US3229029A

US3229029A - Wireway and removable cover therefor

Info

Publication number: US3229029A
Application number: US281736A
Authority: US
Inventors: Irving F Weiss
Original assignee: ECP Manufacturing CO
Current assignee: ECP Manufacturing CO
Priority date: 1963-05-20
Filing date: 1963-05-20
Publication date: 1966-01-11
Anticipated expiration: 1983-01-11

Description

Jan. 11, 1966 I. F. WEISS 3,229,029

WIREWAY AND REMOVABLE COVER THEREFOR Filed May 120, 1963 o I "fill/1111111011111 FIG.|

INVENTOR. WIRVING KF/W SS sa /L ATTORNEY United States Patent 0 "ice 3,229,029 WIREWAY AND REMOVABLE COVER THEREFOR Irving F. Weiss, University Heights, Ohio, assignor to ECP Manufacturing (30., Cleveland, Ohio, at corpora tion of Ohio Filed May 20, 1963, Ser. No. 281,736 12 Ciaims. (Cl. 174-401) The present invention relates to wireways and more particularly to wireways of modular construction.

The modular wireway of the present invention is particularly usable for mounting on electrical panelboard and other supports to retain electrical wires in an orderly and accessible manner among various electrical devices. Prior wireways used for this purpose have presented several problems. First, prior wireways are generally heavy, bulky, and cumbersome to mount on the panelboard. With prior wireways it is necessary to completely and carefully plan the position of the wireways and the location of their securement holes at the same time the layouts are made for the positions of the electrical devices. Generally, the wireways are custom tailored for each panelboard to assure that their securement holes are properly located. This is expensive and results in a large, specialized inventory of many different sizes of wireways. This also results in a high loss because the many short pieces left after cutting the required wireway lengths cannot be used and are scrapped.

One wireway construction which overcomes many of the prior difficulties is presented in Patent No. 3,156,765 entitled Wireway, by the present inventor. This wireway is of a modular wireway design wherein the wireway bottom, sidewalls and cover are separate pieces and interiit to form a coverable wireway channel. The wireway bottoms are separately fastened to the panelboard in the desired wireway layout and then the sidewalls are secured to the bottoms. This modular construction is quickly assembled on the panelboard, and, since the same side wall material is usable on all the various sizes of hottoms, it eliminates stocking a complete wireway in each wireway size. Moreover, there is no waste in the sidewall material as scrap pieces can be pieced together when connected to the bottom.

In the present modular wireway, the sidewalls are secured to the panelboard by small clip members fastened to the panelboard at spaced intervals along the wireway location. A complete wireway bottom is not required. The sidewalls and clip members include interlocking portions which cooperate to fix the sidewalls in a spaced parallel relation projecting from the panelboard. Various width wireways are provided by making the clip members in several sizes. Further, various height wireways are obtained by making the sidewall material in several sizes. As will be apparent from the foregoing the use of the several different sizes of clip members and side Wall material provide a multiple of different wireway sizes.

For example, an inventory of six sizes of clip members and four sizes of side wall material provides twenty four different combinations of wireway widths and heights. With the wireways prior to this invention and that in the above Patent No. 3,156,765, this would require an inventory of twenty-four wireways. The required inventory is then reduced to less than one-half of that required for the prior wireways.

Another problem in prior wireways is in attaching the covers securely to the sidewalls. The connection between the cover and the sidewalls must be secure enough to withstand accidental release because of an over-filled, bulging wireway as well as other causes. At the same time, this cover must be easily removable intentionally. In addition, the cover must remain on the wireway regardless of the position of the wireway.

3,229,029 Patented Jan. 11, 1966 Wireways are often arranged vertically on panelboards and, in the past, the force of gravity has caused the covers to slip longitudinally on the sidewall. This vertical slippage is pres-ent even in some of the prior bead and socket cover connections.

Where the wireway parts are extruded plastic members, it is almost improssible to maintain close tolerances between the size of the bead and the size of the receiving socket. This is due in part to a difference in extrusion die wear and in part to the uncontrollable nature of the plastic extrusion process. Thus, it is fairly common to have a bead socket which does not securely grip a bead even though the extrusion dies were originally sized to provide a secure gripping connection.

