US3771339A

US3771339A - Protective apparatus for door locks employing latch-rods

Info

Publication number: US3771339A
Application number: US00220028A
Authority: US
Inventors: E Smith
Original assignee: Individual
Current assignee: Individual
Priority date: 1972-01-24
Filing date: 1972-01-24
Publication date: 1973-11-13
Anticipated expiration: 1990-11-13

Abstract

Protective mechanism for door locks employing hand-operated latch-rods extending to engage opposite sides of a door frame, the latch-rods being secured in position by a combination lock or the like; the protective mechanism designed to absorb the force to prevent damage to the combination lock when the bolt-rods are manipulated in a locked position during a security sweep or the like.

Description

11mm States atent Smith 14 1 Nov. 13, 1973 [54] PROTECTIVE APPARATUS FOR DOOR 2,787,154 4/1957 Wesberry 70/118 LOCKS EMPLOYING LATCH-RODS Inventor: Elmer Smith, 1275 B Oakdale 2:766:608 /1956 Him /303 Ave, El Cajon, Calif. 92021 [22] Filed; Jam 24, 1972 Primary Examiner-Albert G. Craig, Jr. [21] A l N 220 028 Attorney-R. S. Sciascia et al.

[57] ABSTRACT 70/118 70/ Protective mechanism for door locks employing hand 58 Field of Search 70/82, 104, 113, Operated latch'rods extendmg f 70/114 116 117 118 119 120 121 of a door frame, the latch-rods being secured 1n posii i tion by a combination lock or the l1ke; the protective A mechanism designed to absorb the force to prevent damage to the combination lock when the bolt-rods [56] References Cited are manipulated in a locked position during a security UNITED STATES PATENTS Sweep or the like 1,511,231 l0/1924 Miles et a1. 292/40 2,240,162 4 1941 Nemec 292/148 2 Claims 5 Drawmg Flgures 928,905 7/1909 Cottrell 70/71 PATENTEHKUV I 3 I975 SHEET 2 [1F 3 PAIENIEUNUV 13 mm 3.771. 339

- sum 3 0F 3 1 I PROTECTIVE APPARATUS FOR DOOR LOCKS EMPLOYING LATCH-RODS STATEMENT OF GOVERNMENT INTEREST The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION The invention relates to protective mechanism for door locks designed for latch-rod type doors employing combination locks or the like, but it is to be understood that it can be used for any purposes for which it is found applicable.

The use of latch-rod locking mechanism is a wellestablished practice, especially for large doors where security of a room is a major consideration. U. S. Pat. No. 2,787,154 issued on Apr. 2, 1957 may be considered a typical installation of this type. The lock mechanism includes oppositely movable latch-rods designed to engage corresponding keepers at the top and bottom sides of the door frame. The latch-rods'are actuated by a suitable handle or knob through a ratchet gear or suitable linkage. As shown in the aforementioned patent, a lock is provided to secure the latch-rods in the latched position. Where a routine periodic security sweep or check is maintained over such a locked door, the force of frequent manipulation of the handle will be transmitted directly to the lock bolt and exert a strain on the delicate lock mechanism, especially if it is a combination lock as is usually the case where the room contains classified military papers.

The above described patent does provide a shear pin to prevent forcible release of the latch-rods, but it is not designed to protect the lock mechanism against the problem herein described.

Another manner of overcoming the above problem is to provide a combination lock which is so rugged as to enable the lock to withstand the forces described. There is no problem in building a stronger lock, except for the high manufacturing cost involved.

The invention apparatus is designed in effect to protectthe combination lock from damage by transmitting the force exerted on the latch-rods to a frame attached to the door instead of directly to the lock mechanism. Thus the invention prevents damage to and the need for frequent replacement of the delicate and expensive lock mechanism, and assures proper and continuous functioning of the door and the security of the room associatedtherewith. In addition a less rugged, and therefor a less expensive lock may be employed to accomplish the same purpose.

