Fork level indicator with magnetic dampening means

• US 6,981,331 B1
• Filed: 07/30/2004
• Issued: 01/03/2006
• Est. Priority Date: 07/30/2004
• Status: Active Grant

• Current Assignee: John W. Poe Jr
• Original Assignee: John W. Poe Jr
• Inventors: Dungan, William L., Forrest, Paul B., Poe, John W. Jr.
• Primary Examiner(s): BENNETT, GEORGE B
• Application Number:
  US10/902,965
• Time in Patent Office: 522 Days
• Field of Search: 333/33, 333/44, 333/45, 333/91, 333/97, 334/02, 33D/IG.1
• US Class Current: 33/397
• CPC Class Codes: G01C 9/12 by using a single pendulum plumb lines G01C15/10
• CPC Class Codes: Y10S 33/01 Magnetic

Abstract

A magnetically damped fork level indicating device comprises a housing having a gauge section; an elongate indicator arm pivotally coupled to the housing, the arm having first and second sections disposed on opposite sides of the axis; a weight coupled to the indicator arm so as to cause the first section to assume a predetermined orientation with respect to level ground; wherein the indicator arm at least partially overlies the gauge section and wherein the relative position of the indicator arm and the gauge section indicate the relative angular relationship between the orientation of the forks and level ground; a dampening means comprising a first magnet associated with the arm and moveable therewith and a second magnet associated with the housing and spaced from the first magnet, the second magnet magnetically coupled to the first magnet so as to dampen oscillations of the arm.

Claims

1. A magnetically damped fork level indicating device for use with a forklift having a moveable mast with forks connected thereto to move therewith, said forklift having an operator seat location, comprising:

a housing having a gauge section facing generally toward the operator seat location;

an elongate indicator arm pivotally coupled to said housing for rotation about an axis generally perpendicular to said mast, wherein said indicator arm has a first section and a second section disposed on opposite sides of said axis;

a weight coupled to said indicator arm so as to cause said first section to assume a predetermined orientation with respect to level ground under the influence of gravity;

wherein said indicator arm at least partially overlies said gauge section and wherein the relative position of said indicator arm and said gauge section indicate the relative angular relationship between the orientation of the forks and level ground;

a dampening means for dampening oscillations of said indicator arm, said dampening means comprising a first magnet associated with said indicator arm and moveable therewith and a second magnet associated with said housing and spaced from said first magnet, said second magnet magnetically coupled to said first magnet so as to dampen oscillations of said indicator arm.

2. The device of claim 1 wherein said predetermined orientation with respect to level ground is generally parallel to level ground.

3. The device of claim 1 wherein said frame releaseably mounts to said mast.

4. The device of claim 1 wherein said second magnet comprises a magnetic strip.

5. The device of claim 4 wherein said second magnet comprises a magnetic strip attached to a rib disposed in said housing.

6. The device of claim 5 wherein said rib is convexly curved relative to said axis.

7. The device of claim 1 wherein said first and second sections are configured to counterbalance each other about said axis.

8. The device of claim 1 wherein said second magnet remains spaced from said first magnet by at least a minimum distance throughout the rotation of said indicator arm through an arc of at least ±

15°

about a neutral position, wherein said neutral position corresponds to the forks being substantially parallel with level ground.

9. The device of claim 1 wherein said first section of said indicator arm comprises a bend distal from said axis and a tip more distal from said axis than said bend;

said tip extending substantially parallel to said axis and overlying said cause section.

10. The device of claim 1 wherein said first section overlies an upper portion of said gauge section to indicate the forks are tilted upward with respect to level ground and wherein said first section overlies a lower portion of said gauge section to indicate the forks are tilted downward with respect to level ground.

11. The device of claim 1:

wherein said frame releaseably mounts to said mast;

wherein said second magnet comprises a magnetic strip attached to a rib disposed in said housing, said rib convexly curved relative to said axis;

wherein said first and second sections are of different lengths and configured to counterbalance each other about said axis;

wherein said second magnet remains spaced from said first magnet by at least a minimum distance throughout the rotation of said indicator arm through an arc of at least ±

15°

about a neutral position, wherein said neutral position corresponds to the forks being substantially parallel with level ground; and

wherein said first section overlies an upper portion of said gauge section to indicate the forks are tilted upward with respect to level ground and wherein said first section overlies a lower portion of said gauge section to indicate the forks are tilted downward with respect to level ground.

12. The device of claim 11 wherein said weight couples to said indicator arm via a snap-fit connection.

13. A magnetically damped fork level indicating device for use with a forklift having a moveable mast with forks connected thereto to move therewith, comprising:

a housing having a gauge section;

an elongate indicator arm pivotally coupled to said housing for rotation about an axis generally perpendicular to said mast, wherein said indicator arm has a first section and a second section disposed on opposite sides of said axis;

a weight coupled to said indicator arm so as to cause said first section to assume a predetermined orientation with respect to level around under the influence of gravity;

wherein said indicator arm at least partially overlies said gauge section and wherein the relative position of said indicator arm and said gauge section indicate the relative angular relationship between the orientation of the forks and level ground;

a dampening means for dampening oscillations of said indicator arm, said dampening means comprising a first magnet associated with said indicator arm and moveable therewith and a second magnet associated with said housing and spaced from said first magnet, said second magnet magnetically coupled to said first magnet so as to dampen oscillations of said indicator arm;

wherein said first and second sections are of different lengths.

14. The device of claim 13 wherein said first and second sections are configured to counterbalance each other about said axis.

15. A method of indicating the relative angle between the forks of a forklift and level ground, comprising:

mounting a housing to a mast of the forklift so that a gauge section of said housing faces generally toward an operator seat location of the forklift, said housing having an indicator arm rotatably coupled thereto for rotation about an axis, said indicator arm having a weight coupled thereto so as to cause a first section of said indicator arm to assume a predetermined orientation with respect to level ground under the influence of gravity;

damping oscillations of said arm relative to said housing via the magnetic interaction of a first magnet associated with said arm and a second magnet associated with said housing, said magnets separated by a gap.

16. The method of claim 15 wherein at least one of said first and second magnets are strip magnets.

17. The method of claim 15 wherein said indicator arm has first and second sections disposed on opposite sides of said axis, wherein said first and second sections are of different lengths and configured to counterbalance each other about said axis.

18. The method of claim 15 wherein said second magnet remains spaced from said first magnet by at least a minimum distance throughout the rotation of said indicator arm through an arc of at least ±

15°

about a neutral position, wherein said neutral position corresponds to the forks being substantially parallel with level ground.

19. The method of claim 15 further comprising indicating that the forks are tilted upward with respect to level ground by having said first section overlies an upper portion of a gauge section and indicating that the forks are tilted downward with respect to level ground by having said first section overlies a lower portion of said gauge section.

20. The method of claim 15 further comprising removing said housing from said mast and remounting said housing to another mast of the same forklift such that said housing is coupled to the new mast at a different portion of the housing.