Ford New Holland, Inc.

Bradley A Nielsen

Steven Carson Young

Stephen J Churchill

James W Macqueene

David G Sokol

Richard Paul Strosser

Scott Alan Rempe

Matthew T Miller

Michael E Langford

Shairyl I Pearce

Garrett E Swierenga

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. If the hitch is not captured, or the hitch control system is in the open-loop mode, and uncommanded downward hitch motion is detected, the microprocessor energizes the safety disconnect relay to disable the hitch valve thereby preventing uncommanded downward motion of the hitch. When the hitch is captured and the control system is in a closed-loop control mode, feedback signals from the hitch act through a closed-loop to maintain the hitch at the position specified by the quadrant lever.

Draft control system with safety disconnect

A vehicle transmission system having shift lever control of synchronized couplers for selection of ranges of gears and electro-hydraulic powershift clutches for selection of a gear within the selected range is provided with controls for avoiding unexpected speeds or speed changes under certain conditions. On start-up, if the vehicle is stationary, a microprocessor automatically selects which powershift gear is effective, the selection being such that the start-up speed is as nearly uniform as possible within the limits imposed by the positions of the shift levers.

Transmission start-up control

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. The true ground speed is automatically and repeatedly divided by the rate of rotation of the tractor rear axle when conditions are such that wheel slippage is unlikely. The multiple divisions produce plural indications of a correction factor. These indications are filtered to obtain a correction factor which accounts for variations in the effective rolling radius of the wheels. Once the correction factor has been determined it is applied to the wheel speed sensor output to calculate the theoretical ground speed of the vehicle.

Hitch positioning with slip override control and calibrated wheel speed

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. As the hitch approaches the commanded position the system reverts to the normal filtering so that the system is more sensitive to the draft feedback signal.

Draft control system with dual mode draft sensitivity

In a transmission system, a solenoid controlled electro-hydraulically actuated creeper gear coupler permits selection of very low speeds and provision is made to prevent creeper gear engagement/disengagement unless conrolled by the operator and then only if specified conditions exist. Current flow through the solenoid which actuates the creeper gear is monitored at all times to provide a controlled engagement/disengagement of the creeper gear in the event the monitoried conditions are not within prescribed limits. The current is monitored as the creeper solenoid is energized to insure sufficient pull-in current and while it is energized to insure sufficient hold-in current. The solenoid current is also monitored when the solenoid is not energized. Short or open circuit conditions are detected before they can cause an unexpected engagement or disengagement of the creeper gear.

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New Holland, PA, United States of America

Bradley A Nielsen