Side-shift limiter

Abstract

A side shift limiting attachment for a material handing vehicle alerts the vehicles operator and restricts side shifting, lifting, tilting and/or rotation of the attachment when the side shift displacement is approaching or has reached a limit for a lift height.

We claim: 
     
       1. A system for limiting a lateral position of a load face for and associated with a material handling vehicle, the system comprising:
 (a) a lateral position sensor arranged to output a lateral position datum quantifying representative of a distance between a material handling vehicle lateral datum longitudinal centerline and a load face lateral datum; 
 (b) a height sensor arranged to output a height datum quantifying representative of a height of a vertical the load face datum relative to a surface supporting said material handling vehicle; and 
 (c) a controller arranged to receive said lateral position datum and said height datum and to output a first side shift control signal when said lateral position datum corresponds to a first side shift limit for at said height datum and output a second side shift control signal when said lateral position datum corresponds to a second side shift limit at said height datum, the first side shift limit having a magnitude greater than that of the second side shift limit relative to the longitudinal centerline, and each of the first and second side shift control signals restricting the lateral motion of the load face. 
 
     
     
       2. The system for limiting a lateral position of a load face for a material handling vehicle of  claim 1  further comprising a tilt sensor arranged to output a tilt datum quantifying an angle of said load face, said controller arranged to receive said tilt datum and output said side shift control signal when said lateral position datum corresponds to a side shift limit for said height datum and said tilt datum. 
     
     
       3. The system for limiting a lateral position of a load face for a material handling vehicle of  claim 1  further comprising a side shift indicator responsive to at least one of said first side shift control signal and said second side shift control signal to announce that said load face lateral datum corresponds to the respectively associated said side shift limit. 
     
     
       4. The system for limiting a lateral position of a load face for a material handling vehicle of  claim 3  wherein announcement that said load face lateral datum corresponds to said side shift limit the side shift indicator comprises an optical signal. 
     
     
       5. The system for limiting a lateral position of a load face for a material handling vehicle of  claim 3  wherein announcement that said load face lateral datum corresponds to said side shift limit the side shift indicator comprises an audible signal. 
     
     
       6. The system for limiting a lateral position of a load face for a material handling vehicle of  claim 3  further comprising a second side shift indicator responsive to a second side shift control signal output by said controller to announce that said load face lateral datum is proximate at least one of said first side shift limit and said second side shift limit. 
     
     
       7. The system for limiting a lateral position of a load face for a material handling vehicle of  claim 6  wherein announcement that said load face lateral datum corresponds to said side shift limit said side shift indicator comprises a first optical signal and said announcement that said load face lateral datum is proximate said side shift limit second side shift indictor comprises a second optical signal. 
     
     
       8. The system for limiting a lateral position of a load face for a material handling vehicle of  claim 6  wherein announcement that said load face lateral datum corresponds to said side shift limit said side shift indicator comprises a first audible signal and said announcement that said load face lateral datum is proximate said side shift limit second side shift indicator comprises a second audible signal. 
     
     
       9. The system for limiting a lateral position of a load face for a material handling vehicle of  claim 1  further comprising a side shift control responsive to where said first side shift control signal to restrict restricts a speed of lateral movement of said load face when said lateral position datum corresponds to said first side shift limit. 
     
     
       10. The system for limiting a lateral position of a load face for a material handling vehicle of claim  1  9wherein said side shift control responsive to said second side shift control signal blocks lateral movement of said load face when said lateral position datum corresponds to said side shift limit. 
     
     
       11. The system for limiting a lateral position of a load face for a material handling vehicle of  claim 9  further comprising a side shift indicator responsive to said first side shift control signal to announce that said load face lateral datum corresponds to said first side shift limit. 
     
     
       12. The system for limiting a lateral position of a load face for a material handling vehicle of  claim 11  wherein announcement that said load face lateral datum corresponds to said side shift limit said side shift indicator comprises an optical signal. 
     
     
       13. The system for limiting a lateral position of a load face for a material handling vehicle of  claim 11  wherein announcement that said load face lateral datum corresponds to said side shift limit said side shift indicator comprises an audible signal. 
     
     
       14. The system for limiting a lateral position of a load face for a material handling vehicle of  claim 11  further comprising a second side shift indicator responsive to a the second side shift control signal output by said controller to announce that said load face lateral datum is proximate said second side shift limit. 
     
     
       15. The system for limiting a lateral position of a load face for a material handling vehicle of  claim 14  wherein announcement that said load face lateral datum corresponds to said side shift limit said side shift indicator comprises a first optical signal and said announcement that said load face lateral datum is proximate said side shift limit second side shift indicator comprises a second optical signal. 
     
     
       16. The system for limiting a lateral position of a load face for a material handling vehicle of  claim 14  wherein announcement that said load face lateral datum corresponds to said side shift limit said side shift indicator comprises a first audible signal and said announcement that said load face lateral datum is proximate said side shift limit second side shift indicator comprises a second audible signal. 
     
     
       17. The system for limiting a lateral position of a load face for a material handling vehicle of  claim 9  wherein said side shift control permits permitting lateral movement of said load face to decrease a distance between said material handling vehicle lateral datum longitudinal centerline and said load face lateral datum when said lateral position datum corresponds to at least one of said first side shift limit and said second side shift limit. 
     
     
       18. The system for limiting a lateral position of a load face for a material handling vehicle of  claim 9  further comprising a rotator control responsive to said side shift control signal to interrupt rotation of said load face when said lateral position datum corresponds to at least one of said first side shift limit and said second side shift limit. 
     
