Abstract: An improved accuracy is ensured for the calculation of the travel distance of a bulldozer by obtaining the accurate vehicle speed and travel direction of the bulldozer. To this end, arrangement is made such that a check is made to determine whether actual tractive force F exerted on the blade exceeds a predetermined shoe slip threshold value F.sub.0 ; switching between vehicle speed detectors (between a Doppler sensor and Sprocket rotating speed detector) is made according to the determination so that suitable one of the vehicle speed detectors detects the vehicle speed of the bulldozer; and the vehicle speed detected by the selected vehicle speed detector is integrated, whereby the travel distance of the bulldozer is calculated.

Abstract: A sectional rate control unit for an agricultural implement is disclosed herein. The sectional rate control unit is preferably used with a planting system including a planting implement coupled to a work vehicle. The implement includes a frame having at least one section supporting multiple row units which are configured to apply a product (e.g., seed, fertilizer, insecticide, herbicide) to the rows in a field. Each section includes a product delivery apparatus having a target delivery rate controlled by a section application control signal and at least one product channel for delivering an amount of the product to each of the row units. The control unit includes an electronic product sensor coupled to each of the sections and the product channel. The product sensor is configured to generate a product rate signal representative of the amount of the product delivered to the row units. An electronic display located in the cab is configured to generate an image in response to a display signal.

Abstract: Smooth, effective dumping is achieved by automating. A switching point, at which a carrying mode is switched to a dumping mode during automatic driving in a dozing operation, is set beforehand. A dumping attitude of the blade is also preset for a desired traveling distance of the bulldozer from the switching point to a dumping point. The actual traveling distance of the bulldozer from the switching point is detected, based on which the blade is controlled so as to take the preset attitude.

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 system for controlling wheel slippage of a vehicle carrying or trailing an implement when slip above a slip limit is detected. 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 a first sensor for sensing an operating parameter such as draft force or implement position, a second sensor for sensing the vehicle's apparent speed, and a third sensor for sensing the vehicle's ground speed. The system may include a fourth sensor for sensing a second operating parameter. The system also includes a control circuit configured to generate a slip signal based upon the apparent speed and the ground speed, and to operate in a first manner when the slip signal is below a slip limit and in a second manner when the slip signal is above the slip limit.

Abstract: A tractor electronic linkage control system comprises electronic draft force and linkage position sensors (30, 33) and manual draft force and linkage position controls (31, 32). An electronic control unit 17 derives draft and position error signals and continually compares them to determine whether the system is to operate in draft control mode, where the draft error signal governs linkage movement, or position control mode, where the position error signal governs linkage movement.

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 ground leveling control system for a bulldozer, comprising: (a) a cutting edge position detector for detecting a position of a cutting edge of a blade with respect to the ground; and (b) a blade controller for controlling the blade to be lifted or lowered such that the cutting edge position of the blade detected by the cutting edge position detector is kept coincident with a preset target cutting edge position.

Abstract: A dozing system for use in a bulldozer, having the capability of estimating a loading ratio (the ratio of soil loaded on the blade to the loading capacity of the blade) with high accuracy so that a mode shift from digging to carrying can be stably performed. Data pieces each representing the digging distance of the bulldozer and the associated loading ratio are obtained from n previous dozing operations and stored. The average of the stored data pieces obtained from n operations is calculated and according to the average, data representative of a digging distance and its associated loading ratio obtained from the present dozing operation is compensated.

Abstract: A control system for engaging, disengaging and re-engaging a front wheel drive in an agricultural vehicle includes a control circuit configured to receive signals representative of vehicle operating parameters and to generate control signals corresponding to the desired state (i.e. engaged or disengaged) of a front wheel drive engagement circuit. Sensors are associated with the rear wheels, rear service brakes, implement positioning circuit, the vehicle body and the front axle to provide parameter signals related to wheel speed, braking, implement position and vehicle speed. Control logic executed by the control circuit in a continuously cycled routine determines the desired state of the engagement circuit based upon all operating parameters. The control circuit applies an appropriate control signal to the engagement circuit causing engagement or disengagement in accordance with the desired state.

