Abstract: A dozing system that enables automatic control for all kinds of soil properties and less frequently requires manual control intervention. The system is designed such that the blade is lifted or lowered at a start of excavation in dozing operation in an automatic drive mode such that the actual cutting angle .theta. of a blade detected by an actual cutting angle detector becomes coincident with a target cutting angle (maximum cutting angle) .theta..sub.0 preset by a target cutting angle setting device.

Abstract: A tractive force control apparatus and method for preventing a torque converter from being stalled while a working machine is operated during excavation and earth carrying work using a construction machine. In this apparatus, an engine rotational speed sensor (2), a torque converter output shaft rotational speed sensor (4) and a lift combination solenoid valve (12) are connected to a control apparatus. A pilot pressure control valve (11) for a blade lift is connected to a first lift operating valve (13), and also to a second lift operating valve (14) via the lift combination solenoid valve (12). First and second hydraulic pumps (20, 21) and lift cylinders (15, 15) are connected respectively via the first and second lift operating valves (13, 14). A traction output is computed in the control apparatus (16), and, when the traction output is lower than a target level, the lift combination solenoid valve (12) is turned off to reduce a flow rate of oil to the lift cylinders (15, 15).

Abstract: A working machine control device for construction machinery provided with a plurality of joined working arms, an attachment mounted to the leading end of the working arms and a plurality of actuators for driving the working arms and the attachment, includes a function to adjust a pushing force between the attachment and a working plane by automatically controlling at least one of the actuators. The control device also includes a load detecting unit for detecting a load applied from the working plane to the attachment, working machine posture detecting devices for detecting postures of the working arms and the attachment and a computing unit for computing the pushing force between the attachment and the working plane on the basis of output values from the load detecting unit and the working machine posture detecting devices. The computing unit outputs a component of the pushing force in a direction perpendicular to the working plane.

Abstract: A power attachment is attachable to a power machine which has a power circuit. The power machine also includes an operator input device receiving an operator input and providing an output signal indicative of the operator input. The attachment includes a tool and an actuator, coupled to the tool, to drive the tool. The actuator is also connectable to the power circuit of the power machine. A controller is operably coupled to the actuator and is operably couplable to the operator input device. The controller controls operation of the tool based on an operator input signal provided by the operator input device.

Abstract: An apparatus and method for controlling a hydraulically operated construction machine having a plurality of tandem articulated members which move in a particular pattern, wherein movement of one of the articulated members is controlled in response to movement of a second one of the articulated members. Anticipated future movement of the second articulated member is determined and the first articulated member is controlled as a function at least of the anticipated future movement of the second articulated member. Anticipated future movement is determined by measuring actual delay between movement of the first and second articulated members. Operation of the articulated members is a function of operation of an actuator and a selectable command level.

Abstract: A row cultivator 10 is drawn behind a prime mover illustrated by the wheels 11 with rows defined by mounds illustrated in terms of the lines 12 before the cultivator and the reshaped mounds being illustrated by the lines 13 located behind the cultivator. As can be seen the rows before the cultivator include an irregularity. In this case there are wide rows shown at 14 and relatively narrow rows shown at 15. The cultivator 10 includes a fixed rigid tool bar 16 and a moveable tool bar 17 travelling behind the fixed tool bar 16 and pivotable relative thereto via connecting bars 18, 19 and 20. Where the rows to be reshaped are all evenly spaced the connecting bars 18, 19 and 20 would be positioned parallel to the rows. The moveable tool bar 17 is displaced to the left.

Abstract: The present invention provides a method for selecting a steering method for an earthmoving machine having a blade and first and second tracks. One embodiment of the present invention includes selecting a steering method based on the position error of the machine. In another embodiment of the present invention the steering method is selected based on the elevation of the work implement, and the position error.