SUMMARY OF THE INVENTION An apparatus is provided for protecting combination locks on doors employing opposite extendable latchrods designed to engage the door frame. The latch-rods extend upwardly and downwardly from a central housing mounted on the door, the rods being manually manipulated between latched and unlatched positions by a handle through a ratchet gear arrangement or the like. The conventional practice is to provide a separate lock to secure the latch-rods in the locked position. U. S. Navy security regulations require a combination lock where the room is to house security classified material. The invention comprises a heavy duty U-shaped frame bolted or otherwise supported to the door. The legs of the frame have a transverse drilled passage aligned with STATEMENT OF THE OBJECTS OF THE INVENTION An important object of this invention is to provide a protective apparatus for the lock mechanism of a latchrod type of door lock.

Another important object is to provide protective apparatus for a combination lock to enable the use of a less rugged lock and therefore one that is less expensive.

Still other objects are to reduce the frequency of maintenance of security doors, and the need for emergency repair because of security considerations.

Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing where like reference numerals refer to similar parts throughout the figures, there is shown in FIG. 1 a door 10 mounted in a casing 12 of a shielded room, being only one type of installation on which a latch-rod type of locking mechanism 14 can be employed.

Latch mechanism 14 is of conventional design and includes a pair of vertically extending latch-rods 16 and 18, each rod being fabricated of two pieces and bolted together at 19. The innermost ends of rods 16 and 18 are interconnected by a rack and pinion gear arrangement, not shown, enclosed in gear box 20 bolted at 21 to door 10. The outer ends of both latch-rods are slidably restrained in respective housings 22, each rod terminating in a normally projecting roller latch 24 adapted to engage a respective cam keeper 25 mounted on door casing 12 for latching door 10 to a closed position. Latch-rods l6 and 18 and gear box roller latch 26 are actuated between open and closed positions by a double handle 28, one on each side of the door, connected to the gear box mechanism.

Latch mechanism 14 is locked in the latched position by a lock 30, usually a combination type, mounted on the door. Lock 30- has a conventional bolt 32 that was heretofore designed to mate with a corresponding slot in upper latch-rod 16 when the latter is in a latched position for locking same. Frequent manipulation of handle 28 during security sweeps for the purpose of checking the locked condition of the door exerts a direct force on bolt 32 and the delicate lock mechanism that eventually damages the mechanism and requires costly emergency repairs complicating the maintenance of security of the room.

The door mechanism described above is conventional commercially available equipment. The invention presently to be described modifies the conventional door locking mechanism by providing a protective apparatus 34 to eliminate the strain to which the combination lock mechanism is normally subjected.

Protective apparatus 34 comprises a heavy duty U- shaped frame 36 (see FIGS. 4 and having a base portion 38 conveniently bolted at 40 to the top of gear box 20 which in turn is secured by bolts 21 to door 10. The

frame legs

42 and 44 are spaced apart to provide a longitudinal slot 46 to receive slidably a T-shaped strike 48 (see FIG. 2) screwed at 50 to the side of upper latchrod 16. To avoid any binding of strike 48 as it rides up and down in slot 46, the free ends of

legs

42 and 44 are rigidly secured together by a cap plate 52 screwed thereto. The projecting lip portion of strike 48 and

frame legs

42 and 44 are each provided with transverse drilled

openings

54 and 56, respectively adapted to be aligned when the latch-rod 16 is in a lockable position to receive a bolt extension rod 58 threaded to the existing conventional bolt 32 of combination lock 30. Steel bushings 60 are press-fitted into openings 56 to receive bolt rod 58 which is also made of hardened steel to enhance wearability of the sliding parts.

Referring to FIG. 3, a cam plate 62 is screwed to the outer side of upper latch-rod 16 and positioned to be in the path of and engage lock button 64 when the locking mechanism is actuated to a locked position. In this position bolt rod extension 58 is aligned with

transverse openings

54 and 56 in the frame and strike, respectively, and when triggered by button 64 will be released to engage the respective openings to lock latch-rod 16 in the locked position to frame.

