Abstract: Provided is a work machine capable of achieving both low fuel consumption and ensuring of workability. The work machine is configured to, in a state where an output of an engine or hydraulic pump has increased to an increase threshold (S12: Yes) with the rotational speed being at a first rotational speed (S11: Yes), raise the rotational speed from the first rotational speed to a second rotational speed (S13); in a process of raising the rotational speed to the second rotational speed, output, to a regulator, a signal instructing reduction in the discharge rate (S14) so as to keep the output of the engine or hydraulic pump constant; and after the rotational speed has reached the second rotational speed, output, to the regulator, a signal instructing increase in the discharge rate (S16) so as to make the output of the engine or hydraulic pump have a value corresponding to a request load.

Abstract: A multi-port, rotary actuated valve assembly for controlling fluid flow in a vehicle is provided, which includes a valve housing defining a puck-receiving cavity. A puck is positioned within the puck-receiving cavity and is rotatable therein. The puck has a plurality of chambers that interconnect different combinations of ports provided in the valve housing depending on the rotational position of the puck. The chambers in the puck include at least a first chamber and a second chamber, each of which include a chamber opening on the distal end of the puck. The opening to the first chamber on the distal end of the puck is radially inboard of the opening to the second chamber such that at least two separate and parallel fluid flow paths are provided on the distal end of the puck along which fluid may enter or exit the first and second chambers, respectively.

Abstract: A multi-mode fluid control valve that has a housing with a fluid control chamber having a first end wall with at least one passage and a second end wall with at least two passages. There is also a puck positioned in the fluid control chamber that is rotatably connected to a drive shaft at a drive shaft connection aperture in the puck. The puck has a first side facing the first end wall of the flow control chamber. The puck has at least two passages separated by divider walls. The puck further includes at least one flow diverter extending between the first side of the puck to the second side of the puck. The flow diverter is adjacent one of the two passages and is configured to divert fluid in the fluid control chamber toward the passage that is adjacent the flow diverter.

Abstract: A controller 21 mounted on a work machine calculates a target carried load representing a target value for a carried load carried by the work machine on the basis of loadage of a transportation machine in case the loadage is changed, calculates a minimum integration load value depending on the magnitude of the calculated target carried load, and calculates the loadage by integrating the carried load in case it is determined that a work implement has performed a loading operation on the transportation machine and in case the calculated carried load is equal to or larger than the minimum integration load value.

Abstract: A drive system of a construction machine includes: a controller that controls a fuel injection valve, so an actual rotation speed of an engine is adjusted to a setting rotation speed; a hydraulic circuit including a boom cylinder supplied with hydraulic oil from a pump driven by the engine, configured so energy is regenerated as motive power owing to the pump being driven by pressurized oil discharged from the boom cylinder at boom lowering; and a boom operation device including a boom operation lever. At boom lowering, the controller cuts a fuel supply to the engine when a cutting condition is satisfied, which is defined to include that an operating amount of the lever is less than or equal to a first threshold, and resumes the fuel supply when the cutting condition stops being satisfied or when the actual rotation speed of the engine becomes less than a second threshold.

Abstract: A control device of an electric motor includes: an operating state setting unit configured to set an operating state; a maximum output acquiring unit configured to acquire maximum output of the electric motor that is preset according to the operating state set; a speed detecting unit configured to detect a speed of the electric motor; a torque limit value calculating unit configured to calculate a torque limit value based on the speed and the maximum output; and a torque limiting unit configured to limit torque of the electric motor by the torque limit value when accelerating the electric motor.

Abstract: Hydraulic systems and methods for using such systems in a variety of machinery, including but not limited to machines having multiple functions performed by one or more hydraulic circuits. The systems enable valves and actuators within the systems to reconfigure themselves so that flow from assistive loads on one or more actuators can be used to move one or more other actuators subjected to a resistive load.

Abstract: A first target engine speed is set in response to a command value commanded by a command unit. A second target engine speed equal to or lower than the first target engine speed is set based on the first target engine speed. When the first target engine speed is reduced, the second target engine speed is set to be constant or be decreased and a reduction range for decreasing the first target engine speed to the second target engine speed is set to be decreased. The reduction range is set at zero when the first target engine speed is equal to or lower than an engine speed at least at a maximum torque point.