Abstract: A hydraulic pump is driven by a first prime mover. An actuator, which is controlled by a control valve, is operated by a pressure oil fed from the hydraulic pump. A second prime mover, which is an electric motor, is provided separately from the first prime mover. A pilot pump is driven by the motor. Hydraulic oil is conducted from the pilot pump to a pilot port of the control valve through a pilot oil pipe. A remote control valve is provided in the pilot oil pipe, and change-over operation of the control valve is controlled by the remote control valve. In an on-load state, a command value for controlling the motor is set at a target current value corresponding to a normal pressure, while in an off-load state the command value is set at a target current value which is lower. By so doing, there does not occur any unnecessary power loss even in an off-load state.

Abstract: A control system for a tractor with a semi-mounted plough (2) hitched to it comprises a control system (13) for setting a delay between the lifting/lowering of the tractor linkage (3) and the rear of the plough (2) to cause the individual ploughshares to enter to leave work along a given line parallel to a field boundary. To accommodate field boundaries which are not perpendicular to the ploughing direction, adjustment values representative of the angle of each field boundary to the ploughing direction may be entered into a control unit (13) to cause the delay between lifting/lowering of the front and rear of the plough to be adjusted automatically as each field boundary is reached to take account of the angle of that boundary and also whether the plough is being taken out of or put into work.

Abstract: Disclosed is a method for controlling the above-ground "raise height" of a seed-planting row unit on an agricultural planter having a row marker, a marker switch and a positioning assembly such as a solenoid valve and hydraulic cylinder for raising and lowering the row unit. The method includes enabling the positioning assembly to raise the row unit and changing the marker switch from its first to its second position when the row unit reaches a predetermined height. The positioning assembly is thereby disabled. Such assembly is re-enabled after a brief time delay. The method is carried out using a unique implement control circuit connected to the marker switch and the positioning assembly.

Abstract: A system for reducing oscillations of an implement carried by a vehicle in a lifted position during travel. The implement is coupled to an implement positioning system including an actuator for raising and lowering the implement in response to a control signal. The system includes at least one load sensor for sensing implement load, a position sensor for sensing implement position, and a control circuit configured to generate a control signal to the actuator in a first manner based at least upon implement position and in a second manner based at least upon implement load. The control circuit transitions from the first manner of operation to the second manner of operation upon detecting oscillations of the implement beyond a predetermined magnitude.

Abstract: A bulldozer blade (10) is automatically reset to a predetermined excavating pitch while the bulldozer (20) is traveling backwardly after it has completed an operation of excavating, carrying, or dumping earth. The bulldozer blade (10) can be set to an excavating pitch, a carrying pitch, or a dumping pitch when excavating, carrying, or dumping earth while the bulldozer is traveling forwardly, the bulldozer blade being attached to the leading ends of frame members (15A, 15B) which are pivotally mounted on opposite sides of the vehicle body (20a) in such a manner that the bulldozer blade can swing longitudinally.

Abstract: A device and method for automatically vibrating the working members of a power construction vehicle such as a power excavator is disclosed. The device and method effectively change both the amplitude of vibration and the number of vibrations of a working member in proportion to a levering angle of an associated control lever during an excavating, breaking or ground hardening operation of a construction vehicle. The automatic vibration device is thus free from any select switch. The device simplifies the construction of the hydraulic system and more easily controls the automatic vibration operations, and thereby is convenient to operators.

Abstract: The present invention is directed toward estimating certain operating parameters of an earth moving machine. Advantageously, the present invention utilizes a Kalman filter to estimate the pitch, pitch rate and ground speed of the earth moving machine as a function of the sensed pitch and ground speed signals. By estimating the pitch and ground speed, the present invention overcomes the prior problems of sensing signal noise and bias. The present invention overcomes these problems by combining pitch, pitch rate and ground speed, and determining an estimate of pitch and ground speed by using a sensor measurement model, machine process model and Kalman filter update equations.

Abstract: A control apparatus for use with two opposed ground markers of an agricultural machine comprises a hydraulic circuit including a plurality of hydraulic valves for communicating fluid actuate movements of the marker cylinders and an electrical control system including a plurality of manually operable actuating switches to effect operation of said hydraulic valves. Each of the switches provides an output in response to a single actuation thereof and there is provided an output timer operable to effect operation of the hydraulic valves for a period of time sufficient to effect a stroke of the cylinders. The electrical control system provides an output in response to actuation of selected ones of the switches only in response to actuation of the switch for a predetermined time period sufficient to avoid inadvertent actuation.

