Hitch assembly control system

A system for controlling elevation of a hitch assembly mounted to an off-highway implement having an operator station and to which a ground penetrating implement is adapted to be connected, said hitch assembly including an actuator for vertically moving the hitch assembly through a range of positions, said actuator being responsive to control signals applied thereto, said hitch assembly control system comprising:

• an electronic controller for applying said control signals to said actuator in response to a plurality of inputs, said controller including logic circuitry responsive to said inputs for operating said hitch assembly in at least three different states of operation;
• at least one sensor for monitoring the ground speed of the tractor and providing a ground speed signal input to the electronic controller;
• an operator command mechanism positionable under the influence of an operator for setting a lower limit position for the hitch and for conditioning said electronic controller to operate in a first state depending upon the relationship between the elevation of the hitch assembly and the position of the movable apparatus of the operator command mechanism;
• a switch assembly for conditioning said controller to operate in a second state, said switch assembly being movable between first and second positions under the influence of the operator for independently controlling the elevation of the hitch assembly between said lower limit position and an upper limit position, wherein when said switch assembly is in the first position the actuator is operated to move the hitch assembly upwardly and when the switch assembly is in the second position the actuator is operated to move the hitch assembly downwardly;
• and
• a draft force command mechanism operational under the influence of the operator for conditioning the controller to operate the hitch assembly in a third state during which the controller automatically controls the actuator such that the hitch assembly is vertically moved within predetermined limits whereby a substantially constant draft force is developed through implement/ground interaction and applied to the hitch assembly, said draft command mechanism conditioning the controller into the third state of operation in response to the tractor ground speed signal exceeding a predetermined threshold level and the switch assembly being positioned in the second position and when a sensed draft force established by implement/ground interaction has exceeded at least once a reference draft force set by the draft force command mechanism.

A system for controlling elevation of a hitch assembly to which a ground penetrating implement is adapted to be connected, said hitch assembly including an actuator for vertically moving the hitch through a range of positions between a lower position and an upper position, said control apparatus comprising:

• a primary operator controlled mechanism connected to said actuator and settable in different positions for elevationally moving said hitch assembly and for establishing a desired work position for the hitch during implement operations;
• a control unit for calculating an error value representing a difference between a sensed hitch assembly position and a desired work position for the hitch assembly and for controlling actuation of said actuator in response to the error value calculated;
• and
• a second operator controlled mechanism connected to the control unit and operable independently of said primary operator controlled mechanism and settable in different positions for effecting upper vertical movement of the hitch assembly to a preselected upper limit notwithstanding the set position of said primary operator controlled mechanism.

A system for controlling elevation of a hitch assembly to which a ground penetrating implement is adapted to be connected, said hitch assembly including an actuator for vertically moving the hitch assembly through a range of positions, said actuator being operated in response to control signals applied thereto, said control system comprising:

• a control unit including first electronics for computing a first error value representative of the difference between a sensed draft force produced by the ground/implement interaction and an operator controlled reference draft force, second electronics for computing a second error value representative of the difference between a sensed hitch position and an operator controlled reference hitch position, said operator controlled reference hitch position being set by an operator controlled hitch command mechanism including an apparatus which is selectively movable between upper and lower settings, and with the lower setting of the selectively movable apparatus being determinative of the lowermost setting of the hitch assembly during operation of the hitch assembly, with said control unit operating under the influence of a program which is responsive to said first and second electronics for deriving said control signals for said actuator from the error values calculated by said first and second electronics, said program of the control unit further controlling operation of the actuator such that the hitch assembly is prevented from moving beneath the lower limit set by the selectively movable apparatus of the hitch command mechanism.

A system for controlling elevation of a hitch assembly relative to a frame of an off-highway implement to which the hitch assembly is attached, said hitch assembly being adapted to have a ground penetrating implement connected thereto, and wherein said hitch assembly includes an actuator for vertically moving the hitch assembly between upper and lower positions, and with said actuator being responsive to control signals applied thereto, said control system comprising:

• an operator command mechanism including a movable apparatus for selectively setting a reference position for the hitch assembly;
• an operator settable mechanism including a movable apparatus for selectively setting a reference draft force for the hitch assembly;
• a control unit for computing a first error value representative of the difference between a sensed draft force produced by ground/implement interaction and the reference draft force selected by the operator, said control unit having further capability of computing a second error value representative of the difference between a sensed hitch position and the reference position for the hitch assembly selected by the operator, said control unit further including a program for deriving said control signals for the actuator from the first and second computed error values;
• and
• an operator controlled assembly connected to said control unit for commanding said hitch assembly to move within a predetermined range of vertical travel independently of the reference hitch position and the reference draft force.

A system for controlling elevation of a hitch assembly relative to a frame of an off-highway implement to which the hitch assembly is attached, said off-highway implement having an operation station and with said hitch assembly having a ground penetrating device connected thereto and includes an actuator for vertically moving the hitch assembly through a range of positions between lower and upper positions, said actuator being operated in response to control signals applied thereto, said control system comprising:

• an electronic controller having a plurality of inputs thereto for indicating hitch assembly operation and a program for deriving said control signals used to control the actuator as a function of said inputs;
• a switch assembly connected to the controller and arranged at the operator station, said switch assembly including a switch which is selectively movable between first and second positions under the influence of the operator for controlling the elevation of the hitch assembly relative to the implement frame between lower and upper positions;
• and
• an operator controlled adjustable mechanism connected to the controller for controlling elevational movements of the hitch assembly between the upper and lower positions at a substantially constant rate and independent of the weight of the ground penetrating device attached to the hitch assembly.