Security lock and key
US4040279A · kind A · utility
Inventors
Key dates
| Filing date | Oct 4, 1976 |
| Grant date | Aug 9, 1977 |
| Priority date | — |
| Expiry date | Oct 4, 1996 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T70/7949
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
Attempts to pick the plunger-type (barrel) lock disclosed are frustrated by the necessity of holding one axially movable part in place against the force of a spring while retracting another axially movable member to open the lock. The key that opens the lock has a central pin stationary in use for holding back a position while radially spreading fingers frictionally engage and thereby permit withdrawal of an axially movable cylinder coaxial with the piston. A frangible member is provided for installing the lock without using the special key so that the number of keys can be strictly controlled. The key will open not only the lock of this invention, but also other kinds of plunger-type locks in common use by gas and electric utility companies.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.