In the present wireway, the bead element is tear-drop shaped and forms the upper longitudinal edge of the side wall material. The longitudinal edges of the cover material include socket portions which receive and engage the tear-drop shaped head in at least one of two places, one of which is just under the largest dimension of the generally rounded portion of the bead and the other of which is along the tapered sides of the head to near where it joins the side wall material. The socket portions each include distensible lip walls of uniform thickness. The head receiving socket as formed by the uniform thickness lip walls require less material and provide greater flexibility than with prior socket formations. In addition, the distensible lips when gripping the tear-drop shaped bead drive the bead interiorly of the socket and force the very top of the rounded surface of the bead against a back wall of the socket. This assures that the socket will always grip the bead and hold the cover from slipping even though the bead may vary in size.

Accordingly, an object of the present invention is to provide a new and improved wireway of a modular construction wherein a multiple of combinations of wireway heights and widths is possible from a minimum number of pieces.

Another object of the present invention is to provide a new and improved wireway construction of modular design wherein a given wireway may be secured to any panelboard regardless of the location of the securement holes.

Still another object of the present invention is to provide a new and improved wireway wherein the wireway channel is substantially bottomless.

Yet another object of the present invention is to provide a new and improved wireway wherein the cover is securely retained on the sidewalls but is easily intentionally removed from them.

A further object of the present invention is to provide a new and improved wireway and cover having coacting bead and socket portions wherein the socket portion is always in tight gripping engagement with the bead portion.

Other objects and a fuller understanding of the invention may be had by referring to the following description and claims taken in conjunction with the accompanying drawings in which:

FIGURE 1 is a fragmentary perspective view with parts broken away, of the modular wireway of the present invention;

FIGURE 2 is an end view with a sidewall removed and other parts in cross-section of the wireway of FIGURE 1;

FIGURE 3 is an elevational view in cross-section of a side-wall of the wireway shown in FIGURE 1;

FIGURE 4 is a fragmentary end view with parts in cross section of an alternate form of the wireway of the present invention.

FIGURE 5 is a fragmentary view of the bead and socket arrangement shown in FIGURE 3 wherein the head is oversized; and,

FIGURE 6 is a fragmentary view of the bead and socket arrangement shown in FIGURE 3 wherein the head is undersized.

Referring now to the drawings wherein like reference characters indicate like or corresponding parts throughout the several views, a wireway employing the present invention is indicated generally by the reference character 11 in FIGURE 1. The wireway 11 is mounted on a panelboard 12 and includes a pair of spaced, parallel side-wall pieces 13, 14 defining a wireway channel be tween them, clip members 15 removably securing the wall pieces 13, 14 to the panelboar-d 12, and a cover 16 removably secured to the tops of the wall pieces 13, 14. The wall pieces 13, 14, the cover 16, and the clip members 15 are made of flexible material, preferably a synthetic or the like plastic. The preferred synthetic plastic is a high impact rigid vinyl plastic which is non-flammable, an electrical insulator, and easily fabricated. In some applications of the clip member 15, the plastic material used may be more or less rigid depending on the relative amounts of stiffness and resiliency desired.

The wall pieces 13, 14 are both cut from identical wireway side wall material. The side wall material is substan tially L shaped in cross-section as is shown in FIGURE 3. The wall material is made in several heights and includes a foot portion 20, a wall portion 21, and a tear-drop shaped bead 22 along the top of the wall portion 21. The tear-drop shaped bead 22 has a small tapered portion adjacent the wall portion 21 and a larger generally rounded portion defining the extreme outer longitudinal edge of the side wall material. The wall portion 21 also has a plurality of rectangular openings 23 at closely spaced intervals throughout the longitudinal extent of the wireway wall material. Each rectangular opening 23 extends transversely from just above the foot portions 2% to adjacent the bead 22. The many rectangular openings provided in each side of the wireway 11 permit electrical wires to enter and exit anywhere along the wireway 11.

The cover 16 also is elongated and includes a longitudinally extending back 25 and bead sockets 26 at the longitudinal sides of the back 25. As shown in FIGURE 3, each bead socket 26 is formed by a pair of distensible lips having inwardly

angled portions

27, 28 and slightly outwardly angled portions 29, 36). The angled portions 27-30 are of uniform thickness and together define a bead socket which is undersized so that the inwardly

angled portions

27, 28 grip the bead 22 immediately under the largest dimension of its generally rounded portion, at the tapered sides of the head 22 and/ or at the juncture of the bead 22 and the wall 21. Thus, if the generally rounded portion of the tear-drop shaped bead 22 is oversized the distensible lips of the socket 26 rigidly grip the bead 22 just under the largest dimension of its rounded portion as is shown in FIGURE 5. If the rounded portion of the bead 22 is undersized then the distensible lips grip the tear-drop shaped bead on its tapered sides at or close to the juncture of the bead 22 and the wall 21 as is shown in FIGURE 6.

