US2986676A - Panel board arrangement for embedded load terminals - Google Patents

Description

May 30, 1961 w. H. EDMUNDS PANEL BOARD ARRANGEMENT FOR EMBEDDED LOAD TERMINALS Filed July 30, 1956 5 Sheets-Sheet l R 0 m m EE WM A 1 i M Z M y 1961 w. H. EDMUNDS 2,986,676

PANEL BOARD ARRANGEMENT FOR EMBEDDED LOAD TERMINALS Filed July 50, 1956 5 Sheets-Sheet 2 IN VEN TOR. [0/1 LIAM fi/IFflAO 5007mm May 30, 1961 w. H. EDMUNDS PANEL BOARD ARRANGEMENT FOR EMBEDDED LOAD TERMINALS Filed July 30, 1956 5 Sheets-Sheet 3 w. H. EDMUNDS 2,986,676 PANEL BOARD ARRANGEMENT FOR EMBEDDED LoAD TERMINALS 5 Sheets-Sheet 4 May 30, 1961 Filed July 30, 1956 y 1961 w. H. EDMUNDS 2,986,676

PANEL BOARD ARRANGEMENT FOR EMBEDDED LoAD TERMINALS Filed July 50, 1956 5 Sheets-Sheet 5 INVENTOR. Mil/HM 607F010 inn/0w:

United States Patent PANEL BOARD ARRANGEMENT FOR EMBEDDED LOAD TERMlNALS William Harold Edmunds, Havertown, Pa., assiguor to I-T-E Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Filed July 30, 1956, Ser. No. 601,065

4 Claims. (Cl. 317-119) My present invention is based on US. Patent No. 2,766,405 to W. H. Edmunds, issued October 9, 1956, entitled Panel Board Bus Arrangement and Circuit Breaker Mounting Base, and assigned to the assignee of the instant invention, and relates to a panel board arrangement wherein the molded mounting block of the panel board contains both the bus bar assembly and the load terminal units.

Panel board constructions have been so arranged that two supporting means were necessary, one for the bus arrangement and the other for the circuit breakers. Recent inventions have proposed a composite panel board so that the supporting means for the circuit breakers and source bus bars is a unitary structure. This structure is set forth in U.S. Patent 2,737,613 to M. A. Morris, entitled Panel Board Terminal Mounting Blocks, issued March 6, 1956, and assigned to the same assignee as the instant application. Structures of a unitary supporting means for both the bus arrangement and the removable circuit breakers have the advantage of requiring less steel, have an over-all saving in weight, are smaller in size and are economical to manufacture and install.

The panel board of my present invention is a composite structure and thus has all the advantages above noted. However, in addition to these advantages, my invention has additional advantages and overcomes the disadvantages of these prior art composite panel boards as will hereinafter be noted.

The main advantage of my present invention is achieved by embedding the load terminals within the composite molded mounting block so that it is not necessary to disconnect the load lines from the circuit breaker before the circuit breaker is removed from the panel board.

Thus, the panel board can be completely wired to both the source and load prior to the mounting of the circuit breakers thereon to thereby enable the user of the panel board to removably mount the circuit breakers for complete electrical connection without the necessity of performing any wiring or connecting operations.

Composite panel boards comprising a particular bus arrangement and a unitary supporting means may be manufactured in any of several methods. One such method is set forth in the above-mentioned application whereby the support mounting is molded in a unitary piece.

The bus arrangement is then positioned and attached to the mounting in appropriate passageway or grooves and recesses which form the configuration of the molded unitary mounting member. An insulating base or plate is then secured to the surface adjacent the passageways to form a cover and protective support for the bus arrangernent.

Another method of manufacturing composite panel boards has been to pro-position the bus arrangement in a mold and then mold the insulating mounting structure around this bus arrangement.

Still another method of manufacture is to provide a mounting with appropriate passageways and recesses in its upper surface. The bus arrangement is positioned through these openings and protected by means of a sealing compound.

The panel board of my present invention can be manufactured by any of the above-mentioned methods and has all the advantages associated therewith.

One embodiment of my invention is directed to a composite panel board wherein both the embedded bus bar arrangement and load terminals do not extend above the surface of the mounting block and the only exposed conducting portion is that part of the bus assembly which must be connected to the electrical source.

