Tractor and towed implement with elevation control system for implement including pressure responsive valve actuator

Automotive apparatus comprising

• a tractor,
• a towed implement including a tool,
• connection means connecting the implement to the tractor,
• means including a hydraulic motor for adjusting the elevation of the tool relative to the earth's surface,
• a source of hydraulic fluid under pressure,
• a reservoir,
• valve means for selectively connecting the motor to the source and reservoir,
• hydraulic line means having a drooping pressure versus flow characteristic,
• motive means responsive to the pressure in said line means for actuating the valve means,
• operator controlled vent means carried by the tractor for varying the pressure in said line means,
• negative feedback vent means connected to the tool for varying the pressure of said line means, upon movement of the tool in response to movement of the operator controlled vent means, to negate the effect of the change of the pressure of said line means caused by the operator controlled vent means,
• said connection means including load sensor means responsive to tension in the connection means for varying the pressure of said line means to elevate said tool when the tension in the connection means rises from below a certain value to above said value,
• said connection means comprising one member connected to the tractor and another member connected to the implement,
• said load sensor means comprising a body having a cylindrical cavity,
• said body being connected to one of said members,
• a cylindrical piston axially slidably movable in said cavity,
• a piston rod extending through and axially slidable in an aperture in an end wall of said body in fluid tight relationship therewith and connecting at one end to said piston and its other end with said another of said members of the connection means,
• fluid pressure means for supplying pressurized fluid at selected pressure to the piston on the same side thereof as said piston rod is connected,
• a wall transverse to the axis of said body disposed on the side of the piston opposite to said piston rod dividing the cavity into a space adjacent the piston and an end space,
• port means in the body connecting the cavity space adjacent the piston to said reservoir,
• port means in the body connecting said end space with said line means, and
• valve core means extending into and axially slidable within a port in said wall and connected at one end to said piston on the opposite end of the piston rod,
• said valve core means having tapered groove means in the portion thereof adapted to be within said wall port,
• said groove means being of increasing cross-sectional area progressing in the direction toward said piston.

Automotive apparatus comprising

• a tractor,
• a towed implement including a tool,
• connection means connecting the implement to the tractor,
• means including a hydraulic motor for adjusting the elevation of the tool relative to the earth's surface,
• a source of hydraulic fluid under pressure,
• a reservoir,
• valve means for selectively connecting the motor to the source and reservoir,
• hydraulic line means having a drooping pressure versus flow characteristic,
• motive means responsive to the pressure in said line means for actuating the valve means,
• operator controlled vent means carried by the tractor for varying the pressure in said line means,
• negative feedback vent means connected to the tool for varying the pressure of said line means, upon movement of the tool in response to movement of the operator controlled vent means, to negate the effect of the change of the pressure of said line means caused by the operator controlled vent means,
• wherein said operator controlled vent means and said feedback means connected to the tool are of like construction, each including a vent valve having a body with a cylindrical bore and diametrically opposed nozzle ports in the body and a generally cylindrical rotor rotatably mounted concentric with said bore and having an undercut eccentric cylindric land extending between said ports when the vent valve is in closed position, the space between said bore and said land being connected to the reservoir.

Automotive apparatus comprising

• a tractor driven by an engine,
• a towed implement including a tool,
• connection means connecting said implement to the tractor,
• hydraulic positioning means carried by the tractor for raising and lowering the tool,
• a hydraulic liquid supply for said positioning means,
• servo valve means for directing the positioning means, by controlling said hydraulic liquid supply to the positioning means,
• said servo valve means including valve means for controlling said hydraulic liquid to said positioning means and piston-cylinder means for controlling the hydraulic liquid controlling valve means,
• a fluid supply for said piston-cylinder means having a drooping pressure versus flow characteristic,
• manual means carried by the tractor for actuating the servo means by appropriate setting of the manual means,
• tension responsive means carried by the connection means for actuating the servo means to direct the positioning means to elevate the tool upon tension in the connection means in excess of a preselected amount,
• speed responsive means responsive to the rotational speed of the engine to direct the positioning means to elevate the tool upon engine rotational speed in excess of a preselected amount,
• said manual, tension responsive, and speed responsive means each including a flow path for venting said fluid supply to the piston-cylinder means and a variable restrictor for the respective flow path responsive respectively to setting of the manual means, tension of the connection means, and engine speed, for varying such venting, and
• feedback means responsive to the elevation of the implement for deactivating the servo means to maintain the tool at an elevation determined by the setting of said manual means except upon occurrence at least one of said tension and speed in excess of the respective preselected amount.