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: 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: A draft control mechanism for a tractor having a three-point hitch for attachment of a ground-engaging implement. The draft control mechanism utilizes an upper link arm connected to the tractor with a single load pin which houses a strain sensor for generating the control signals to control a lift mechanism connected to the implement. The pin is attached between two flanges of an upper link bracket to the rear of the tractor. Each flange includes a bushing surrounding the portion of the pin disposed therein. The pin includes a pin extension protruding from the outer side of one of the bracket flanges. A sealing cover is disposed over the pin extension with a rotation stop to restrict pin rotation.

Abstract: A method is provided for controlling the bounce of a work implement attached to a machine having an electro-hydraulic system. The method comprises the steps of sensing the operating pressure in an actuator arrangement connected between the frame of the machine and the work implement, monitoring an upper and a lower operating pressure level in the actuator arrangement to establish a threshold pressure level and altering the pressure level in the actuator arrangement in the event the threshold level is exceeded to re-establish the threshold pressure level. Once the original threshold level is attained, the system is reset. This effectively eliminates the bounce of the work implement at the initial onset of the bounce and resets the system to react to future bounces.

Abstract: A dozing system for a bulldozer with which dozing can be carried out by a simple operation without giving a great deal of fatigue to the operator.When the running slip of a vehicle body is not detected by a running slip detector, a blade is lifted or lowered by a comparison controller such that an actual tractive force of the vehicle body detected by an actual tractive force detector becomes coincident with a target tractive force set by e.g., a dial, whereby the amount of loads applied to the blade by excavating and moving earth can be maintained constant. On the other hand, when the running slip of the vehicle body is detected by the running slip detector, the comparison controller lifts the blade, thereby reducing the amount of loads applied to the blade by excavating and moving earth in order to eliminate the running slip.

Abstract: An arrangement for sensing the draft force on a linkage such as a tractor three-point linkage comprises a backplate (12) with flexible webs (16) extending from it.Depending from the webs (16) are spurs (18) which, at their lower end, join each other and form a rearwardly extending member (24). A bore (15) extends through the backplate (12) and rearwardly extending member (24), in which a force sensing pin (30) is received. The bracket may be made from a single casting.

Abstract: A load control unit for a bulldozer, comprising an actual tractive force detector for detecting the actual tractive force of a vehicle body; target tractive force setting switch for setting a target tractive force for an automatic blade control mode in dozing operation; and blade controller for controlling a blade to be lifted or lowered such that if there is a difference between the actual tractive force detected by the actual tractive force detector and the target tractive force set by the target tractive force setting switch when digging is started with the automatic blade control mode in dozing operation, the actual tractive force gradually comes closer to the target tractive force.

Abstract: A dozing control unit for a bulldozer, comprising an actual tractive force detector for detecting the actual tractive force of a vehicle body; a driving mode selector button capable of switching a manual operation mode to an automatic driving mode in dozing operation; and a blade controller for controlling a blade to be lifted or lowered such that if there is a difference between the actual tractive force detected by the actual tractive force detector and a target tractive force set for the automatic driving mode when the manual operation mode is switched to the automatic driving mode by the driving mode selector button, the actual tractive force gradually comes closer to the target tractive force.

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: A straight-ahead traveling control system for a bulldozer comprising: (a) a driving mode setting device which can set an automatic blade control mode for dozing operation; (b) a yaw angle detector for detecting the yaw angle of a vehicle body in relation to a target traveling direction for the vehicle body; (c) a blade tilt angle detector for detecting the tilt angle of the blade tilting laterally in relation to the ground; and (d) a blade controller for controlling tilting of the blade based on a first blade tilting amount used for driving the vehicle body straight ahead and a second blade tilting amount used for forming a laterally horizontal earth surface after digging by the blade, the first blade tilting amount being obtained from the yaw angle of the vehicle body detected by the yaw angle detector and the second blade tilting amount being obtained from the tilt angle of the blade detected by the blade tilt angle detector, when the driving mode setting device has set the automatic blade control mode.

