanes by the hydraulic oil.

Abstract: The present invention is configured so that it is possible to select any one of a first mode in which a first adjustment valve 13 and a second adjustment valve 20 operate solely on the basis of manipulation of a main manipulation tool (turning lever 8i), a second mode in which the first adjustment valve 13 operates solely on the basis of manipulation of the main manipulation tool (8i) and the second adjustment valve 20 operates solely on the basis of manipulation of a secondary manipulation tool (brake pedal 8j), and a third mode in which the first adjustment valve 13 operates solely on the basis of manipulation of the main manipulation tool (8i) and the second adjustment valve 20 operates on the basis of manipulation of the secondary manipulation tool (8j) while operating on the basis of manipulation of the main manipulation tool (8i).

Abstract: A method of controlling a continuously variable transmission for a vehicle. The continuously variable transmission has a hydrostat with a position-regulating valve and is designed to co-operate in driving connection with a drive input shaft and a drive output shaft such that when the position-regulating valve is energized, the hydrostat is adjusted to accelerate the vehicle. The method includes monitoring the energization of the position-regulating valve cyclically by a safety function. The safety function is provided in order to recognize undesired energization of the position-regulating valve that leads to unwanted acceleration of the vehicle, and then to separate the transmission at least from the drive output shaft so as to prevent unwanted acceleration of the vehicle. The safety function is triggered at least when a limit value for the energization of the position-regulating valve is exceeded.

Abstract: The crane includes a swing brake device installed between a hydraulic motor and a control valve and having a flow restrictor; a first backpressure detector detecting a motor backpressure between the flow restrictor and one of ports of the hydraulic motor; a second backpressure detector detecting a motor backpressure between the flow restrictor and the other port of the hydraulic motor; and a control device. The control device has an external-force direction estimation unit that estimates a swing direction of an upperstructure under an external force acting on the upperstructure on the basis of a motor backpressure detected by the first backpuressure detector and a motor backpressure detected by the second backpressure during an operating state of the swing brake device. The control device has a notification control unit that causes the notification device to provide notification of the estimated swing direction of the upperstructure.

Abstract: A speed control system for a hydrostatic transmission includes an engine having a drive shaft connected to a hydraulic pump. At least one hydrostatic motor is connected to the pump in a closed circuit by a flow line. Connected to the motor via a system shaft is a vehicle system. A controller is connected to a plurality of sensors and a proportional high pressure relief valve that is connected to the flow line between the pump and the motor. Based on information received from the sensors, the controller sets the pressure relief valve to limit the pressure to a valve that will not over-speed the engine and allows the demands of the speed control system to be attained. This may be accomplished through the use of various algorithms.

Abstract: A turning drive device is provided that converts power of an engine into electric power and turns a turning body using the converted electric power. The turning drive device includes an electrical energy storage unit that stores electrical energy, a turning motor that is driven by an electric power from the electrical energy storage unit and is configured to drive a turning body, an inverter that controls a drive operation of the turning motor, a controller that is connected to the inverter via a control signal line, and an emergency operation part that supplies a command to the inverter when an abnormality occurs in a control operation of the turning motor. The inverter blocks the control signal line based on a signal from the emergency operation part and controls the drive operation of the turning motor.

Abstract: A hydraulic motor 100 includes a switching valve 3 which is connected to a pilot passage 54 by which a pressure fluid is introduced into a back pressure chamber 21 of a relief valve 2 and takes a first changeover position 3a where the back pressure chamber 21 is connected to a tank 102 or a second changeover position 3b where the pilot passage 54 is connected to the back pressure chamber 21. By this switching valve 3, the pressure fluid supplied to a hydraulic motor mechanism 1 is introduced into the back pressure chamber 21 via the pilot passage 54 when the hydraulic motor mechanism 1 is in operation, whereas the back pressure chamber 21 is connected to the tank 102 as the pressure in the pilot passage 54 becomes not higher than a predetermined pressure when the hydraulic motor mechanism 1 is being braked.

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: A slewing-type working machine includes: a hydraulic motor for slewing an upper slewing body; a hydraulic pump; a slewing operation device including an operation member; a control valve controlling the hydraulic motor based on an operation signal of the slewing operation device; first and second pipe-lines connecting first and second ports of the hydraulic motor to the control valve; communication switching devices switching communication and cutoff between both pipe-lines and a tank; an electric motor; an electric storage device; and a controller, which communicates an outlet-side pipe-line to the tank during slewing, makes a brake based on a regenerative action by the electric motor and the electric storage device and causes the electric storage device to store regenerative power, upon deceleration operation. Upon failure occurrence, the controller brings the communication switching devices to a communication-cutoff state and stops the regenerative action to secure slewing.

