US4025140A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Locking device for the prongs of an electrical plug
Assignee: Tula Machine Co Inc
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Filing: 1975-11-28
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Granted: 1977-05-24
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Expires: 1995-11-28
Abstract
Abstract In one embodiment a protective housing adapted to be locked upon and cover a prong of an electrical plug is disclosed. The housing has a chamber to receive a prong of the plug and has a collared recess and threaded bore on one side communicating with the chamber to receive a lock screw that impinges upon the prongs. The head of the lock screw is guidably received in the collared recess and has a side slot. A key is provided with a tab at one end that engages the slot and the collared recess allows the key to turn the lock screw to and from its locked position against the prong. In another embodiment a lock screw with a slotted head and key therefor is described wherein the bottom contour of the slot is provided with convolutions conforming with the extended end edge of the blade of a key therefore adapted to turn the lock screw within a housing to impinge the end of the screw against the prong of an electrical plug thereby holding the housing over the prongs so that unintentional connection to an outlet is prevented.
Inventors
- 👤 Edwin J. Matys
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 14:42
CPC Classifications
H; H01; H01R; H01R13/00; H01R13/44; H01R13/447; H01R13/60; Y; Y10; Y10S; Y10S411/00; Y10S411/919
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
168 words
A locking device to cover a prong of an electrical plug and prevent inadvertent use comprising: a housing defining a chamber opening to one side thereof and adapted to receive and cover a prong of an electrical plug; said housing having a collared recess on a second side adjacent said one side; a threaded bore extending from said recess into communication with said chamber; a locking screw engageable within said threaded bore for pressure contact with said prong within said chamber; said locking screw having a head portion guidably received within said collar; said head portion having an outer face and a slotted side; and a key member having a shank portion with an end matable with the face of said head portion of said locking screw and a tab portion receivable in said slotted side whereby upon engagement of said key member with said head portion of said locking screw allows said locking screw to be turned into and out of said pressure contact with said prong.
Claim 2
Dependent Claim
168 words
A locking device to cover a prong of an electrical plug and prevent inadvertent use comprising: a housing defining a chamber opening to one side thereof and adapted to receive and cover a prong of an electrical plug; said housing having a collared recess on a second side adjacent said one side; a threaded bore extending from said recess into communication with said chamber; a locking screw engageable within said threaded bore for pressure contact with said prong within said chamber; said locking screw having a head portion guidably received within said collar; said head portion having an outer face and a slotted side; and a key member having a shank portion with an end matable with the face of said head portion of said locking screw and a tab portion receivable in said slotted side whereby upon engagement of said key member with said head portion of said locking screw allows said locking screw to be turned into and out of said pressure contact with said prong.
Claim 3
Dependent Claim
43 words
A locking device in accordance with claim 1 in which: said head portion has an outer contoured face; and said shank portion of said key member has a contoured end matable with the contoured face of said head portion of said locking screw.
Claim 4
Dependent Claim
44 words
A locking device in accordance with claim 1 in which: said head portion has an outer conical face; and said shank portion of said key member has a conical contoured end matable with the contained face of said head portion of said screw member.
Claim 5
Dependent Claim
99 words
A locking device in accordance with claim 1 in which: said housing defines a second open-ended chamber having an outer wall and an internal wall between said first and second chambers adapted to receive and cover a second prong of an electrical plug; and the lateral distance between one side of said internal wall defining said first chamber and the inside of said outer wall is substantially the same as the lateral spacing of said prongs whereby the pressure contact of said locking screw upon said one prong forces the respective prongs against the inner sidewalls of said chambers.
Claim 6
Dependent Claim
186 words
A locking device to cover the prongs of an electrical plug and prevent inadvertent use comprising: a housing defining a pair of adjoining substantially perpendicular sidewalls; a pair of chambers extending through one of said sidewalls adapted to receive and cover the prongs of an electrical plug; a threaded bore extending through the other sidewall in communication with one of said chambers and having a collared recess at the other end; a locking screw engageable within said threaded bore and having a head portion guidably received by said collared recess; said head portion having an outwardly facing conical end; a key slot in said conical end, said slot having its longitudinal axis extending in a line diametrically through the apex of said conical end; said key slot having a contoured bottom defining a central protuberance and a straight walled side portion opening to the base of said head portion; and a key member having a shank portion; said shank portion terminating in a contoured edge matable with the contoured bottom of said slot and having a tab mating with said open side portion of said slot.
Claim 7
Dependent Claim
186 words
A locking device to cover the prongs of an electrical plug and prevent inadvertent use comprising: a housing defining a pair of adjoining substantially perpendicular sidewalls; a pair of chambers extending through one of said sidewalls adapted to receive and cover the prongs of an electrical plug; a threaded bore extending through the other sidewall in communication with one of said chambers and having a collared recess at the other end; a locking screw engageable within said threaded bore and having a head portion guidably received by said collared recess; said head portion having an outwardly facing conical end; a key slot in said conical end, said slot having its longitudinal axis extending in a line diametrically through the apex of said conical end; said key slot having a contoured bottom defining a central protuberance and a straight walled side portion opening to the base of said head portion; and a key member having a shank portion; said shank portion terminating in a contoured edge matable with the contoured bottom of said slot and having a tab mating with said open side portion of said slot.
Claim 8
Dependent Claim
51 words
A locking device in accordance with claim 5 in which: said contoured bottom of said slot in said head portion includes at least one depression spaced from the center and sides of said locking screw head and said central protuberance extends to and defines said central apex of said head portion.
Claim 9
Dependent Claim
40 words
A locking device in accordance with claim 5 in which: said contoured bottom of said slot includes at least a pair of indentations having arcuate outside walls and angular inside walls terminating at the central protuberance of said lock screw.
Claim 10
Dependent Claim
29 words
A locking device in accordance with claim 5 in which: said contoured bottom of said slot includes at least a pair of arcuate indentations and an arcuate central protuberance.
Claim 11
Dependent Claim
27 words
A locking device in accordance with claim 5 which: said contoured bottom of said slot includes at least a pair of arcuate protuberances with pointed depressions therebetween.
Claim 12
Dependent Claim
28 words
A locking device in accordance with claim 5 in which: said contoured bottom includes protuberances which extend into coincidence with the top surface of said screw head portion.
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) | 1980-05-23 | 1980-11-22 | 1981-05-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-05-23 | 1984-11-22 | 1985-05-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-05-23 | 1988-11-22 | 1989-05-24 | $7700.00 | Window Closed / Lapsed |