Lock (mechanism)

“ Every lever is under lock and key, each being a part of the key which unlocks some of the others, and each forming a part of the lock which secures some of the others against possible movement, while each is at the same time subject to the control of all those which are related to it.
"This result, complex and difficult as it seems, is achieved by mechanism of great simplicity and beauty. Immediately under the floor of the platform, and just in front of the levers, are arranged several series of vibrating and sliding bars, somewhat like the tumblers of a lock, placed horizontally. ”

“ The chief parts of a lock are: the bolt, its essential feature, the selvage, the plate which appears at the edge of the door or drawer, the box, which contains the mechanism including the tumbler, ward, spring, etc., the key-pin, into or around which the key is inserted, the strike, the plate attached opposite the selvage, (often left out as in drawer-locks, but essential in hook-bolt locks, and self-locking locks,) and the escutcheon, the plate around the keyhole.
Locks may be classified: (1) According to their uses, of which there are two types. (a) , Fig. ”

“ Of late years numerous locks have been invented for the special uses to which they are to be applied. Thus, one type of lock is that for safety deposit vaults and boxes, in which a primary key in the keeping of a janitor operates alone the tumblers or guard mechanism to set the lock, while the box owner may use a secondary key to completely unlock the box or vault. ”

“ These locks embody the most complicated mechanism, and represent the highest art of modern lock making. The architect in preparing plans of buildings for banks and trust companies is frequently called on to approve or to specify the fastenings for vault and safe doors. While the owners of such buildings will probably predetermine the kind of lock to be employed, nevertheless they will be guided by the advice of the architect in the selection of some particular make. ”

“ The constructing a key having a groove in its shank to receive the detector tumbler.”
fig. 46. Movable stump.
When the American locks became known in England, Mr. Hobbs undertook the superintendence of their manufacture, and their introduction into the commercial world. Such a lock as that just described must necessarily be a complex piece of mechanism; it is intended for use in the doors of receptacles containing property of great value; and the aim has been to baffle all the methods at present known of picking locks, by a combination of mechanism necessarily elaborate. ”

“ A very elaborate tumbler-lock, patented 23d February, 1790, by Mr. Rowntree, contrasts remarkably with the simplicity of Barron’s lock. Mr. Rowntree’s lock consisted of tumblers combined with revolving discs or wheels. Its mechanism may be understood from the following description and engravings. ”

“ In the specification of reissue No. 8,035, the following statements were made: 'The object of my invention is to construct a time-lock, and to combine it with the multiple sliding bolt-work of a safe or vault-door, so that, by the continuous movement of its time mechanism, locking and unlocking will be effected daily or periodically. * * * The gist of my invention, therefor, is the combination in a time-lock of time mechanism revolving a graduated dial, which serves to oscillate a pivoted bent lever. ”

“ His next remark on the subject is a sensible one: “Notwithstanding the large size of these locks, and all the apparatus with which they are provided, they correspond but ill with the solidity of the rest of the coffer. If we have given a representation of one, it is chiefly to shew how little confidence one could have in such a lock, and what are its defects, in order that we may avoid them.” It is not difficult, by tracing the action of the several levers, to see how one movement of the key, in the centre of the lid, would act upon all the bolts. ”

“ They have been too simple to require it, and too little varied to permit it. That some such fastenings must be employed wherever doors of any kind are used is sufficiently apparent; and there is a little (though only a little) information obtainable, which shews the nature of the fastenings adopted in early times. The bolt, the hasp, the chain, the bar, the latch, the lock, all were known, in one or other of their various forms, in those ages which we are accustomed to consider classical. Travellers, generally speaking, do not descend to locks, or rather they do not think about them ”

“ The springs, which by the turning of the key must be raised together with the tumblers, are attached to levers, and press upon the latter at their centre of gravity, in consequence of which all crowding towards either side is prevented, and the key can be turned with facility, in spite of the many combination parts which it has to raise; and the springs themselves are by their positions so little called into action, that their strength can never be impaired by use.
The lock has also another very complete arrangement in the detector-tumbler, which is attached to the cap or covering of the lock. ”

“ Unless, therefore, a method be contrived to bring the notches on the ends of the levers in a direct line with each other, and to retain them in that position till an exact impression of the irregular surface which the levers will then exhibit can be taken, the workman will in vain attempt to fit a key to the lock, or by any effort of art to move the bolt. ”

“ The outer rings are moved with the finger, so as to throw the various interior grooves out of a right line, and thus prevent the withdrawal of the spindle. As each ring may be turned round through a large or a small arc, and all turned in different degrees, the variations of relative position may be almost infinite. The letters on the outer rings are to assist the owner to remember the particular combination which he had adopted in the act of locking; for no other combination than this will suffice to open the lock. ”

“ The particular construction of my lock is that the two time movements rotate a graduated dial so arranged that its motion oscillates, at certain regular, determinable intervals, a pivoted bent lever, which in turn, in one instance, for automatic locking, lifts the free part of, and thus oscillates on its stationary pivot a metallic dog or obstruction, so as to cause it to rest in the way, and prevent the retraction, of the sliding bolt-work ”

“ The inner cylinder can then be turned, by which the bolt is locked or unlocked. If, by the use of a false key, any pin be pushed in too far, it will be as ineffectual in opening the lock as if it were not thrust in far enough; and some of these locks having been made with as many as forty pins, the chances are very numerous against the right combination being hit upon. There is a combination of something like the Egyptian with something like the Bramah lock, here attempted. ”

