Safety clutch for an agricultural vehicle

1 . A safety clutch for an agricultural vehicle, said safety clutch comprising:

(i) a driven rotational element comprising a recess;

(ii) a roller configured to be received in the recess of the driven rotational element;

(iii) a biasing unit configured to urge the roller into the recess with a biasing force, wherein the roller is configured to move between:

a first position in which the roller is seated in the recess of the driven rotational element to drive the driven rotational element to rotate; and

a second position in which the roller is unseated from the recess of the driven rotational element, and

(iv) an actuator having a moveable end that is positioned against the roller and is operable to move the roller from the first position to the second position in response to an override input;

wherein the roller is configured to move between the first position and second position in response to:

(a) a relative torque between the roller and the driven rotational element overcoming the biasing force; and

(b) the actuator moving the roller in response to the override input, wherein the override input is independent of the relative torque.

2 . The safety clutch according to claim 1 , wherein the biasing unit comprises:

a pivot arm comprising a pivot, wherein the pivot arm is configured to be coupled with a driving rotational element;

a resiliently deformable member configured to provide the biasing force; and

a lever configured to pivot about the pivot of the pivot arm,

wherein the lever is coupled to the resiliently deformable member on a first side of the pivot and rotatably coupled with the roller on a second side of the pivot.

3 . The safety clutch according to claim 2 , wherein the pivot arm comprises an alignment opening through which a rod of the resiliently deformable member is configured to extend.

4 . The safety clutch according to claim 2 , wherein the biasing unit is rotatable about a rotational axis of the driven rotational element.

5 . The safety clutch according to claim 1 , wherein the recess of the driven rotational element comprises a concave region adjacent to one or more convex regions.

6 . The safety clutch according to claim 1 , wherein the driven rotational element comprises a disc with the recess in a periphery of the disc.

7 . The safety clutch according to claim 1 , wherein the driven rotational element comprises a shear arm comprising the recess at one end thereof, wherein the shear arm is rotationally coupled with a disc.

8 . The safety clutch according to claim 1 , wherein, in use, the driven rotational element is configured to be rotated through 360 degrees about a rotational axis of the driven rotational element.

9 . The safety clutch according to claim 1 , wherein the roller is configured to be urged against the driven rotational element in the second position by the biasing force,

the safety clutch further comprising a rotational speed monitor to determine a rotational speed of the driven rotational element.

10 . The safety clutch according to claim 1 , further comprising a locking mechanism configured to lock the roller in the second position after the roller has transitioned from the first position to the second position.

11 . The safety clutch according to claim 1 , wherein the actuator is configured to move the roller to an intermediate position between the first and second position to reduce the amount of relative torque between the roller and the driven rotational element overcoming the biasing force.

12 . The safety clutch according to claim 1 , wherein the safety clutch further comprises a plurality of rollers, wherein each roller is configured to be received in a correlating recess in the driven rotational element.

13 . The safety clutch according to claim 12 , further comprising a plurality of actuators, wherein each actuator is configured to move a corresponding roller of the plurality of rollers and wherein a first actuator of the plurality of actuators is configured to situate a first roller of the plurality of rollers in the first position, and a second actuator of the plurality of actuators is configured to locate a second roller of the plurality of rollers in the second position.

14 . An agricultural vehicle comprising the safety clutch according to claim 1 .

15 . A trailed agricultural accessory comprising the safety clutch according to claim 1 .

16 . The safety clutch according to claim 1 , wherein the actuator is a piston and the moveable end is defined on an end of the piston, wherein said end of the piston is positioned directly against the roller.

17 . In a safety clutch for an agricultural vehicle, said safety clutch comprising: (i) a driven rotational element comprising a recess; (ii) a roller configured to be received in the recess of the driven rotational element; (iii) a biasing unit configured to urge the roller into the recess with a biasing force, wherein the roller is configured to move between: a first position in which the roller is seated in the recess of the driven rotational element to drive the driven rotational element to rotate; and a second position in which the roller is unseated from the recess of the driven rotational element, and (iv) an actuator having a moveable end that is positioned against the roller and is operable to move the roller from the first position to the second position in response to an override input, a method of operating the safety clutch comprises:

actuating the actuator to move the roller from the first position to the second position in response to: (a) a relative torque between the roller and the driven rotational element overcoming the biasing force; and (b) the actuator moving the roller in response to the override input, wherein the override input is independent of the relative torque.

18 . The method of claim 17 , wherein the actuator is a piston and the moveable end is defined on an end of the piston, wherein said end of the piston is positioned directly against the roller.