US3870354A

US3870354A - Drop bolt snap latch locking mechanism

Info

Publication number: US3870354A
Application number: US371141A
Authority: US
Inventors: Herman Prahl
Original assignee: Individual
Current assignee: Individual
Priority date: 1973-06-18
Filing date: 1973-06-18
Publication date: 1975-03-11
Anticipated expiration: 1992-03-11

Abstract

A drop bolt locking combination capable of snap latch operation is provided with a resiliently biased bolt element and cooperating strike member which enables the bolt element to be moved to a withdrawn position and then snapped into locking arrangement with the strike member upon closing of the door. The bolt element has a plurality of fingers having spring biased ball bearings therein while the strike member has beveled flanges thereon for engaging the ball bearings and moving the bolt element a sufficient distance against spring biasing to permit closing of the door without the necessity of withdrawing the bolt element by knob operation.

Description

United States Patent Prahl DROP BOLT SNAP LATCH LOCKING MECHANISM Primary ExaminerAlbert G. Craig, Jr. [76] Inventor: Herman Prahl, 48-38 Fifty Eight Attorney Agent 9 firm-Harvey Zeuer W d 'd ,N.Y. H377 e 57 ABSTRACT [22] Flled: June 1973 A drop bolt locking combination capable of snap latch [21] Appl. N0.: 371,141 operation is provided with a resiliently biased bolt element and cooperating strike member which enables the bolt element to be moved to a withdrawn position tg zg fig and then snapped into locking arrangement with the [58] Fie'ld "70/91 97 6 106 143 strike member upon closing of the door. The bolt ele- 7O/462 41562 16 ment has a plurality of fingers having spring biased 157 ball bearings therein while the strike member has bevi eled flanges thereon for engaging the ball bearings and [56] References Cited moving the bolt element a sufficient distance against spring biasing to permit closing of the door without UNITED STATES PATENTS the necessity of withdrawing the bolt element by knob 1,253,734 l/l9l8 Sheinman 70/106 operation 1,378,504 5 1921 White 1,399J58 12/1921 Segal 70 104 4 ClaImS 5 Drawlng Flgures 96 i 104\\ \1 84x7 l j DROP BOLT SNAP LATCH LOCKING MECHANISM BACKGROUND OF THE INVENTION The present invention relates to drop bolt lock mechanisms and particularly to a drop bolt lock mechanism capable of snap latch operation.

In recent years, lock security has become of increasing importance. While numerous improvements have been made in the attempt to devise pick proof locks by modifying the key operated cylinder mechanism, these improvements are of little significance where the bolt element may be displaced from the outside without the use of a key or the requirement for rotating the key plug within the cylinder lock. Methods for accomplishing this are well known. As a result, there has been a resort to drop bolt locks which provide substantial protection against the displacement of the bolt element without the use of a key. This, however, in most situations, has required the use of two locks since in many situations people desire the convenience of having a snap latch for affording only partial security under circumstances when they are to be home or when they are to be out for only a few minutes or in situations when they do not wish to go to the door each time that a visitor without a key leaves.

It is therefore an object of the present invention to provide a drop bolt lock which is capable of operating in a snap latch fashion thereby avoiding the necessity of the use of two locks while at the same time increasing the security provided where the lock is used in the snap latch fashion.

It is a further object of the present invention to provide such a drop bolt lock which is capable of operating in a snap latch fashion on both swing open doors and on sliding doors.

SUMMARY OF THE INVENTION The above objects are accomplished by means of the present invention which briefly includes a drop bolt lock having a resiliently biased bolt element normally biased in a locking direction and having finger means on the bolt element cooperative with a strike member to move the bolt element to a retracted position upon closing the door to enable snap latch operation. The finger means is of a hollow cylindrical shape and includes a spring within the hollow section and a ball bearing projecting therefrom. The strike member is beveled along an edge to engage the ball bearing and lift the bolt element. Beveling of the strike member and usage of the ball bearing enables the utilization of the lock on either swing doors or sliding doors.

BRIEF DESCRIPTION OF DRAWINGS I drop bolt lock and strike member engaged in the snap lock position.