Abstract: Provided is a slewing type construction machine including an upper slewing body and a slewing speed sensor that detects a slewing speed of the upper slewing body, enabling accurate control to be achieved regardless of an error in output from the slewing speed sensor. The construction machine includes an upper slewing body, a slewing motor, a hydraulic pump, a control valve, a slewing operation device, a slewing brake, a slewing speed sensor, a slewing operation detector that detects an operation applied to the slewing operation device, and a controller. The controller stores, during a slewing operation, a slewing speed detected by the slewing speed sensor at set time intervals, actuates the slewing brake based on a neutral return operation of the slewing operation device, and resets a stored value of the slewing speed that is stored during actuation of the slewing brake, to zero.

Abstract: A hydraulic system for a machine is disclosed. The hydraulic system has a source of pressurized fluid, a fluid actuator, and a tank. The hydraulic system utilizes a directional control valve to direct flow between the source, the actuator, and the tank. The hydraulic further utilizes a variable backpressure control valve to control the system backpressure.

Abstract: Provided is a braking control apparatus for a slewing type working machine capable of giving a braking operation easily intuitively grasped.

Abstract: There is provided a slewing control device that enables to detect breakdown of a driving system of a mechanical brake, and generate a torque for holding a slewing body in a stopped state to thereby prevent movement of the slewing body when an anomaly has occurred. In a working machine for driving a slewing body by an electric motor 1, judgment is made as to whether a mechanical brake 4 is in an inconsistent state, based on a command to be outputted to a brake circuit B, and a pressure detected by a brake pressure sensor 17. The inconsistent state is a state that the mechanical brake 4 is in a brake released state when an activation command for switching the mechanical brake 4 to a brake activated state is outputted. If it is judged that the mechanical brake 4 is in the inconsistent state, a command for obtaining a braking torque for holding the slewing body in a stopped state is outputted to the electric motor 1.

Abstract: This disclosure provides for pressure limiting a hydraulic system to a desired pressure value by a particular circuit by controlling and closing the compensator when the desired pressure setting is achieved. Closing the compensator will reduced the pressure head and flow in the circuit resulting in improved efficiency. One illustrated embodiment of the disclosure provides a relief valve in the pilot signal for a compensator. The method relates to limiting the pressure on an open side of the compensator, such that the pressure on the other side closes the compensator thereby limiting the pressure and also flow in the hydraulic circuit. In other words, the pressure on the open side is limited by the relief valve. Thus, the pressure on the other side increases thereby regulating the flow and pressure through the compensator.

Abstract: A hydraulic system is adapted to recover potential and kinetic energy of a work attachment of a work machine. A valve arrangement may configure the hydraulic system in various modes. The hydraulic system may provide suspension and/or actuation for the work attachment. The energy of the work attachment may move a rod of a first cylinder. The rod may pressurize fluid within the first cylinder. The pressurized fluid may flow from the first cylinder through a valve and into an accumulator. The first cylinder may amplify pressure of the fluid. The pressurized fluid in the accumulator may actuate the first cylinder. The movement of the rod of the first cylinder may cause simultaneous actuation of a second cylinder. A controller may monitor pressures and positions of components of the hydraulic system and control the valve arrangement.

Abstract: A motor control device for construction machinery includes a hydraulic pump; a hydraulic motor driven by pressure oil from the hydraulic pump; a control valve that controls a flow of the pressure oil from the hydraulic pump to the hydraulic motor; a pair of main conduit lines that connect the hydraulic motor and the control valve on a delivery side and a return side thereof; an operation member that operates a spool of the control valve to either a neutral position that does not allow the pressure oil for driving from the hydraulic pump to pass through control valve to the hydraulic motor or a non-neutral position that allows the pressure oil for driving to pass through the control valve to the hydraulic motor; a braking pressure generating device that generates braking pressure in the main conduit lines on the return side in a state where the spool of the control valve is positioned in the neutral position as a result of being operated by the operation member, the braking pressure opposing rotation of the hy

Abstract: Provided is a braking control apparatus for a slewing type working machine capable of giving a braking operation easily intuitively grasped.

Abstract: A hydraulic circuit having a holding valve of an external pilot pressure operation type is provided, which can make a double check valve, which is installed to prevent an actuator from being pushed due to leakage of hydraulic fluid of a main control valve, be opened by an external signal pressure being supplied to shift the main control valve.

