Interface system for a towed implement

In a tractor/towed implement combination having a tractor hitch, 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, the hitch control valve having a variable pressure outlet, a control unit for controlling the hitch control valve as a function of a sensed parameter signal and an operator generated command signal, an implement cylinder for raising and lowering a tool of the towed implement and a selector valve for selectively connecting the variable pressure outlet of the hitch control valve to the implement cylinder, characterized by:

• means for automatically raising the hitch to a position where it will not interfere with the towed implement when the selector valve connects the hitch control valve to the implement cylinder, the selector valve comprising a two-position, four-way valve having a first inlet connected to the pump, a second inlet connected to an outlet of the hitch control valve, a first outlet for connecting to the implement cylinder, a second outlet connected to the rockshaft cylinder, and a manually movable valve member having a first position wherein the pump is communicated with the first outlet and the second inlet is communicated with the rock shaft cylinder, and having a second position wherein the pump is communicated to the rock shaft cylinder and the second inlet is communicated with the first outlet.

A tractor/towed implement combination comprising:

• a tractor hitch;
• a hydraulic pump;
• a hydraulic sump;
• a rockshaft cylinder for raising and lowering the hitch;
• a hitch control valve having a variable pressure outlet;
• a control unit for controlling the hitch control valve as a function of a sensed parameter signal and an operator generated command signal;
• an implement cylinder for raising and lowering a tool of the towed implement;
• and
• a selector valve having a first port connected to the pump, a second port connected to the variable pressure outlet of the hitch control valve, a third port for communicating with the implement cylinder, a fourth port communicated with the rockshaft cylinder, and a valve member movable to a first position wherein the first port is communicated with the third port and the second port is communicated with the fourth port and the rock shaft cylinder, and to a second position wherein the first port and the pump are communicated with the rock shaft cylinder and the second port is communicated with the third port and the implement cylinder.