DETAILED DESCRIPTION OF THE INVENTION Referring to the drawings and particularly to FIGS. lthrough '3 there is shown a drop bolt lock generally designated as 10 in FIG. 1 having its cover removed. The lock 10 includes a base plate 12 which may be secured to a door with the edge of the door being designated 14. The base plate 12 may be secured to the door by means of screws 16. The base plate 12 includes an aperture therein for the operating element 18 which may be secured to the key plug of a cylinder lock (not shown) or which may be operable by the rod of a rim lock. The base plate 12 also has cut-

outs

20 and 22 perpendicular to the door edge 14 for cooperation with a strike element as to be explained hereafter.

Cover 24 is provided for covering the base plate 12 and mechanism internal thereto. The cover 24 has a peripheral flange 26. On an edge of the flange 26 is a projecting tab 28 for mating with the base plate 12 under a raised portion 30. At the opposite end of the flange are

apertures

32 and 34 for alignment with threaded bores 36 and 38, respectively, in tabs '40 and 42, respectively; of the base plate 12 whereby the cover 24 may be secured to the base plate 12 by means of screws not shown. The cover 24 may also have an operating element 44 mounted therein for rotation of a knob. Cover 24 is provided with

spaces

46 and 48 for cooperation with a strike element as'to be explained hereinafter.

The base plate 12 and cover 24 constitute a housing for bolt element 50. The bolt element 50 is operable by either of

operating elements

18 and 44. The bolt element 50 has a bolt head 52 as shown in FIG. 4. The bolt head 52 is secured between a pair of plates, only one of which is shown as S1. The bolt head 52 includes a pair of

cylindrical fingers

54 and 56 which extend parallel to door edge 14 and are guided for movement in a vertical direction in

apertures

58 and 60, respectively, in flange 26. Additionally, guiding the bolt element 50 is a pin 62 on cover 24 which mates with elongated slot 64 in plate 51 of bolt element 50. Under snap latch operating conditions pin 62 abuts against the lower edge of tab 66. The internal operating mechanism of the bolt element 50 between its plates is identical to the corresponding structure of applicants copending US. Application Ser. No. 182,590 filed on Sept. 22, 1971, now US. Pat. No. 3,759,074 dated Sept. 18, 1973 and the description therein is incorporated here by reference.

Also included on the cover 24 is a pin 68 having a torsion spring 70 thereon which normally biases the bolt element 50 downwardly. A cutout 72 is provided in plate 51 permitting the bolt element 50 to be moved upwardly against the bias of spring 70 for snap latch operation, as to be explained hereinafter, and permitting further upward movement whereby keeper 74 may be moved in slot 76 in cover 24 into cutout 78 in bolt element 50 to hold the bolt element 50 in a retracted position whereby no locking action is provided.

Strike element 80 shown in FIG. 2 consists of a base 82 having a pair of projecting

flanges

84 and 86. The strike element 80 is mounted on the door frame adjacent the edge 88 thereof by

screws

90, 92 and 94. When the door is closed the

flanges

84 and 86 enter the spaces provided by

cutouts

20 and 22 of the base plate 12 and

spaces

46 and 48 of the cover 24.

Referring now to FIGS. 4 and 5, there is shown the novel bolt head and strike construction which permit the usage of the drop bolt lock of the instant invention in a snap latch mode of operationrReferring first to bolt head 52, the

cylindrical fingers

54 and 56 are provided with

springs

96 and 98, respectively, and

ball bearings

100 and 102, respectively. Referring next to the strike element 80,

flanges

84 and 86 are provided with

bevelled edges

104 and 106.

In mounting the strike element 80 and locking mechanism it is necessary to arrange these members so that when the bolt element 50 is in the snap latch position with the tab 66 in engagement with pin 62, the

ball bearings

100 and 102 will strike

bevelled edges

104 and 106 when the door is closed. Furthermore, the

bevelled edges

104 and 106 must be of sufficient height so that when the door is closed and the

fingers

54 and 56 are within

apertures

108 and 110, respectively, the vertical cylindrical surfaces of

fingers

54 and 56 must reside within the

apertures

108 and 110, respectively.