Automotive apparatus comprising

• a tractor,
• a towed implement including a tool,
• connection means connecting the implement to the tractor,
• height adjusting means including hydraulic motor means for adjusting the elevation of the tool relative to the earth's surface,
• a source of hydraulic fluid under pressure,
• a reservoir,
• valve means for selectively connecting the motor means to the source and reservoir and in a neutral position to disconnect the motor means from both the source and the reservoir,
• operator controlled means carried by the tractor for changing the position of said valve means to effect raising and lowering of said tool,
• feedback means responsive to the elevation of the tool for restoring the valve means to neutral position when the tool has reached a position determined by the setting of the operator controlling the valve means,
• characterized by the fact that said operator controlled means includes:
• hydraulic line means having a drooping pressure versus flow characteristic,
• motive means responsive to the pressure in said line means for actuating the valve means,
• said feedback means being negative feedback means connected to the tool for actuating the valve means upon movement of the tool in response to movement of the operator controlled valve means, to negate the effect on the valve means of the change of the pressure of said line means caused by the operator controlled valve means,
• said hydraulic motor means being double acting, being adapted to receive in its entirety pressure fluid from said source and to deliver from its entirety fluid to said reservoir to move the hydraulic motor means positively in both one direction and another according to the position of the valve means to effect raising and lowering of the tool.

Automotive apparatus comprising

• a tractor,
• a towed implement including a tool,
• connection means connecting the implement to the tractor,
• means including a hydraulic motor for adjusting the elevation of the tool relative to the earth's surface,
• a source of hydraulic fluid under pressure,
• a reservoir,
• valve means for selectively connecting the motor to the source and reservoir,
• hydraulic line means having a drooping pressure versus flow characteristic,
• motive means responsive to the pressure in said line means for actuating the valve means,
• operator controlled vent means carried by the tractor for varying the pressure in said line means,
• negative feedback means connected to the tool for actuating the valve means upon movement of the tool in response to movement of the operator controlled vent means, to negate the effect on the valve means of the change of the pressure of said line means caused by the operator controlled vent means,
• said connection means including load sensor means responsive to tension in the connection means for varying the pressure of said line means to elevate said tool when the tension in the connection means rises from below a certain value to above said value,
• said connection means comprising one member connected to the tractor and another member connected to the implement,
• said load sensor means comprising a body having a cylindrical cavity,
• said body being connected to one of said members,
• a cylindrical piston axially slidably movable in said cavity,
• a piston rod extending through and axially slidable in an aperture in an end wall of said body in fluid tight relationship therewith and connecting at one end to said piston and its other end with said another of said members of the connection means,
• fluid pressure means for supplying pressurized fluid at selected pressure to the piston on the same side thereof as said piston rod is connected,
• a wall transverse to the body axis disposed on the side of the piston opposite to said piston rod dividing the cavity into a space adjacent the piston and an end space,
• port means in the body connecting the cavity space adjacent the piston to said reservoir,
• port means in the body connecting said end space with said line means, and
• valve core means extending into and axially slidable within a port in said wall and connected at one end to said piston on the opposite end of the piston rod,
• said valve core means having tapered groove means in the portion thereof adapted to be within said wall port,
• said groove means being of increasing cross-sectional area progressing in the direction toward said piston.