Center pivot irrigation system

1. A center pivot irrigation system having a center pivot, said system being for watering crops growing upon agricultural ground, said ground having a ground surface, said system comprising:

(a) a plurality of towers which are rollable upon tower wheels, the plurality of towers being arranged in a series along a radial axis extending from the center pivot, each tower of the plurality of towers having a circumferential leg and a counter-circumferential leg, each tower wheel having a rotation axis substantially parallel to the radial axis;

(b) a plurality of circumferential pivot arms, each arm of the plurality of circumferential pivot arms having a distal end, each arm of the plurality of circumferential pivot arms having a proximal end which is pivotally attached to one of the circumferential legs;

(c) a plurality of counter-circumferential pivot arms, each arm of the plurality of counter-circumferential pivot arms having a distal end, each arm of the plurality of counter-circumferential pivot arms having a proximal end which is pivotally attached to one of the counter-circumferential legs;

(d) a plurality of circumferential linear motion actuators, each actuator of the plurality of circumferential linear motion actuators extending between one of the circumferential pivot arms and one of the circumferential legs, said each actuator being adapted for alternatively upwardly retracting and downwardly extending the one of the circumferential pivot arms;

(e) a plurality of counter-circumferential linear motion actuators, each actuator of the plurality of counter-circumferential linear motion actuators extending between one of the counter-circumferential pivot arms and one of the counter-circumferential legs, said each actuator being adapted for alternatively upwardly retracting and downwardly extending the one of the counter-circumferential pivot arms;

(f) a plurality of circumferential ground contact assemblies, each assembly of the plurality of circumferential ground contact assemblies being fixedly attached to the distal end of one of the circumferential pivot arms, said each assembly being adapted for, upon a downward extension of the one of the circumferential pivot arms, downwardly biasing against the ground surface; and

(g) a plurality of counter-circumferential ground contact assemblies, each assembly of the plurality of counter-circumferential ground contact assemblies being fixedly attached to the distal end of one of the counter-circumferential pivot arms, said each assembly being adapted for, upon a downward extension of the one of the counter-circumferential pivot arms, downwardly biasing against the ground surface, wherein each circumferential ground contact assembly comprises a circumferential ground contact member, wherein each counter-circumferential ground contact assembly comprises a counter-circumferential ground contact member, wherein each circumferential ground contact member comprises a circumferential ground contact wheel, wherein each counter-circumferential ground contact member comprises a counter-circumferential wheel, wherein each circumferential ground contact wheel has a rotation axis substantially parallel to the radial axis, and wherein each counter-circumferential ground contact wheel has a rotation axis substantially parallel with the radial axis.

2. The center pivot irrigation system of claim 1 wherein each circumferential ground contact assembly comprises a circumferential extension arm having a distal end and having a pivotally attached proximal end.

3. The center pivot irrigation system of claim 2 wherein each counter-circumferential ground contact assembly comprises a counter-circumferential extension arm having a distal end and having a pivotally attached proximal end.

4. The center pivot irrigation system of claim 3 wherein each circumferential extension arm is adapted for, upon an upward retraction of one of the circumferential pivot arms, pivoting clockwise, and wherein each counter-circumferential extension arm is adapted for, upon an upward retraction of one of the counter-circumferential pivot arms, pivoting counter-clockwise.

5. The center pivot irrigation system of claim 4 wherein each circumferential extension arm is further adapted for, upon a downward extension of one of the circumferential pivot arms, pivoting counter-clockwise, and wherein each counter-circumferential extension arm is further adapted for, upon a downward extension of one of the counter-circumferential pivot arms, pivoting clockwise.

6. The center pivot irrigation system of claim 5 further comprising a plurality of circumferential hyperextension stops, each stop of the plurality of circumferential hyperextension stops being adapted for, upon a downward biasing of one of the circumferential ground contact assemblies against the agricultural ground surface, resisting a counter-clockwise pivoting motion of one of the circumferential extension arms, and comprising a plurality of oppositely-circumferential hyperextension stops, each stop of the plurality of oppositely-circumferential hyperextension stops being adapted for, upon a downward biasing of one of the counter-circumferential ground contact assemblies against the ground surface, resisting a clockwise pivoting motion of one of the counter-circumferential extension arms.

7. The center pivot irrigation system of claim 5 further comprising a plurality of circumferential bar actuators, each actuator of the plurality of circumferential bar actuators being positioned circumferentially from one of the circumferential linear motion actuators, said each circumferential bar actuator having a distal end and having a proximal end pivotally attached to one of the circumferential legs, the distal end of said each actuator being pivotally attached to one of the circumferential extension arms.

8. The center pivot irrigation system of claim 7 further comprising a plurality of counter-circumferential bar actuators, each actuator of the plurality of counter-circumferential bar actuators being positioned counter-circumferentially from one of the counter-circumferential linear motion actuators, said each counter-circumferential bar actuator having a distal end and having a proximal end pivotally attached to one of the counter-circumferential legs, the distal end of said each actuator being pivotally attached to one of the counter-circumferential extension arms.

9. The center pivot irrigation system of claim 1 wherein each actuator of the plurality of circumferential linear motion actuators and each actuator of the plurality of counter-circumferential linear motion actuators comprises an actuator which is selected from the group consisting of electric motor driven jack screw actuators, electric motor driven ball screw actuators, hydraulic rams, pneumatic rams, rack and pinion gear actuators, and winch actuators.