Control devices for agricultural tractor implements

Claim 2

A control device for a three point coupling arrangement of an agricultural tractor, comprising two lower arms carrying two points of said three point coupling arrangement, said arms being pivotally connected at one end to the rear of said tractor, first and second hydraulic actuators on said tractor, means connecting said first and second hydraulic actuators to said pivoted lower Arms to control the angular position of said lower arms, a third hydraulic actuator on said tractor carrying a third connection point of said three point coupling arrangement, means connecting said first and second actuators hydraulically in series such that movement of either of said actuators causes a transfer of fluid from one to the other to cause the other of the said first and second actuators to move in the same direction, means in fluid communication with said connecting means for varying the volume of fluid transferred from one said actuator to the other whereby the relative inclination of said lower arms is adjustable, a source of hydraulic pressure, and independent distributor valve means connected between said hydraulic actuators and said source of hydraulic pressure.

Claim 3

The control device of claim 1 wherein said first actuator has a lower chamber and an upper chamber separated by a piston, transverse stabilisation distributor valve means and lifting distributor valve means selectively connecting said lower chamber of said first actuator to said source of fluid pressure.

Claim 4

The control device of claim 1 wherein said means connecting said first and second actuators hydraulically in series comprises a conduit having at least one branch thereto, transverse regulation distributor valve means selectively connecting said at least one branch of said connecting conduit to said source of hydraulic pressure.

Claim 5

The control device of claim 3 wherein said transverse stabilisation distributor valve means includes means sensitive to the fluid pressure in said connecting conduit between said first and second hydraulic actuators.

Claim 6

The control device of claim 2 wherein said lifting distributor valve means includes a valve follower arrangement comprising: a valve body having a bore therein, a sleeve slidable within said bore in said valve body, a first control lever controlling the position of said sleeve in said bore, means connecting said bore to said first and second actuators whereby said sleeve controls the delivery of fluid to said first and second hydraulic actuators, a valve obturator slidable within said sleeve, and means connecting said valve obturator to said lower arms controlled by said first and second hydraulic actuators whereby said valve obturator is moved to follow the movement of said sleeve upon movement of said lower arms determined by said movement of said sleeve.

Claim 7

The control device of claim 5 wherein said valve body of said lifting distributor valve means has two first fluid passageways, a non-return ball valve connecting said two first fluid passageways in said valve body of said lifting distributor valve means, two orifices in said sleeve connecting respective ones of said first fluid passageways to the internal bore of said sleeve, a second fluid passageway in said valve body of said lifting distributor valve means communicating with said bore in said valve body and a discharge chamber via a discharge passageway, and further valve obturator means slidable in said valve body to open or close said second fluid passageway.

Claim 8

The control device of claim 6 wherein said further valve obturator means is biased by adjustable spring biasing means, said spring biasing means controlling the pressure at which said further valve obturator means moves to open said second fluid passageway to allow communication between said internal bore of said sleeve and said discharge passageway.

Claim 9

The control device of claim 5 wherein there are lost motion coupling means coupling said first control lever to release valve means, means resiliently biasing said release valve means to a closed position to control the connection of said interconnected chambers of said first and second hydraulic actuators to said discharge chamber when said first control lever is moved to take up said lost motion and open said release valve means against the action of said resilient baising means.

Claim 10

The control device of claim 3 wherein said transverse regulation distributor valve means comprises a valve body, a bore in said valve body, a valve obturator slidable in said bore in said valve body, a second control lever, means connecting said second control lever to said valve obturator in said valve body of said transverse regulation distributor valve means, means connecting said bore in said valve body to said source of fluid pressure, means connecting said bore in said valve body to said intercommunicating chambers of said first and second hydraulic actuators, and means connecting said bore in said valve body to said lifting distributor valve means, said second control lever being movable to move said valve obturator to connect said intercommunicating chambers of said first and second hydraulic actuators to said source of fluid pressure or to connect said lifting distributor to said source of fluid pressure.