Abstract: A pump control device for a construction machine includes a pump regulator, a pump pressure detector, a travelling operation detector, a working operation detector, and a controller instructing the pump flow rate depending on the pump pressure to the pump regulator. The controller stores first and second P-Q characteristics as a horsepower characteristic and instructs the pump flow rate to the pump regulator, based on the first P-Q characteristic when a travelling operation is detected, and based on the second P-Q characteristic when a working operation is detected. The second P-Q characteristic is equal to the first P-Q characteristic in a low-pressure region while is one giving a low characteristic relatively to the first P-Q characteristic so as to increase a horsepower difference as the pump pressure increases, in intermediate-pressure and high-pressure regions.

Abstract: An industrial vehicle includes a hydraulic mechanism, an operation lever, and a pump, a hydraulic control valve unit, a lever operation detector, an internal combustion engine controller, and a valve controller that controls the hydraulic control valve unit. When the lever operation detector detects the operation of the operation lever under a situation in which a speed of the internal combustion engine is less than or equal to a predetermined speed, the valve controller operates the hydraulic control valve unit to discharge the hydraulic oil without supplying the hydraulic oil to the hydraulic mechanism and instructs the internal combustion engine controller to increase the speed of the internal combustion engine, and subsequently operates the hydraulic control valve unit to supply the hydraulic mechanism with the hydraulic oil.

Abstract: An engine control device includes an engine-driven variable displacement hydraulic pump, a hydraulic actuator driven by oil from the pump, a control valve which controls the oil discharged from the pump, and supplies the oil to and from the hydraulic actuator, pump displacement detecting means, command means for selecting and commanding variable command values, and setting means for setting a first target engine speed in accordance with a command value, and a second target engine speed lower than the first target engine speed based on the first target engine speed. When the pump displacement increases and exceeds a first predetermined pump displacement when the engine is controlled based on the second target engine speed, a target engine speed is changed from the second target engine speed to a third target engine speed higher than the second target engine speed and equal to or lower than the first target engine speed.

Abstract: A method of manufacturing a coated medical device, such as a medical guide wire, including at least applying a first colored coating to at least a first portion of an outer surface of a medical guide wire, securing a first end of the medical guide wire, and for each a designated quantity of turns, turn a second end of the medical guide wire upon a longitudinal axis of the medical guide wire. The method of manufacturing also includes securing the second end of the medical guide wire, blocking at least a first portion of the coated surface of the medical guide wire, applying a second contrasting colored coating to at least a second, unblocked portion of the outer surface of the medical guide wire and releasing the first end and the second end of the medical guide wire to display at least one spiral marking formed along a length of the medical guide wire.

Abstract: An engine lag down control system for construction machinery has a machinery body controller having first, second and third torque control units and a solenoid valve. The first torque control unit controls a torque control valve to a minimum pump torque corresponding to a target number of engine revolutions when a non-operated state of a control device has continued beyond a monitoring time. The second torque control unit controls the torque control valve such that the above-described minimum pump torque is held for a predetermined holding time subsequent to the operation of the control device from the non-operated state. The third torque control unit controls the torque control valve such that from a time point of a lapse of the predetermined holding time, the pump torque is gradually increased on a basis of a predetermined torque increment rate.

Abstract: A working vehicle with an HST in which over-rotation of a hydraulic pump in the HST or the pump input shaft thereof is prevented when a main clutch is disconnected during a run. When a main clutch connection/disconnection detection means detects the disconnection state of the main clutch during a run, a control means judges whether a vehicle speed detected by a vehicle speed detection means is at least a set speed or not, and if the vehicle speed is at least the set speed, the movable swash plate of the hydraulic pump in an HST is controlled to sustain it at the current inclination angle.

Abstract: A method and system for configuring a hydromechanical transmission having a hydraulic pump and a hydraulic motor driven by the hydraulic pump and a pressure-driven actuator employs a particular torque-pressure curve configuration to maximize torque resolution with respect to actuator pressure changes while ensuring that the curve is substantially monotonic in each dimension and at any available motor speed within a predetermined motor speed limit and any available actuator pressure within predetermined actuator pressure limits. The resultant four-dimensional association between actuator pressure, motor speed, primary power source speed and motor torque allows selection of an actuator pressure to provide a desired torque.

