Abstract: A controller regulates a hydraulic pump for hydraulic equipment to allow long-term use of environmentally safe hydraulic fluids. This is accomplished by limiting the hydraulic pump power output to a level established to prevent the operating temperature from exceeding a specified level. A manual mode for switching between power curves permits alternate use of hydraulic fluids having different maximum operating temperatures. An automatic mode detects the type of hydraulic fluid and automatically selects and applies a suitable power mode curve to limit the maximum operating temperature to a value suitable for the detected type of fluid.

Abstract: An excavator control apparatus for shovel-type construction equipment includes an automatic digging control section, a digging load control device, and an operation command correcting device. The shovel-type construction equipment has a boom, an arm and a bucket that are successively and rotatably connected in an operation section. The boom, the arm and the bucket are each connected to at least one cylinder that extends and retracts according to the operation of a lever. The digging load control device permits an automatic digging routine to be executed by controlling the extension and retraction of the cylinder. The digging load control device transmits operation commands to the cylinder to maintain a digging load approximately equal to a set digging load during automatic digging. The operation command correcting device corrects the operation commands transmitted to the cylinder by manual operation of the lever without cancelling the automatic digging routine.

Abstract: A device for controlling an engine includes a main control unit for outputting a control signal in response to a signal from an accelerator dial, and a sub-control unit for controlling an actuator that actuates a control lever of a fuel feeding device in response to a control signal from the main control unit and a signal from a key switch. The sub-control unit controls the actuator in response to an off signal from the key switch so that the control lever is moved to a fuel stop position and, after the operation of the engine has been halted, controls the actuator so that the control lever is moved to a start position.

Abstract: A valve control unit includes a main hydraulic oil circuit and a pilot oil circuit. The main circuit includes a main pump, a main valve downstream from the main pump, and a hydraulic actuator downstream from the main valve. The pilot oil circuit circulates pressurized pilot oil to control the main valve and includes a pilot oil pump, an automatic control switching valve downstream from the pilot oil pump, a manual limit switching valve downstream from the pilot oil pump, a manual control switching valve downstream from the manual limit switching valve, and a pilot oil chamber downstream from the manual control switching valve. The pilot oil chamber is located near the main valve such that the flow of pressurized pilot oil moves the main valve.

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: In controlling a hydraulic excavator equipped with a front mechanism having multiple foldable and rotatable joints, the controlling method described enables complex joint actions to be controlled readily by manipulating electrical joy sticks. Translational and rotational control commands are input to a certain point on the longitudinal axis of a rear arm through the joy sticks and cooperative actions of multiple joints are achieved simultaneously.

Abstract: A method for controlling a hydraulic pump driven by an engine, including measuring a temperature of at least one of the engine and a hydraulic fluid, comparing the measured temperature with a first predetermined temperature to judge as to whether the measured temperature is higher than the first predetermined temperature or not, comparing the measured temperature with a second predetermined temperature to calculate a difference between the measured temperature and the second predetermined temperature, and decreasing an output flow rate of the hydraulic pump by a degree according to the difference between the measured temperature and the second predetermined temperature, when the measured temperature is judged to be higher than the first predetermined temperature.

Abstract: An actuator for an accelarator includes a casing and a driving part having a reversibly revolvable motor disposed in the casing, a decelerator for decelerating revolution of the motor, and an output pulley, connected to the decelerator, for taking up or letting out a control cable cable. The actuator also includes a control part composed of an operation part, and a control mechanism for controlling the revolution of the motor on the basis of a deviation between a position of the operation part and a position of the output part,wherein the driving part and the control part are integrally coaxially connected to each other.

Abstract: The right and left front wheels of an asphalt finisher are each supported by a beam, one end of which is mounted to the body of the asphalt finisher by way of a pin such that the beam can swing, and the other end of the beam is mounted to the end of the piston rod of a hydraulic cylinder which is vertically mounted to the body of the asphalt finisher in a downward direction, both cylinders being connected to each other by way of a single oil line. As a result, when either one of the front wheels encounters an obstacle, the sideward inclination of the body can be eliminated.

Abstract: In a method for controlling an engine for driving a hydraulic pump to supply a pressurized fluid to at least one hydraulic actuator in a construction machinery, a fuel flow supplied to the engine is decreased so that an output rotational speed of the engine is decreased to decrease an excess output of the engine, and the fuel flow is increased to increase the output rotational speed of the engine when a load of the engine for driving the hydraulic pump is more than a first level after the engine output decreasing step.

Abstract: A method for controlling a hydraulic pump included by an apparatus, comprises the steps of: measuring a circumferential atmospheric temperature of the apparatus, comparing the measured circumferential atmospheric temperature with a first temperature to judge as to whether the measured circumferential atmospheric temperature is higher than the first temperature or not, and decreasing an output of the hydraulic pump when the measured circumferential atmospheric temperature is judged to be higher than the first temperature.

Abstract: An excavator includes an upper structure swingably supported by a lower structure. A worker position sensor consists of a plurality of radio frequency transceivers provided in the excavator and a radio frequency transceiver carried by each of the excavation workers working within the working range of the excavator. A signal processing unit determines whether the relative distance between each worker and the excavator is either of short distance, slightly long distance or long distance and identifies the position of each worker for each of the predetermined identifying areas. A determining signal from the signal processing unit is supplied to a control unit. The control unit is connected to a drive unit which includes electro-hydraulic proportional valves for energizing actuators for positioning, swing, and traveling of the excavator. This control unit is also connected to a machine sensor which includes a swing angle sensor, a traveling level sensor, and a swing operation lever sensor.