Abstract: A hydrostatic drive system has a consumer (7), in particular a hydraulic motor, located in the open circuit. Associated with the consumer (7) is at least one pressure limiting device (11a; 11b) that can be actuated in the braking phase for the generation of a braking pressure that is present on the discharge side of the consumer (7) from a minimum response pressure in the direction of an increase of the response pressure. A feeder device (12a; 12b) provides a feed of pressure fluid into the admission side of the consumer (7). The pressure limiting device (11a; 11b) and the feeder device (12a; 12b) are integrated into a valve unit (10a; 10b).

Abstract: The invention relates to a hydrostatic drive (1) and to a method of braking a hydrostatic drive (1). In the hydrostatic drive (1), in a closed circuit a hydraulic pump (3) is connected by a first and a second working line (11, 12) to a hydraulic motor (4). The hydrostatic drive (1) comprises a brake actuation device (37) as well as at least one pressure relief valve (26, 30), which is connected to the working line disposed downstream of the hydraulic motor (4). The hydraulic pump (3) upon detection of an actuation of the brake actuation device (37) is adjustable to a braking delivery rate. The hydraulic motor (4) is adjusted in dependence upon the actuating intensity of the brake actuation device (37) in the direction of a larger absorption volume if the actuating intensity of the brake actuation device (37) increases.

Abstract: A hydraulic system 10 of the present invention has a hydraulic pump driven by a driving source 14, a hydraulic pump motor 52 driven by an operating oil discharged from the hydraulic pump and flowing in an oil path 50, an inertial body 60 connected to a rotary shaft of the hydraulic pump motor, an oil path 62 connected between an outlet port of the hydraulic pump motor and a load 22, an unloading oil path 64 branched from the oil path 62, and an on-off valve 68 inserted in the unloading oil path. In this configuration, as the on-off valve is opened and closed, a high pressure is generated in the oil path 62 by making use of kinetic energy of the inertial body. The inertial body is driven by hydraulic power and the inertial body is separated from the driving source, which also provides an effect of increasing degrees of freedom for an instrument layout.

Abstract: Arranged in a hydraulic circuit is a valve with an L-shaped duct arrangement, which is formed by a transverse duct 2 and a longitudinal duct 3. Formed in extension of the longitudinal duct 3 is a holding and guiding bore 4, in which a throttling element, comprising a throttle slide 10 and a valve piston 21 that can be displaced therein, can be displaced longitudinally. The valve piston 21 has a passage hole 25, which is connected to the interior of the throttling element and two proportionate annular chambers 17a and 17b. Of these, the proportionate annular chamber 17b is connected to a pilot control valve via a control duct 19. Depending on the direction and pressure of the hydraulic fluid flowing through the L-shaped duct arrangement, the throttling element is moved in or out and extended or compressed in the process.

Abstract: A drive mechanism is disclosed which includes a hydraulic pump whereby at least two hydraulic motors may be supplied with pressure medium. The drive mechanism in accordance with the invention has on the meter-in side or on the meter-out side of each hydraulic motor a variable hydraulic resistor that is biased into a basic position of minimum open cross-section and may be subjected to a control pressure in a direction of increased open cross-section. This control pressure is dependent on the pressure on the meter-in side or on the meter-out side of the hydraulic motor.

Abstract: An electronic control for damping oscillation of a swinging backhoe assembly includes a crossover valve that connects the hydraulic lines that supply hydraulic fluid to the boom swing cylinders to each other whenever an electronic controller senses incipient oscillation or swinging of the backhoe assembly. The electronic controller senses such parameters as pressure in the conduits and the position of the operator controls or the position of the boom swing control valve that the operator controls to determine incipient oscillation when the backhoe assembly is stopped. The crossover valve may remain open for a predetermined period of time.

Abstract: The invention pertains to an electrohydraulic servo door drive for operating a door, a window, or the like, with a hold-open function, where a valve is installed in the hydraulic circuit to implement the hold-open function. To create an electrohydraulic servo door drive which requires less space and can be produced at lower cost, it is provided according to the invention that the valve is designed as a hydraulically controlled hold-open valve.

Abstract: The present invention relates to a hydraulic type brake system which includes a unit for adjusting a back pressure in a turn driving hydraulic circuit mounted in a construction heavy equipment such as an excavator, etc., and in particular to a hydraulic type brake apparatus which is used together with a relief valve installed various actuator driving hydraulic circuits for adjusting a back pressure in a lower flow side of a relief valve for thereby adjusting an opening pressure of a relief valve. There is provided a back pressure adjusting unit adapted to adjust an opening pressure of the relief valve by adjusting a back pressure of the hydraulic circuit in a lower flow portion of the relief valve based on a co-operation with the actuator.

