Weighing device for fork lift truck
First Claim
1. A weighing device for use with a fork lift truck and the like having forks to lift loads comprising:
- a stationary plate mounted to the fork lift truck, a moveable plate, first flexure means mounted to the moveable and stationary plates to maintain the plates in substantially vertical parallel relationship, the forks being mounted to the moveable plate, the weight of loads introduced on the forks causing the moveable plate to be pulled vertically downwardly, load cell means interposed between the stationary and moveable plates, second and third flexure means coupled to opposite ends of the load cell means, first and second mounting means connecting the second and third flexure means to the stationary and moveable plates respectively, the second and third flexure means responding in equal and opposite direction to bending moments resulting from the cantilever effect caused by the location of loads on the forks from toe to heel to prevent the load cell means from being responsive to said cantilever effect, the load cell means being responsive to vertical tension forces transmitted thereto by loads under measurement on the forks to derive an accurate indication of the weight thereof.
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Accused Products
Abstract
A weighing system for use with a fork lift truck and the like having a stationary plate mounted to the fork lift truck, a moveable plate, the forks of the fork lift truck being mounted thereto, and flexure elements mounted to the stationary and moveable plates to maintain said plates in substantially vertical parallel relationship. A load cell is coupled at one end through flexure means to the stationary plate, and at its other end through additional flexure means to the moveable plate, the moveable plate being pulled vertically downwardly when a load is placed on the forks to thereby put the load cell in tension. The load cell comprises a strain gauge which converts the tension forces applied thereto as a result of downward movement of the moveable plate to a proportionate electrical signal, that is converted to a visual indication of the weight under measurement on the forks. Overload stop means are provided to limit the downward vertical movement of the moveable plate to prevent damage to the load cell, and structured to prevent overloads from pulling the moveable plate away from the stationary plate, which in conjunction with the flexure elements previously described prevents undue strain from being applied to the weighing structure and particularly the load cell. Additional stop means are provided to inhibit materials which might be caught underneath the forks from pushing the forks upwardly to prevent corresponding movement of the moveable plate from damaging the load cell.
26 Citations
15 Claims
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1. A weighing device for use with a fork lift truck and the like having forks to lift loads comprising:
- a stationary plate mounted to the fork lift truck, a moveable plate, first flexure means mounted to the moveable and stationary plates to maintain the plates in substantially vertical parallel relationship, the forks being mounted to the moveable plate, the weight of loads introduced on the forks causing the moveable plate to be pulled vertically downwardly, load cell means interposed between the stationary and moveable plates, second and third flexure means coupled to opposite ends of the load cell means, first and second mounting means connecting the second and third flexure means to the stationary and moveable plates respectively, the second and third flexure means responding in equal and opposite direction to bending moments resulting from the cantilever effect caused by the location of loads on the forks from toe to heel to prevent the load cell means from being responsive to said cantilever effect, the load cell means being responsive to vertical tension forces transmitted thereto by loads under measurement on the forks to derive an accurate indication of the weight thereof.
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2. The weighing device recited in claim 1 wherein the second and third flexure means each comprises structural rods.
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3. The weighing device recited in claim 1 further comprising overload means preset to limit the vertical downward movement of the moveable plate to prevent damage to the load cell means due to overloading the forks.
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4. The weighing device recited in claim 1 wherein the load cell means comprises:
- first and second combinations of a load cell with second and third flexure means connected to opposite ends thereof interposed and connected between the stationary and moveable plates respectively, the first and second combinations being located at the opposite sides of the weighing device formed by the stationary and moveable plates.
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5. The weighing device recited in claim 1 wherein the first flexure means comprise four individual flexure elements mounted to the stationary and moveable plates at the four side corners formed thereby and means to adjust the four individual flexure elements prior to rigidly mounting same to obtain accurate weight measurements.
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6. The weighing device recited in claim 2 further comprising overload means preset to limit the vertical downward movement of the moveable plate to prevent damage to the load cell means due to overloading the forks.
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7. The weighing device recited in claim 6 wherein the overload means are further operative to prevent the moveable plate from being pulled away from the stationary plate due to overloads on the forks to prevent damage to the load cell means.
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8. The weighing device recited in claim 7 further comprising stop means operative to limit The vertically upward movement of the forks in the event materials are caught thereunder to prevent damage to the load cell means.
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9. The weighing device recited in claim 3 wherein the overload means are further operative to prevent the moveable plate from being pulled away from the stationary plate due to overloads on the forks to prevent damage to the load cell means.
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10. The weighing device recited in claim 9 further comprising stop means operative to limit the vertically upward movement of the forks in the event materials are caught thereunder to prevent damage to the load cell means.
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11. The weighing device recited in claim 5 wherein the second and third flexure means each comprises structural rods.
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12. The weighing device recited in claim 11 wherein the load cell means comprises:
- first and second combinations of a load cell with second and third flexure means connected to opposite ends thereof interposed and connected between the stationary and moveable plates respectively, the first and second combinations being located at the opposite sides of the weighing device formed by the stationary and moveable plates.
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13. The weighing device recited in claim 12 further comprising overload means preset to limit the vertical downward movement of the moveable plate to prevent damage to the load cell means due to overloading the forks.
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14. The weighing device recited in claim 13 wherein the overload means are further operative to prevent the moveable plate from being pulled away from the stationary plate due to overloads on the forks to prevent damage to the load cell means.
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15. The weighing device recited in claim 14 further comprising stop means operative to limit the vertically upward movement of the forks in the event materials are caught thereunder to prevent damage to the load cell means.
Specification