US2919094A

US2919094A - Leg lock for a stand

Info

Publication number: US2919094A
Application number: US431392A
Authority: US
Inventors: Russell E Petrick
Original assignee: Knox Manufacturing Co
Current assignee: Knox Manufacturing Co
Priority date: 1954-05-21
Filing date: 1954-05-21
Publication date: 1959-12-29
Anticipated expiration: 1976-12-29

Description

Dec. 29, 1959 R, E, PETRlCK 2,919,094

LEG LOCK FOR A STAND Filed May 21, 1954 United States Patent O LEG LOCK FOR A STAND Russell E. Petrick, Park Ridge, Ill., assignor to Knox Manufacturing Company, a corporation of Illinois Application May 21, 1954, Serial No. 431,392 `3 Claims. (Cl. 248-171) This invention relates to portable stands for movie picture screens and the like, and more particularly to a locking device for releasably -holding the leg members of such a stand in their folded position.

This application is a continuation-in-part of an application of this inventor entitled A Portable Stand, filed December 28, 1953, and bearing Serial Number 400,598, now Patent No. 2,886,274.

The primary' object of the present invention is to provide a portable stand having folda'ble leg members and 'bracing links which -are moi/able between a locked folded position and 'an outwardly spread position.

Another object is to provide a portable stand having a spring-urged leg unit adapted for limited sliding movement longitudinally of an upright 'standard to lock and unlock the leg unit from folded position.

A further object is to provide a portable 'stand in which an end of 'a bracing link in folded position is at a slight angle to the upright standard so that movement of the leg unit as a whole unlocks the leg members and also urges the bracing link end and its adjacent leg member toward outwardly spread position.

' Another object is to provide a leg unit having a latching means engaging the mid portion of a leg member so that the shock of latching engagement is reduced.

The invention is illustrated in a preferred embodiment in the accompanying drawings, in which:

Fig. 1 is a perspective view of the leg unit in spread position;

Fig. 2, van enlarged broken elevational view partly in section showing 'a leg member in locked folded position;

Fig. 3, an enlarged broken elevational view partly in section showing a leg member in outwardly spread position;

Fig. 4, a broken top plan view of the leg unit in outwardly spread position;

Fig. 5, a broken sectional view taken as indicated on line 5 5 of Fig. 3; and

Fig. 6, a broken sectional view taken as 'indicated on line 6-6 of Fig. 5.

In the embodiment illustrated, a plurality of leg members 8 are -pivotally secured by rivets 9 to an upper collar 10 mounted for slidable movement longitudinally of the -upright standard '11. The leg members and the standard are generally made of metal, the leg members 8 preferably being channel shaped so that they may lie closely adjacent the standard when in folded position, and the standard 11 preferably being tubular so that it may slidably receive a telescoping extension, not shown. Decorative tips 12 may be provided on each leg member to cover any sharp edges upon the leg ends. A cap 13 is secured to the lower end of the standard 11 by a machine screw or a spot-weld to close the lower end.

Bracing links 14 are yconnected at one end to each of the leg members 8 by rivets 15 and at the other end to a lower collar 16 by rivets 17. The lower collar '16 is limited in its slidable movement longitudinally of the standard 11 'by a pin 18 impaling the lower collar 16 and passing through an elong'ated slot 19 in the upright standard 11. As best seen in Fig. 6, the pin 18 also passes through a pair of ears 20 of a -bracket 21 and holds the bracket in position within the tubular standard "1'1. The lower surface 122 of the bracket 21 and the cap 13 confine a compression spring 23 'in the lower end of the standard 11. The spring 23 is slightly compressed so that 'it normally bears upwardly upon the surface 22 to hold the lower collar 16 in its uppermost position longitudinally of the standard 11. This position is shown in Fig. 6 with the pin 18 at the upper end of the slot 19 in the standard 1'1.

The bracing links -14 are joinedV to the leg members 8 and the lower collar 16 so that the upper end of each link will be positioned at a slight outward angle from the standard 11 when the leg unit is in folded position. The 'angle of the folded links 14 is important in unlocking the legs and moving them to their spread position, as will be more fully explained hereafter.

A stationary member, generally designated 24, is fixed upon the standard 11 by a rivet or spot-weld. This member may include one or more hook members 25 having notches 25a preferably opening downwardly of the upright standard 11. Each of the -hook members 25 is positioned so that it engages a cooperating latching portion on the leg unit when the leg unit is moved to folded position adjacent the standard 11. A finger poition 26 is provided on the upper collar 10 to facil'itate movement of the upper collar longitudinally of the standard. As the upper 'collar 1h 'is vraised by the finger porton 26, the leg members are pivoted toward folded position approximately parallel to the standard 11, and the bracing links 14, pivoting about the lower collar 13 and the rivets 15, 'are recessed within the c'hannels of the leg members 8.