In operation, when a door having the described locking mechanism is closed against a door frame having the described strike element,

ball bearings

100 and 102 strike bevelled

edges

104 and 106, respectively, to move bolt element 50 upwardly against the biasing of spring 70. While this occurs,

ball bearings

100 and 102 also move upwardly against the biasing of

springs

96 and 98, respectively, reducing the necessary movement of the bolt element 50 thereby reducing the force necessary to close the door. Additionally,

ball bearings

100 and 102 rotate further reducing the friction and force necessary. It is noted that since

bevelled edges

104 and 106 extend around

flanges

84 and 86, the mechanism may be used on either swinging doors or sliding doors. Once the door has been closed,

cylindrical fingers

54 and 56 reside within

cylindrical bores

108 and 110, respectively, and prevent biasing of bolt element 50 upwardly by pushing or pulling on the door and thereby prevent opening the door without utilization of

operating elements

18 or 44.

The drop locking mechanism described may also be used as a locking bolt lock by rotating the

operating elements

18 or 44 to move tab 66 to a position beneath pin 62 in the manner described in the aforementioned copending application.

While the present invention has been described with respect to an illustrative embodiment thereof, modifications will now become apparent to those of ordinary skill in the art. For instance, while the locking mechanism has been described whereby the bolt element is guided for movement by elements on the cover 24, it is equally possible to place the flange 26 and guiding pin 62 on the base plate 12. Furthermore, it is possible to use a different bolt element than that described herein provided the same bolt head is used. It is therefore intended that the scope of the invention be determined bythe chains appended hereto.

What is claimed is:

l. A drop bolt locking mechanism and strike member combination capable of snap latch operation comprising:

a bolt element housing for mounting upon a door with a portion of said housing extending beyond the edgeof said door, said portion consisting of a plurality of sections with spaces between said sections extending in a direction substantially perpendicular to said edge of said door;

a bolt element mounted within said housing for movement therein relative to said housing in a direction substantially parallel to said edge of said door, said bolt element having finger means thereon for movement in said spaces in a direction parallel to said edge of said door;

means in said housing for resiliently biasing said bolt element in a first direction parallel to said edge of said door for normally maintaining said finger means in said spaces; 7

a strike member for mounting on the door frame opposite said housing, said strike member having a plurality of projecting flange means for mating with said spaces and said flanges having apertures therein for receipt of said finger means;

said flange means having bevelled edges for engaging said finger means and pushing said bolt element in a second direction opposite to said first direction upon closing of said door to enable said snap latch operation; and

said finger means having ball bearings projecting therefrom into said spaces to facilitate said snap latch operation.

2. The combination according to claim 1 wherein said finger means are hollow cylindrical extensions of said bolt element and said ball bearings project from their open ends extending into said spaces and means within said cylindrical extensions biasing said ball bearings into said spaces.

3. The combination according to claim 1 further including means for moving said bolt element to a position wherein said finger means is withdrawn from said spaces and means for retaining said finger means withdrawn from said spaces.

4. The combination according to claim 1 further including means for moving said bolt element to a locking bolt position.

Claims

1. A drop bolt locking mechanism and strike member combination capable of snap latch operation comprising: a bolt element housing for mounting upon a door with a portion of said housing extending beyond the edge of said door, said portion consisting of a plurality of sections with spaces between said sections extending in a direction substantially perpendicular to said edge of said door; a bolt element mounted within said housing for movement therein relative to said housing in a direction substantially parallel to said edge of said door, said bolt element having finger means thereon for movement in said spaces in a direction parallel to said edge of said door; means in said housing for resiliently biasing said bolt element in a first direction parallel to said edge of said door for normally maintaining said finger means in said spaces; a strike member for mounting on the door frame opposite said housing, said strike member having a plurality of projecting flange means for mating with said spaces and said flanges having apertures therein for receipt of said finger means; said flange means having bevelled edges for engaging said finger means and pushing said bolt element in a second direction opposite to said first direction upon closing of said door to enable said snap latch operation; and said finger means having ball bearings projecting therefrom into said spaces to facilitate said snap latch operation.