Lock key

May 9, 1939.

P. W. OLSON

LOCK KEY

2,157,142

Filed July 9, 1934

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Patented May 9, 1939

2,157,142

UNITED STATES PATENT OFFICE

2,157,142

LOCK KE Y

Phillip W. Olson, Grand Rapids, Mich., assignor to Automatic Instrument Company, a corporation of Michigan

Application July 9, 1934, Serial No. 734:252

Claims. (CI. 70—406)

This invention relates to lock keys, :and a main object of the invention is to provide a key which is difficult to duplicate without the proper equipment, and which cannot be made 5 by filing straight across the edges of the blade.

Another object of the invention is to provide a key with the comers cut away to form a central web with tumbler operating ledges at the sides of the key facing in the same direction 10 as the edges thereof.

Another object of the invention is to provide such a key which is accurately guided in the keyway; and to provide a key which may be inserted either side up in the lock.

Other Objects and advantages will become more apparent in the following description, taken with reference to the accompanying drawing, in which—

Fig. 1 is a longitudinal cross section of a cyl20 inder lock, with a key embodying this invention inserted therein;

Fig. 2 is a transverse section taken on the line 2—2 of Fig. 1;

Fig. 3 is a perspective view of the key; and 25 Fig. 4 is a view looking at the end of the key.

This invention relates to keys for locks of the rotary cylinder type having a plurality of tumbler elements normally positioned to lock the cylinder against rotation in its casing. Locks of 30 this general type are disclosed in my co-pending applications Serial No. 712,240 for Lock tumblers, filed February 20, 1934, and Serial No. 713,007 for Cylinder locks, filed February 26, 1934, and now Patent No. 2,023,208.

The key 6 has a flat blade 8 rectangular in cross section which is insertable in the keyway 9 of the lock which comprises a housing 10 in which is rotatably mounted a tumbler cylinder 10α, in which said keyway is formed.

On each side of the keyway are provided transverse tumbler slots I i having plate tumblers ! 2 slidably mounted therein. The ends of the tumblers normally project into longitudinal grooves formed in the bore of the housing for locking the 45 cylinder from rotating therein, as will be understood by anyone acquainted with this art.

The tumblers and slots are wider at one end than at the other, and are stepped to provide shoulders 13 and 13α, in the tumbler and slot 50 respectively, between which coiled springs (4 are compressed for pressing the larger ends of the tumblers outwardly from the cylinder.

On the inner sides of the tumblers are formed lugs 15 which project into the keyway. The 55 inner edges of the tumblers are also shouldered as shown, so that after the tumblers are inserted into the ends of the slots, they are retained in the cylinder by longitudinally insertable bars Ί8, which also define the upper and lower sides of-the key-way. The bars -18 -are secured in _po- g sition-’.by >a cover 19 which-is fixedly secured to the outer end of the housing 10.

The corners of the key-blade 8 are cut away to provide ledges 20, 21, 22 and 23, the ledges on the opposite sides of the blade being sepa- io rated by central webs 24 which extend to the edges of the blade and fill the space between the upper and lower sides of the keyway, thus accurately guiding the key longitudinally in the slot. 15

The key being inserted in the position shown in Fig. 2, the conformation of the ledges 28 and 23 is made so that when the key is in position the lugs 15 are positioned so that the tumblers are withdrawn completely into the cylinder and 20 the cylinder is then free to turn.

By constructing the lock so that the tumblers on the opposite sides of the keyway are moved in opposite directions, the other ledges 21 and 22, have no function in this position of the key; 25 but by making these ledges conform to the diagonally opposite ledges, the tumblers may be correctly operated by these ledges when the key is turned the other side up.

The lugs 15 are of course formed in different 30 locations on the edges of the tumblers for varying the locks, with the result that the tumbler operating ledges which are directly opposite, such as 20 and 21, are, at least in some portion, in overlapping relation. Therefore it is impos- 35 sible to form the key by hand filling. Also if the web is cut away, the key-blade would not be properly positioned in the keyway.