The length of the bead 22 in cross section from its juncture with the wall portion 21 to the very tip of its rounded surface is greater than the perpendicular dimension from the inside surface of a back socket wall 31 to a line passing through the junctures of the

angled portions

27, 29 and 28, 30. In other words, the longer cross-sectional dimension of the head 22 is sized such that when the distensible lips of the socket 26 engage the tapered side surfaces of the bead 22, the lips drive the head against the back wall 31. The bead 22 is then always held in abutment with the back wall 31 by the angled portions 27-36 which always engage the bead 22 anywhere from its largest dimension to the juncture of the head 22 and the wireway wall 21. Thus, the latter bead and sockct connection provides three positive areas of contact be- 4;; tween the bead 22 and the socket 26 in an arrangement which assures that all beads will be rigidly secured in all sockets regardless of variations in tolerances.

The slightly outwardly

angled portions

29, 30 act as guides when the bead sockets 26 are snapped over the beads 22. The latter structure is especially important where the bead portions are cut as at 24 opposite the rectangular openings 23 to permit the lateral insertion and removal of Wires through the openings 23. When the bead is cut as at 24, the outwardly

angled portions

29, 30 serve to align laterally displaced bead portions on each side of the cut 24 as the cover In is placed on the wireway. In addition, the distensible lips reinforce the bead 22 and the uppermost areas of the wall portion 21 after the cover 16 is in place. The innermost outwardly slanted portion 319 is extended further than the outermost outwardly angled portion 29 to assist in seating the cover 16 when the wireway channel is bulging with electrical wires as is explained in the above-referenced co-pending application.

Another feature of the present bead and socket connection is illustrated in FIGURE 2 wherein a one-sided, covered wireway channel is shown. The latter wireway channel arrangement is often used with its open side adjacent the electrical devices on the panelboard 12. When the cover is cantilevered in this manner, it is rigidly held in a position substantially parallel to the panelboard by the angled portions 27-39 acting against vertically displayed points on the tapered sides of the bead 22, In other words, clockwise rotation of the cover 26 is resisted by the angled portions 28, engaging the lowermost area of the tapered bead sides at or near the juncture with the wall portion 21 and the

angled portions

27, 29 engaging the upper tapered surface of the head just under its maximum dimension.

The foot portion 21} includes a triangularly shaped ridge 32 etxending parallel to the wall portion 21. The triangular ridge 32 has a slanted upper surface 33 at an angle b to a bottom surface of the foot portion 29 and a slanted side surface 34 at an angle a to the slanted surface 33. In the preferred form of the wireway shown, the angle b is approximately 9, the angle a is a right angle, and the angle the slanted surface 34 makes to a perpendicular line passing through the apex of the ridge 32 is the angle b and is 9. The height of the apex formed by the slanted surfaces 33, 34 above a plane defined by the bottom surface 35 of the foot portion 20 is indicated by the reference character B.

As shown in FIGURE 2, the clip member 15 includes a heavy midportion 38 and extending and portions 39 which are smaller in thickness compared to the mid-portion. The midportion 38 includes a holddown hole or aperture 41) which receives a bolt or other fastening device 41 to rigidly secure the clip member 15 to the panel board 12. As shown, the holddown hole is in the exact center of the rectangular clip member, although it may be also offset to one side of center toalter its clipping or interlocking relationship with the foot portion 20. An annular flange 42 protrudes from the top surface of the clip member 15 and surrounds the holddown hole 4t) to shield the bolt 41 from contacting any wires in the wireway. When the clip member 15 is in use, as is shown in FIGURE 1, the under surfaces of the end portions 39 overlap the upper surfaces of the foot portions 20 to securely retain the wall pieces 13, 14 in position.

