US3002368A

US3002368A - Plunger-type lock

Info

Publication number: US3002368A
Application number: US47269A
Authority: US
Inventors: Sigurd M Moberg
Original assignee: EJ Brooks Co
Current assignee: EJ Brooks Co
Priority date: 1960-08-03
Filing date: 1960-08-03
Publication date: 1961-10-03
Anticipated expiration: 1978-10-03

Description

Oct. 3, 1961 s. M. MOBERG PLUNGER-TYPE Loox Filed Aug. 5, 1960 IN VEN TOR: 5/60@ M. MME/e@ 3,0()2,368 PLUNGER-TYPE LOCK Sigurd M. Moberg, Pompton Plains, NJ., assgnor to E. J. rooks Company, Newark, NJ., a corporation of New ersey Filed Aug. 3, 1960, Ser. No. 47,269 6 Claims. (Cl. 70-14) 'Ihis invention relates to improvements in plungertype locks of the general character disclosed in my previously led application Serial No. 33,271 (series of 1960), filed June l, 1960. More particularly, this invention relates to improvements in the lock which have the eiect of rendering the lock much more diicult, indeed, well nigh impossible to pick or open without a proper key.

The stated object of rendering the lock more difcult or impossible to pick is achieved by the present invention of which a preferred embodimetn is shown Vin the accornpanying drawing without, however, limiting the invention to that particular embodiment.

In the drawing: A

FIGURE 1 shows the improved lock as applied to y'a iixed arm and a movable valve arm to hold those arms in registering relationship for the purpose of locking a valve in a pipeline in closed position.

FIG. 2 shows the lock in with a valve in a pipeline but top of the lock.

FIG. 3 is an enlarged central axial sectional View of the lock substantially on the line 3-3 of FIG. 1; the lock being shown in locked condition.

FlG. 4 is a view substantially similar to FIG. 3 but showing the effect of an attempt to open the lock by means other than a key particularly designed and provided for that purpose.

The lock, identiiied generally by the reference character 12, comprises a generally cylindrical shank 14, an enlarged head 16 ixedly integral with said shank at one end of the latter (the upper end as illustrated in the drawing), and a removable, cup-shaped head or cap 18 which is adapted to be locked to and released from the lower end of the shank 14 by means hereinafter described.

In the use illustrated in the drawing, a valve 20 in a pipeline 22 is provided with a iixed or stationary arm 24 and a movable valve-operating arm 26. If it is desired that the valve 2t) be locked in closed condition, the arm 26 is brought to its position as indicated in full lines in FIGS. 1 and 2 in which an aperture 28 therein registers with a similar aperture 30 in the stationary arm 24. Then the lock, minus its removable cap 18, is applied to the mentioned valve arms by introducing the shank 14 downwardly through the

apertures

28 and 30 until the enlarged head 16, which is larger than the aperture 28, abuts against the portions of the arm 26 which dene said aperture. That leaves the shank 14 extending through the

apertures

28 and 30 and substantially below the arm 24. Then, by suitable use of a key, the cap 18 is applied and locked upon the lower end of the shank. It should be obvious that, by similar use and manipulation of the lock and its various parts, it may be employed with various kinds of members to lock them together. The present invention, however, is concerned more directly with improved means embodied in the lock making it more diicult, and, indeed, well nigh impossible, yfor the cap 18 to be removed from the shank 14 except by the use of a proper key.

Referring particularly to the cap 18 is provided with two internal

annular grooves

32 and 34 within one or the other of which a pair of steel balls 36 seats and is held seated by a plunger 58 which extends within a counterbore 40 in the lower end of the shank 14 and the just-stated association looking down upon the FlG. 3, it may be seen that aired States Patenti@ at least one and possibly with lice blocks the balls 36 trom moving radially inwardly in transverse bores 42 within which they are disposed. As the balls are thus held against shitting in the bores 42 in the shank of the lock, it follows that the balls are held securely in place extending partly within one or the other of the

annular grooves

32 or 34 so that the cap 18 is held securely against removal from the remainder of the lock. The lower end of the plunger 38 is formed with a reduced portion 44 and, when the plunger is shifted upwardlyr by suitable key means to the point where portion 44 is in alignment with the balls 36, the latter are free to move radially inwardly within the shank to `a sufficient extent to allow them to be entirely clear of the cap 18 whereupon the latter may easily be removed to open the lock.

The plunger 38 is formed with an integral annular shoulder 46, which, by abutment with an annular ledge 48 in the shank 14, limits the downward movement of the plunger 38 to its locking position as indicated in FIG. 3. The plunger is normally held yieldably downwardly in such locking position by a coil spring 56 which encircles an upper extension 52 of the plunger 38, both of which are disposed within a main bore 54 in said shank. The spring 50 is compressed between the upper surface of the shoulder 46 and an undersurface 56 oi a plug 58 which is forcetted, screw-itted, or otherwise firmly fitted into an enlarged bore 60 in the head 16.