Abstract: A dozing system for a bulldozer, comprising an actual tractive force detector for detecting an actual tractive force of a vehicle body; a target tractive force setting device for setting a target tractive force for a vehicle body; a tractive force deviation calculator for calculating the deviation between the actual tractive force detected by the actual tractive force detector and the target tractive force set by the target tractive force setting device; and a comparison control unit for controlling a blade to be lifted or lowered such that the absolute value of the deviation is increased, when at least the absolute value of the deviation is less than a preset value and tile actual tractive force is approaching the target tractive force.

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: An implement control system includes desired draft force setting apparatus and draft force sensing apparatus providing a draft force signal. It also includes engine speed sensing apparatus arranged to provide an engine speed signal of the same form as the draft force signal. The draft force signal and engine speed signal are averaged and compared with the set desired draft force to produce an error signal which is used to control the movement of the implement. The system is particularly suitable for the control of engine driven implements such as stone-breakers and rotivators where it prevents the engine stalling under heavy load, it is, however, suitable for use with fully-mounted, semi-mounted and trailed implements.

Abstract: A control system for controlling a hydraulically operable link mechanism mounted on a working vehicle. The link mechanism includes lift arms, a hydraulic actuator for controlling the lift arms, a first and a second lower links each connected at one end thereof to a working implement, and connecting rods interconnecting the lift arms and the first and second lower links, respectively. The control system includes a first coupling for pivotally connecting the first lower link to one side of a vehicle body, a second coupling for pivotally connecting the second lower link to the other side of the vehicle body, strain gauges provided for the first and second couplings, respectively, and a control device for controlling the actuator based on detection signals received from the strain gauges.

Abstract: An apparatus is provided for determining the location of a digging implement at a work site. The apparatus includes an undercarriage, a car body rotatably connected to the undercarriage, a receiver connected to the car body, a positioning system for determining the location of the receiver in three dimensional space, the positioning system determining the location of the receiver at a plurality of points along an arc, and a processor for determining the location and orientation of the car body in response to the location of the plurality of points.

Abstract: A hitch assembly control system including an actuator which positions the hitch assembly in response to control signals provided to an electrically driven actuator. The control system further includes an electronic controller operated under the influence of a program for deriving the control signals for the actuator from a series of inputs which monitor and measure various performance criteria. The program functions to operate the hitch assembly in a plurality of different operating states. In a DRAFT state, the hitch assembly position is controlled under the influence of at least four independently set variables. The control system of the present invention is capable of calibrating the hitch assembly configuration as well, as the limits of hitch assembly operation. Moreover, the control system of the present invention is capable of detecting, categorizing and recording failures which occur in the various states of hitch assembly operation.

Abstract: The present invention relates to a method for controlling a power output of an engine of a crawler vehicle; such as, large sized bulldozers, at a time when shoe slip of such crawler vehicle occurs in operation, the crawler vehicle being provided with working equipments; such as, dozing units or blades, ripping units or rippers or the like. More particularly, the present invention relates to an adaptive engine power output mode setting method for automatically keeping the engine of the crawler vehicle in an optimum power output condition according to rates of the shoe slip or shoe slip rates of the crawler vehicle.

Abstract: In an automatic draft control system for positioning a hitch, velocity feedback loop techniques are employed to control the rate of movement of the hitch. When the system is operating in an open loop position control mode, a switch mounted on a tractor fender enables an operator to manually control raising/lowering of the hitch for the purpose of attaching an implement. Hitch position is sensed and a microprocessor calculates the first derivative of the hitch position signal to determine actual hitch velocity. The actual velocity is subtracted from a desired velocity value to obtain a velocity error signal. The error signal is subjected to an integral control algorithm and the integrated value is used to energize raise or lower solenoids controlling a valve which raises or lowers the hitch. When the actual hitch velocity is equal to or greater than the desired hitch velocity, the integrated value is saved. When the next raise/lower sequence is initiated the integrator is reset to the saved value.

Abstract: In an automatic hitch control system wherein a hitch is raised or lowered in response to operation of a valve, and the valve is controlled by solenoids which are selectively energized by connecting them to ground through switch drivers, a safety disconnect relay is provided for preventing uncommanded motion of the hitch such as might occur if the lead between a solenoid and its driver should be grounded or if the driver should fail in an "on" state. The relay has contacts connected between the solenoids and the positive voltage for operating them. A microprocessor senses hitch position, the position of a quadrant lever and the speed of the tractor carrying the hitch. From the conditions sensed, the microprocessor determines if the tractor is moving, if the hitch is captured, if the hitch is moving and whether the hitch control system is in an open-loop control mode in which manual switches may be used to control hitch movement.