     
       19. The system for limiting a lateral position of a load face for a material handling vehicle of  claim 1  further comprising a lifting control responsive to said side shift control signal to prevent increasing said height datum when said lateral position datum corresponds to said side shift limit. 
     
     
       20. The system for limiting a lateral position of a load face for a material handling vehicle of  claim 2  further comprising a tilting control responsive to said side shift control signal to prevent an increase in said tilt datum when said lateral position datum corresponds to said side shift limit. 
     
     
       21. A load handling attachment for a material handling vehicle, said load handling attachment comprising;
 (a) a load face defined by a load engaging member and movable laterally and vertically relative to said material handling vehicle; 
 (b) a lateral position sensor arranged to output a lateral position datum quantifying representative of a distance to a lateral load face datum from a reference position; 
 (c) a height sensor arranged to output a height datum quantifying representative of a distance between a load face height datum and a surface supporting said material handing vehicle; and 
 (d) a controller arranged to receive said lateral position datum and said height datum and operable according to a stored instruction to output a first side shift control signal when said lateral position datum exceeds a first side shift limit for at said height datum and selectively output a second side shift control signal when said lateral position datum exceeds a second side shift limit at said height datum, the second side shift limit different in magnitude from that of the first side shift limit, each of the first and second side shift control signals restricting the lateral motion of the load face. 
 
     
     
       22. The load handling attachment of  claim 21  further comprising a side shift control device to limit a speed of lateral displacement of said lateral load face datum in response to said first side shift control signal. 
     
     
       23. The load handling attachment of  claim 22  wherein said side shift control device prevents a lateral displacement of said lateral load face datum in response to said second side shift control signal. 
     
     
       24. The load handling attachment of  claim 23  wherein said side shift control device permits decreasing said lateral displacement of said lateral load face datum when increasing said lateral displacement is blocked. 
     
     
       25. The load handing attachment of  claim 21  further comprising a tilt sensor arranged to quantify an angular orientation of said load face, said controller arranged and operable according to a stored instruction to output said a respective one of the first side shift control signal and the second side shift control signal when said lateral position datum exceeds a side shift limit for said height datum at a predetermined angular orientation. 
     
     
       26. The load handling attachment of  claim 21  further comprising:
 (a) an actuator arranged to selectively rotate said load face; and 
 (b) a rotation control arranged to limit a speed of rotation of said load face in response to at least one of said first side shift control signal and a rotation control signal from said controller and said second side shift control signal. 
 
     
     
       27. The load handling attachment of  claim 21  further comprising an audible side shift indicator responsive to said side shift control signal to audibly annunciate that said lateral displacement of said load face is proximate a side shift limit. 
     
     
       28. The load handling attachment of  claim 21  further comprising a visual side shift indicator responsive to said side shift control signal to visually signal that said lateral displacement of said load face is proximate a side shift limit. 
     
     
       29. The load handling attachment of  claim 21  further comprising a lifting control device responsive to said side shift control signal to prevent an increase in said height datum when said lateral position datum exceeds a side shift limit for said height datum. 
     
     
       30. The load handling attachment of  claim 25  further comprising a tilting control device responsive to said side shift control signal to prevent a change in said angular orientation of said load face when said lateral position datum exceeds a side shift limit. 
     
     
       31. A method for limiting a lateral position of a load face for a material handling vehicle, the method comprising the steps of:
 (a) quantifying a distance between a material handling vehicle lateral datum and a load face lateral datum; 
 (b) quantifying a height of a vertical load face datum relative to a surface supporting said material handling vehicle; and 
 (c) limiting a the speed of at which lateral displacement of said load face datum when occurs whenever said distance between said material handling vehicle lateral datum and said load face lateral datum corresponds to exceeds a limit at said height datum. 
 
     
     
       32. The method of limiting the lateral position of a load face for a material handling vehicle of  claim 31  further comprising the steps of:
 (a) quantifying an angle of said load face; and 
 (b) further limiting said speed of lateral displacement when said distance between said material handling vehicle lateral datum and said load face lateral datum corresponds to a limit at said height datum and said angle of said load face. 
 
     
     
       33. The method of limiting the lateral position of a load face for a material handling vehicle of  claim 31  further comprising the step of displaying an optical signal when said distance between said material handling vehicle lateral datum and said load face lateral datum is proximate said limit. 
     
     
       34. The method of limiting the lateral position of a load face for a material handling vehicle of  claim 31  further comprising the step of annunciating an audible signal when said when said distance between said material handling vehicle lateral datum and said load face lateral datum is proximate said limit. 
     
     
       35. The method of limiting the lateral position of a load face for a material handling vehicle of  claim 31  further comprising the step of preventing an increase in said height of said vertical load face datum when said distance between said material handling vehicle lateral datum and said load face lateral datum corresponds to said limit. 
     
     
       36. The method of limiting the lateral position of a load face for a material handling vehicle of  claim 31  further comprising the steps of:
 (a) quantifying an angle of said load face; and 
 (b) preventing an increase in said angle of said load face when said distance between said material handling vehicle lateral datum and said load face lateral datum corresponds to said limit. 
 
     
     
       37. The system of claim 1 where the first side shift limit and the second side shift limit at said height datum are each predetermined prior to a time that the material handling vehicle engages a load.  
     
     
       38. The load handling attachment of claim 21 where the first side shift limit and the second side shift limit at said height datum are each predetermined prior to a time that the load handling attachment engages a load.  
     
     
       39. The method of claim 31 where the limit at said height datum is predetermined prior to a time that the material handling vehicle engages a load.