As best shown in FIGURE 2, the under surfaces of the end portions 39 include triangular ridges 4-5 extending parallel to end surfaces 47 of the clip member 15. Each triangular ridge 46 includes a surface 48 slanted inwardly and downwardly from the end surface 47 and a locking surface 49 at right angles to the bottom surface of the clip member 15. When the foot portions 20 are secured or snapped under the end portions 39 as is shown in FIGURES 1 and 2, the

triangular ridges

32, 46 mate and the outer terminal edge of thelocking surfaces 49 of the end portions 39 engages the bottom of the slanted side surfaces 34 of the foot portions 20 to interlock the foot portions 20 against outward lateral movement relative to the clip member 15.

The undersides of the end portions 39 each further include a tensing surface 50, an abutment surface 51 and a recessed surface 52 extending between the tensing and abutment surfaces 50, 51. The end portions 39 are thinnest in the area of the recessed surfaces 52 so that the depth of the recessed surfaces 52 is somewhat determinative of the relative flexibility of the end portions 39. Stitfening webs 53 extend from the center of the clip member to adjacent the recessed surfaces 52 to increase the rigidity of the midportion 38.

The tensing surfaces 50 are at an elevational distance A from a plane defined by a bottom surface 54 of the clip member 15. This distance A is less than the height B of the apex of the triangular ridge 32 of the foot portion 20. When the foot portions 20 are interlocked under the end portions 39, the apex of the triangular ridges 32 engage the tensing surfaces 50 and move the end portions 39 away from the panelboard 12 to tense the end portions 39 by flexing the clip member in an area between its secured midportion 38 and the movable end portions 39. In this tensed state, the end portions 39 urge or force the foot portions 20 against the panelboard 12 and effectively provide a spring biased clip. The differential between the height B of the ridges 32 and the elevation A of the tensing surfaces 50 determines the amount or degree of tensing of the end portions and, therefore, also the amount of the force urging the foot portions 20 against the panelboard 12 to resist separation of the wireway.

As noted above, outward lateral displacement of the foot portions 20 is limited by abutment or engagement of the

surfaces

34, 49 of the foot and

end portions

20, 39 respectively. Inward lateral movement of the foot portions 20 is limited by engagement of innermost side surfaces 56 of the foot portions 20 and the abutment surfaces 51 of the clip member 15. The distance between the abutment and locking

surfaces

51, 49 of the clip member is slightly greater than the distance between the slanted and end surfaces 34, 56 of the foot portion to permit slight lateral movement of the wall pieces 13, 14 relative to the clip member 15. This permissible lateral play or movement assures that the triangular ridges 32 of the foot portions are fully received behind the triangular ridges 46 of the clip member. This permissible play also prevents the foot portions 20 from binding within the clip member 15 to permit the wall pieces 13, 14 to be longitudinally moved while gripped by several clip members 15 for adjustment of the position or location of the wall pieces 13, 14 during assembly of a complete wireway system.

Release spaces 59 are defined between the outer ends 47 of the end portions 39 and the juncture of the wall and

foot portions

21, 20 so that the end of a screwdriver or like tool may he slipped between the wall portions 21 andthe outer ends 47 and twisted to snap the end portions 39 free of their interlocked relation with the foot portions 20. Release of the foot portions 20 from the clip members 15 may also be effected by Sliding the wall pieces 13, 14 endwise until they are clear of the clip members 15.

The facility of assembly of the many wireways required on an electrical panelboard is one of the principal advantages of the present invention. A method of assembling the wireway 11 involves first, laying out the centerlines of the raceways on the panelboard 12. Holddown holes are then made in the panelboard 12 at spaced intervals along the center lines and near the intersections of centerlines. The clip members 15 are the secured to the panelboard at each holddown hole location. Lengths of the sidewall material are then cut to size and assembled on the panelboard in mirror image relation to form the channel-like wireways by merely laterally shoving their foot portions 20 under the end portions 39 of the clip members 15 until the foot portions snap in place. There is no material waste since leftover wall pieces can be placed end-to-end and a single clip member 15 positioned to overlap the abutted foot portions of two contiguous wall pieces.

An alternate clip member 61 is shown in FIGURE 4 and is used to form a bottomless wireway channel which may be assembled before securement to a panelboard, or assembled and mounted elevated as by a post 62 from the panelboard. The clip member 61 includes upper resilient clip portions 63 and lower support portions 64. The undersides of the clip portions 63 are identical to the undersides of the end portions 39 of the clip member 15 as described above.

