Yale & Towne Manuf'g Co. v. Corbin

36 F. 765, 1888 U.S. App. LEXIS 2682
CourtU.S. Circuit Court for the District of Connecticut
DecidedNovember 27, 1888
StatusPublished

This text of 36 F. 765 (Yale & Towne Manuf'g Co. v. Corbin) is published on Counsel Stack Legal Research, covering U.S. Circuit Court for the District of Connecticut primary law. Counsel Stack provides free access to over 12 million legal documents including statutes, case law, regulations, and constitutions.

Bluebook
Yale & Towne Manuf'g Co. v. Corbin, 36 F. 765, 1888 U.S. App. LEXIS 2682 (circtdct 1888).

Opinion

Shipman, J.

This is a bill in equity to restrain the defendants from the alleged infringement of three letters patent, viz., No. 180,287, dated July 25, 1876, to Henry R. Towne, for an improvement in locks and latches; No. 234,002, dated November 2, 1880, to Charles C. Dicker-man, for an improved lock and key; and No. 234,213, datecj. November 9,1880, to Warren H. Taylor, for improvements in lock cylinders. The Dickerman patent is the most important, and will be first considered. The application for this patent was pending for a long time in the patent-office. The claims, as presented from time to time, were rejected, and therefore the specification and claims were frequently amended. The final specification was carefully drawn, and presents clearly the views which the assignee and plaintiff had of the nature of the invention. The history of the application shows with significance that the patent-office limited the scope of the patented invention to a narrow compass, and that this is especially true of the first claim. The important part of the specification is as follows:

“My invention relates to that class of locks in which, for economy of construction and convenience in use, the keys are made of thin sheet-metal; and it consists, particularly, of an improved construction of the key and its hub or trunnion, so as to increase the safety of the lock against picking, and so, also, as to admit of the key being wholly formed of a single piece of thin sheet-metal, and yet insuring its thorough guiding and support during its insertion and rotation. My invention applies particularly to locks operated by sheet-[766]*766metal keys, and provided with rotating plugs, or roll-backs, for guiding the key, and supporting it during its revolution to operate the lock. The locks to which my invention relates may be also provided with key-hole escutcheons, as hereinafter described. The objects of my invention are to obviate a great difficulty which has been found with flat keys, viz., the tilting of the key, and also to increase the difficulty of picking the lock. In the old forms of locks the keys rotate on round stems in suitable round bearings in the front and back plates of the lock. If a flat key is used, it is necessary to provide some device to guide it during its insertion, and to support it during its rotation. The device usually employed has been ahubor trunnion, which has been fitted in the bearing formerly used for the round-stemmed keys. In this plug has been cut a straight slot or key-way, into which the key could be inserted, and, the key being in place, the key and' hub would revolve together, so that the bits of the key could operate the tumblers. The dilliculty of this construction is.that it offers inadequate resistance to the tilting of the key; that is, to its vibrating on an axis at right angles to the length of the key. The result of this tendency to tilt is twofold: First, it prevents the easy insertion of the key into the lock; and, second, it allows the key to get out of place during its rotation, and thus either stick, or perhaps fail entirely to operate the lock. In my patent No. 111,732 I have shown a key provided with a laterally-projecting rib, which, in connection with the hub therein shown, will obviate the difficulty of tilting, above pointed out. This construction, however, while effectively remedying the difficulty of tilting, adds nothing to the security of the lock against picking, and practically precludes the use of sheet-metal in the construction of keys, because a rectangular key-bit, having a rib projecting out from one side of it, with no corresponding depression on the opposite side of the bit, cannot economically be made of thin sheet-metal, if it can be made of it at all. ■ My present invention enables me to construct a key entirely of sheet metal, and yet provided with’longitudinal grooves and ribs or sinuosities, whereby the sheet-metal key is effectively guided in the lock during insertion and rotation, the security of the lock is increased by the obstacles presented to the introduction of picking tools; and these advantages are obtained without materially increasing the cost of this sheet-metal key beyond that of others of the ordinary flat form. The ordinary method of picking locks is by the insertion of a picking tool, which is placed against the tumblers. The tool is then tilted up and down, retractive pressure at the same time being*kept on the bolt, the tumblers being finally adjusted by this tentative process until the bolt can be retracted. It is evident that if any obstruction is made to this tilting of a picking tool, the difficulty of picking will be increased, and my invention increases this difficulty by making the key-way in the plug of a sinuous or contracted form. Such a novel form of key-way in a slotted rotary key-hub, of course calls for a corresponding sinuously-shaped key of like wavy outline on its opposite sides, and such a key is much stronger and better in every respect than the ordinary flat plate-key. * * *
“Figs. 3, 8, 11, and 12 show a modified application of my invention, which consists of forming the key of thin sheet-metal, in the ordinary way, and in subsequently milling, or otherwise cutting a longitudinal groove or depression in both of its sides. In this case, the hub or trunnion has a corresponding rib or projection on both of its inner walls, thus forming a key-way of a cross-section coincident with that of the key. This construction, and that shown by Fig. 22, although accomplishing the desired results in some measure, does so at a greater cost of manufacture, and at the expense of weakening the key, and is therefore less desirable than those forms which are more properly termed ‘sinuous,’ and which preserve the parallelism of the sides of the key and key-way. * * * I am aware that a key-blade of angular zigzag outline has heretofore been made, as in the patent of Holmes and Butler; but [767]*767that key is what is known as a ‘ push-key,’ i. e., the moment the key is pushed into place the lock may be unlocked without rotating the key. The result is that, in this class of locks, picking tools do not have to be tilted to effect the desired object, and therefore corrugations are not safeguards. Moreover, the Holmes and Butler key is bitted upon its end, and is not made complete oí a single piece of sheet-metal. * * * It will be perceived that my invention does not contemplate the use of a flat, rectangular key-blade, having a mere lateral rib or projection from one or both of its sides, because that would not accomplish two very useful objects desirable to be attained in connection with my present invention, as above stated, viz., to prevent picking, and to cheaply and easily manufacture a parallel-sided plate-key of equal thickness throughout, and of greater strength than other parallel-sided plate-keys for rotary locks. I only use ribs upon my key where the forming of grooves by depression necessarily causes them; the essential thing being to obtain a key and a key-liole of sinuous contour, as best illustrated in Rigs. 6 and 9 and 18 and 19, and to combine the advantages of these with a rotating key, and thus improve the generally preferred class of locks operated by rotary keys.
“In my said patent No. 111,782, Rig. 8 shows a rectangular plate-key, with a rib projecting from one side of its blade, and Rig. 9 shows a corresponding rectangular key-hole, with a recess in one of its sides, to accommodate the rib. The only purpose of this rib and recess is to aid in guiding and securing the key in position in the lock. It does not at all tend to prevent picking.

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Bluebook (online)
36 F. 765, 1888 U.S. App. LEXIS 2682, Counsel Stack Legal Research, https://law.counselstack.com/opinion/yale-towne-manufg-co-v-corbin-circtdct-1888.