Abstract: A fluid-operated valve includes a control spool, actuated by a source of pilot pressure to control a pilot flow of fluid from a loading pressure inlet port to a drain line. The pilot flow passes a throttle which reduces the fluid pressure acting in one direction, thereby performing stroke compensation of the actuation of a valve poppet. A differential pressure compensation valve is moved to partially block fluid flow to a rate control orifice group in response to a difference in pressure on the two sides of the rate control orifice group to control further the actuation of the valve poppet, whereby differential pressure is compensated.

Abstract: A buffer valve for a cylinder control unit includes a cylinder having first and second plungers each axially slidable in the cylinder with an intermediate piston disposed between the plungers and slidable in the cylinder with springs urging the plungers in the direction of the intermediately located piston; separate chambers are provided in the cylinder between the piston and the first and second plungers and second chambers are provided on the side of the plungers facing away from the piston; passages are provided in the first and second plungers for communicating between the first and second chambers on opposite sides of each plunger; a bypass passage connecting the first chambers for each plunger is provided with a check valve for allowing flow in only one direction from the first chamber of the first plunger to the first chamber of the second plunger so that when one of the plungers closes off communication between the bypass passage and the cylinder control unit, the check valve will prevent flow from th

Abstract: A counterweight handling device for construction equipment such as cranes in which a counterweight can be elevated to a predetermined height by using particulate hydraulic components then supported on a mounting frame. The counterweight may be supported by a pair of rectangular rotating blocks mounted on the counterweight mounting frame and which slide through a pair of vertical grooves in vertical position into supporting hollows in the counterweight bottom and turn through 90.degree. so as to support the counterweight by blocking the vertical grooves. Alternatively a pair of sliding pins mounted on the counterweight mounting frame may be extended into inverted V shaped notches on the counterweight bottom so as to support the counter weight. The counterweight can then be fastened on the counterweight mounting frame. Later the counterweight can be removed.

Abstract: An engine controller which is arranged to operate a governor through an actuator which is controllable either by an accelerator lever in an operator's station or by radio control. First and second levers are rotatably mounted on a shaft, and are biased respectively by a spring to turn in one direction. The first lever is connected to the governor by a wire in such a manner as to increase the engine speed when turned in a direction reverse to the biased direction. The second lever is connected to the accelerator lever by a second wire in such a manner as to rotate in the reverse direction when the accelerator lever is operated in the direction of acceleration. A pulley is mounted on the shaft, and a third lever is securely fixed to the pulley. The pulley is connected to the actuator by a third wire such that the pulley is rotated according to the rotation of the actuator. A rod is securely fixed to the first lever to transmit the reverse rotations of the second and third levers to the first lever.

Abstract: A torque control system for variable delivery pumps receiving torque from an engine employs a signal related to an engine torque available at each engine speed setting to control the torque, and thus the amount of engine power that is absorbed by the variable delivery pumps. In a low-power regime, wherein the fuel injected into the engine is less than maximum, torque control is effected by comparing the available torque with an amount of torque that would be available at maximum fuel injection. In a high-power regime, wherein the fuel injected is at least a predetermined value, torque contol is effected by comparing the available torque with an amount of torque that is available at a combination of a set engine speed and an actual engine speed. A bias circuit biases the stable speed operating point a small amount below the maximum speed, whereby improved fuel economy is attained.

Abstract: A track guiding guard for a crawler type vehicle which is mounted along the lower side of a track frame is disclosed. The track guiding guard comprises a pair of left and right guard members which rotatably support track rollers. Each guard member has a slanted bottom surface which defines a limit angle of inclination between the same and the upper surfaces of track shoes that face the bottom surface, the angle diverging laterally outward. Each guard member further defines a predetermined gap between the inner side surface of the lower end thereof and the outer ends of track pins that face the inner side surface. The gap is so set that when the bottom surface of the guard member is seated on the upper surfaces of the track shoes, the inner side surface of the lower end of the guard member substantially comes into contact with the outer ends of the track pins.

Abstract: There is disclosed a method and apparatus for aligning and assembling disk-shaped works having projections on outer peripheries thereof.A vessel-shaped work is positioned and a plurality of disk-shaped works in a stacked condition are guided to a position on the opening edge of the vessel-shaped work by the work guide means, and then the pin provided for up and down movement on the rotary head is either inserted between adjacent ones of the projections of the disk-shaped works or contacted with and stopped by an upper face of one of the projections of the disk-shaped works. Also when the pin is stopped by the upper face of the one projection, as the rotary head is rotated, the pin is moved in the circumferential direction of the disk-shaped works so that it is disengaged from the upper face of the one projection and then engaged with an adjacent one of the projections of the disk-shaped work. Thus, the disk-shaped works are finally rotated in an integral relationship by the pin.

Abstract: An energy regenerative circuit in a hydraulic apparatus wherein when a direction control valve is at the actuator unloaded-side chamber acting position, the discharge fluid line of a variable displacement pump is connected to a fluid tank via the direction control valve, by-pass fluid line change-over valve and by-pass fluid line that has a signal orifice. The by-pass fluid line is connected to a capacity control mechanism of the variable displacement pump via a signal fluid line on the upstream side of the signal orifice. The loaded-side chamber of the actuator is so connected that the pressurized fluid thereof is partly added through the direction control valve to the fluid line through which the pressurized fluid discharged from the variable displacement pump is fed to the loaded-side chamber.