Abstract: The finishing precision and uniformity of hardness of a surface finished by a construction machine, such as back-hoe, is improved by modifying the targets of a position-tracking control system based on work-load applied to the end effector of the construction machine. For example, compaction of a surface, contoured by a position-tracking, back-hoe, can be made more uniform. This is accomplished by adjusting actuator targets, otherwise controlled on the basis of positional and speed constraints, in response to a detected work load acting on the end effector. To detect work load, a hydraulic fluid pressure signal can be applied to a computer which generates target position and speed commands to the feedback system. The control circuit may be arranged to hold work load constant (generating a constant compaction force for example) or, in response to a priority signal, the circuit can give a selected weight to both the positional constraints and the work load constraints.

Abstract: A device for controlling a pushable implement provided with at least one gauge wheel. The device includes a hitch system comprising two lower longitudinal arms (5, 6) with a tool-engaging member (9) at the front ends thereof, an upper engagement assembly (C) joining a third point of engagement (17) to the implement (3), at least one lifting jack (12, 13), and a distribution unit (21) for controlling the raising and lowering of the longitudinal arms (5, 6). A controller (28) operates the distribution unit in response to a degree of slippage measured by a unit (M). The upper engagement assembly (C) includes at least one third-point jack (18; 18a, 18b) connected to a second fluid distribution unit (30, 30') controlled by said controller (28) so that when the longitudinal arms (5, 6) are raised, the second distribution unit (30, 30') switches to a position in which part of the load is shifted onto the tractor as the lower longitudinal arms are raised.

Abstract: A system or method for controlling the position of an implement coupled to a work vehicle. The implement is moveable by a hydraulic positioning assembly including an actuator and a valve assembly which control the flow of fluid to the actuator in response to control signals. The valve assembly includes raise and lower valves, each valve requiring a control signal equal to a threshold value before the valve opens and fluid begins to flow. The system includes a sensor to detect the position of the implement and a control circuit. In response to a change in a position command, the control circuit applies a control signal to the appropriate raise or lower valve based upon the respective threshold value. The control signal may include a component for moving the implement at a desired rate of movement. After undesirable implement movement is detected, the control circuit modifies the threshold value.

Abstract: A hydraulic drive system for the pitch cylinders (4A, 4B) of a bulldozer blade apparatus can include (a) main hydraulic pumps (30A, 30B) and an assistant hydraulic pump (31) to make up the assistant hydraulic circuit, (b) variable displacement hydraulic pumps (21A, 21B), or (c) fixed displacement hydraulic pumps (30A, 30B) and a plurality of solenoid selector valves such that the pitch cylinders can be connected in series. The assistant hydraulic pump (31) is connectable to delivery lines of the main hydraulic pumps through an assistant solenoid selector valve (32) which is controlled by an external signal. The blade (10) can be formed so that a line (14) tangential to the lower edge of the curved panel of the blade is inclined rearwardly with respect to the front face (13) of the blade edge member (12). Earth-moving work can be performed by inclining the blade (10) rearwardly by an angle (.theta..sub.

Abstract: A control mechanism for an aerator mechanism, the control mechanism being coupled with the engine for automatically slowing the engine when the aerator mechanism is shifted between transport and operating positions. The engine control mechanism includes a solenoid coupled with an operator engagable position control mechanism and an arm of an engine governor such that the governor will slow the engine when the position control mechanism is engaged to shift the aerator mechanism between transport and operating positions.