OPERATION The operation of the invention apparatus will be described with reference to the several figures. To lock door in the closed position, door handle 28 is grasped and rotated to move upper and lower latchrods 16 and 18 outwardly through the mechanism in gear box 20. Upper movement of upper rod 16 causes strike 48 to ride upwardly in frame slot 46 from the unlocked position shown in FIG. 5 to the locked position in FIG. 4, the arrows indicating the rod movement to the next position. As shown in FIG. 5 in the lockable position, strike opening 54 is aligned with frame openings 56 at which time cam 62 (FIG. 3) triggers the release of bolt 32 enabling bolt extension 58 to extend through the openings to lock strike 48 and upper bolt 16 to and between

frame legs

42 and 44. In the locked position the roller latches 24 on the free ends of the upper and lower latch rods and roller latch 26 to engage the respective keepers on the door frame. Locking upper latch-rod l6 simultaneously moves lower latchrod 18 to the locked position by means of the gear mechanism in box 20. With door 10 thus locked in the closed position, routine manipulation of handle 28 exterior of the door (not shown) during security sweeps will exert a force that will be transmitted by frame 36 to the door instead of to combination lock 30 preventing damage thereto.

The invention modification avoids frequent repairs to the combination locks, which repairs are not only costly but inconvenient as the room which may contain highly classified documents must be guarded at all times the room cannot be otherwise secured in accordance with prescribed Navy security regulations. Another savings is realized in that a less expensive combination lock can be employed since it need not be made as rugged to withstand the wear and strain exerted on the mechanism.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. In combination with a door employing a locking mechanism including a manually operable latch-rod and a lock having a bolt for securing said latch-rod in a locked position the improvement residing in: v

a U-shaped frame having two legs with an intermediate slot therebetween;

said frame being supported on the door;

each of said legs having an aperture to receive the bolt;

said latch-rod having a strike with an apertured lip portion slidably extending into said slot,

the strike lip aperture being alignable with the apertures in the frame legs when the latch-rod is in the fully locked position;

whereby any pressure exerted on the locked latchrod will be transmitted to the frame without damaging the lock.

2. In combination with a door employing a locking mechanism including a pair of oppositely extendable latch-rods, a handle connected to said latch-rods for manually moving the rods to latching and unlatching positions with respect to a door frame, a combination lock for locking the latch-rods in the latched position, said lock having a sliding bolt for engaging one of said latch rods, the improvement residing in a U-shaped frame supported on the door, said frame having an intermediate slot;

a strike secured to one of said latch-rods and having a laterally projecting lip slidably disposed in the frame slot; 7

said strike lip and frame legs having transverse drilled openings; a rod extension fixed to the bolt end and adapted ,to project into said openings to lock the latch-rod in a locked position;

whereby any pressure exerted on the latch-rods in a latched position by manipulation of handle will be transmitted to the frame without damaging the lock.

Claims

1. In combination with a door employing a locking mechanism including a manually operable latch-rod and a lock having a bolt for securing said latch-rod in a locked poSition the improvement residing in: a U-shaped frame having two legs with an intermediate slot therebetween; said frame being supported on the door; each of said legs having an aperture to receive the bolt; said latch-rod having a strike with an apertured lip portion slidably extending into said slot, the strike lip aperture being alignable with the apertures in the frame legs when the latch-rod is in the fully locked position; whereby any pressure exerted on the locked latch-rod will be transmitted to the frame without damaging the lock.

2. In combination with a door employing a locking mechanism including a pair of oppositely extendable latch-rods, a handle connected to said latch-rods for manually moving the rods to latching and unlatching positions with respect to a door frame, a combination lock for locking the latch-rods in the latched position, said lock having a sliding bolt for engaging one of said latch-rods, the improvement residing in a U-shaped frame supported on the door, said frame having an intermediate slot; a strike secured to one of said latch-rods and having a laterally projecting lip slidably disposed in the frame slot; said strike lip and frame legs having transverse drilled openings; a rod extension fixed to the bolt end and adapted to project into said openings to lock the latch-rod in a locked position; whereby any pressure exerted on the latch-rods in a latched position by manipulation of handle will be transmitted to the frame without damaging the lock.