US2032974A

US2032974A - bradshaw

Info

Publication number: US2032974A
Authority: US
Publication date: 1936-03-03
Anticipated expiration: 1953-03-03

Description

M51121! 3, 1936. I A, B A 2,032,974-

LOCK

Filed June 10, 1935 F/GJZ a g INVENTOR ATTO RN EY Patented Mar. 3, 1936 UNITED STATES PATENT OFFICE LOCK Application June 10, 1935, SerialNo. 25,894

1 Claim.

This invention relates to locks of the character employing spring-pressed slidable tumblers actuated into releasing position by the insertion of a key in a keyway of a plug of the lock, and has for the primary object the provision of antipicking means which will practically eliminate the possibility of picking the tumblers and if shifted by the picking instrument will efi'ect locking of the plug to its cylinder so that should even the tumblers be successfully actuated or picked the plug will remain locked to the cylinder of the lock.

With these and other objects in view, this invention consists in certain novel features of construction, combination and arrangement of parts to be hereinafter more fully described and claimed.

For a complete understanding of my invention, reference is to be had to the following description and accompanying drawing, in which Figure 1 is an end View illustrating a keyway in the plug of a lock.

Figure 2 is a side elevation illustrating the cylinder of the lock with the plug therein and showing a slot in the cylinder for the reception of the anti-picking means.

Figure 3 is a view similar to Figure 2, showing another side of the cylinder with a slot for the reception of the spring-pressed tumblers of the plug.

Figure 4 is a sectional view taken on the line 4-4 of Figure 3 showing the anti-picking means.

Figure 5 is a sectional view taken on the line 5--5 of Figure 3 showing the spring-pressed slidable tumblers securing the plug against rotation in the cylinder of the lock.

Figure 6 is a sectional view taken on the line 66 of Figure 4.

Figure '7 is a sectional view taken on the line 'l-l of Figure 5.

Figure 8 is a detail view showing the construction and the arrangement of the anti-picking means.

Figure 9 is a detail sectional View showing associated tumblers.

Figure 10 is a plan view illustrating one of the tumblers.

Figure 11 is a sectional view taken on the line ll-|I of Figure 10.

Figure 12 is a plan view illustrating the key for effecting operation of the anti-picking means and the tumblers to free the plug from the cylinder of the lock.

Referring in detail to the drawing, the numeral l indicates acylinder of a lock provided with pairs of oppositely arranged

slots

2 and 3. Rotatably mounted in the cylinder is a plug 4 having a flange 5 at one end to abut one end of the cylinder. The plug 4 is provided with a keyway 6 opening outwardly through the flanged end of the plug. Formed in the plug and communicative with the keyway is a chamber 1 which slidably receives pairs of tumblers 8 each having a key slot 9. The tumblers of each pair are 10 urged in opposite directions by a coil spring Ill bearing against shoulders or ribs ll formed on said tumblers. The tumblers of each pair on their opposing faces are grooved to receive the ribs I l with the springs l0 confined in the grooves 5 between the shoulders. The springs l0 act to urge the tumblers apart and into the slot 2 of the cylinder thereby securing the plug to the cylinder against rotation or removal therefrom.

The plug at opposite sides of the keyway is 20 equipped with chambers l2 communicative with the keyway and arranged laterally of each other. The chambers also open outwardly through the periphery of the plug to communicate with the slot 3 of the cylinder. Guard elements l3 are 25 slidably mounted in the chambers I2 and are provided with pointed portions I4 adapted to normally traverse the keyway and engage in notches l5 formed in the walls of the keyway by the action of springs l6. One of the guard ele- 30 ments is arranged adjacent the mouth of the keyway while the other guard element is between the guard element located adjacent the mouth and the tumbler. The successful operation of the guard and the tumblers depends upon a key 35 ll, as shown in Figure 12. One portion of the bit of the key is designed to slide the pairs of tumblers out of the slot 2 of the cylinder when the key is shoved into the keyway, said portion of the bit of the key when striking the guards i3 40 causing said guards to slide outwardly into the slots 3 of the cylinder. A portion of the bit of the key adjacent the handle is provided with notches to permit the guards to enter and there- 5 by permit the springs Hi to position the guards out of the slots 3 of the cylinder. The key completely pushed into the keyway brings about the foregoing described operation of the tumblers and the guards and frees the plug of the cylinder. Should an attempt be made, by the employment of an instrument other than the regular key, to actuate the tumblers, the guards will check the movement of the instrument into the keyway for the actuation of the tumblers. However, should a person be successful in passing the guard with the instrument to reach the tumblers said guards will be forced outwardly into the slots 3 of the cylinder and thereby still maintain the plug locked to the cylinder even if the tumblers were successfully picked or actuated to bring about disengagement of the tumblers from the slot 2. Therefore, it will be seen from the foregoing description and the accompanying drawing that a practical means has been provided which will effectively prevent picking of the tumblers and even if the tumblers are reached for successful operation, the anti-picking means will efiectively secure the plug to the cylinder.

The guards when extended into the slots 3 and in contact with opposite walls of said slots so position the plug in the cylinder that the ends of the tumblers will be positioned in spaced relation to the walls of the slot 2.

Having described the invention, I claim:

In a lock, 2, cylinder having guard and tumbler slots, a plug mounted in said cylinder for rotation and having a keyway and tumbler and guard chambers, spring actuated tumblers mounted in said tumbler chamber and normally entering the tumbler slots of the cylinder, and. having key slots to receive a key in the keyway for moving the tumblers out of the tumbler slots of the cylinder, said guard chambers being arranged laterally of each other and at opposite sides of the keyway, guard elements slidable in the guard chambers and having pointed portions adapted to traverse the keyway, said plug having notches in walls of the keyway to receive the pointed ends of the guards, and springs secured to the plug and engaging the guards to normally position the pointed ends thereof in the notches and thereby close the keyway between the mouth of the latter and the tumblers. 20

AUSTIN A. BRADSHAW.