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US 5,348,101 AGranted
Hydraulic system for a towed implement
AssigneeDeere & Company
InventorsRobert E. Fox, William L. Smith, Jr., Thomas E. Boe
Life of this patent
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AssigneeDeere & Company
InventorsRobert E. Fox, William L. Smith, Jr., Thomas E. Boe
Estimating the term…
A hydraulic rockshaft control circuit which includes a three-way valve that normally operates the rockshaft is connected to the lift cylinder on a trailing implement. A hitch lock valve connected to the rockshaft control valve maintains the rockshaft in a preselected position regardless of changes in pressure at the valve output. The extend side of the lift cylinder is connected to the control valve output so that the tractor hitch control is used to operate the trailing implement cylinder. To overcome the inability of the three-way valve to positively retract the trailing implement cylinder, a reducing/relieving valve is connected to the retract side of the cylinder and is adjusted to provide just enough pressure to retract the cylinder and raise the implement wheels from ground contact when the extend side is connected to return pressure. A position feedback system on the implement is connected to the hitch control unit (HCU) on the tractor. When the HCU senses a feedback signal from the implement, the HCU control mode changes from rockshaft control to trailing implement control wherein implement position is set and maintained in a manner similar to that for the conventional rockshaft control. A voltage readout from the feedback signal provides a visual indication of implement position.
In a hydraulic system for a tractor having a source of hydraulic fluid under pressure with a reservoir, at least one selective control valve (SCV) for controlling a remote hydraulic function, a rockshaft with a rockshaft cylinder, a hydraulic control circuit including control valve structure connected between the source and the rockshaft a hitch control unit for one-way operation of the rockshaft cylinder, an implement position control for an implement connected to the tractor, the implement having a remote cylinder with first and second ends and a rod moveable in first and second directions, the position control comprising:
In a hydraulic system for a tractor having a source of hydraulic fluid under pressure with a reservoir, a rockshaft with a rockshaft cylinder, a hydraulic control circuit including control valve structure connected between the source and the rockshaft cylinder, and a hitch control unit for operation of the rockshaft cylinder as a single-acting cylinder, an implement position control for an implement connected to the tractor, the implement having an operable remote cylinder with first and second ends, the position control comprising:
In a hydraulic system for a tractor having a source of hydraulic fluid under pressure with a reservoir, a rockshaft with a rockshaft cylinder, a hydraulic control circuit including control valve structure connected between the source and the rockshaft and a hitch control unit for single-acting operation of the rockshaft cylinder, an implement position control for an implement connected to the tractor, the implement having a remote cylinder with first and second ends, the position control comprising:
In a hydraulic system for a tractor having a source of hydraulic fluid under pressure with a reservoir, a hydraulically controlled rockshaft connected to tractor hitch structure for moving the hitch structure vertically between raised and lowered positions, at least one selective control valve (SCV) for controlling a remote hydraulic function, hitch control valve structure connected to the source and having an output port connected to the rockshaft, a hitch control unit (HCU) connected to the control valve structure for operating the rockshaft, the HCU having a first operator control for setting rockshaft operating position and a second operator control for raising and lowering the rockshaft and moving the rockshaft to the operating position determined by the first operator control, an implement position control system for an implement connected to the tractor and having a remote cylinder with first and second hydraulic ports, the position control comprising:
Dependencies are inferred from the claim text.