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On the Construction of Locks and Keys by John Chubb
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CONSTRUCTION OF LOCKS AND KEYS. 13
sliders. B is a thin plate fixed in the lock, through which the barrel, or frame A passes, and is prevented from turning for the purpose of moving the bolt, by the projecting parts of the sliders that move in the fixed plate B, till the notches in each of them are, by the application of the correspondent part of the key, pushed into contact, or in a line with the plate A. At the end of each slider, in the cylindrical parts C C C &c., is fixed a spiral spring, which always restores them after the key is withdrawn, similar to A B C &c., by their own gravity."
It will be observed, that in Bramah's lock, a compound of both endway pushing and revolving motion is given to the key, instead of the simple rotatory movement of Barren's lock.
For many years, indeed until the present time, both Barren's and Bramah's locks have maintained their ground, which is owing, in a great degree, to the care and attention paid to their manufacture, by the original makers and their successors. Those who are practically acquainted with the inconvenience resulting from the ordinary locks, which are generally very badly made, will appreciate the advantage of a well-made and properly-acting lock on either of the principles now described.
The original patent for Chubb's lock was taken out in the year 1818, by Jeremiah Chubb; this has been improved upon by the successive patents of Charles Chubb, in 1824; by Charles Chubb and Ebenezer Hunter, in 1833; by John Chubb, in 1846; and by John Chubb and Ebenezer Hunter, in 1847.
It will be sufficient to describe the last-patented lock, which, while retaining the peculiarities of the former inventions, has received such modifications and improvements as were, in practice, found to be necessary.
It may here be stated, in order to render the drawing more intelligible, that Chubb's lock consists of six separate and distinct double-acting tumblers, with the addition of a "detector," by which any attempt to pick, or open the lock, by a false key. is immediately notified on the next application of its own key. The detector is the great and peculiar feature by which Chubb's lock is so well known.
Fig. 6 gives a representation of a lock made on this principle. A is the bolt, B the square stud riveted into, and forming part of the bolt; C are the tumblers, six in number, moving on the centre pin D, placed one over the other, but perfectly separate and distinct, so as to allow all of them to be elevated to different heights. E is a divided spring, forming six separate springs, pressing upon the ends of the six tumblers. F is the detector-spring. It will be observed,
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On the Construction of Locks and Keys by John Chubb