Patent US4599645A successfully refreshed from Google Patents.
Patent US4074794A successfully refreshed from Google Patents.
US4074794A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Height indicator and control for fork lift trucks
Assignee: Caterpillar Industrial Inc
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Filing: 1975-10-31
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Granted: 1978-02-21
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Expires: 1995-10-31
Abstract
Abstract Electrically operated means for indicating the fork height on a fork lift truck are shown. Heights less than a predetermined minimum are not shown in order to provide a better indication at heights which are difficult for the operator to estimate. Control means are also shown for automatically stopping the forks at a height presettable by digital and by analog means.
Inventors
- 👤 Rolland D. Scholl
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 14:30
CPC Classifications
G; G05; G05B; G05B19/00; G05B19/02; G05B19/18; G05B19/19; G05B19/21; G05B19/23; G05B19/238; B; B66; B66F; B66F9/00; B66F9/06; B66F9/075; B66F9/0755; G05D; G05D3/00; G05D3/12; G05D3/20
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
160 words
Height control apparatus for fork lift trucks, comprising: a. signal-generating means operatively associated with the fork lifting mechanism of said fork lift truck to provide an electrical signal representative of actual fork height; b. presettable height selection means for producing a height selection signal; c. comparator means connected to said signal-generating means and said height selection means for comparing said actual fork height signal and said height selection signal; d. fork control means on said fork lift truck for raising and lowering said forks, said fork control means being normally biased into a fork stopping position but being releasably holdable in raising or lowering positions by locking means; e. electromagnetic means associated with said fork control means for releasing said locking means; and, f. means connecting said comparator means and said electromagnetic means for actuating said electromagnetic means to release said locking means when the actual height of said forks correspond to the height selected by said height selection means.
Claim 2
Dependent Claim
160 words
Height control apparatus for fork lift trucks, comprising: a. signal-generating means operatively associated with the fork lifting mechanism of said fork lift truck to provide an electrical signal representative of actual fork height; b. presettable height selection means for producing a height selection signal; c. comparator means connected to said signal-generating means and said height selection means for comparing said actual fork height signal and said height selection signal; d. fork control means on said fork lift truck for raising and lowering said forks, said fork control means being normally biased into a fork stopping position but being releasably holdable in raising or lowering positions by locking means; e. electromagnetic means associated with said fork control means for releasing said locking means; and, f. means connecting said comparator means and said electromagnetic means for actuating said electromagnetic means to release said locking means when the actual height of said forks correspond to the height selected by said height selection means.
Claim 3
Dependent Claim
61 words
The apparatus of claim 1, which includes a plurality of said presettable height selection means, and in which said fork control means include switch means operatively associated therewith, said switch means being arranged to connect one of said plurality of height selection means to said comparator means while said forks are being raised, and another while said forks are being lowered.
Claim 4
Dependent Claim
24 words
The apparatus of claim 2, further comprising selector switch means for selectively connecting different ones of said height selection means to said comparator means.
Claim 5
Dependent Claim
98 words
The apparatus of claim 1, in which said signal generating means include magnetic means arranged to move with said fork lifting mechanism, pick-up means located adjacent said fork lifting mechanism for generating electrical pulses upon movement of said magnetic means therepast, and pulse counting means arranged to count said pulses and provide a digital output representative of total pulse count; and in which said height selection means produce a selectable digital output which equals the output of said pulse counting means when the actual height of said forks corresponds to the height selected by said height selection means.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-02-20 | 1981-08-22 | 1982-02-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-02-20 | 1985-08-22 | 1986-02-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-02-20 | 1989-08-22 | 1990-02-21 | $7700.00 | Window Closed / Lapsed |