Abstract: An automatic draft control for controlling the position of a tractor-mounted hitch includes a slip override circuit responsive to a wheel signal for modifying a hitch position command so that hitch draft is reduced by raising the hitch when the degree of tractor wheel slip exceeds a threshold value. The slip is determined by measuring theoretical (no-slip) ground speed with a sensor which senses the rate of rotation of the tractor rear axle, and measuring true ground speed with a radar unit mounted on one side of the tractor. Because the radar unit does not indicate the speed of the center line of the tractor as it turns, the slip signal is prevented from modifying the hitch position command if the hitch is raised since the hitch is usually raised when turning and there is no need to modify the position command with the slip signal when the hitch is raised.

Abstract: The device is mounted in an agricultural machine comprising two links for drawing an implement, a lifter member and a central control unit for controlling the member. The device comprises: two horizontal bars carried in the form of brackets from the chassis of the machine; and four resistive elements deposited on flat faces of the bars symmetrically with respect to a neutral axis defined in this latter, made of a material having an electrical resistance proportional to the deformations to which they are subject and connected in a Wheatstone bridge circuit in such a way such that this arrangement generates an electrical signal proportional to the imbalance of the bridge caused by the deformations to which the elements are subjected, and which are transmitted from the traction force on the implement.

Abstract: A towed implement with an implement cylinder may be coupled to the hitch of a tractor which includes a hydraulic pump, a hydraulic sump, a rockshaft cylinder for raising and lowering the hitch, a hitch control valve for controlling fluid flow to the rockshaft cylinder, a control unit for controlling the hitch control valve as a function of a sensed parameter signal and an operator generated command signal. A two-position, four-way selector valve selectively connects the hitch control valve to the implement cylinder and operates to automatically raise the hitch to its top position when the selector valve connects the hitch control valve to the implement cylinder. A manually operated four position, four-way selective control valve is connected between the selector valve and the implement cylinder and a towed implement position sensor is connected to the electronic control unit of the tractor hitch control system.

Abstract: A tractor-mounted three-point hitch for pulling a tillage implement is controlled by a closed loop including draft sensors for sensing the draft on the hitch and providing a draft feedback signal. An operator-controlled quadrant lever provides command signals for commanding the positioning of the hitch relative to the ground. During rapid hitch movement commanded by movement of the quadrant lever while the implement is above the ground, the draft feedback signal, which is normally filtered to eliminate frequencies above about 3.2 Hz, is more heavily filtered to eliminate frequencies above 0.5 Hz. This makes the loop less sensitive to the draft feedback signal and reduces vibrations which would otherwise occur because of oscillations in the draft feedback signal. The oscillations are caused by interaction of the weight of the implement bouncing because of the pneumatic tires on the tractor, and movement of the hitch to correct for the apparent change in draft.

Abstract: A control device controls the draft for moving the working machine, such as a plow, up or down. The working machine is mounted on a tractor by way of a hydraulic lifting device which is adjusted to the tilling depth predetermined by a tilling depth setter which depends on the increase or decrease of traction resistance detected by a draft sensor. When the lifting machine is changed from the ascending position to the descending position, the draft control function is stopped for a specified short time or a specified short distance to lower the working machine quickly. However, the quick lowering of the working machine is inhibited when the relationship between the detected value by the draft sensor and the preset value by the tilling depth setter is not at the descending position of the working machine.

Abstract: A draft force sensor includes a bendable shaft which extends laterally though a pair of spaced apart supports. Draft links are coupled to the ends of the shaft. A curved flexible strap is positioned between the supports and has its ends coupled to the shaft by adjustable support brackets. In a no-load condition the strap is concave in a direction facing the shaft. A displacement transducer, such as a rectilinear potentiometer, linear variable transformer or other electrical device which is sensitive to displacement, is mounted between the shaft and the central portion of the strap. The displacement transducer senses the change of distance from the shaft to the "arch" of the strap and generates an electrical signal indicative of the forces on the shaft. The load from the draft links is applied to the ends of the shaft, causing it to bend and causing the strap to flex in the opposite direction. Thus, the shaft and strap act as a mechanical amplifier.