Adjacent clip and

support portions

63, 64 define openings 65 which receive the foot portions 20 to releasably connect the wall pieces 13, 14 to the clip member 61. In its preferred form, the clip member 61 is extruded, molded or otherwise formed entirely of a suitable plastic material having sutlicient rigidity to support the wall pieces 13, 14 and yet sutficient resiliency to permit fiexure of the clip portions 63.

In summary, the present invention may be briefly described as a modular wireway having elongated side walls fabricated from identical side wall material, arranged in spaced relation on a panelboard, and secured to the panelboard by a plurality of clip members located at spaced intervals along the location of the wireway. The side walls and the clip members include mating parts which are interlockable by pressing the side walls into the clip members to fix the side walls in their spaced relation. The invention contemplates that the side wall material may be made in several different heights and the clip members in several different widths to provide a multiple of possible wireway height and width combinations. The

invention further contemplates that the wireway is coverable with a removable elongated cover having socket portions which snap on head portions of the side walls to hold the cover in place. The head portions are teardrop shaped and the socket portions have distensible lips which always engage the tapered sides of the head portion and drive it against the back of the socket portion.

Although the invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.

What is claimed is:

1. A modular wireway for retaining wires in an orderly and accessible formation on a support structure, said wireway comprising:

(a) a plurality of sidewalls having wall portions arranged in spaced, substantially parallel relation and foot portions projecting from the wall portions near longitudinal edges of the wall portions;

(b) clip means having retaining portions overlying said foot portions;

(c) said foot portions and said retaining portions having interlocking surfaces limiting lateral movement of said sidewalls relative to the clip means; and,

(d) the overlapping portions of said clip means being resiliently urged against said foot portions and pressing said foot portions against a supporting surface whereby said sidewalls are maintained in substantially spaced, parallel relation by said clip means and define a wireway channel between them.

2. A modular wireway for retaining wires in an orderly and accessible formation on a support structure, said wireway comprising:

(a) a plurality of side walls having wall portions ar- 3,229,029 7 :8 ranged in spaced, substantially parallel relation and back portions are of a uniform thickness and are also foot portions'projecting from the wall portions near planar between said angled portions. longitudinal edges of the wall portions; 9. Wireway side wall material to-be secured in standb) clip means having retaining portions overlapping ing relation on a support surface by a clip means, said said foot portions; side wall material comprising:

(c) said foot portions and said retaining portions having interlocking surfaces limiting lateral movement of said sidewalls relative to the clip means;

(d)'the retaining portions of said clip means being resiliently urged against said foot portions and press- :(a) an elongated Wall portion;

('b) an elongated foot portion projectingfrom the bottom of said wall portion for abutment on said support surface, said foot portion having a substantially planar locking surface adjacent said wall ing said foot portions against a supporting surface 10 portion;

so that said sidewalls are maintained in substantially (C) a ridge formed on said locking surface and extendspaced, parallel relation by said clip means; and, ing parallel to saidwall portion, said ridge projecting (c) said retaining portions and the support surface deabove the Plane of the locking surface and being fining foot portion receiving grooves extending longiengageable h the d p means to tense said clip tudinally of the wireway defined by said side walls i I and adapted for laterally receiving said foot por- Silld rldgelflcluding an pp Surface at a Slight tions, whereby said sidewalls are assembled and gl t0 Said locking surface and a side surface maintained in their spaced, parallel relation defiria g aid Wallportion and di po ed t Substaning the wireway by laterally inserting the foot portlany Ilght angles to Said pp Surface, Said Side tions into said foot portion receiving grooves. 3. The device of claim 2 wherein said clip means comsurface' being engageable with a side surface on the clip means; and, (e) said slight angle being substantially the angle of prises a plurality of individual clip members located at longitudinally spaced intervals throughout the longitudinal extent of the wireway.

4. The device of claim 2 including, in combination: (f) said retaining and foot portions having mating tensing surfaces, and the relative elevation of the the tensed clip means relative to the support surface so as to maintain the side surfaces'in area contact. it). A clip member for securing side walls in a spaced relation so as to define a wireway channel, said clip member comprising:

tensing surfaces on the retaining portions when not overlapping the foot portions being less than the elevation of the tensing surfaces on the foot portions so that when said retaining and foot portions are in an overlapping relation said retaining portions are flexed and urge said foot portionsagainst said supporting surface.

5. T he device of claim 2 including in combination:

(f) said interlocking surfaces comprising ridges on said retaining and foot portions extending throughout substantially the entire longitudinalextent of said portions and engaging to prevent lateral movement of said side walls.

