US1789757A

US1789757A - Tumbler lock

Info

Publication number: US1789757A
Application number: US80992A
Authority: US
Inventors: Edward N Jacobi
Original assignee: Briggs and Stratton Corp
Current assignee: Briggs and Stratton Corp
Priority date: 1926-01-13
Filing date: 1926-01-13
Publication date: 1931-01-20
Anticipated expiration: 1948-01-20

Description

Jan. 20, 1931. E. N. ,'IAcoBlv f '71,789,757

'IUMBLER LOCK Filed Jan 13, 192e 2 sheets-sheet v1 WITNESSES l A." n TOR/Wig Jan; 2o, 1931'.

w/TNEsSs 6 VENTOR UM 6M@ ATTORNEY Patented Jan. 2o, .1931

UNITED STATES APATENT orrica EDWARD N. JACOBI, OF MILWAUKEE, WISCONSIN, ASSIGNOR TO IBB'IG'GrSl STRAT- TON CORPORATION, OF MILWAUKEE, WISCONSIN, A CORPORATION 0F DELAWARE TUMBLEB LOCK applicati@ mea January 13, 192e. serial No. sassari This invention has for its object to effect I certain'improvements in the art of manufacturing tumbler locks whereby the llock parts may be inexpensively manufactured of 5 such uniformity that they are interchangeable and so accurately proportioned that, when assembled, the tumbler ends lie flush with the cylindricalsurface of the lock cylin`der, making unnecessary the usual expen- 10 sive hand operation of filing the tumblers Hush with the lock cylinder andvobviating damage to the lock cylinder incident thereto. More or less hand work and machining facture of tumbler locks with'the result that slight variations were unavoidable and, notwithstanding the exercise of the greatest care, some hand filing of protruding tumbler ends was necessary to permit the lock cylinder to snugly lit within the bore of the lock-case and work without catching. This hand filing has constituted an important item in the cost of manufacture of such locks and the. roughened surfaces of the tumbler ends and of the lock cylinder due thereto have been objectionable both-on account of the unsightly appearance of otherwise wellexecuted work and on account of impairment of kthe smooth working conditions of the loc s." f

With this invention machining and hand work are eliminated, avoiding the objections' above noted, reducing the cost of manufacture, and improving the appearance as well as the smooth operation of the locks. ,i

Another object of the invention is to so design the lock cylinder as to make it suitable for production by die casting whereby the desired uniformity of dimensions may be obtained an'd still afford suiicient strength.

Another object of the invention is to prof -vide a lock With a lock cylinder of frangible material and .so constructed that, upon an attempt to force the lock, it will fracture without releasing its lockin engagement and its fractured state will .ba e further attempts.

With the above and other objects in view the invention consists in the tumbler lock has heretofore been necessary in the manuand method of producing same as herein claimed and all equivalents.

Referring to the accompanying drawings in-which like characters of reference indicate the' same parts in different views.

Fig. 1 is a longitudinal sectional view of a lock cylinder with its key and tumblers constructed' in accordance with this `invention; l

Fig. 2 is a detailed view of a set of standardized interchangeable tumblers therefor Fig. 3 is a front view of the loc-k cylinder;

Fig. 4; is a transverse sectional view there- 0f on the plane of line 4 4 of Fig. 1; d Fig. 5 is a bottom view of he lock cylin- Fig. V6 is a transverse sectional view on the plane of line 6-6 of Fig. 5, and

Fig. 7 is a sectional View of the lock containing such lockcylinder and showing the fracture of the lock cylinder as when an attempt is made to force the lock.

In these drawings, 10 indicates a lock cylinder, which is die cast for uniformity of dimensions, particularly as to the distance y between the bottom wall of the key slot 11 and the upper cylindrical surface of the lock cylinder.

The key 12 fitting in this key slot 11 and engaging the key bearing surfaces formed at the ends thereof is provided with the usual shoulders 13 to engage the stop shoulders 14 of the key slot to determine the operative position and its serrated upper edge forms key .bits 15 of various heights, where theusual regularly spaced slide tumblers 16 engage with s ring pressure holding the key seated on sai key bearing surfaces.