Abstract: To provide a hydraulic drive device for a work machine that is capable of ensuring reduction in fuel consumption even in actual work where an operating condition changes every moment. Operating condition identifying unit (41) for identifying the operating condition and hydraulic pump control system (40b) for controlling absorption torque of hydraulic pump (18) are provided. When the operating condition identified by operating condition identifying unit (41) is a specific operating condition, hydraulic pump control system (40b) controls the absorption torque of hydraulic pump (18) to achieve hydraulic pump absorption torque characteristic line (PLb) matching the absorption torque of hydraulic pump (18) with output torque of engine (17) at engine output torque point Mb at which a fuel consumption rate is substantially minimum.

Abstract: A computing section computes a reference revolution-speed decrease modification amount DNLR; and multiplies an engine revolution speed modification gain KNL by a reference revolution-speed decrease modification amount DNL and then DNLR, to thereby compute an engine revolution-speed decrease modification amount DND based on input change of an operation pilot pressure, which is modified in accordance with DNLR. At the time when a lever operation input from an operation command unit is changed from full stroke to half stroke, if a pump delivery pressure is in a pressure range of a pump absorption torque control region Y where the pump delivery pressure is lower than that in a region X, the reference revolution-speed decrease modification amount computing section 700v computes the modification amount DNLR to be 0, and therefore lowering of a target engine revolution speed with auto-acceleration control is not caused.

Abstract: A method is described for controlling a hydraulic system, particularly of mobile working machine, with at least one internal combustion engine driving at least one hydraulic pump with adjustable volumetric displacement and possibly additional fixed-displacement pumps.

Abstract: A hydraulic controller in which driving sound and the number of parts can be reduced, and a long service life can be realized, and a hydraulic drive unit provided with said hydraulic controller. The hydraulic controller for a hydraulic drive unit includes a housing that includes an electric motor housing configured to house an electric motor, an oil pump housing configured to house a hydraulic pump, and a valve housing configured to house valves are integrated together.

Abstract: A control valve, and a control module including such a control valve, for selectively controlling a flow of pressurised hydraulic fluid from a pump in a hydraulically powered vehicle seat adjustment system. The control valve including a duct for pressurised fluid delivered from the pump, and a moveable valve member which selectively closes off the duct. The control valve also includes an integral set of contacts which are arranged to activate the pump to provide a supply of pressurised hydraulic fluid to the duct when the valve member is in the second operative position in which hydraulic fluid is permitted to flow though the duct. The control valves are preferably mounted within the control module which defines an internal chamber forming a reservoir of the hydraulically powered vehicle seat adjustment system. The control module is mounted upon a side valance of the seat as a single integrated unit.

Abstract: Provided is a force-controlled hydro-elastic actuator, including a hydraulic actuator, having a connection to hydraulic fluid and including a mechanical displacement member positioned to be mechanically displaced by fluid flow at the actuator. A valve is connected at the hydraulic actuator connection and has a port for input and output of fluid to and from the valve. At least one elastic element is provided in series with the mechanical displacement member of the hydraulic actuator and is positioned to deliver, to a load, force generated by the hydraulic actuator. A transducer is positioned to measure a physical parameter indicative of the force delivered by the elastic element and to generate a corresponding transducer signal. A force controller is connected between the transducer and the valve to control the valve, based on the transducer signal, for correspondingly actuating the hydraulic actuator and deflecting the elastic element.

Abstract: An electrohydraulic pressure supply unit involving the joint operation of two energy converters, which can be adjusted independent of each other, including an electric motor with speed control that drives a variable displacement pump with a variable displacement volume. The electric motor converts electrical output (loss-encumbered), into mechanical output, meaning into speed n and torque T. The pump then converts this mechanical output (also loss-encumbered) into hydraulic output. The hydraulic output is determined by the pressure difference &Dgr;p across the pump and the volume flow Q. The pressure difference &Dgr;p generally is impressed by the consumer or load on the system. The volume flow Q is the result of the displacement volume V and the motor speed n. The torque T, which must be generated by the motor, is derived from the displacement volume V and the pressure differential &Dgr;p.

