Abstract: A control for a drawbar of a hitch for a work machine, and at least one method of operation thereof, which provides operator selectable operating modes having different characteristics for different operating conditions and operator preferences, some of which modes being automatically adaptable for changing conditions, such as loading conditions and the like. Selectable operating modes can include, but are not limited to, a locked out mode; a stiffness mode; a position limited mode; a varying load mode; and an active mode.

Abstract: A method is provided for automatically determining a hitch raise rate calibration value for a hitch control system having a hydraulic actuator for moving the hitch, a valve for controlling flow of hydraulic fluid to the actuator and an electronic hitch control unit. The method includes applying a first control signal to the valve to cause the hitch to raise, determining a first hitch velocity as the hitch moves in response to the first control signal, and repeating these steps for a second control signal. The raise rate calibration value is then calculated as a function of a desired raise velocity, the first and second control signals and the first and second velocities.

Abstract: A three-point hitch suitable for operation with wide implements is constructed by substituting a pair of flotation actuators for the usual drop links that are normally coupled between a pair of rocker arms and a pair of lower draft links. These drop links are coupled to a hydraulic circuit including, according to one embodiment, individual accumulators for each flotation actuator, and according to a second embodiment, both actuators are coupled to a single accumulator. The accumulator(s) act to cause a pre-selected lifting force to be exerted by the flotation actuators so that a predetermined amount of the weight of an implement mounted to the draft links is counterbalanced, leaving a desired ground pressure being exerted by the implement during operation. When using individual accumulators, a side-to-side weight balance can be achieved since different accumulator settings may be used.

Abstract: An apparatus and method for controlling variation in the pitch of an agricultural vehicle, where the apparatus includes a controller that controls a position of an implement attached to the agricultural vehicle, and a first valve that is coupled to, and receives a first control signal from, the controller. The apparatus further includes a suspension cylinder having a first chamber that is hydraulically coupled to the first valve. The first control signal provided from the controller is functionally related to a first additional control signal provided by the controller, and the first additional control signal is used to determine the position of the implement.

Abstract: A method and apparatus for determining a velocity of an implement and thereby moving an implement to a desired position. A control system has input signals representative of the implement arm limit position, the implement arm actual position and the implement arm desired position and outputs a signal representative of a desired velocity. The control system determines an arm velocity as a function of the arm limit position and the arm actual position and a second velocity as a function of the arm actual position and the arm desired position. The desired velocity is a function of the arm velocity when the arm velocity has a predetermined relationship to the second velocity, and the desired velocity is a function of the second velocity when the arm velocity signal does not have the predetermined relationship to the second velocity.

Abstract: An earth-moving machine is provided with a first actuator cylinder, which can impart to a lifting arm oscillation around a corresponding pivoting shaft, and with a second actuator cylinder, which can maintain a loading unit in a pre-determined angular position during oscillation of the lifting arm itself; the first and the second actuator cylinder being disposed adjacent and parallel to one another, and being connected mechanically to one another in order to increase the resistance of the second actuator cylinder to the load generated on the second actuator cylinder itself by the lifting arm.

Abstract: A system for controlling a function of a machine system including an off-road work vehicle, a moveable device, and a positioning assembly including an actuator for moving the device in response to a control signal. The system includes an operator-adjustable input device which generates an input signal, and a control circuit which generates the control signal for moving the moveable device in a first or a second manner depending upon the rate of change of the input signal. The first manner is selected when the input signal changes slowly, and the second manner is selected when the input signal changes quickly. The system may include a sensor for sensing a parameter of the machine system and a command device for generating a command signal. A control signal is generated based at least upon the difference between the sensed parameter and command signals. Also disclosed is a system for controlling the elevation of an implement carried or trailed by a work vehicle.

Abstract: The present invention provides variable force traction enhance systems for vehicles. The systems include one or more hydraulic cylinders connected to an implement and fluidly connected to one or more hydrostatic transmissions. The hydraulic cylinders actuate the implement in response to changes in the hydraulic fluid pressures in the hydrostatic transmissions. The actuated implement automatically shifts weight to vehicle drive wheels to improve traction and automatically prevents a rear end of the vehicle from bucking.

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: 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: 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: Implement draft control devices are typically utilized on agricultural vehicles such as tractors and on other earthworking type vehicles. Advantageously, such control systems should respond quickly to changing soil conditions, while remaining stable so that the hitch and implement systems do not oscillate or are not changed in a rapid or erratic fashion. The instant embodiment of a draft control system includes a control system that receives hitch position control signals and engine acceleration signals, and controllably modifies the hitch position control signals in response to the rate of acceleration and deceleration of the engine. By utilizing engine acceleration and deceleration rates as opposed to mere changes in engine speed, the system is able to respond quickly to needed changes in implement depth while remaining stable during operation.

Abstract: A control system and method for adjusting the depth of a tractor-drawn draft implement in response to a detection of draft load. The control system compares actual engine rpm to a stored or mapped value of engine rpm at zero engine load conditions for the throttle setting in use. An indication of engine lug-down is thereby obtained. Through the use of another memory related to the engine torque versus rpm curve, for the actual throttle setting in use, a draft load signal is obtained. As determined by an operator sensitivity setting, a preselected portion of the draft load signal is then combined with a preselected portion of an actual draft depth position signal to form a feedback signal. A signal represntative of the draft depth desired by the operator is then combined with the feedback signal to form a command signal for raising or lowering the draft implement via a hydraulic powerlift valve.