As it is not feasible in a die casting to make the tumbler slots separate a. lon 'tudinally extending diametrical cored slot lglis formed through the lock cylinder with opposite grooves 18 in its side walls, within which the tumblers slide. The tumblers have openings 19, through which the key passes, as usual, and in order that they may bear with pressure on the serrated edge of the key, each is provided with a spring 20 housed within the cyl-'- inder in cylindrical recesses 21 and en `vby an `outwardly projecting arm 22 -To no' l `spring recesses 21 operi directly to the o avoid weakening the structure, the several spring recesses 21 are arranged alternately on opposite sides of the opening 17 and said recesses extend in one direction to the ysurface ofthe cylinder. In order tov position the spring 20 as close as possible to the center line ofthe tumbler slide, its recess 21 is made to open directly into the opening 17 and this materially reduces the length ofthe guide groove -18 on this side ofthe tumbler, but compensation is provided for the interruption of the guide groove 18 by extending the' arm 22 into a guide groove 23 inV the wall of the recess, thus giving the tumbler slide opposite edge bearings at both ends to prevent #24' which `project from the side walls of the recesses for a short distance.

The spring pressure of the tumbler slides upon the upper serrated edge of the key forces the lower straight edge of the key into bearing engagement with the bottom wall of the key slot 11 at both ends thereof, which,

- as before stated, is in predetermined definite relation to the cylindrical surface of the lock cylinder and forms the .base line from which the key bits 15 are -dimensioned The tumblers 16, preferably sheet, metal stampings, are formed in sets Ofdifferent standardized sizes, one set being shown in Fig. 2 as consisting of the three sizes A, B and C. While the outer dimensions of these tumblers are the same and the size of the openings -19 are the same2 the distance from the up-per end of the opening to the upper end of the tumbler differs in the different sizes, such distance for tumbler A being indicated as a', that for tumbler B as b', and thaty for tumblerA C as c.

. Not only are the effective dimensions df the tumblers thus standardized and made uniform for all tumblers of a given size, but

the bit heights of the key are also standardized, a uniformdimension from the base line -formed by the bottom straight edgeiof the key to the tumbler bearing surface of the key bit being always t-he same for tumblers of a given size. Thus all key bits for A tumblers have the bit height dimension a complemenf tary to tumbler dimension a so that lthe two together equal the dimension y of the lock cylinder, and all key .bits -for tumblers B have 'the dimension b complementary to tumbler dimension b so that the twof'together equal the dimension y 'of the lock` cylinder, and all key bits fortumblers C have the dimension c complementary to tumbler dimension c so that the two together equa-l the dimension g/ of the lock cylinder. In this manner any A tumbler, when assembled in position to encylinder, perfect registration of all tumblers necessarily follows and there is no occasion for filing tumblers and for marring the smooth surface of the lock cylinder in doing so.

Such results are incapable of accomplishment in quantity production with lock cylinders made with machining or hand work so that the die casting of lock cylinders is essential to the maintenance of the uniform dimensions ncessary for the purpose.

Although guards 25 may be used at the entrance to the key slot, as usual, to require a key of particular sectional shape, provision has been made to facilitate the entry of the key by providing the key with a pointed end having the downwardly directed cam surface to guide it into proper bearing enga ement with the bottom of the key slot at the ar end of the opening 171 and with the upwardly directed cam surface for lifting the tumblers and, in order that the key may not bind byA being .inserted in an angular position influenced by the pressure of the spring-pressed tumblers, one or more bridges 26 are formed across the opening 17 connecting with and forming oblique extensions of the walls of tumbler grooves 18, as .best seen in Fig. 5. It is found -in practice that these bridges 26 may be so arranged without interfering with the coringy of the lock cylinder die. The bridges 26 terminate j ust below the level of the bottom of the key slot but serve to lift the key when engaged by the downwardly directed cam on the end of the key should the key be inserted in an inclined position and thus prevent binding and facilitate the insertion of the key.-

Also upper guide shoulders 27 are formed at both ends of the key slot to insure the proper seating of the key by their engagement with a longitudinally extending shoulder 28 on the key itself.