Abstract: A hydraulic control system (1) has a hydraulic motor (10), which is connected with a control valve (2) via two working lines (8, 9), the control valve (2) being connected with a low-pressure connection (T) and, via a compensation valve (4), with a high-pressure connection (P), to ensure that a return compensation valve (14, 15) is arranged in each working line, each return compensation valve (14, 15) having a nominal flow line (29), which extends unintersectedly in relation to the nominal flow line (28) of the compensation valve (4).

Abstract: A hydraulic circuit for controlling a consumer of a mobile work tool, wherein the pressure in supply and outlet lines towards the consumer is limited by means of pilot-controlled pressure control valves. The pilot control stage of these pressure control valves may be adjusted in accordance with a pilot control pressure corresponding to the load of the work tool.

Abstract: A hydraulic elevator system of an inverter control method directly controlling a flow amount of a pressed oil discharged from a hydraulic pump by a speed control of a motor driving the hydraulic pump, which can improve energy efficiency and stability. The hydraulic elevator system includes a reverse check valve connected between a hydraulic cylinder operated by the pressed oil to lift/lower an elevator car and a hydraulic pump driven to discharge the pressed oil, opened to pass the pressed oil by the pressure of the discharged pressed oil in a driving of the hydraulic pump, and closed to prevent the pressed oil from being reversed by using a pilot pressed oil of the hydraulic cylinder as a power source in a stopping of the hydraulic pump; and a pilot hydraulic cylinder operated by the pilot pressed oil from the hydraulic cylinder in order to apply an additional close force to the reverse check valve in the lifting/lowering or emergency stopping of the elevator car.

Abstract: A hydraulic vehicle drive, having a closed hydraulic circuit consists of a variable displacement pump and one or several hydraulic motors. The variable displacement pump is driven by a diesel engine. During the braking or pushing operation of the vehicle, the hydraulic motor becomes a pump and drives the variable displacement pump which, in turn, acts as a motor upon the diesel engine and acts to accelerate the latter. Thus, the intended braking effect prevents the danger that the diesel engine will reach non-permissible high revolutions per unit time, which is particularly dangerous for diesel engines with turbochargers. In order to prevent non-permissible high revolutions per unit time, a pressure regulator acting as a throttle is placed in the return line between the hydraulic motor and the variable displacement pump. The valve throttles the rate of flow when the pressure of the hydraulic fluid in the line exceeds a certain desired value during the braking operation.

Abstract: A feller-buncher includes a first axle having a number of first wheels attached thereto and a second axle having a number of second wheels attached thereto. The feller-buncher also includes a first hydraulic motor operable to rotate the first axle and a second hydraulic motor operable to rotate the second axle. The feller-buncher also includes a first hydraulic pump operable to supply pressurized hydraulic fluid. Yet further, the feller-buncher includes a first flow sharing valve fluidly coupled to each of the first hydraulic pump, the first hydraulic motor, and the second hydraulic motor. The first flow sharing valve is configured to distribute the pressurized hydraulic fluid from the first hydraulic pump evenly between the first hydraulic motor and the second hydraulic motor, whereby the first axle and the second axle are driven at a substantially equal speed relative to one another. A method of operating a feller-buncher is also disclosed.

Abstract: A hydrostatic drive system with a pump and at least one consuming device that is connected to the pump can be actuated by a control valve. The control valve can be actuated as a function of an actuator that specifies a desired speed of movement and a direction of movement of the consuming device. The control valve in the center position, makes possible an unpressurized circulation of the pump. The control valve can be actuated electrically, and there is a sensor that measures the actual speed of movement of the consuming device. The control valve, the speed-of-movement sensor and the actuator are connected with an electronic control that controls the control valve as a function of the direction and speed of movement specified by the deflection of the actuator and of the actual speed of movement of the consuming device as measured by the speed-of-movement sensor. The speed-of-movement sensor may be a delivery flow sensor.

