Patent US3734325A successfully refreshed from Google Patents.
US3734325A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Safety interlock for fluid-operated, load-handling apparatus
Assignee: DW Zimmerman Manufacturing Inc
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Filing: 1971-03-31
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Granted: 1973-05-22
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Expires: 1991-03-31
Abstract
Abstract Load-handling apparatus is provided which includes a safety interlock to prevent the disengagement of a load when the apparatus is in an operative condition to balance or raise the load. The apparatus includes a fluid-operated hoist and a fluidoperated, load-engaging unit. A blocking valve is provided which is responsive to pressure of fluid for the hoist, which valve presents the load-engaging unit from disengaging the load when the pressure is at least equal to a predetermined value which is usually sufficient to at least balance the load.
Inventors
- 👤 C Stone
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 01:45
CPC Classifications
B; B66; B66C; B66C1/00; B66C1/10; B66C1/42; B66C1/44; B66C1/54; B66C1/02; B66C1/0212; B66C1/0218; B66C1/0237; B66C1/0243; B66C1/0256; B66D; B66D3/00; B66D3/12; B66D2700/00; B66D2700/02; B66D2700/023
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
196 words
Apparatus for handling loads comprising a fluid-operated hoist including a hoist chamber, a flexible member, and a piston in said chamber for raising and lowering the flexible member in response to pressure of fluid in said chamber, a load-handling unit connected to said flexible member, fluid-operated engaging means carried by said load-handling unit for engaging and disengaging a load, a hand-controlled valve remotely positioned from said fluid-operated hoist for controlling pressure of fluid in said chamber, said valve having at least two positions, the chamber pressure being at one value when said valve is in one position and the chamber pressure being at a higher value when said valve is in the other position, a manually-operated Valve for supplying fluid under pressure to said fluid-operated engaging means to cause said engaging means to disengage a load carried thereby, and a pressure-responsive valve communicating with said fluid-operated engaging means and responsive to the pressure of fluid in said hoist chamber, said pressure-responsive valve being closed when said hand-operated valve is in the other position, said pressure-responsive valve, when closed, preventing operation of said fluid-operated engaging means to disengage the load even when said manually-operated valve is opened.
Claim 2
Dependent Claim
196 words
Apparatus for handling loads comprising a fluid-operated hoist including a hoist chamber, a flexible member, and a piston in said chamber for raising and lowering the flexible member in response to pressure of fluid in said chamber, a load-handling unit connected to said flexible member, fluid-operated engaging means carried by said load-handling unit for engaging and disengaging a load, a hand-controlled valve remotely positioned from said fluid-operated hoist for controlling pressure of fluid in said chamber, said valve having at least two positions, the chamber pressure being at one value when said valve is in one position and the chamber pressure being at a higher value when said valve is in the other position, a manually-operated Valve for supplying fluid under pressure to said fluid-operated engaging means to cause said engaging means to disengage a load carried thereby, and a pressure-responsive valve communicating with said fluid-operated engaging means and responsive to the pressure of fluid in said hoist chamber, said pressure-responsive valve being closed when said hand-operated valve is in the other position, said pressure-responsive valve, when closed, preventing operation of said fluid-operated engaging means to disengage the load even when said manually-operated valve is opened.
Claim 3
Dependent Claim
23 words
Apparatus according to claim 1 characterized further by a pilot fluid-controlled regulator and a first line connecting the regulator with said hand-controlled valve.
Claim 4
Dependent Claim
48 words
Apparatus according to claim 2 characterized by said hand-controlled valve having a third position with the chamber pressure being at a still higher value when said hand-controlled valve is in the third position, said pressure-responsive valve also being closed when said hand-controlled valve is in the third position.
Claim 5
Dependent Claim
175 words
Apparatus for handling loads comprising a fluid-operated hoist including a chamber, a flexible member, and means for raising and lowering the flexible member in response to fluid pressure in said chamber, a load-handling unit connected to said flexible member, said unit comprising at least one vacuum cup, means for establishing a vacuum in said cup, a valve for controlling pressure of fluid in said chamber, said valve having at least two positions, the chamber pressure being at one value when said valve is in one position and the chamber pressure being at a higher value when said valve is in another position, a manually-operated valve communicating with said vacuum cup and effective to destroy the vacuum in said cup when said manually-operated valve is opened, a pressure-responsive valve interposed between said vacuum cup and said manually-operated valve to render said manually-operated valve ineffective when said pressure-responsive valve is closed, and means connecting said pressure-responsive valve with the hoist chamber to cause said pressure-responsive valve to close when the chamber pressure is at the higher value.
Claim 6
Dependent Claim
175 words
Apparatus for handling loads comprising a fluid-operated hoist including a chamber, a flexible member, and means for raising and lowering the flexible member in response to fluid pressure in said chamber, a load-handling unit connected to said flexible member, said unit comprising at least one vacuum cup, means for establishing a vacuum in said cup, a valve for controlling pressure of fluid in said chamber, said valve having at least two positions, the chamber pressure being at one value when said valve is in one position and the chamber pressure being at a higher value when said valve is in another position, a manually-operated valve communicating with said vacuum cup and effective to destroy the vacuum in said cup when said manually-operated valve is opened, a pressure-responsive valve interposed between said vacuum cup and said manually-operated valve to render said manually-operated valve ineffective when said pressure-responsive valve is closed, and means connecting said pressure-responsive valve with the hoist chamber to cause said pressure-responsive valve to close when the chamber pressure is at the higher value.
Claim 7
Dependent Claim
39 words
Apparatus according to claim 4 characterized by said manually-operated valve including positive-pressure means for supplying fluid under positive-pressure to said vacuum cup when said manually-operated valve is open, said pressure-responsive valve preventing the supply of the fluid, when closed.
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) | 1976-05-21 | 1976-11-20 | 1977-05-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-05-21 | 1980-11-20 | 1981-05-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-05-21 | 1984-11-20 | 1985-05-22 | $7700.00 | Window Closed / Lapsed |