Additional locking system for combination lock
US4222251A · kind A · utility
Assignees
Inventor
Key dates
| Filing date | Sep 8, 1978 |
| Grant date | Sep 16, 1980 |
| Priority date | — |
| Expiry date | Sep 8, 1998 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T70/7915
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
An additional locking system is provided for a combination lock. The combination lock includes a housing, a locking mechanism and a bolt in the housing movable between a first position projecting out of the housing and a second position generally withdrawn in the housing. The bolt can be moved to the second position only when the locking mechanism is in an unlocked condition. The additional locking system provides an additional lock for the bolt in the first position, and a heat responsive member prevents the additional locking system from locking the bolt until the housing is heated above a predetermined temperature. The additional locking system includes a spring with an arm thereon in the housing. The bolt includes a slot and the spring is mounted such that the arm is adjacent the slot, and the spring biases the arm toward the slot. The heat responsive member is a fuse in the housing urging the spring against the biasing to hold the arm out of the slot. When the fuse is melted when heat above a predetermined temperature is applied to the housing, the fuse no longer holds the spring against the biasing so that the spring can move the arm into the slot.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.