Abstract: A control system is disclosed that controls the position of a grading implement of a construction machine according to a site plan. The control system has three basic components: a stationary tracking station, a computer connected to the tracking station, and an implement controller attached to the construction machine. The tracking station measures a distance and an azimuth (horizontal) angle to a remote target located on the construction machine and communicates that position information to the computer. The computer consults a stored site plan to determine what elevation is desired at that position and calculates a corresponding zenith (vertical) angle, and communicates the desired zenith angle to the tracking station. The tracking station in turn positions a zenith-reference laser beam at the desired zenith angle. The implement controller senses the zenith-reference laser beam and adjusts the grading implement relative to the zenith-reference laser beam until its desired position is obtained.

Abstract: A system and process for controlling an excavation implement during excavation between an above-ground position and a below-ground position. The excavation implement is actuated by use of the engine operating at a target output level. A computer controls the rate at which the excavation implement is moved in a generally vertical direction while excavating earth between the above-ground and below-ground positions. A sensor senses a performance parameter indicative of either engine performance or excavation implement performance as the excavation implement progresses through the earth. The computer modifies actuation of the excavation implement in response to the sensed performance parameter to maintain the engine at the target output level when the engine is subject to variations in loading as the excavation implement moves between the above-ground and below-ground positions.

Abstract: A system for regulating wheel slippage of a vehicle carrying or trailing an implement. The system includes sensors for sensing the vehicle's apparent speed and ground speed and an input device. The system also includes a control circuit configured to generate a slip signal based at least upon the apparent speed and the ground speed, and to generate a control signal applied to an actuator for moving the implement. The input device can be manipulated to enable and disable slip regulation and to set a slip reference value. The input device can be manipulated to derive the slip reference value from the slip signal, and to increment and decrement the slip reference value. The control circuit regulates wheel slippage by modifying the control signal when the slip signal exceeds the slip reference value with slip regulation enabled.

Abstract: An area where a front device 1A is movable is set in advance. A target speed vector of the front device is modified such that its component in the direction toward a boundary of the set area is reduced, by using signals obtained by reducing operation signals input from control lever units 4a-4c when a mode switch 20 is turned on and the front device is within and near the boundary of the set area, and by using the operation signals as they are when the mode switch 20 is turned off. When the front device is outside the set area, the target speed vector is modified so that the front device is returned to the set area. Thus, excavation within a limited area can be performed efficiently and smoothly, and an operator can select one of an accuracy precedence work mode and a speed precedence work mode at his own discretion.

Abstract: A power attachment is attachable to a power machine which has a power circuit. The power machine also includes an operator input device receiving an operator input and providing an output signal indicative of the operator input. The attachment includes a tool and an actuator, coupled to the tool, to drive the tool. The actuator is also connectable to the power circuit of the power machine. A controller is operably coupled to the actuator and is operably coupleable to the operator input device. The controller controls operation of the tool based on an operator input signal provided by the operator input device.

Abstract: A running slip control system for a bulldozer, comprising: (a) a running slip detector for detecting the running slip of a vehicle body; and (b) a blade controller for lifting a blade to eliminate the running slip when the running slip detector detects the occurrence of running slip.

Abstract: A blade control system for a bulldozer, comprising: (a) a pitch angle detector for detecting a pitch angle of a vehicle body when the vehicle body inclines back and forth; (b) an actual tractive force detector for detecting an actual tractive force of the vehicle body; and (c) a controller for correcting the actual tractive force detected by the actual tractive force detector according to the pitch angle detected by the pitch angle detector and for controlling the blade to be lifted or lowered such that the corrected actual tractive force becomes equal to a target tractive force.

Abstract: An apparatus controls the movement of a ripper for a machine. Tilt and lift cylinders controllably actuate the ripper. Hydraulic control valves control the flow of hydraulic fluid to the respective cylinder. An auto-return button produces an auto-return signal in response to being depressed by the machine operator. A controller receives the auto-return signal and delivers a ripper control signal to the hydraulic control valves to automatically raise the ripper to a predetermined position.

Abstract: A control system for regulating the elevational position of an implement carried or trailed by a vehicle, such as a tractor, includes draft force sensors for detecting the draft force produced by interaction of the implement with the ground, and a command device for setting a reference level of draft force. A control circuit coupled to the sensors and to the command device generates a draft force error signal representing the deviation of the sensed draft force from the desired level, and a draft force derivative signal representing the rate of change of the sensed draft force. The control circuit generates control signals for raising and lowering the implement following a predetermined control routine in response at least to the draft error signals. The rate of movement of the implement in response to the control signals is limited in response to the draft force error signal and the draft derivative signal.