6. A wireway comprising:

'(a) a pair of spaced substantially parallel side walls;

-(b) means for securing the side walls to'a support;

(0) said sidewalls having longitudinally extending outer edge portions, said outer edge portions including generally tear-drop shaped beads having generally rounded surfaces defining the outermost edges of the side walls and tapered side surfaces extending from the rounded surfaces to surfaces of the remainders of the side walls;

(d) an elongated cover having lips comprising inwardly angled portions having inner surfaces generally paralleling the taperedside surfaces of the beads frictionally gripping primarily the tapered side-surfaces of said beads; and, V (e) the cross-sectional dimension of each such bead from its rounded surface at an outermost edge of the side wall to the smallest dimension of the bead be- (a) a body of resilient material having:

(i) a mid-portion; and, (ii) end portions extending from said mid-portion;

(b) said mid-portion having a substantially planar under surface for securement to a support;

(c) the upper surfaces of said clipmember above both said mid-portion and said end portions substantially paralleling the under surface;

((1) the undersurfaces of said end portions defining planes spaced from the plane of the undersurface of I said midportion so that said end portions are thinner and more fiexible than said midportion;

(e) said end portions including parallel locking ridges projecting downwardly from the undersurfaces of said end portions and being arranged substantially parallel to the outer ends of said end portions.

11. The-combination of claim ltl'wherein said body of resilient material further includes,- in combination:

(f) a planarsupport portion extending parallel to'and spaced from said end portions, said said support and end portions defining aside wall connection opening between them.

i2. A modular wireway for retaining wires in an orderly and accessible formation on a support structure, sald wireway comprising:

(a) a plurality-of wall forming and cover supporting means arranged in spaced, substantiallyparallel relation, said wall forming and cover supportingmeans including projecting footportions;

(b) clip means having retaining portions overlying said foot portions; (c) securement'rneans securing-said clip means to said tween'said tapered-side surfaces isgreater than the Support Structure. depth of a socket defined by p 2 measured ((1) said foot portiens and said retainin port ons havfrom a back wall surface COHHBCUHS lnwardly ing'interlocking' surfaces limitin lateral movement angled portions to the point of SIPaHeSt dlstanc? f said-wall formin and cover su o tir me l tween said inwardly angled portions so that when tive to Said clip g pp 1 ansle athe angled portionsgrip the tapered side surfaces 55 the ,retainin z of the bead,' they urge the rounded end Of {116 bead resiliently urgel :gainstsaiii fi b f p r iior is g c l p r e i f securely against sa1d back wall surfac i g said foot portions against a supporting surface 7. Thedev ce of claim 6 including, in combination: o that saidwall forming and cover supportin means i Said P further Compflslng y outwardly are maintainedin substantially spaced araliel'r l angled portions for guiding said lips when snapped. tion by said clip means; i p e aon said heads. 3. The device of claim 7 wherein the angled portions (f) a cover'from said support surface and being aligned Wlih. the other ends of said wall formof the lips are-of a uniform thickness, are substantially planar, and extend in converging planes from spaced parallel locations on a back portion of the cover, said ing and cover support means; and, (g) said cover and-the'other ends of said'wall forming and cover supporting means having connecting portions for releasably securing said cover to said other ends of the wall forming and cover supporting means so as to define a covered wireWay channel between the parallel Wall forming and cover supporting means.

References Cited by the Examiner UNITED STATES PATENTS 827,613 7/1906 Brown 50474 1,620,130 3/1927 Pietzsch 18935 10 FOREIGN PATENTS 1,045,430 11/1953 France.

OTHER REFERENCES Advertisement, Panduit, Plastic Snap Cover Wiring Duct, Bulletin D2a, Mar. 20, 1961, Page 2.

Figures of Type E and C used.

JOHN F. BURNS, Primary Examiner.

3,156,765 10/1964 Weiss 174- 72 X 10 HN P. WILDMAN, DARRELL L. CLAY, Examiners.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,229,029 January 11, 1966 Irving Fa Weiss It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 2, line 7, for "improssible" read impossible column 4, line 29, for "displayed" read displaced line 37, for "eftxending" read extending column 5, line 72, for "the" read then column 8, line 47, for "said", second occurrence, read and line 71, after "cover" insert spaced Signed and sealed this 29th day of November 1966.

( L) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents