Weigh sensed lift truck forks

• US 6,730,861 B1
• Filed: 11/06/2000
• Issued: 05/04/2004
• Est. Priority Date: 11/04/1999
• Status: Expired due to Fees

• Current Assignee: Weigh Point Incorporated
• Original Assignee: Weigh Point Incorporated
• Inventors: Simons, Gerald S.
• Primary Examiner(s): GIBSON, RANDY W
• Application Number:
  US09/705,798
• Time in Patent Office: 1,275 Days
• Field of Search: 177/136, 177/139, 177/141, 177/140, 177/154, 177/155, 177/156
• US Class Current: 177/136
• CPC Class Codes: B66F 17/003 for fork-lift trucks
• CPC Class Codes: B66F 9/12 Platforms; Forks; Other load supporting or gripping members
• CPC Class Codes: G01G 19/083 lift truck scale

Abstract

Weigh sensed lift truck forks in which each standard fork is modified to accept an assembly including load sensing cells, spacers and a fork cover. Each cover provides protection for load cells affixed through spacers between the fork and fork cover, standard fork tip functionality and a load bearing surface and structure that interfaces through the spacers with the load cells and fork subassembly to provide accurate load weight data. The design of the components and method of their assembly result in improved manufacturing efficiency and cost effectiveness, easier installation, improved load weighing functionality, improved structural robustness, easier servicing and improved safety.

Claims

1. Weigh sensed lift truck forks used in pairs, each half of said pair comprising:

(a) a standard fork as used on lift trucks with its tip removed, the said standard fork being further modified to provide attachment positions for reinforcing ribs that extend past the remaining front end of said standard fork;

(b) A load bearing cover with the modified tip removed from said standard fork affixed into a notch in the front end of said cover, the said cover being responsive to load weight thereon and lateral forces and providing the required full top and side surface coverage of said standard fork;

(c) at least one electronically matched load cell having an end that flexes in response to weight resulting from a load being positioned on the top surface of said cover to which said load cell is attached;

(d) fastener attaching flexing end of said load cell to underside of said cover;

(e) fasteners attaching non-flexing end of said load cell to said standard fork; and

(f) spacers through which said fasteners align, positioning the top surface of the flexing end of said load cell relative to the underside of said cover and, the non-flexing end of said load cell relative to said standard fork.

2. Weigh sensed lift truck forks according to claim 1 wherein said standard fork is modified with a machined channel along the center of its top surface into which said load cell is tightly affixed at its non-flexing end to the bottom surface of said channel having said spacers that provide limited bending space for the flexing end of the said load cell positioned between the underside of said load cell and the bottom surface of said channel.

3. Weigh sensed lift truck forks according to claim 2 wherein the positioning of said load cell above the bottom surface of said channel by means of said spacers allows room for downward bending action of flexing end of said load cell to provide weight sensing capability when said load cell is subjected to load weight regardless of the height of said standard fork.

4. Weigh sensed lift truck forks according to claim 3 wherein said the positioning of said load cell with said spacers ensures the flexing end of said load cell will bottom out on bottom surface of said channel to prevent further flexing of said load cell before load weight exceeds the functional limit of said load cells, thus providing vertical overload protection.

5. Weigh sensed lift truck forks according to claim 1 wherein said load cell is electrically connected to an appropriately mounted commercial display, sending a weight signal to such display during flexure of said load cell in response to a load weight positioned on the top surface of said cover, thus providing load weighing capability to said standard fork.

6. Weigh sensed lift truck forks according to claim 1 wherein the front tip of said standard fork is removed and modified for fitting into a notch in the front end of said cover by the removal of side sections leaving recessed faces along the rear vertical edges of said front tip, after which said front tip is affixed to the notch in the front end of said cover in a flush manner, forming a cover and cover tip that allows standard lift truck fork functionality while maintaining the load weighing capability of the invention.

7. Weigh sensed lift truck forks according to claim 6 wherein the remaining front end of said standard fork after the removal of said front tip, is further modified to interface with said cover tip by the removal of side sections leaving recessed faces along the front vertical edges of said standard fork to which reinforcing ribs are affixed in a flush manner, the said ribs providing structural reinforcement for said cover and cover tip where they extend past the remaining front end of said standard fork.

8. Weigh sensed lift truck forks according to claim 1 wherein said fastener attaching the flexing end of said load cell to said cover is not fully tightened and spacing is provided between any adjacent faces of said fastener, said spacer, said cover, said load cell, said fork, said cover tip and said reinforcing ribs allowing enough lateral movement between said components to provide lateral overload protection of said load cell when subjected to excessive lateral forces.

9. Weigh sensed lift truck forks according to claims 7 or 8 wherein the rear vertical surface of said cover tip and the front vertical surface of said standard fork are adjacent and will bottom out against each other before force applied to the front of said cover tip exceeds the functional limit of said load cells, thus providing further lateral overload protection from the front.

10. Weigh sensed lift truck forks according to claims 7 or 8 wherein the rear side vertical surface of said cover tip and inside vertical surfaces of said reinforcing ribs are adjacent and will bottom out against each other before force applied to either side of said cover exceeds the functional limit of said load cells, thus providing further lateral overload protection from the side.

11. Weigh sensed lift truck forks according to claim 8 wherein said spacing between said fastener, said spacer, said cover and upper portion of flexing end of said load cell prevents binding between the said assembly components that could adversely affect the readout accuracy of an attached load weight display.

12. Weigh sensed lift truck forks according to claim 8 wherein a tension pin is driven into aligned holes, one hole made through the head of said fastener and one hole made through the adjacent surface of said cover, thus creating a locking configuration and preventing further loosening of said partially tightened fastener that attaches the flexing end of said load cell to said cover.

13. Weigh sensed lift truck forks according to claim 1 wherein the said cover completely encloses the top and side surfaces of the said standard fork, maximizing the functional load weighing surface, increasing protection of internal assembly components from excessive loads and forces, and, in conjunction with electronically matched said load cell, making load positioning on the surface of said cover non-critical for accurate load weight measurement.

14. Weigh sensed lift truck forks according to claim 1 wherein said standard fork has upper and lower brackets affixed to its rear vertical face by which it attaches in a typical manner in pairs to a lift truck without the need for modifications or additional attachment components such as a secondary carriage, thus allowing proper positioning and balance between said standard fork and said lift truck, and improving safety during lifting, weighing and transport functions.

15. Weigh sensed lift truck forks according to claim 1 wherein the low profile of the load bearing surface of the invention assembly, facilitated by the integration of the said fork tip into the said cover, and the uniform surface of said cover enhance easy access of the load bearing surface under a typical standard pallet and loads with limited access space while still maintaining the load weighing capability of the invention.