“ Then another ring which binds more than the rest is treated in a similar way; until at length all the rings seem to be so far liberated as to indicate that the notches are in the right positions. In the dial-lock, similarly, when a pressure has been brought to bear upon the bolt in the right direction, a trial of the pointers will soon bring the notch in each wheel to the required position. ”

“ When the key is inserted, and the fastening device thrown back, it will be seen that the rims of the wheels are held stationary by the key, while the centers may be turned to any different position by the spindle, thus setting the lock to a new combination. ”

“ These are very good little padlocks, with an excellent lever action, 'dogged against detent,' as the technical phrase goes; so that only the key properly made for each lock will open it. They are so good, indeed, as locks, that it would be a waste of time to try picking them, when, because of their small size, it is so very easy to break them apart, just as you have done yourself, and just as I could probably have done in half the time, having had rather more experience. Now that is what has been done with your lock by the person who has your bonds. ”

“ There are no machines more common than locks: they are sufficiently complex to merit the name of machine; but I know of no others the structure of which is so little understood by those who use them. It is rare to find any one who knows wherein the goodness of a lock consists, or the degree of security that he can attach to it. The outside of a lock is usually all that attracts attention. ”

“ Flint locks, whether as applied to the fowling-piece or the musket, will soon be forgotten, or remembered only to give a romantic interest to some tale of other times, as the arbalast and long-bow serve only to remind us of our Norman and Saxon ancestors! It requires some mechanical knowledge and some experience, to decide on the merit of a lock. ”

“ I do not state this circumstance as a point essential or of any importance to the purpose of the lock, but to prove more clearly what I have before observed upon its principle and properties; for if such difficulties occur to a skilled workman, as to render it almost, if not altogether impracticable to form a key when the lock is open to his inspection and its parts accessible to his hand, it pretty clearly demonstrates the impossibility of accomplishing it when no part of the movement can be touched or seen. ”

“ When a person who was outside wished to enter, it was necessary for him to insert the key in a little hole and to raise the bolt; and in time this species of fastening was improved by the insertion of the bolt in an iron frame or rim permanently attached to the door by a chain, and fastening the door by the insertion of the hasp, through the eye of which was forced the bolt inside the lock by applying the key. ”

“ And if it were possible to [26] collect all the by-gone specimens of lock-oddities, we should probably find among them many highly-ingenious letter-locks; for supposing a man to have a mechanical turn of mind, a lock is by no means an unworthy medium for displaying it; the pieces of metal are so small as to be easily manageable at a small work-bench in a small room. ”

“ With each of the dials are combined adjusting disks or arms, O, or some equivalent mechanical device, each of which carries a stud, or a pin or projection, which acts upon a yoke or lever, which connects with and guards the combination-lock the number of hours or time for which it is designated said lock is to remain locked, and thus controls the action of its lock-bolt or bearing while the same is in a locked condition. ”

“ By another contrivance it is rendered impracticable to move a pick or picks round in the lock more than a small distance, unless the tumblers could previously be all lifted to their right positions, which can only be done by the right key. ”

“ Opposite the center or hub, q, of each wheel, and located in the outer rim, I place a locking device or bolt, r, which, when forced in against the said center or hub, holds the same firmly in place with the outer rim; but, when thrown out, disengages said parts, and allows the centers to turn free while the rims remain stationary. Against the locking device or bolt, r, rests a cam or eccentric, s. Through each or all of these cams, and also through the back plate of the lock, is inserted a key, P, Fig. ”

“ If parties do not know your letters, nothing but violence, applied by some means or other, can enable them to get into your safe; for the lock will not open to any thing but its talisman. Take off all the large wheels and open the lock: you will see that the large wheels have a number of false chambers; if you get the spurs of the bolt into three real chambers and one false, you are as fast as ever, for all four must be right.
“Having placed your key and pointer outside the door to point to W on brass-plate No. ”

“ The stem, therefore, can be left by the principal of an establishment for locking up by a subordinate; but the bit, which is the essential part of the key required for opening the lock, need never be used or seen by any one but the principal himself. As the hole in the external door-plate for the stem of the key has a notch on one side only to admit the key stem, and the cylinder is prevented from making a complete revolution, the stem of the key cannot be withdrawn from the lock except when the bolt is shot ”

“ The simple fixed-guard or warded lock is so utterly worthless for security, no matter what amount of good workmanship be bestowed upon it, that it demands but short notice. It was contrived with the intention of making the passage to the bolt intricate; but it will be seen at once that this intricacy does not really offer any security. The wards of a lock are circular arcs of thin metal, so arranged as to require a key of peculiar pattern to pass amongst them, the shape of the cuts in the key being a section of the wards. ”

“ That a very large and strong lock on this construction only requires a very small key. 2. That no key is required to lock it, although it is free from the inconvenience pertaining to spring-locks, viz. that the door cannot be shut without locking itself. Moreover this lock is more secure than any spring-lock can be. 3. That it cannot get out of order from the usual causes of the tumblers sticking together or their springs breaking, inasmuch as the action of the tumblers does not depend on any thing but the key and the handle, and there are no tumbler-springs. ”

“ The walls of steel or iron which separate the security parts from the tumblers, and the cylinder which revolves with the key, present formidable barriers to all descriptions of pick-locks, and render the lock a most positive and reliable security. The tumblers consist of rolled very smooth steel plates, in which the fire-crust has not been filed away, partly in order that the lock might not need oiling, as all these parts are very smooth, and partly that the [96] combination pieces might not easily rust, a thing to which the adhering fire-crust is not favourable. ”