Abstract: A remotely guided brush cutting, chipping and clearing apparatus, dependent upon remote positioning data and radio communication signals, having an apparatus locator system for determining the location of the apparatus and a guidance system for achieving and maintaining the desired direction of travel for the apparatus, relative to the surface of the earth and method for guiding the apparatus.

Abstract: A hydraulic drive system for the pitch cylinders (4A, 4B) of a bulldozer blade apparatus can include (a) main hydraulic pumps (30A, 30B) and an assistant hydraulic pump (31) to make up the assistant hydraulic circuit, (b) variable displacement hydraulic pumps (21A, 21B), or (c) fixed displacement hydraulic pumps (30A, 30B) and a plurality of solenoid selector valves such that the pitch cylinders can be connected in series. The assistant hydraulic pump (31) is connectable to delivery lines of the main hydraulic pumps through an assistant solenoid selector valve (32) which is controlled by an external signal. The blade (10) can be formed so that a line (14) tangential to the lower edge of the curved panel of the blade is inclined rearwardly with respect to the front face (13) of the blade edge member (12). Earth-moving work can be performed by inclining the blade (10) rearwardly by an angle (.theta..sub.

Abstract: The MFD kickout switch controls the drive system on a tractor's front wheels in response to the controlled movement of a three point hitch. Tractors which are equipped with a system that disengages the front drive wheels when a tighter turning radius is needed can utilize the kickout switch to automatically disengage the front wheel drive when an associated three point hitch is raised.

Abstract: An apparatus and method for controlling a hydraulically operated construction machine, having a plurality of tandem articulated members which are controlled in a manner that movement of one of the members is controlled in response to movement of another of the members, in order to move the members in a predetermined pattern. The members are controlled in response to the anticipated future movement of the another member. Anticipated future movement of the another member may be determined, for example, as a function of the present position and velocity of the another member and system delay in movement of the another member. Where the another member is controlled manually by an operator control lever coupled with a manual hydraulic control valve, anticipated future movement may be determined by monitoring actuation of the control lever.

Abstract: Apparatus and method for automatically controlling the position of an earthmoving implement of an earthmoving machine in response to varying ground profiles.

Abstract: A control system controls a plurality of control devices (such as a four wheel drive control valve, a differential lock control valve and a PTO control valve) of a work vehicle having an implement hitch coupled to a hitch actuator which is controlled by a hitch control unit. The control system has operating switches for adjusting the operation modes of the control devices and the hitch actuator. The control unit also has means for activating and deactivating an automatic mode for the control devices in response to manipulation of a first switch and means for activating the automatic mode upon a manual operation signal delivered to the hitch control unit to change the operation modes of the functions of the control devices. The control system includes an automatic switch which is manipulatable independent from the other switches. A sensor senses the position of the hitch.

Abstract: A device for improving the workability and drivability of a tracked vehicle whose blade height is automatically controlled, in which when changeover of a speed step from reverse to forward is detected by a transmission lever position detector (3), a controller (15) controls to raise or lower the blade (8) to a target value which is the height of the blade (8) initially set by an initial height setter (4). With a blade raising lever (1) operated, the blade (8) is controlled to rise or lower in proportion to the height of the blade during manual operation. The height is detected by a blade-height detector (14) and the blade is controlled to rise or lower to a target value which is the detected value of height.

Abstract: In one aspect of the present invention, an automatic control system for loading a bucket of a wheel loader is disclosed. The system includes a pressure sensor that produces pressure signals in response to the hydraulic pressures associated with one of the lift and tilt cylinders. A microprocessor receives the pressure signals, compares at least one of the pressure signals to a predetermined one of a plurality of pressure setpoints, and produces lift and tilt command signals in response to the pressure comparisons. Finally, an electrohydraulic system receives the lift command signals and controllably extends the lift cylinder to raise the bucket through the material, and receives the tilt command signals and controllably extends the tilt cylinder to tilt the bucket to capture the material.