Abstract: A control valve (10) is provided for mobile or stationary hydraulic equipment for automatically increasing or decreasing speed of a prime mover in response to operation of a hand lever to extend a hydraulic cylinder. A prime mover speed control valve (42) is integrated with a spool (12) in a single housing (10) for the purpose of simultaneously controlling the supply of fluid to a hydraulic cylinder (16) and to a cylinder (61) controlling prime mover speed. When the spool (12) is in the "CYLINDER EXTEND" or "NEUTRAL" position for the implement cylinder, a hydraulic control signal is provided from port (55) to the prime mover control cylinder (61) to signal increased prime mover speed and increased output from a hydraulic pump (17). When the spool (12) is in the "CYLINDER RETRACT" position for the implement cylinder (16), the spool (12) blocks the signal from port (55) while allowing fluid to drain from the implement cylinder (16) to a reservoir (29).

Abstract: The current operational condition is discriminated as being the vehicle propulsion condition or the performing work condition. When the vehicle propulsion operational condition is discriminated, the maximum engine revolution speed is limited to a first revolution speed and the maximum displacement is limited to a first displacement value. When the performing work condition is discriminated, the maximum engine revolution speed is limited to a second revolution speed equal to or lower than the first revolution speed and the maximum displacement is limited to a second displacement value higher than the first displacement value.

Abstract: A control system for automatically controlling the operation of a hydraulic system for heavy construction equipment. The system of this invention provides a controller optimally connected to sensors and to control devices on the hydraulic system so that it automatically and optimally preheats the engine coolant and the hydraulic fluid of the heavy construction equipment before a normal starting operation in order to reach to an optimal operating temperature in a relatively short time. The control system automatically checks the operating temperature of the engine coolant and the hydraulic fluid by temperature sensors, and alarms the operator to any overheat condition by an alarm device. The control system also automatically controls the operational mode in order to remove the overheat condition thus preventing the temperature of the engine coolant and the hydraulic fluid from rising above a predetermined temperature.

Abstract: A hydraulic apparatus for a construction machine, which is adapted to prevent the number of revolutions of an engine from increasing when the flow of the fluid discharged by a variable displacement hydraulic pump driven by the engine is cut off. The hydraulic apparatus comprises a proportional solenoid (11) connected to a fuel supply control lever (13) so as to vary the horsepower characteristics of the engine, which are set by the action of a governor (12) based on manipulated variable of the fuel supply control lever (13) when the flow of the fluid discharged by said pump is cut off, and a controller (10) for controlling the proportional solenoid (11). In this apparatus, a decrement (.DELTA.Nr) in a target number of revolutions per minute (Nr) of the engine, which can be obtained by subtracting a target number of revolutions per minute (Nrb) of the engine at the desired engine horsepower characteristics (l.sub.

Abstract: A hydraulic drive system for a construction machine comprising a prime mover (1), a hydraulic pump (2) of variable displacement type driven by the prime mover, at least one hydraulic actuator (6) driven by a hydraulic fluid delivered from the hydraulic pump, control valves connected between the hydraulic pump and the actuator for controlling a flow rate of the hydraulic fluid supplied to the actuator dependent on the operation amount of control apparatus, pump control apparatus for controlling a displacement volume of the hydraulic pump dependent on the operation amount of the control apparatus such that the delivery rate of the hydraulic pump is increased with an increase in the operation amount, and prime mover control apparatus (29) for controlling a revolution speed of the prime mover.

Abstract: A hydraulic drive system comprising a prime mover (21), a hydraulic pump (22) driven by the prime mover, a plurality of hydraulic actuators (23-28) driven by hydraulic fluid supplied from the hydraulic pump, a plurality of flow control valves (29-34) for controlling flow of the hydraulic fluid supplied to the actuators, and a plurality of pressure compensating valve (35-40) for controlling respective differential pressures across the respective flow control valves, in which each of the pressure compensating valves applies a control force (f-F.sub.c) in a valve opening direction for setting a target value of the differential pressure across the flow control valve. There are provided a first detector (60) for detecting the target rotational speed (N.sub.0) of the prime mover (21), and controllers (61, 62, 63) for controlling the control force on the basis of the target rotational speed detected by at least the first detector such that the control force (f-F.sub.

Abstract: In a method for operating a drive unit comprised of an internal combustion engine and a hydraulic aggregate group, the amount of fuel supplied to the engine is limited by a proportionally acting RPM regulator. When the engine is overloaded the power absorption of the hydraulic aggregate group is reduced by an electronic maximum load regulator and under no-load operation the engine is shifted from an automatic idling circuit to the idling speed after a specified time and the power absorption of the aggregate group is reduced to a minimum. For partial-load operation, the power absorption of the aggregate group can be limited selectably to a power below the maximum power put out by the engine. In order to render such a process more economical, the engine is operated in the range of the idling control characteristic during partial-load operation.

Abstract: An apparatus for controlling a power shovel or like construction machine which assures that various control modes for performing certain operations can reliably be selected by merely activating a switch corresponding to the operation to be performed. When a certain operation is selected, a CPU and an operation panel inputs a signal indicative of the selected operation into a pump controller. The pump controller outputs a signal indicative of the magnitude of the target engine revolution number and a magnitude of composite suction torque of the pumps adapted to the selected operation to an electric governor controller and a TVC valve. In response to this signal, the governor controller controls a governor and swash plates of the pumps such that the target engine revolution number is reached and the output torque from the engine matches the composite suction torque of the pumps.

Abstract: A controller for a hydraulic fluid flow control apparatus determines a quantity necessary for loading/unloading operations according to a signal from a lever operating degree detector, and controls a variable displacement type hydraulic pump to obtain the quantity. Accordingly, unnecessary hydraulic fluid flow in the hydraulic apparatus is reduced. The controller determines when a vehicle is stopped according to a signal from a clutch ON-OFF detector or a neutral sensor, and can raise the rpm of an engine. Therefore, when the loading/unloading operations are being executed while the vehicle is stopped, there is no need to operate the accelerator pedal.

Abstract: A variable displacement hydraulic pump and a hydraulic motor are connected in a closed circuit. A pressure oil supply means includes the variable displacement hydraulic pump and a tilting controlling means for controlling a tilt angle of the hydraulic pump and supplies an amount of pressure oil corresponding to the tilt angle of the hydraulic pump to the hydraulic motor. When rotation of a prime mover is detected by a rotation detecting means, an opening and closing valve is changed over to a first position in which the pressure oil supply means is permitted to supply pressure oil. When stopping of the prime mover is detected by the rotation detecting means, the opening and closing valve is changed to a second position in which the pressure oil supply means is inhibited from supplying pressure oil.

Abstract: A vehicle steering system with power assistance means comprises an output component 4 displaceable relative to a housing 1 for that component and in response to a steering input for effecting a steering maneuver. The housing 1 is mounted for displacement relative to a frame part 9 of the vehicle. An hydraulic servo motor 13 is provided for assisting displacement of the output component 4 and reacting between the output component 4 and the vehicle frame part 9. An hydraulic pump 44 supplies working fluid to the servo motor 13 and a control valve 20 controls the supply of working fluid to the servo motor 13 in response to relative displacement between the housing 1 and the frame part 9 as a reaction to a steering maneuver and that response controls the servo motor 13 to assist the maneuver.

Abstract: A hydraulic drive system is equipped with an engine, a plurality of hydraulic pumps adapted to be driven by the engine and including a variable displacement hydraulic pump provided with a displacement varying mechanism, a hydraulic motor connected to the variable displacement pump, a hydraulic actuator for actuating the displacement varying mechanism of the variable displacement hydraulic pump, a working fluid feeding means for feeding the hydraulic actuator with a hydraulic fluid of a pressure according to the degree of control of an accelerator lever which is adapted to instruct a target revolution number of the engine, and a low-pressure circuit for allowing the hydraulic fluid to be discharged therethrough from the hydraulic actuator.

Abstract: A drive control system for a hydraulic construction machine, comprises a prime mover driven by a hydraulic pump, at least one hydraulic actuator driven by hydraulic fluid discharge from the hydraulic pump, first rotational speed setting arrangement including a first operating arrangement for setting rotational speed of the prime mover, and a second operating arranngement for controlling operation of the hydraulic actuator (3).

Abstract: The precise and smooth control of the hydraulic fluid supplied to a hydraulic system, such as the lifting cylinders of a turret stockpicker, under varying operating conditions includes an optical encoder on the operator's control handle connected to an electronic control of a hydraulic pump motor, which s initially operated at a predetermined minimum speed, and a hydraulic valve which provides the initial control of hydraulic fluid under the control of an operator's handle. Because the pump is initially at a low speed, greater efficiency of the system is realized, an important feature in a battery operated vehicle. As the operator moves the handle from the off or neutral towards the fully open position, the hydraulic valve will open and reach its fully open position as the handle passes approximately the one-third on position.

Abstract: The invention is vehicle propulsion system having a pump driven by an engine, a hydraulic motor driven by the pump, and a ground engaging wheel driven by the hydraulic motor. On the drive shaft connected between the engine and the pump is a flywheel whose moment of inertia is varied by radially translating weights on the flywheel. Under normal vehicle operating conditions, the weights are translated outward, whereby rotational energy is stored in the flywheel. When more power is needed then the engine can provide, the weights on the flywheel translate inwardly so that the flywheel imparts rotational energy to the pump through the drive shaft. The propulsion system has means to maintain the engine in a narrow r.p.m. range where the engine is most efficient. Vehicle speed and direction is varied by controlling the flow speed and direction from the pump, which determines the speed and direction of the hydraulic motor.

Abstract: An automotive drive system for machines and vehicles, comprising a driving motor the speed of which can be continuously varied by means of a control member and a converter having control means for controlling its output speed in dependence on a depression of the speed of the driving motor determined by means of signal transmitters is arranged so that the power or torque available from the driving motor is better employed. This is achieved by controlling (adjusting) the converter to minimum transmission ratio independently of the driving motor speed when the driving motor speed resulting during operation of the drive system is greater than the driving motor speed given by a predetermined speed(rotation) depression, and on reaching the predetermined speed (rotation) depression the converter is controlled in dependence on the driving motor speed so that the driving motor speed does not fall below the controlling characteristic curve corresponding to the predetermined speed (rotation) depression.

Abstract: A control device for a drive unit, preferably the drive unit of a power vehicle, is provided having a hydrostatic transmission where the adjusting device of the latter and the adjusting device of the internal combustion engine are controlled by means of a servo piston loaded by control pressure, whereby the internal combustion engine is prevented during reversing from being adjusted to an increased power output through a circuit before the adjusting device of the hydrostatic transmission has passed through the zero-stroke position, and where the circuit has two shut off valves whose outlets are connected with a line, which are connected to the spring-side pressure chamber of the operating cylinder of the internal combustion engine through a multiway valve.

Abstract: A control system of hydraulic construction machinery includes a prime mover, at least one variable displacement pump driven by the prime mover, at least one actuator hydraulically driven by the pump, maximum revolution number altering device for the prime mover, maximum displacment volume altering device for the pump and an information provider device for providing information on the operation mode of the actuator, whereby the maximum revolution number altering means and maximum displacement volume altering means are controlled by the information provider device to provide a maximum number of revolutions and a maximum displacement volume which suit the operation mode indicated by the output signal.

Abstract: A control system for a hydraulic excavator having a prime mover, revolution number control device for the prime mover, at least one variable displacement hydraulic pump driven by the prime mover, displacement volume control device for the pump, actuators driven by pressurized fluid discharged from the pump and working elements driven by the respective actuators. The control system includes maximum revolution number altering device for the prime mover associated with the revolution number control device, maximum displacement volume altering device for the pump associated with the displacement volume control devices, devices for sensing the operation condition of the actuators, devices for selecting an operation mode for each working element and control devices.

Abstract: A hydraulic reaction force apparatus for a power steering system has a pump, a power cylinder, a control valve, a first variable orifice, a hydraulic reaction force chamber, and a spool valve. The spool valve has a supply port connected to the pump, a reaction port connected to the hydraulic reaction force chamber, a tank port connected to a tank and a second variable orifice controlled by a spool in the spool valve. The opening of the second variable orifice is changed by a displacement of the spool caused by the pressure difference between upstream and downstream pressures of the first variable orifice, thereby connecting the reaction port to the supply port and the tank port and controlling the magnitude of the hydraulic reaction force.

Abstract: Apparatus for controlling a steering force of a handle in an automobile having a power steering system in which a driving shaft of an auxiliary fluid pump for obtaining pressure oil for a hydraulic reaction chamber of the power steering system is made common to a driving shaft of a fluid pump for the power steering system to increase a quantity of discharge and oil pressure of the auxiliary pump. Oil pressure with respect to the hydraulic reaction chamber is controlled by the speed and steering angle of the automobile to obtain a proper steering force.

Abstract: A hydraulic drive system for civil engineering and construction machinery having at least one hydraulic pump driven by a prime mover, at least one hydraulic actuator connected to the hydraulic pump, and at least one hydraulic cylinder, the hydraulic actuator and hydraulic cylinder being adapted to operate movable members. The hydraulic drive system is provided with a hydraulic pump-motor coupled to the prime mover, a first conduit for connecting the hydraulic pump-motor to one side of the hydraulic cylinder which moves a movable member in a direction in which the potential energy thereof increases in magnitude upon feeding of liquid under pressure thereinto, a second conduit for connecting the other side of the hydraulic cylinder to a reservoir, and an arrangement for controlling the hydraulic pump-motor in such a manner that it functions as a motor when the operator operates the system to move the movable member in a direction in which the potential energy thereof is reduced in magnitude.

Abstract: A drive control circuit for a dental treatment table with a hydraulic cylinder for elevating and lowering a seat comprising a hydraulic drive circuit equipped with a hydraulic pump, a first hydraulic valve for elevating said cylinder, and a second hydraulic valve for lowering said cylinder, and a hydraulic pump operation circuit equipped with an air switch, a first air valve for controlling said air switch and said hydraulic valve for elevating said cylinder, and a second valve for controlling said hydraulic valve for lowering said cylinder. The drive control circuit may further comprise a second cylinder for tilting a backrest which can be controlled by the hydraulic drive circuit and the hydraulic pump operation circuit.

Abstract: A number of systems exist wherein a plurality of hydraulic motors (28a, 28b, 28c) receive pressurized fluid from a single pump (14) which is itself driven by an electric motor (12). Apparatus has been available for adjusting the power supplied to the electric motor (12), and thereby adjusting the pump (14) flow rate, in response to the operator activating one or more of the hydraulic motors (28a, 28b, 28c). However, such apparatus has generally been bulky, complicated and/or difficult to install and/or service. An improvement is provided wherein a single switch (22) is placed in either an open or closed position as an elongated member (34) placed transversely to a plurality of generally parallel rod member (20a, 20b, 20c) is rotated in response to longitudinal travel in either direction from a neutral position (32) of one of the rod member (20a, 20b, 20c).

Abstract: A pressure regulating valve varies an input fluid pressure from a pump to a steering pressure either stepwise or continuously varied in accordance with the vehicle speed and, when a power cylinder control valve alternatively admits the steering pressure into two working chambers of a power cylinder, a reaction chamber control valve alternatively admits the input fluid pressure into only a reaction force chamber of the power cylinder control valve, corresponding to the working chamber fed with the steering pressure, to produce in the reaction force chamber a reaction force increased with increases in the vehicle speed.

Abstract: Coordinated control of engine speed, transmission drive ratio and drive direction is provided for with a single foot pedal and a compact economical linkage arrangement for coupling the pedal to a vehicle engine and hydrostatic transmission. Forward rocking of the pedal from a neutral position progressively increases transmission drive ratio in the forward direction while backward rocking of the pedal from the neutral position progressively increases the drive ratio in the reverse direction. The pedal linkage further produces a unidirectional progressive motion of the engine speed control upon being rocked in either the forward or backward direction and this engine speed control motion may be continued by additional pedal movement after the transmission control member has reached the maximum possible movement in either direction.