US121680A - Improvement in lockx - Google Patents

Description

THOMAS STEWART. Improvement inA Locks.

Patented nec; 5, 1371.

No. :Z1-,680.

mpg/Ess sa,

PATENT FIE.

THOMAS STEWART, OF PHILADELPHIA, PENNSYLVANIA.

IMPROVEMENT IN LOCKS.

Specification forming part of Letters Patent No. 121,680, dated December 5, 1871.

To all whom it may concern:

Be it known that I, THOMAS STEWART, of Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented an Improvement in Locks, of which the following is a specification My invention consists of a key-hole guard, arranged within and combined with a door-lock, as fully described hereafter, so that when the door is locked from the inside the said guard shall slide with the bolt and cover the outer key-hole, and so that when the door is locked or unlocked from the outside the said guard shall merely rise and fall without sliding, and. serve as a supplementary tumbler for the bolt.

In the accompanying drawing, Figure l represents my improved lock, partly in section, with one of the side plates removed and the bolt drawn back; Fig. 2, the saine as Fig. 1, with the bolt shot forward; Figs. 3 and 4, the lock viewed from a side opposite that shown in Figs. l and 2; Fig. 5, a transverse section on the line l 2, Fig. l, showing the operation of the key when inserted into the lock from the inner side of the door; Fig. 6, a transverse section, showing the key inserted at the opposite side; and Fig. 7, a sectional view of the lock on the line 3 4, Fig. 2.

A represents the lock-case, of which a and a are the opposite side plates; b, the front; c, the back; and d, the bottom; there being two keyholes, e and e', in the side plates at points directly opposite each other, the former of which is toward the outside and the latter toward the inner side of the-door, to which the lock is attached. A bolt, B, is' arranged to slide in the lock-case, and is guided partly by the openingf in the front of the latter, partly by projections g and h of the side plate a', and partly by a plate, D, secured within the lower portion of the lockcase. A hole, e2, is formed in the plate D, on line with the two key-holes, for the passage of a key, F, which can be inserted through either of the said key-holes for the purpose of forcing outward or withdrawing the bolt after lifting a spring-tumbler', C, a projection, i, on which is adapted to either of two notches, 7c 7c', formed on the upper edge of the said bolt. (See Figs. 1,2, and 7.) The guard H, which forms the principal feature of my invention, is arranged within the lock-case between the plate D and side plate a, and is combined with the bolt in the manner which I will now proceed to describe, so that when the door is locked from the inside the said guard shall be drawn forward by and with the bolt so as to cover the key-hole e and thus prevent the introduction of a key through the latter from the outside of the door; but so that when the door is locked from the outside the said guard shall remain stationary, so as not to interfere with the introduction of a key from either side of the door. The said guard has an arm, m, a pin, p, at the extremity of which enters a slot, p', formed in the bolt; and the guard is also provided with a lug, q, adapted to either of two notches, s and s', formed on the upper edge ofthe bolt, from either of which notches the said guard can be lifted, when drawn back, by means of a projection, t, on the key. (See Figs. 3 and 6.)

The operation of the lock is as follows: When the parts are in the position shown in Figs. 1, 3, and 5 and the key is introduced through the keyhole e and turned for the purpose of locking the door from the inside, the tumbler will be operated in the usual manner so as to first permit the bolt to slide forward, and then retain it; and the guard H, whose lug q is contained within the notch s of the bolt, and forms, therefore, in effect a part of the latter, will be carried forward with the same, as shown in Figs. 2 and 1, so as to cover the outside key-hole a. This, it will be evident, will effectually prevent the introduction of a key through the said outer key-hole c, or the picking of the' lock from the outside of the door by any of the instruments commonly used by burglars. The lifting of the guard so as to uncover the keyhole will also be prevented by the projection h of the lock-case, which extends over the lug q of the said guard. (See Fig. 2.) When the door is unlocked from the inside the sliding guard H will be drawn back with the bolt so as to again uncover the outer key-hole c. (See Fig. 3.) If it be now desired to lock the door from the outside the key is inserted through the outer keyhole c and turned, as shown in Fig. 6, when the guard, owing to the pressure of the projection t of the key against its under edge, will be lifted simultaneously with the tumbler, so as to withdraw its lug q from the notch s of the bolt, and thus permit the latter to slide forward independently, (see dotted lines, Fig. 3,) the guard being prevented from following the bolt by the projection h of the lock-case, which is struck by the lug q of the said guard. When the door is thus locked the lug q ofthe guard tnlls into the notrh s ofthe bolt, t'roni which it is lifted to ihll ueuin into the notch s of the szlid boltl when the hitter is drawn back.

It Will thus he seen that, while the guard loses the outer key-hole when the door is loeked t'ronl the inside, and thus prevents the pickin,"v of the i lock, it also serves :is u suppleinentury tumbler, 5

and increases the diliieulty ot' ithdruuing the bolt, except by the proper key, when the door is loeked from the outside.

I claim as my invention- The combination, With :i lock, of :1 keyhole

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