Abstract: A steering system for a bulldozer, comprising a steering direction indicating device for indicating a lateral direction in which a vehicle body is to be steered, a dozing operation detector for judging by detection whether the bulldozer is in dozing operation, a steering controller for controlling the vehicle body to be steered in the lateral direction indicated by the steering direction indicating device when the dozing operation detector judges that the bulldozer is in dozing operation, by tilting a blade in the indicated lateral direction in order to impose offset load on the vehicle body, and by causing a difference between the relative travel speeds of right and left crawler belts attached to the vehicle body at least when light load occurs in the dozing operation.

Abstract: When a prime mover (1) is driven, a controller (25) outputs an open-drive signal for bringing an opening/shutting valve (23) into an open position and, upon a control lever (68, etc.) being operated, a hydraulic fluid is supplied from an auxiliary hydraulic pump (7) through pressure reducing valves to driving sectors of directional control valves (8 to 16) for shifting them. A flow rate and a direction of flow of the hydraulic fluid from main hydraulic pumps (3, 4) are thereby adjusted so that actuators (57A, 57B, 57C, 56A, 54) can be each operated at a speed depending on the amount by which the control lever is operated. When one of the actuators (57A, 57B, 57C, 56A, 54) is to be driven when the prime mover (1) is not driven, an open command is selected in a selection command device (24), whereupon the controller (25) outputs the open-drive signal, causing the opening/shutting valve (23) to open a line interconnecting the accumulator (21) and the pressure reducing valve (17), etc.

Abstract: An apparatus for generating a signal indicative of the hardness of soil. The apparatus has a frame to be moved relative to soil on which a hardness analysis is to be conducted and a sensing element mounted to the frame so that the sensing element engages soil relative to which the frame is moved and structure associated therewith generates a) a first signal as the sensing element encounters soil of a first hardness and b) a second signal as the sensing element encounters soil of a second hardness.

Abstract: A hitch assembly control system is provided in which signals representative of battery voltage are used to generate a correction factor that is applied to control signals to a hitch actuator circuit to improve consistency in control. In an alternative embodiment, a correction factor is generated from signals representative of electrical parameters of solenoid coils included in the actuator circuit and this correction factor is applied to control signals to the actuator circuit. Also provided is a calibration method for a vehicle control system in which certain physical and electrical parameters of the vehicle and the control system are measured and stored during a calibration sequence for later use in the control of an implement coupled to an attachment member of the vehicle. A control method for a vehicle is also provided in which correction factors are generated from measurements of battery voltage or a solenoid coil parameter, and applied to control signals generated by a control circuit.

Abstract: A hydraulic excavator adapted to be changed over simply to a fine operation mode so as to control the capacity of a hydraulic pump through load-sensing control to thereby make it possible to perform accurate work when the machine needs to be finely operated temporarily for operations such as ground levelling, and position adjustment on a dump vessel, wherein the fine operation mode is easily cleared to switch the excavator to a standard mode to thereby improve operability, as well as work efficiency. When the excavator is switched to the fine operation mode so as to control the capacity of the hydraulic pump through load-sensing control for accurate work, the engine is driven at such a torque and engine revolution as permitting a minimum fuel consumption, thus reducing the fuel consumption of the engine.

Abstract: An automatic drive control system for a bulldozer comprising a digging start detector for detecting that the bulldozer is in a digging start position, a digging end detector for detecting that the bulldozer is in a digging end position, a driving direction detector for detecting the momentarily varying driving direction of the bulldozer, and a drive controller for shifting a transmission into a forward gear when the digging start detector detects that the bulldozer is presently in the digging start position; shifting the transmission into a reverse gear when the digging end detector detects that the bulldozer is presently in the digging end position; and controlling the bulldozer such that the driving direction detected by the driving direction detector is made coincident with a target driving direction when the bulldozer is moving from the digging start position towards the digging end position.