Abstract: An articulated tractor has left and right laterally spaced apart, fore-and-aft extending side frame members which are rigidly attached between front and rear drawbar supports. The tractor also includes left and right draft links, each draft link having a front end coupled to a corresponding one of the side frame members and a rear end for coupling to an implement. A draft force sensing mechanism includes a displacement transducer mounted on one of the side frame members. A lever is pivotally mounted near the transducer and carries a plunger or shaft which operatively engages the transducer. A rod has a first end fixed to the other side frame member and a second end coupled to the lever so that changes in draft force cause deflection of the side frame members and movement of the lever relative to the transducer. The transducer responds by generating a signal representing the draft force. Movement of the rod is amplified by the lever.

Abstract: A microprocessor-based control system includes an automatic calibration and configuration feature. A calibration and configuration algorithm operates to establish the sensor ranges of all sensors installed and disables certain configurable features if the associated sensors are not present. The algorithm also provides a functional test of the control system during the calibration process.

Abstract: A force sensor has a hollow flexible body with a fixed end and a free end. The force to be measured is applied perpendicular to the axis of the flexible body by a link coupled to the free end. A rigid gauge rod is connected to the free end of the flexible body and extends through the interior of the flexible body. The rod carries on its free end a permanent magnet which is near a Hall-effect sensor which is fixed to the fixed end of the body. The flexible body has a relatively low bending stiffness at its free end (in the area of force application) and an increasing bending stiffness towards its fixed end. The flexible body has a relatively low bending stiffness in the direction of force application and a higher bending stiffness in a perpendicular direction. The permanent magnet is arranged so that its poles are aligned parallel to the direction of force application.

Abstract: A hitch control system includes various sensors, an operator command lever, a spring-centered three position raise/lower switch, a control unit which generates control signals as a function thereof and an actuator which moves the hitch in response to the control signals. The control system permits the operator to move the hitch to a working position via manipulation of the command and a single manipulation of the raise/lower switch. The control system ignores switch manipulation unless the manipulation persists for at least a certain time period, or if the switch is manipulated in a different manner within a certain time of the earlier manipulation. In a failure mode the control system permits the hitch to be moved to a working position via manipulation of the raise/lower switch when the command lever cannot be so used.

Abstract: A microprocessor-based control system includes an automatic calibration and configuration feature. A calibration and configuration algorithm operates to establish the sensor ranges of all sensors installed and disables certain configurable features if the associated sensors are not present. The algorithm also provides a functional test of the control system during the calibration process.

Abstract: A hydraulic control apparatus for a tractor comprising a control valve for a hydraulic unit for a work device, a position control lever and a draft control lever for changing over the valve through position and draft link assemblies, a position feedback assembly, a draft feedback assembly for switching the valve to maintain the draft on the work device at an approximately constant value, and a position control spool operating arm and a draft control spool operating arm arranged above and below the spool of the valve in intersecting relation thereto, the draft feedback assembly being interlocked with the draft link assembly. The control valve is disposed under the case of the hydraulic unit, while the link assemblies are accommodated in a space inside one side wall of the case and having an open lower side to make the apparatus easy to assemble.

Abstract: Impact rippers are useful in fracturing rocks, concrete, etc. which cannot be fractured by ripping alone. Operating the impactor of the impact ripper without sufficient loading applied to the ripper tip is detrimental to the life of the impact ripper. The subject control system includes a pilot operated selector valve which blocks pressurized fluid from the impactor in the absence of pilot fluid thereto and is shifted by pressurized pilot fluid to a position to direct pressurized fluid to the impactor. A pressure switch is rendered conductive when the fluid pressure generated in a hydraulic cylinder exceeds a predetermined value due to loading on the ripper tip. This actuates a solenoid valve to direct pressurized pilot fluid to the selector valve. Thus the impactor is activated only when the loading on the ripper tip is above a preselected threshold and is automatically deactivated when the loading on the ripper tip drops below the preselected threshold.

