Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.


  1. Advanced Patent Search
Publication numberUS850446 A
Publication typeGrant
Publication dateApr 16, 1907
Filing dateJan 19, 1907
Priority dateJan 19, 1907
Publication numberUS 850446 A, US 850446A, US-A-850446, US850446 A, US850446A
InventorsAlexander Robbins
Original AssigneeAlexander Robbins
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Keyhole-guard for locks.
US 850446 A
Abstract  available in
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)



Woe $352 81 THE NORRIS PETERS co., wAsHnvcTflN, 0. c,



Specification of Letters Patent.

Patented April 16, 1907.

Application filed January 19, 1907. Serial No. 353,023.

To all whom it may concern:

Be it known that I, ALEXANDER ROBBINS, a citizen of the United States, residing at Allegheny, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in Keyhole- Guards for Locks; and I do declare the following to be a full, clear, and exact descrip tion of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to the letters and figures of reference marked thereon, which form a part of this specification.

This invention relates to an improved keyhole-guard for door-locks; and it consists in arranging a shield or guard within the face plate of the lock in such manner as to cover the key-opening, a means for locking said guard and releasing the same; and the invention further consists in the certain details of construction and combination of parts, as will be fully described hereinafter.

In the accompanying drawings, Figure 1 is a rear elevation of the face-plate of an ordinary door-lock, showin my improved shield or guard for closing the key-opening, the same being constructed and arranged in accordance with my invention. Fig. 2 is a sectional side elevation of the same. Fig. 8 is a front elevation of the face-plate, showing the position-of the lock for keeping the guard closed and also the position of the thumbpiece for moving said guard downward.

To construct a keyhole-guard in accordance with my invention and adapt the same for use in connection with the ordinary faceplate 1 of a common door-lock, I arrange at the rear of said plate a slidable piece 4, having an opening 7 to span the knob-bar 3, which will admit of said piece being moved vertically a short distance. The upper end of this piece 4 is formed with a small hook 10 to engage with one end of a short spiral spring 8, the other end of which is attached to a projecting piece 9, attached to the inner wall of the said door-plate 1, the object of said spring being to lift the piece 4 upward to its normal position. Near the lower end of the sliding piece 4. is an opening 11, whichwhen said piece is in its normal position will register with the key-opening 5 in the faceplate 1. Near the top of the face-plate 1 is a vertical slot 6, which is formed for the reception of a thumb-piece 19, formed integral with or attached to the upper part of the sliding plate 4, the said thumb-piece projecting through the slot 6 and is used for the purpose of pressing the sliding piece downward, thereby bringing a solid portion of said piece over the key-opening 5. To lock the sliding piece in this latter position, a small springactuated tumbler-lock 12 fitted with a removable key 14, is arranged at a suitable position on the outside of the door-plate 1. This lock may be of any well-known construction and is connected with the sliding piece 4 by two parts 17 and 18, the one part smaller than the other and arranged in a horizontal and vertical position. The inner part 17 operates in a slot 16,formed in the sliding piece 4, and the outer part 18 acts as a guide and retaining piece. These two parts 17 and 18 form the lock proper and are capable of being revolved either by the key or by the spring within the lock 12, when within an enlargedpart 15 of the slot 16. The part 17 when turned at right angles to the position shown on the drawings at Fig. 1 will engage with the shoulders of the enlargement and hold the sliding piece its lowered position, from which it can be released only by means of the key 14.

In operation, the parts being in their normal position, such as shown at Fig. 1 of the drawings, the thumb piece 19 is presseddownward to the limit of the slot 6, the latchkey turned a quarter-revolution to engage the part 17 with the shoulders 15 of the slot 16, and the said key removed, thereby covering the keyhole 5 to prevent the insertion of a key therein. only necessary to use the latch-key 14, release the lock part 17 by turning the same in line with the slot 16, at which time the spring 8 will bring the sliding piece 4 back to its normal position, leaving the keyhole free from obstruction.

By the use of this device in connection with the locks of outside doors of dwellinghouses or in other places-such as on trunks, boxes, &cthe lock cannot beopened without the use of the second key.

It is obvious that slight modifications and changes may be made in the details of construction without departing from the spirit of the invention. Therefore I do not wish to confine myself to the exact construction shown and described, but wish to claim all such modified forms as would come properly within the general scope of the invention.

A modified form of the invention would be To open the keyhole 5, it is the placing of the shield or guard within the shell or casing of the door-lock or upon the outside surface of the same. I

Having thus described my invention, what I claim, and desire to secure by Letters Patent, is-

The hereindescribed keyhole guard or shield for locks, comprising in combination with the lock-plate 1, the sliding piece 4 arranged at the rear of said plate and adapted to cover the keyhole 5, an opening 11 in said sliding piece to register with said keyhole, a spring to keep the sliding piece in its normal

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3246495 *Sep 10, 1963Apr 19, 1966Gen Motors CorpShutter assembly
US5007263 *Jun 22, 1990Apr 16, 1991Taylor Bryan VSecurity device
US6397648 *Mar 30, 2001Jun 4, 2002Kryptonite CorporationU-lock keyway protector
US20150128669 *Apr 29, 2013May 14, 2015Georgios ChrimatopoulosProtection mechanism of a door's key hole
Cooperative ClassificationE05B17/142