Abstract: An off-highway vehicle having an earth moving implement has a tilt function associated with the implement. For example, a bulldozer has a tilt function associated with the bulldozer blade. The vehicle has a processor adapted to receive a position signal from a position sensor associated with the tilt function of the implement. The operator engages a switch to activate an automatic tilt function. A selector switch is provided so that the operator can select between a plurality of pre-set blade angles. The selector switch outputs a target position signal associated with a pre-set angle to the processor. The processor automatically calculates a command signal for the tilt function based on the difference between the position signal and the target position signal. The processor issues the command signal to the tilt function causing the tilt function to move the implement to the pre-set angle associated with the switch position.

Abstract: An infrared remote-controlled soil compacting device is controlled such that the device cannot be set into operation as long as the operator with the sending unit is within close vicinity of the soil compacting device so that an accidental operation or propelling in the wrong direction is prevented. This is achieved by providing an infrared close range radiation in addition to the infrared control radiation required for the operational control of the device. The close range radiation has a substantially reduced intensity relative to the control radiation so that the close range radiation can be received within the receiving unit only within close vicinity of the sending unit. When the close range radiation is received within the receiving unit the generation or release of electric signals affecting propelling of the soil compacting device is suppressed.

Abstract: Even when a bucket is changed to an optional special bucket, path control as intended by an operator can be automatically performed without making a correction of the angle of the original bucket. For this purpose, in an operation mode determining section (9), there is calculated the possibility (U2) of an operation mode being a nose-fixed mode, depending on how much a bucket attitude angle (.gamma.) deviates from a predetermined angle, and there is also calculated the possibility (U1) of the operation mode being the fixed-angle to the ground mode, depending on the magnitude of a computed value of the allowable angle held with respect to the ground, whereby the operation mode during the automatic path control can be automatically determined by comparing these possibilities (U1, U2).

Abstract: The present invention relates to a method for automatically controlling the speed ratio of swing and boom operation of the excavator, which makes the operator perform the dig-up task in a easy and precise manner by adapting an electronic control using micro-module and sensors and so forth. The controlling method according to the present invention utilizes the angular velocity for the swing and the boom operation which is dependent on the position of the truck and is preset by the operator in the input/output board of the controller. When the dig-up task is performed, the operator will operate the joy sticks for the swing and the boom as much as possible and the controller enables the swing operation to move to the desired position without dropping a lump of earth. Again, when the operator operates the joy sticks for the dipper and the bucket in the same manner, the dipper and the bucket will move to the position in which the truck is placed.

Abstract: A one-way pressure bleed off path is provided between the series cylinder depth control circuit and an additional hydraulic circuit for an agricultural implement to prevent pressure build-up and hose expansion that otherwise would cause uneven series cylinder extension and uneven implement depth. A line including an orifice and a one-way check valve is added between the depth control circuit and the second circuit, such as the wing fold circuit for the implement, to bleed off any series cylinder pressure build-up through the otherwise unused second circuit. The orifice limits the amount of oil that is returned to reservoir during operation of the series circuit to lower the implement. The check valve isolates the depth control circuit and the second circuit to prevent unwanted cylinder operation while the wings are being folded.

Abstract: A device for controlling the height of a blade of a tracked vehicle includes a blade height position detector, a blade height controller for raising and lowering the blade, and a device for setting an initial height of the blade. When the transmission of the vehicle is shifted from the reverse to the forward position, the height of the blade is lowered to the target value. A switch selects between the target value set by the initial height setting device and a manually selected height depending whether or not the switching device selects the automatic operation or manual operation of the blade height controller.

Abstract: An hydraulic elevating mechanism for lifting and lowering an engineering structure which is sluingly supported around a rotational axis on a base unit, has two or more hydraulic lift cylinders pivoted to the base unit at one end and to the engineering structure to be slued at the other. The lift cylinders are controlled by hydraulic control circuits separated from each other and such that at least one of the lift cylinders is connected to a pressure reservoir.