US145836A - Improvement in burglar-alarms - Google Patents

Description

F. w. BL'AKEMURE.

BurgIar-'Alarms- Patented Dec. 23,1873.

INVENTORY.

UNITED STATES PATENT CDEEICE FRANCIS IV. BLAKEMORE, OF PHILADELPHIA, PENNSYLVANIA.

IMPROVEMENT IN BURGLAR-ALARMS.

Specification forming part of Letters Patent No. 145,836, dated December 23, 1873; application iiled October 18, 1873.

To all whom fit may concern:

Be it known that I, FRANCIS W. BLAKEMORE, of Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented. certain new and useful Improvements in Alarm Door-Bells; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled vin the art to which it pertains to make and use it, reference being had to the accompanying drawings, which form part of this specification, in` which- Fignre 1 is a front elevation of the alarmbell in position on the door. Fig. 2 is a view of the lower bracket, showing the crank-lever turned down to permit the door to be opened without giving an alarm.

My invention has for its object to provide an alarm door-bell of simple construction, that may be manufactured at slight expense, and will operate effectively, and without danger of easily getting out of order. The nature of my invention consists in the peculiar construction, arrangement, and combination of the devices for operating the clapper, which strikes by gravity, and is so arranged that it will be raised only when the door is being opened, remaining undisturbed while the door is being closed. l

Referring to the accompanying drawing, A is the gong, screwed on a horizontal central stai or standard, which is made fast, by suitable means, to a base-plate or bracket, B, de-

signed to be secured by screws to the top jam or frame of the door. C is the clapper, connected, by the rod d, with drum D, which is journaled on a pin or pivot, b, on the baseplate B. b is another pin or fulerum on said base-plate, so arranged that as the rod d comes in contact with it as the clapper descends a spring or return mot-ion of said rod is produced, elevating the clapper slightly, so as to permit the necessary vibrations. E is an oblique flange or bevel on the drum D, and F is a plate or bracket, to be screwed on the door, having a pivoted crank-lever, G, the weighted arm g of which is prevented from descending below a horizontal line by the pin or stop g2.

The other arm g1 of the lever G projects above the upper line of the door, so as to impinge upon the flange E.

When the door is being started open the arm l g1 presses against the inner side of the flange, causing the-clapper C to rise. When the door is opened still farther, the arm g1 passes the flange E, and the clapper descends by gravity, and gives the alarm. In closing the door, the arm g1 passes outside the flange without disturbing the latter, the crank-lever G yielding, as shown in dotted linens.

The advantages of this construction are brieiiy as follows: The clapper being made to strike by gravity alone, the cost of manlifacture is greatly reduced; and by dispensing with a spring for actuating said clapper the most frequent cause of disarrangementl and breakage is avoided. So, too, by this construction it will be found impossible to open the door without giving an alarm, as the bell will strike if the door be moved but an inch or two. lith other constructions the door may be opened sufficiently, without giving an alarm, to permit a stick or a persons fingers tobe passed through the opening, and the clapper thereby prevented from striking.

1f desired, the crank-lever may be thrown out of engagement with the flange E, occupying the position shown in Fig. 2, when the door may be opened without giving an alarm.

IVhat I claim as my invention islhe drum D, provided with the gravity-hainmer C and oblique plate E, in combination with the plate B, secured to the door-j amb, and holding the gong A and stud b', and the bell-crank G, having the weighted arm g resting upon the stud gl, said crank being attached to the door, all constructed and arranged as shown, and for the purpose specified.

In testimony that I claim the foregoing I have hereunto set my hand this 15th day of October, 1873.

FRANCIS W. BLAKEMORE.

Witnesses:

JAMES P. PETIT, EUGENE B. EAnsoN.

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