Abstract: In a device for controlling a slip and a traction force of an implement coupled to a tractor by a hoisting unit, a slip contol system is combined with a traction force control system. The control device includes a drive speed sensor connected to the tractor and an acceleration sensor positioned on the tractor. A measured acceleration value is compared in a comparator circuit with an adjusted output signal of the drive speed sensor, and an actual slip value is determined by integration from an acceleration difference signal. The actual slip value is used for adjusting a control value generated in the traction force control system to control a position of the hoisting unit.

Abstract: A method of controlling an attachment to an agricultural tractor in which the absolute movement of the attachment is determined by a motion sensor mounted thereon and is utilized as a control standard while the relative motion of the attachment with respect to the tractor, influenced by the controller and carried out by a power lift, is determined in such a way that the absolute movement of the attachment becomes zero. This control method achieves that the attachment maintains a constant position in space in spite of the pitch movements of the tractor acting as disturbances. This guarantees an automatic tilling process, for instance a uniform depth of the furrows when plowing. By utilizing superimposed feedbacks of further control standards, such as relative position and motor load, changes in the absolute position of the attachment are possible and overloading of the motor is avoided.

Abstract: To avoid skidding of the driving wheels of a tractor (1) which runs on tires and which is fitted with hydraulic lifting devices (3, 4) on which are mounted working tools (35, 45) which are buried in the ground (in this case ploughs), the apparatus includes detector structure for determining the force for forward movement of the tractor, comparing that force to a reference value and producing pulses of less than one second, for alternately raising the two lifting devices (3, 4), the amplitude of the pulses being proportional to the excess of the forward movement force, up to a limit amplitude of centimeters approximately. The pulses are too short for the tools (35, 45) to lift with respect to the ground and the amplitude of the raising movement appears as squashing of the tires, which increases grip in order to overcome the excess of forward movement force.

Abstract: An automatic feedback control system for use with an off-road vehicle having an adjustable-elevation, ground-engaging implement, such as an agricultural tractor with a three-point hitch and a plough or cultivator, is disclosed. The automatic control system provides an engine-sensing draft control system which adjusts the height or elevation of the ground-engaging implement so as to maintain the draft or load forces experienced by the vehicle at a substantially constant level. The determination of the draft being produced by the ground-engaging implement is determined by the engine speed deviation from a target point speed which is indicated by an operator-set desired no-load engine speed and an operator-set engine lug-down value or load.

Abstract: A hitch control system includes an algorithm which prevents undesired and/or unexpected hitch movement upon start-up of the control system, depending upon the actual hitch position, the commanded hitch position and an operator set limit position.

Abstract: Impact rippers are useful for ripping solid rock. The service life of the impactor can be extended if the impactor is operated only when the ripper shank is loaded sufficient to transmit the impact energy into the material being ripped. The subject control system uses control signals generated by a plurality of signal generating means when the ripper shanks are loaded above a predetermined level to control the operation of the hydraulically actuated impactors associated with such ripper shanks. The number of control signals being generated is also used to control the volume of fluid made available for use by the impactors being operated at an given time to control the operating speed thereof. Thus, only the impactor(s) associated with a ripper shank(s) loaded above the predetermined level is operated thereby avoiding non-productive and harmful impactor operation if the ripper shank(s) is not sufficiently loaded.

Abstract: A power transmission device for a tractor in which a main shifting device and a secondary shifting device are disposed in front and back of one another within a transmission case which is mounted on a rear part of the tractor body is disclosed. Drive power, which is transmitted from an engine, is changed in speed by the main shifting device and secondary shifting device and then transmitted to an axle through a differential shaft. The differential shaft is disposed between the main shifting device and secondary shifting device. A lower link for connecting a piece of agricultural machinery is pivotably connected to the transmission case on the side of the secondary shifting device and behind the differential shaft. Various shafts within the transmission case are arranged on two different vertical level above and below the differential shaft, which extends at right angles with respect to these shafts. The differential shaft is connected to the axle through a reduction gear apparatus which has a counter-shaft.