' At least one of the bracing links 114, and preferably -all three of them, 'have a narrow lip 27 at one end. The lip 27 is positioned so that it will snap into the downwardly turned notch 25a of the hook member 25 when the leg unit is moved to folded position. As the upper collar 10 is moved lupwardly on the standard 1'1, the lip 27 first Strikes the rounded tip portion 28 of the hook member 25. The tip portion 28 cams the bracing links '14 'and the lower-collar 16 downwardly against the action of the compression spring 23. Subsequently the lip 27 rides oif the rounded tip 28 and snaps into the notch 25a in the lhook portion 25 to secure the leg unit in locked folded position. It is clear that a pin or stud on a leg member could serve the same function as the lip 27.

By positioning the latching mec'hanism so that it is adjacent the middle portion of each of the leg members, the shock of rapid engagement between the hook member 25 and the 'lip 27 is materially reduced. If the leg members are moved toward folded position at |a uniform angular Velocity, it is clear that the lower portions of each leg member travel at a greater linear Velocity than the upper portions do. Since the leg members are normally pulled shut rapidly by upward movement of the upper collar 10, the location of the l'atching mechauism and the accompanyng reduction in shock is important.

As best seen in Fig. 2, when the leg unit is in locked folded position, each bracing link 14 is inclined outwardly at a slight angle from the standard 11. rThis factor is important in disengaging the leg unit to pennit it to move to its outwardly spread position. Since the entire leg unit is mounted for limited slidable movement relative to the standard 11, downward pressure on the finger portion 26 moves the upper collar 10 and the lower collar 16 downwardly against the upward force of the compression spring 23, and removes the lip 27 from the notch 25a in the hook member 25. Because of the slight angle in the bracing link 14, the downward force on the finger portion26 transmits a component of forceto the upper end of the bracing link 14 in a direction outwardly of the standard 11 which assists in the initial movement of each leg member 8 toward its spread position.

It is desirable that the leg unit be frictionally balanced so that the top collar will Continue to move downwardly slowly under the force of gravity until it comes to rest on the top surface 29 of the stationary member 24. In this position the leg members are in their outermost spread position.

The foregoing detailed description is given for clearness of understanding only and no unnecessary limitations should be understood therefrom, for some modifications will be obvious to those skilled in the art.

I claim:

1. A portable stand comprising: an upright tubular standard; a leg unit including an upper collar slidable' on the standard, a plurality of leg members hinged to said upper collar for movement from an outwardly spread position to a folded position adjacent the standard, and a lower collar mounted on the standard for a limited slidable movement longitudinally of the standard; a compression spring in said standard bearing between the lower end of said standard and a portion of said lower collar to yieldingly maintain said lower collar in its uppermost position on the standard; stationary hook members secured to said standard, each of said members having a downwardly open notch; and bracing links joining said lower collar to each of said legs and being movable with the leg members to folded position adjacent the standard, each of said links having a narrow upper lip positioned to snap into a corresponding notch in one of said book members when the leg members are moved to folded position, and each of said links in folded position being inclined upwardly and outwardly of the standard whereby a downward force on said leg unit compresses the spring disengaging each of the said lips from its corresponding notch and pivoting each of the links outwardly of the standard to move the leg members to their spread position.

2. A portable stand, comprising: anupright standard; a leg unit having .a plurality of legs and bracing links hinged for movement from an outwardly extended position to a folded position adjacent the standard, said leg unit being mounted slidably on the standard for a limited movement longitudinally thereof, each of the bracing links 4 having upperl and lower end portions pivotally secured to one of the legs and to the standard, the upper end portion being outwardly inclined from said standard when in folded position; aV stationary portion on the standard positioned adjacent said leg unit; a latching portion on the leg unit positioned for cooperative locking engagement with said stationary portion when said legs are moved to folded position; and spring means yieldably urging said entire leg unit longitudinally of the standard to maintain said latching portionand stationary portion in locking engagement when the legs are in folded position, said legs being unlocked from folded position by moving the entire leg unit longitudinally of the standard against the action of said spring means to disengage said latching portion from said stationary portion and to urge the upper end portion of each of the bracing links outwardly of the standard to move the leg unit to its outwardly extended position.

3. A portable stand, comprising: an upright standard; an upper and a lower collar each slidably secured on the standard, the lower collar being secured by a pin in slot connection to provide limited movement longitudinally of the standard; spring means normally urging the lower collar in the direction of said stationary latching portion; a leg unit having a plurality of leg members hinged to the upper collar for movement from an outwardl'y spread position to a folded position adjacent the standard, said leg unit including braeing links each having upper and lower end portions pivotally secured to one of the leg members and to the lower collar respectively, the upper end portion being outwardly inclined from the standard when in folded positionya stationary latching portion secured to said standard and positioned adjacent said leg unit; and a cooperating latching portion on the leg unit positioned to yieldingly engage said stationary latching portion and lock the leg members in folded position when swung adjacent the standard, downward movement of the leg unit disengaging said cooperating latching portion and urging the upper end portions of each of the bracing links outwardly of the standard to move the leg members to supporting position.

References Cited in the file of this patent UNITED STATES PATENTS 703,873 Whetham July 1, 1902 1,258,5l8 Ankovitz Mar. 5, 1918 1,364,169 Wolff Jan. 4, 1921 2,549,584 Eller Apr. 17, 1951 hen..