Timer setting mechanism for mechanical dereefer

1. A setting mechanism for a triggering device having a body and employing a rotating part to define a triggering point corresponding to a particular rotational position of said rotating part relative to said body, said setting mechanism comprising:

a knob fixed to said rotating part for rotation therewith;

a selector carried by said knob, said selector selectively fixable relative to said knob in a plurality of alternative positions to radially project from said knob at different angles; and

at least one start abutment disposed in fixed relationship to said body to intersect a rotational path of said selector,

wherein the selector is fixed in a position selected from said plurality of alternative positions and said knob is rotated to bring said selector to bear against said start abutment to define a selected rotational period for said knob between said start abutment and said triggering point.

2. The setting mechanism of claim 1 , comprising a plurality of start abutments, wherein each start abutment in combination with a selector fixed in a position selected from said plurality of positions, defines a different rotational period for said knob.

3. The setting mechanism of claim 2 , wherein only one of said plurality of selector positions is compatible with each said start abutment.

4. The setting mechanism of claim 1 , wherein said rotational period is representative of a selected period of time.

5. The setting mechanism of claim 1 , wherein said rotating part is a shaft and said knob is fixed to said shaft for rotation therewith.

6. The setting mechanism of claim 1 , wherein said start abutment is defined by an arcuate wall partially coaxially surrounding said knob.

7. The setting mechanism of claim 6 , comprising a plurality of said arcuate walls defining a plurality of start abutments, wherein each start abutment in combination with a selector fixed in a position selected from said plurality of positions, defines a different rotational period for said knob.

8. The setting mechanism of claim 7 , wherein each said arcuate wall defines a hole and said knob defines a plurality of apertures such that one aperture aligns with one of the holes when said selector is positioned against each said start abutment.

9. The setting mechanism of claim 6 , wherein said arcuate wall defines a hole, said knob defines a complementary aperture and said hole and said aperture align when said selector is against said start abutment.

10. The setting mechanism of claim 1 , wherein said selector pivots diametrically across said knob.

11. The setting mechanism of claim 1 , comprising two arcuate walls that partially coaxially surround said knob, said arcuate walls each defining one said start abutment and wherein said selector pivots diametrically across said knob and said plurality of available positions comprises two diametrically opposed positions, only one of said diametrically opposed positions being compatible with each said start abutment to define two different rotational periods for said knob.

12. A setting mechanism for a trigger in which a predefined rotational position of a rotating part relative to a trigger body designates a trigger position, said setting mechanism comprising:

a knob fixed to said rotating part for rotation therewith;

selector means for radially projecting from said knob in a selected one of a plurality of angularly spaced directions; and

start abutment means for defining at least one start abutment fixed relative to said trigger body and positioned to intersect a path of said selector means during rotation of said rotating part,

wherein the selected angular direction of said selector means and the position of said start abutment means relative to said trigger position together define a selected rotational period for said rotating part.

13. The setting mechanism of claim 12 , wherein said at least one start abutment means comprises a plurality of start abutments, each said start abutment compatible with a selected angular direction to define a plurality of alternatively selectable rotational periods for said rotating part.

14. The setting mechanism of claim 13 , wherein the knob defines a plurality of apertures and each said start abutment comprises a start face of an arcuate wall defining a hole and partially surrounding the knob, one said hole aligning with one said aperture for a knob position corresponding to the selector abutting a start face.

15. The setting mechanism of claim 12 , wherein said trigger is a timer.

16. The setting mechanism of claim 12 , wherein said knob comprises at least one radial slot and said selector means comprises a lever alternatively positionable in said at least one radial slot.

17. The setting mechanism of claim 16 , wherein said at least one radial slot comprises two diametrically opposed slots and said lever pivots diametrically across the knob.

18. The setting mechanism of claim 12 , wherein said start abutment means comprises a start face on an arcuate wall partially surrounding said knob.

19. A setting mechanism for a timer having a timer body and employing a rotating part to select a time duration by rotation relative to the timer body of the rotating part in a first direction away from a time out position and measuring the selected duration by controlled rotation of said rotating part counter to said first direction back to said time out position, said setting mechanism comprising:

a knob fixed to said rotating part for rotation therewith, said knob having a rest position corresponding to said time out position;

a selector carried by said knob, said selector selectively fixable to radially project from said knob at one of a plurality of anglular displacements relative to said rest position; and

a plurality of arcuate wall segments partially surrounding the knob in substantially coaxial relationship thereto to define a plurality of arcuate paths of different lengths between said wall segments,

wherein one of said plurality of angular displacements is compatible with each of said arcuate paths to define a rotational period corresponding to movement of said selector along said arcuate path, the length of said arcuate path corresponding to a predetermined time duration.

20. The setting mechanism of claim 19 , wherein said plurality of arcuate wall segments comprises two arcuate wall segments defining two arcuate paths and said selector comprises a lever that pivots diametrically across said knob.

21. The setting mechanism of claim 20 , wherein each said wall segment comprises a start face and defines a hole and said knob defines an aperture complementary to each hole such that one said hole and its complementary aperture align when the knob is in a position corresponding to the selector abutting a start face.