It will be observed that the plug 58 is formed with a main bore 62 at its lower end and a counterbore 64 at its upper end. The main bore 62 is only slightly larger than the outside diameter of the upper end of the extension 52 of the plunger so that, it means for unlocking the lock are such as to maintain the extension 52 in axial alignment with the bore 62 of the plug, the plunger 38 may, by suitable key means, be raised against the compressive force of the spring 50 to an extent sufiicient to bring the reduced portion 44 of the plunger into alignment with the balls 36 so that the latter may move inwardly and release the cap 18 for removal.

The upper end of the plungers extension 52. is formed with a bore 66 ofthe same internal diameter as the counterbore 64 of the plug and in axial alignment with said counterbore.

A key for opening the lock preferably includes a pair of

elongate ngers

68 and 70, each of which is substantially semi-circular in cross section and of such dimensions that, when the two mentioned ngers are in non-locking relationship as hereinafter explained, they may be inserted downwardly into and through the counterbore 64 and also into the bore 66. As the

bores

64 and 66 are of the same internal diameter andas the

key fingers

68 and 70 slide freely within and into said bores but with a fairly accurate lit, it follows that when said key iingers are in use to operate the lock, they hold the plunger 38 and, more particularly, its upper extension 52 in perfect alignment with the bore 62 in the plug 58. Because of such alignment, the plunger of the lock may be raised by said key fingers without any interference against entry of the plungers extension 52'into the bore 62, and movement of the reduced lower end portion 44 of the plunger into alignment with the balls 36 permits the latter to move inwardly and, thus, release the .cap 18 for removal.

As the key for operating the lock forms no essential part of this invention, only the

ngers

68 and 70 of a key are illustrated. The key includes means (not shown herein but shown in my mentioned earlier application) for .enabling the user to move the fingers 68 and l70 longitudithe upper extension 52 in 62. Therefore,

tively to the finger 68, a cam portion 72 at the lower end of yfinger 70 rides upwardly upon a cam surface 74 at the lower end of linger '68 so that the two fingers of the key are forcibly urged away from each other at their lower ends. This causesr the lower ends of the fingers, previously quite free of material frictional engagement or gripping contact with the surface of the bore 66 as upon original insertion of the key, to enter into very tight frictional engagement with the walls of said bore. When, after such gripping contact, the key is bodily pulled upwardly, the key ngers 68 land 70 pull the plunger 38 upwardly to permit the balls 36 to be freed from locking engagement with the cap 18 to enable the latter to -be removed in the manner already explained. By similar operation of the key, the cap 18 may be replaced upon the Vlock after which the key may be manipulated to cause the linger 70 to slide downwardly inrelation to finger 68 and thereby release-the tight frictional engagement of said lingers with the wall defining the bore 66. Then, the key may be removed from the lock and the spring 50 will hold the plunger in locked condition in the manner already explained.

The arrangement -by means of which such a lock, according to this invention, is rendered substantially lpickproof resides chiefly in certain characteristics, relative sizes and relationships of various parts of -the lock with reference to each other and also in certain dispositions of those parts as will now be explained. It will be observed that the diameters of the locking portion of the plunger 38 and of the bore 40 are substantially dierent and, likewise, that the outside diameter of the annular shoulder 46 and the inside diameterof the main bore 54 are quite different.

The mentioned differences are such that the plunger 38 and its shoulder 46 are not merely a sloppy t within the bores 40' and 54 but are suliiciently smaller than the mentioned bores that the plunger is capable of substantial tilting relatively to other parts of the lock unless, by proper key means, such as the described

fingers

68 and 70, the upper end of the plunger is positively held in coaxial relationship to the remainder of the lock. Such possible tilting is further facilitated by reason of the fact that the spring 50 is slightly conical in shape with its larger, upper end disposed considerably outwardly of the bore 62 and the outer surface of -the upper extension 52 of the plunger. Moreover, the spring 50 may advantageously be so formed that its bottom end bears non- -uniforrnly upon the shoulder 46 so that while the-seating of the conical undersurface of said shoulder, in locking position, serves to hold the plunger in non-tilted position to receive a key thereinto, the non-uniform spring action will tend to tilt the plunger immediately upon -unseating of said shoulder, unless, of course, a proper key-has been used, holding the plunger against tilting.

The practical pick-proofing elect of rendering the plunger easily tiltable, as just explained, may best be understood by reference to AFIG'. 4. In-considering that tigure, it may be assumed that an interloper, attempting to open the lock without having a proper key, would resort to something in the nature of a bent piece of wire such as is shown at 76. Before attempting to use the wire, the interloper, perhaps having some knowledge or theory las to how the lock operates, would lirst bend or form a hook 78 at its lower end. He would then insert the hooked end of the wire into the lock and into the bore 66. In attempting to cause the hook 78 to jam against the wall of the bore 66, he almost certainly would cant or tilt the wire tosome extent, and in doing so, would tilt the plunger 38, throwing the upper extension'SZ ofthe plunger toward one'side or,fi.e., out of ycoaxial alignment with the bore 62 in the plug.