The lock cylinder of this invention may be used in a lock-case of any type and may effect a locking engagement in any well known manner but one type of lock is shown in Fig. 7,

wherein the lock-case 29 forms a part of the deadbolt ofa transmission lock for automobiles, the lock vcylinder 10 being confinedA i therein by a hard metal cap 34 and serving to operate a spring-pressed locking'bolt 30 by having a wrist-pin or cam projection 31 on its endengaging a slot in said locking bolt. In this view is shown the protective feature of the die cast lock cylinder of this invention whereby the forcing of the lock is prevented owing to the frangiblenature of the die castposition with respect to the cylinder periph- I to produce the opening 17 with the tumbler grooves and the spring recesses. With the tumblers 16 engaged in the tumbler slots of the lock-case,`l as' when the mechanism is locked, an attempt to force the lock by means of a tool such as a screw-driver 32 driven into the key slot of the lock cylinder and turned by means of a wrench 33, will cause the lock cylinder to fracturetransversely at about the plane of the uppermost tumbler or the plane of the sectional view shown in Fig. 4. The

loose upper end `of the lock cylinder will then t turn freely without affecting the lower portion of the lock cylinder, which remains locked by the tumblers to prevent the release of the mechanism controlled by the lock.

While the lower straight edge of the key and the bottom of the key slot against which it bears and is held by the pressure of the spring tumblers are defined as constituting the base or reference line from which the parts are dimensioned for accurate complementary matching the tumblers to the key bits, it is obvious thatany other reference surfaces on the key and lock cylinder may be employed provided they are held in bearing contact by the pressure of the spring-pressed tumblers.

What I claim as new and desire to secure by Letters Patent is:

1. In a lock, a die cast lock cylinder having a longitudinally extending diametrical opening with grooves in its walls, tumbler slides ittting in said grooves across the opening, said opening and grooves so weakening the die cast lock cylinder that an attempt to turn it by force will cause it to fracture transversely along the plane of the first tumbler without disabling the locking engagement of the tumblers. l

2. In a lock structure, a lock cylinder having a passageway therein for the reception of a key having bits of different predetermined heights, key guiding means in the cylinder passageway and located in a predetermined ery, the cylinder being die cast in one piece to obtain uniformity in such positioning, .and preformed spring pressed plate tumblers fitting in the lock cylinder and having surfaces adapted for engagement on the bits of a key inserted in the cylinder passageway, the key engaging surfaces of the tumblers being at different and predeterminedv distances from the tumbler ends, the predetermined distances between said key engaging surfaces and the ends of the-tumblers and the heights of the corresponding key bits being equal to the distance from the cylinder key guiding means to the cylinder when originally assembled and bearing on the bits of the key adapted for use with the cylinder all tumblers lie flush with the periphery of the lock cylinder so as to require no dressing.

.lock cylinder so as to require no periphery, wherebyvv 3. A lock cylinder having a key slot for the rece tion of a key provided with a bottom straight edge and key bits on its top edge of different but standardized uniform heights, as measured from the straight edge of the key, the key slot being provided with a key bearing surface; in predetermined relation withrespect tothe cylinder periphery and the cylinder being diecast irf one piece to obtain uniformity, preformed spring pressed plate. tumblers fitting in the lock cylinder and having openings lthrough which a key passes Vwhen inserted in the key slot, said tumblers having dierent but standardized uniformdimensions from their openings to their ends, there being a companion complementary tumbler size for each bit size on the keyto be used in the cylinder and the two together equaling the distance from the key bearing surface of the key slot toJLhe periphery of the lock cylinder, whereby when originally assembled and bearing on the bits of the key adapted for use with the cylinder all tumblers lie flush with the periphery of the lock c. linder so as to require no dressing.

4. n a lock including a cylinder having a slot for the reception of a key having bits of different but uniform standardized heights, preformed spring pressed plate tumblers having bit bearing surfaces of different but uniform standardized sizes as measured from the bit bearing surfaces to the ends ofthe tumblers, there being a tumbler size complementary to each key bit size of the key adapted for use with the lock, and the aggregate dimensions of all complementary key bit sizes and tumbler sizes bein eql1a1,and key bearing means in the cylin er key slot and positioned from the wall of the lock cylinder the distance of said equal aggregate dimensions, whereby when the tumblers are originally assembled and bearing on the bits of thev key adapted for use with the` cylinder all tumblers lie flush with the peri hery of the ressing, said lock cylinder constituting a one piece die casting whereby said positioning of the bearing surface relative to the cylinder periphery is predetermined of a uniform standard.

In testimony whereof, I ax my signature.

EDWARD N. J ACOBI.