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Publication numberUS958849 A
Publication typeGrant
Publication dateMay 24, 1910
Filing dateFeb 23, 1909
Priority dateFeb 23, 1909
Publication numberUS 958849 A, US 958849A, US-A-958849, US958849 A, US958849A
InventorsJohn W Benedict
Original AssigneeJohn W Benedict
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
US 958849 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)



APPLICATION FILED 1113.23, 1909.

Patented May 24, 1910 Wit-neon:



Specification of Letters Patent.

Application filed February 23, 1909.

Patented May 24., 1910. Serial No. 479,377.

To all whom it may concern:

Be it known that I, JOHN W. BENEDICT, a citizen of the United States, residing at Hastings, in the county of Barry and State of Michigan, have invented a new and useful Improvement in Keyhole-Guards, of which the following is a specification.

This invention relates to a shield designed to protect locks against picking, either by means of skeleton keys, or by the insertion of any instrument for the purpose of dislodging the original ke thus clearing the keyhole for the insertion of a false key.

The invention consists in providing the lock with a transversely arranged squared shaft carrying two steel guard plates working within the lock casing and covering the keyhole the inner guard plate being provided with a keyhole slot so that the key may be inserted from either side of the door for rotating said shaft, said rotation being prevented when the key is in the slot of the inner guard plate.

In the accompanying drawings, Figure 1 is a vertical section through the lock casing, showing the locking and guard mechanism in elevation. Fig. 2 is a sectional end view. Fig. 3 is a perspective View of the shaft. Figs. 4 and 5 are detail face views of the in ner and outer guard plates, respectively.

In these drawings, 1 represents the lock casing having the usual spring pressed catch 2 and a key operated bolt 3. Tumblers 4 of the usual kind are also provided. Fitting transversely across the casing 1 and arranged between the mechanism of the catch 2 and the inner end of the bolt 3 is a squared shaft 5 into the ends of which are threaded rotatable pins 6 having upon their outer ends milled heads 7 said heads being respectively upon the inner and outer sides of the door. Fitted upon the squared shaft adjacent the outer wall of the casing, but within the casing is a solid keyhole guard plate 8. Fitted upon the opposite end of the squared shaft and adjacent the inner wall of the casing is a plate 9 having a keyhole slot 10. A suitable key 11 for operating the tumblers 4 is adapted to pass through the slot 10.

The plates 8 and 9 are parallel to each other and when the shaft 5 is rotated so that the slot 1-0 will register with the regular keyhole slot of the lock the plate 8 will cover the keyhole in the outer face of the casing 1. The key can then be inserted from inside, but 110 key or instrument for tampering with the lock can be inserted in the lock casing through the keyhole opening upon the outside of the door. Nor can the shaft 5 be rotated from either side of the door for the purpose of causing the shields to clear the keyhole while the key 11 is in the look as the said key passes through plate 9 thus locking the shaft against rotation. But at the same time if the occupant of the house or room locks the door from the outside he can turn the plate 8, after withdrawing the key from the lock to cover the keyhole, and upon return can readily by means of the outer milled head 7 swing the guard 8 out of the way, insert the key and open the door. After again withdrawing the key he can turn the plates 8 and 9 back into normal position and upon locking the door from the inside, the key passing through the slot 10, the guard plate 8 will again be locked into position closing the keyhole from the outer side.

Upon the bottom of the lock casing I form upwardly extending lugs 12 and the lower ends of the guard plates work between said lugs and the side walls of the lock casing, and the lugs by bearing upon the inner faces of the plates 8 and 9, respectively, prevent their being bent inwardly or otherwise sprung out of position.

What I claim is 1. The combination with a lock casing, of a squared shaft means for rotating said shaft, and guard plates fixed upon said shaft and covering the keyhole when in normal position, one of said plates having a keyhole slot formed therein.

2. The combination with a lock casing, a squared shaft transversely arranged in said casing, pins threaded into the ends of said shaft, milled heads on said pins, the heads being respectively upon the outer and inner faces of a door a non-perforated guard plate fixed upon the outer end of the squared shaft and normally covering the keyhole, and a slotted plate fixed upon the inner end of the squared shaft, the slot of said plate alining with the keyhole and admitting a key from the inner side of the door, as and for the purpose set forth.

3. In a lock having a spring catch and a key operated bolt, a squared shaft ar ranged transversely between the spring catch and bolt operating mechanism, means operable from either side of the door for rotating said shaft, and guard plates fixed upon opposite ends of the squared shaft, and simultaneously covering the keyhole, the plate adjacent the inner side of the door having a keyhole slot therein adapted to register when the plate is in normal position With the keyhole of the door.

4:. In a lock a squared shaft, pins passing transversely through the door and lock casing and entering the ends of said shaft, turning means carried by said pins, a solid guard plate fixed upon the squared end of the shaft adjacent the outer side of the lock casing, a plate having a keyhole slot therein fixed upon the inner end of the squared shaft and Working adjacent the inner side of the look casing, and lugs formed upon the bottom of the lock casing and bearing respectively upon the inner facesof said plates.

5. A device of the character described comprising a rectangular bar having cylindrical bearing portions adjacent to each end, and a plate rigidly secured on each end of said bar, the plate on the outer end of said bar entirely covering the keyhole in the door, the plate on the inner end of the bar having an opening therein registering With the keyhole adapted to receive a key, the positioning of the key in the lock preventing the rotation of said bar and plates.




Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US7757524 *Mar 6, 2006Jul 20, 2010Harrow Products LlcFastener shield device for locks
US7918117Jun 11, 2010Apr 5, 2011Harrow Products, Inc.Fastener shield device for locks
US20060150694 *Mar 6, 2006Jul 13, 2006Harrow Products, Inc.Fastener shield device for locks
US20100242555 *Jun 11, 2010Sep 30, 2010Harrow Products, Inc.Fastener shield device for locks
Cooperative ClassificationE05B17/14