Even if the wire werenot thus canted, itis almost certain'that the wire could not serve as a means for holding perfect alignment with-the bore after the hook 78 is jammed within-the bore 66, any upward pull of the wire 76, intended to open the lock would serve only to lift the plunger to a point where the upper end of the extension 52 would abut against the undersurface 56 of the plug 58 as shown in FIG. 4. In that condition, the-plunger 38 would still be in restricting position with reference to the steel balls 36 so that the latter would still seat within the groove 34 (or the groove 32) to prevent removal of the cap 18. Thus, it will be seen that where a plunger lock is given the characteristics of the present invention it is rendered practicallyunopenable except Vwith a proper key.

Obviously, the shapes, relative sizes, and inter-relationships of the various parts of the lock may be varied considerably while, nevertheless, employing the principles of the present invention.

I claim:

1. A plunger-type lock comprising a body, a tiltable plunger reciprocable endwisely in said body between locking and unlocking positions, a portion of said body having an inner abutment surface in position to interfere with said plunger to prevent endwise movement of the latter to its said unlocking position when the plunger is tilted, said body being formed with a recess, coaxial with said plunger and adapted to receive a portion of the plunger when the latter is non-tilted to permit endwise movement of said plungerto its said unlocking position, said plunger being formed with an axial bore, opening toward said recess, and said recess opening at the exterior of the lock and ybeing adapted to receive a key adapted to engage said plunger within said bore to hold the plunger in non-tilted condition and move the plunger from its locking to its unlocking position.

2. A plunger-type lock comprising a cylindrical body, an enlarged head integral with one end of said body, a cap slidable onto the other end of said body, releasable locking means carried by said body at its said other end and adapted, except when released, to interengage between and interlock said body and said cap, a tiltable plunger disposed substantially coaxially in said body, reciprocable between a locking position, in which a portion of said plunger, toward one end thereof, coacts with said locking means to hold the latterin such interlocking interengagement between said cap and body and a non-locking position wherein said plunger is free of such holding coaction with said locking means, said enlarged head being formed with an internal recess coaxial with said plunger and adapted, in the absence of tilting of the plunger, `to receive the other end of the latter in an accurate sliding dit to permit movement of the plunger to non-locking position, said plunger, when tilted, being incapable of having its said other end move into said recess and thus incapable of moving to non-locking position, and said lock being formed with a coaxial aperture at one of its ends, adapted to receive a key which is adapted to engage said plunger to hold the latter in non-tilted condition and move it to unlocking position.

3. A plunger-type lock comprising a cylindrical body formed with an enlarged portion on one end thereof, a coaxial main bore, a coaxial counterbore adjoining said main bore at an inner ledge of said body, and a transverse bore lextending from said counterbore to the exterior of said body, a cap slidable onto the other end of said body and formed with an internal annular groove, a locking element in said transverse bore engageable within said groove to retain said cap upon said body and movable inwardly in said transverse bore to disengage said groove to permit removal of said cap, a tiltable, axially reciprocable plunger having an annular shoulder, engageable with said ledge to limit movement of said plunger in one direction, a cylindrical locking portion extending within lsaid counterbore adapted, when in transverse alignment with said locking element, to hold the latter in engagement within said groove, a cylindrical key-receptive portion extending within vsaid main bore, yieldable means within said body urging said plunger toward a locking position in which said shoulder abuts said ledge, said key-receptive portion of the plunger having a coaxial bore and being adapted to fit with an accurate sliding tit within an opposed recess in said body, and said body having a keyhole, coaxial with said bore in the key-receptive portion of the plunger and of substantially similar diameter as the last-mentioned bore, and an annular abutment surface defining the inner end of said keyhole and adapted, when said plunger is tilted, to interfere with said plunger to prevent movement of the latter toward an unlocking position in which said locking portion is free of said holding engagement with said locking element; said keyhole and said bore in the plunger being adapted to cooperate with a key member extending through the keyhole Vand into the latter bore to hold said plunger against material tilting to enable the plunger to be moved by said key member to said unlocking position.

4. A lock according to claim 3, said locking element being a rigid ball.

5. A lock according to claim 3, said main bore and counterbore being of substantially greater diameters, respeotively, than said key-receptive and locking portions of the plunger, rendering the latter substantially tiltable except when held against tilting by such a key member.

6. A lock according yto claim 3, said yieldable means comprising a coil spring extending within said main bore and about said key-receptive portion of the plunger and compressed between said ledge and said annular abutment surface, and the outside diameter of said keyreceptive portion, adjacent to the latters free extremity, being substantially less than the inside diameter of said spring to avoid material inhibition, by said spring, of tilting of said plunger.

References Cited in the tile of this patent UNITED STATES PATENTS