Abstract: An apparatus for felling and bunching trees is disclosed. The apparatus includes a front frame and a front axle supported by the front frame. The apparatus further includes a number of front wheels mounted on the front axle and a work tool supported by the front frame. The work tool has a blade for felling trees and a number of work arms which are movable to secure the trees within the work tool. The apparatus further includes a front hydraulic motor operable to rotate the front axle. The front hydraulic motor is supported by the front frame. The apparatus yet further includes a first hydraulic pump operable to supply pressurized hydraulic fluid to the front motor. The apparatus still further includes a rear frame which is pivotably coupled to the front frame, a rear axle supported by the rear frame, and a number of rear wheels mounted on the rear axle. The apparatus still further includes a rear hydraulic motor operable to rotate the rear axle. The rear hydraulic motor being supported by the rear frame.

Abstract: A hydraulic steering arrangement with a steering device (2) and an oil tank (3) which are connected with each other via a supply line (5) and a return line (6), wherein a hydraulic pump (1) is integrated into the supply line (5), has an oil reservoir (7) communicating with the return line (6) and a backpressure valve (8) opening in the direction toward the oil tank (3), which is disposed between the oil tank (3) and the oil reservoir (7).

Abstract: The present invention provides a swing hydraulic circuit for use in a construction machine, which is free from a shock upon the starting and stopping of the turning frame even though the reach of the working machine is small and from a delay upon the starting and stopping of the turning frame even though the reach of the working machine is large.

Abstract: A control valve feeds pressurized fluid for moving an actuator in first and second directions. A meter-out valve controls return flow of pressurized fluid from the actuator during actuation in the second direction. The meter-out valve is controlled by a pilot pressure controller independently of the actuator in response both to pilot pressures and to engine speed. The meter-out valve includes both a restricted channel and an unrestricted channel. The restricted channel, and the unrestricted channel are selectively connected dependent on the pilot pressures and the engine speed to supply sufficient fluid flow to permit stable operation of the actuator.

Abstract: Front and rear wheeled units of vehicle are connected together for articulated steering. Wheels on at least one unit are mounted for swivelling relative to the respective unit to provide kingpin steering in combination with articulation steering. A first embodiment has front and rear kingpin steering and articulation steering performed manually and independently of the each other. In a second embodiment, a steering integrator cooperates with actuators which control at least the articulation steering and kingpin steering of the front wheels to automatically integrate two types of steering so that a controlled relationship exists between an articulation angle of the front unit with respect to the rear unit, and swivel angles of the front wheels with respect to the front unit. A manual steering control, e.g. a steering wheel, controls actuation of the steering integrator.

Abstract: An internal safety valve for preventing the discharge chute from rapidly falling due a sudden loss of hydraulic fluid pressure. A safety valve assembly for use in a hydraulic cylinder consisting of a safety valve located in the barrel of a hydraulic cylinder. The moveable piston of the hydraulic cylinder has a cavity for receiving the safety valve therein. The safety valve is actuated when the flow leaving the chute lift cylinder exceeds a predetermined flow. The valve immediately stops the hydraulic fluid from leaving the chute lift cylinder maintaining the position of the discharge chute.

Abstract: A hydrostatic drive system including a pump and a hydraulic motor in an open circuit which includes a feed line and a control valve in the feed line on the inflow side of the hydraulic motor to control the quantity of hydraulic pressure medium supplied to the hydraulic motor. A brake valve is located in the open circuit on the outflow side of the hydraulic motor to receive hydraulic pressure medium flowing out of the hydraulic motor. The control valve and the brake valve are constructed for independent actuation so that the functions of the control valve and the brake valve can be reversed when the direction of rotation of the hydraulic motor is reversed and the actuating pressure on the brake valve in the braking phase depends on the inflow pressure to the hydraulic motor independently of the actuating pressure on the control valve.

Abstract: Described herein is a brake valve which is arranged to prevent low pressure relief actions by relief valves (59A) and (59B) at the time of starting an actuator, for improving the response characteristics and the safety of operation. This brake valve has relief valves (59A) and (59B) and check valves (70A) and (70B) located in coaxial positions, the check valves (70A) and (70B) being arranged to seat on fore end portions of valve seat members (62A) and (62B) when opened, thereby to substantially block the communication of the valve seat members (62A) and (62B) with inlet link passages (56A) and (56B). Therefore, when the check valve (70A) or (70B) is opened at the time of starting the actuator, the valve seat member (62A) or (62B) is supplied with only a throttled flow of hydraulic pressure through the notched portions (73A) or (73B).

Abstract: Herein described is a method and apparatus for controlling braking and stopping of the slewing of an upper slewing body which is slewingably provided on a construction and hoists a load, represented by a rotary crane, wherein the braking torque for braking the upper slewing body and the braking torque for braking a hoisting load are separately obtained by the calculated slewing angular acceleration, and the whole braking torque is calculated on the basis of both the braking torques, thereby achieving a high accurate control of the slewing stop.