Claim 11

The control device of claim 9 wherein there is provided a fixed graduated sector adjacent said second control lever, a pivoted sector having indicator means adjacent said graduated scale, and means connecting said indicator means to said lower arms whereby the position of said indicator means along said graduated sector indicates the relative position of said lower arms.

Claim 12

The control device of claim 10 wherein said means connecting said indicator means to said lower arms comprise: a pivoted sector carrying said indicator means, a drag link connected to said pivoted sector, a bell crank connected to said drag link and mounted on a fixed part of said tractor, a first rocker mounted on one arm of said bell crank, a second pivoted rocker, a first arm of said second pivoted rocker being connected to a first arm of said first rocker, said second rocker being mounted on a fixed part of said tractor, and respective drag links connected between said lower arms and said second arms of said first and second rockers, said pivoted sector having a slot therein, said second control lever extending through said slot whereby the movement of said second control lever is restricted by the instantaneous position of said pivoted sector.

Claim 13

The control device of claim 1 wherein one of said independent distributor valve means connected between said hydraulic actuators and said source of hydraulic pressure is a vertical regulation distributor valve means comprising: a valve body, a bore in said valve body, a valve obturator sliding in said bore in said valve body, a third control lever, means connecting said third control lever to said valve obturator, means connecting said bore in said valve body to said lifting distributor valve means, means connecting said bore in said valve body to said source of fluid pressure, means connecting said bore in said valve body to said chambers of said third hydraulic actuator, said third control lever being movable to move said valve obturator connected thereto to selectively effect connection between said source of fluid pressure and a selected one of said chambers of said third hydraulic actuator or between said source of fluid pressure and said lifting distributor valve means.

Claim 14

The control device of claim 12 wherein said valve body includes a differential manometric device, means connecting said differential manometric device to said third hydraulic actuator whereby said differential manometric device is sensitive to the pressure in the chambers of said third hydraulic actuator and responsive to adjust the lifting distributor valve means to control the force exerted by said third hydraulic actuator.

Claim 15

The control device of claim 2 wherein said transverse stabilisation distributor valve means comprises: a valve body, first and second bores in said valve body, first and second valve obturators sliding in said first and second bores respectively, first means resiliently biasing said first valVe obturator to a first position in said first bore, means connecting said first bore to said conduit interconnecting said first and second hydraulic actuators such that the pressure in said intercommunicating chambers of said first and second hydraulic actuators opposes the said first biasing means to move said first valve obturator to a second position, when said pressure in said intercommunicating chambers is greater than the force exerted by said first resilient biasing means, means connecting said second bore to said upper chamber of said second hydraulic actuator, second resilient biasing means biasing said second obturator to a first position, said pressure in said upper chamber of said second hydraulic actuator opposing said second resilient biasing means to move said second valve obturator to a second position when said pressure is greater than the force exerted by said second biasing means, means connecting said first bore to said second bore and said first bore to said source of fluid pressure, means connecting said second bore to the lower chamber of said first hydraulic actuator, said first valve obturator allowing the passage of fluid from said source of fluid pressure to said lower chamber of said first hydraulic actuator when in said second position and preventing such communication when in said first position, means connecting said upper chamber of said second actuator to said first bore, said first and second obturators allowing connection of said upper chamber of said second hydraulic actuator to said lower chamber of said first hydraulic actuator when said first obturator is in said first positions, and said second obturator is in said second position.

Claim 16

The control device of claim 14 wherein said first obturator intercepts said means connecting said source of pressure to said lower chamber of said first actuator when said first obturator is in said first position to which it is biased upon a reduction of fluid pressure acting on it from said intercommunicating chamber of said first and second hydraulic actuators resulting from a downward force on said arm connected to said first actuator greater than the downward force on said second actuator.

Claim 17

The control device of claim 14 wherein said second valve obturator is movable to said second position where it allows communication between said upper chamber of said second actuator and said lower chamber of said first actuator when there is a resultant upward force on said arm connected to said second actuator.