Sensor for a header height control system

1. A header height sensor for a harvesting head of an agricultural combine, the header height sensor comprising:

an elongate sensor arm ( 112 ) having an upper end ( 150 ) that defines an aperture ( 160 ) configured to receive a shaft ( 154 ) and a lower end;

a reversing joint ( 114 ) that comprises a housing ( 152 ) configured to receive the upper end of the elongate sensor arm ( 112 ); the housing ( 152 ) including a mechanical stop ( 174 ) to prevent movement of the elongate sensor arm 112 ) with respect to the housing ( 152 ) in a first direction beyond the first limit of travel, the reversing joint ( 114 ) further comprising a pair of springs ( 162 , 164 ) disposed on either side of the upper end ( 150 ), the pair of springs ( 162 , 164 ) being coupled to the housing ( 152 ) and to the upper end ( 150 ) to push the upper end ( 150 ) against the mechanical stop ( 174 ), wherein the shaft ( 154 ) extends through both springs ( 162 , 164 ) and through the aperture ( 160 ) in the elongate sensor arm ( 112 ), and is supported at a first end and at the second end on housing ( 152 );

a bracket ( 106 ) configured to be fixed to a plastic point ( 100 ), and being also configured to support an upper portion of the reversing joint ( 114 ) for relative rotational movement about a laterally extending longitudinal axis ( 196 ); and

a rotary position sensor ( 116 ) coupled to bracket 106 and coupled to reversing joint ( 114 ) such that movement of the reversing joint ( 114 ) with respect to the rotary position sensor ( 116 ) causes an electrical signal from rotary position sensor ( 116 ) to change as a function of the relative rotation.

2. The header height sensor of claim 1 , where in the aperture ( 160 ) is oblong to permit the sensor arm ( 112 ) to move laterally at its lower end without breaking.

3. The header height sensor of claim 1 , wherein the sensor arm ( 112 ) is rigid.

4. The header height sensor of claim 1 , wherein the sensor arm ( 112 ) comprises a first beam member ( 118 ) having the aperture ( 160 ), and a second beam member ( 122 ) adjustably fixed to the first beam member ( 118 ) to vary the overall length of the sensor arm 112 .

5. The header height sensor of claim 4 , wherein the first beam member ( 118 ) includes ribs to stiffen the first beam member ( 118 ).

6. The header height sensor of claim 4 , wherein the second beam member is comprised of steel or cast-iron.

7. The header height sensor of claim 4 , further comprising at least one removable fastener fastening the first beam member ( 118 ) to the second beam member ( 122 ).

8. The header height sensor of claim 1 , where in the sensor arm ( 112 ) comprises a steel or iron weight to bias sensor arm ( 112 ) downward against the ground.

9. The header height sensor of claim 1 , further comprising the plastic point having a forward end with a metal tip 104 fixed thereto, wherein the header height sensor is fixed by the bracket 106 to the forward end.

10. The header height sensor of claim 9 , wherein the plastic point has a downwardly opening cavity 110 configured to receive the header height sensor without internal interference when the metal tip is on the ground.

11. The header height sensor of claim 1 , wherein the sensor arm is not curved or flexible.

12. The header height sensor of claim 4 , wherein the second beam member engages the ground during operation in the field and not the first beam member.

13. The header height sensor of claim 4 , wherein the first beam member has an elongate rigid U-shaped construction and is formed of plastic.