Abstract: A hydraulic control system includes a pump, a hydraulic motor and a motor hydraulic circuit interconnecting the pump and the motor. The circuit includes a first hydraulic fluid line extending between the pump and an inlet of the motor and a first control valve located in the fluid line for selectively allowing the flow of fluid between the pump and the motor inlet. A second hydraulic fluid line extends from an outlet of the motor to the first control valve. A circuit is provided for allowing a flow of fluid between the first and second fluid lines. Located in the circuit is a flow control orifice for slowing a flow of fluid between the first and second fluid lines.

Abstract: In the case of a hydraulic control device for an oscillating load moving system comprising a double-acting hydroconsumer (V), which is adapted to be selectively connected to a pressure source (P) or to a reservoir (T) via two separate main lines (9, 10) and a control valve (C), and further comprising a load supporting valve (H), which is arranged in at least one main line (10) between the control valve (C) and the hydroconsumer (V) and which is adapted to be opened from the other main line (9) via a pilot line (16), a damping device (X), which consists of a bypass line (23) and an interference throttle aperture (D2), is connected to the pilot line (16) of the load supporting valve (H). The pilot line (16) has provided therein a throttle aperture (D1) which is smaller than the interference throttle aperture (D2).

Abstract: A hydrostatic drive system for vehicles including a hydromotor with a control unit forming together a drive unit which in the assembled state can be inserted in the seat of the centering device of the drive system, the configuration and arrangement of the wheel brake valve wakes possible to obtain a drive unit with compact dimensions, in axial as well as in radial direction, especially due to the double function of the wheel brake valve which serves simultaneously as a pressure relief valve.

Abstract: A slewing control device for a hydraulic slewing crane adapted to supply a discharge oil from a hydraulic pump through a slewing control valve to a slewing motor and control a rotational direction and a rotational speed of the slewing motor. The slewing control device includes a brake pressure control valve for variably controlling a discharge pressure of the slewing motor, an acceleration pressure control valve for variably controlling a suction pressure of the slewing motor, and a controller for outputting to both pressure control valves a pressure control signal to be determined according to an operational condition of the crane upon braking of a slewing body and controlling both the discharge pressure and the suction pressure of the slewing motor to control a pressure differential therebetween. Accordingly, even when a braking torque is small, the slewing body can be smoothly braked to be stopped at a target position accurately with no oscillation of a suspended load remaining.

Abstract: A method a braking a vehicle which has a drive motor, a hydrostatic drive unit including adjustable hydraulic machines having adjusting devices, and an electronic subassembly controlling the adjusting devices of the hydraulic machines. Continuous adjustment of the hydraulic machines permits the drive motor to exert a braking moment that slows the movement of the vehicle. The method includes rapidly adjusting the hydraulic machines by the electronic subassembly toward a setting that relieves the drive motor completely or partially after a limiting rpm value on the drive motor is exceeded and the higher pressure present in the hydrostatic drive unit reduces the braking energy through the adjusting devices until the speed of the drive motor drops below the limiting rpm value. At this time, the electronic subassembly again adjusts the hydraulic machines to utilize the braking moment.

Abstract: The invention relates to a braking valve arrangement for a hydrostatic drive operated in open circuit, in particular for vehicle drives, wherein a hydraulic pressure medium is supplied to the hydraulic motor from the hydraulic pump via a reversing directional control valve as desired through one of two branches each containing a pressure limiting valve and a braking control valve, and the pressure medium is discharged to the tank through the respective other of the two branches. The braking control valve controls the flow of hydraulic medium through the respective branch depending on the pressure in the respective other branch and has parallel with it a non-return valve opening into the hydraulic motor.

Abstract: The problem of energy wastage in power drive units having fixed displacement hydraulic motors is avoided in a system having a variable displacement hydraulic motor (10) without the expense normally associated with such variable displacement systems by a construction which includes a variable displacement hydraulic motor (10) provided with a hydraulic actuator (14). A servo valve (12) is adapted to be connected to a source of hydraulic fluid under pressure and a controller (24) and is connected to the motor (10) for controlling the flow of fluid thereto in response to signals received from the controller (24). A flow limiter (16) is connected between the servo valve (12) and a return to the fluid source. A flow sensor valve (18) is connected across the flow limiter (16) and is responsive to flow therethrough to provide a hydraulic control signal to the actuator (14) to control the displacement of the motor (10).