The panel board of my present invention has a series of vertical openings molded into the upper surface of the support molding or mounting block. The bus arrangement is imbedded in the molding by either of the heretofore described methods of manufacture. Receiving holes are located at the ends of transverse connecting bars or straps of the buses and are disposed to register with the above-mentioned vertical openings. Hence, the only way electrical contact can be made from the circuit breakers to the imbedded busses is to insert a circuit breaker back connecting prong through the vertical opening to fit into a hole of said bus bar.

Load terminal connectors, one on each side of the mounting block, are positioned in transverse alignment with the receiving holes of the bus assembly. These load terminal connectors are provided with receiving holes which register with a second set of vertical openings in the mounting block. This second set of vertical openings and receiving holes of the load terminal connectors are adapted to receive the second prong from the removably mounted circuit breakers of the panel board.

In addition to the three sets of vertical openings molded into the mounting block, an additional set of horizontal openings is provided which register with the load terminal members. The last mentioned horizontal openings permit entrance of the load conductors for connection to the load terminal members.

With this novel unit, I provide a panel board which has no exposed conducting material, retains all the desirable features of the prior art composite panel board and eliminates all of the undesirable features thereof.

If desired, all the bus bars may be parallel and in a horizontal plane. With this arrangement, the straps of each bus bar in which the receiving holes are located will have to have a vertical bend to permit the strap from each end bus bar to extend over the middle bus bar and still permit all the holes to lie in the same horizontal plane. Two holes are placed in each strap or transverse member located on opposite sides of the center line of the panel board. With this arrangement, each hole is adapted to receive the prong from a different circuit breaker and, if desired, one circuit breaker can be removed from a bus while the other remains electrically connected thereto.

In another embodiment of my invention, a single hole may be placed in each strap to receive a common prong of two circuit breakers.

In still another modification, the necessity for a crossconnecting member or strap for the center bus bar can be eliminated. In this modification, the center bus bar is positioned lower than the outer two bus bars and the receiving holes for the center phase are located in the center bus bar.

In still another embodiment of my invention, the molding may have terminals protruding therefrom for receiving line and load connections and the circuit breakers may then be plugged into the panel board.

Hence, in each embodiment of my novel invention, the panel board supporting the circuit breakers contains all electrical wiring required for connecting the circuit aesaeve breakers, and no electrical connection need be made at the circuit breaker terminals.

Accordingly, a primary object of my invention is to provide a panel board arrangement for supporting circuit breakers wherein all electrical wiring for load and line connections is done at the panel board and the circuit breakers are in plug-in connection relationship with respect to the wired panel board.

Another object of my invention is to provide a novel panel board arrangement in which the bus assembly and load terminal connections are embedded within the molded panel board block.

Still another object of my invention is to provide disconnect means for both terminals of the circuit breaker which are embedded within the panel board molding.

A further object of my invention is to provide a novel arrangement in which a composite panel board houses the circuit breaker connections to both the source and load.

A still further object of my invention is to provide a novel arrangement whereby the circuit breaker can be removably connected to a panel board without the necessity of performing an additional connecting or disconnecting operation to the load circuit.

Still another object of my invention is to provide a panel board construction comprising a mounting block, a bus assembly, and load terminals in which the connecting means to both the bus assembly and load'terminal blocks are located below the surface of the mounting block.

A still further object of my invention is to provide a novel panel board arrangement for removable circuit breakers which is simple in design and enables rapid and easy removal of the circuit breakers therefrom without performing additional operations.

Still another object of my invention is to provide a panel board arrangement for removable circuit breakers in which the bus assembly is positioned and housed in appropriate grooves and recesses within a unitary molding such that no exposed conducting surfaces extend above the molding.

A still further object of my invention is to provide a panel board arrangement which can be manufactured by molding an insulating support around the bus assembly and terminal load connections so that aligned vertical openings can communicate with receiving holes in both the bus assembly and load terminal connectors for guidmg the prongs from each circuit breaker into appropriate openings.

A still further object of my invention is to provide a panel board construction with no exposed electrical parts extending beyond the upper surface of the mounting block in which the circuit breakers attached thereto may be individually removable and replaceable without displacing or removing the remaining circuit breakers.

These and other objects of my invention will become apparent from the following description when taken in connection with the drawings, in which:

Figure l is a perspective view of a portion of my novel panel board showing the molding support transparent to illustrate the manner in which the bus assembly and load terminal connectors are seated in appropriate grooves within the molded block.

Figure 2 is a cross-sectional view of the moled block and illustrates the relative position of the bus bars and load terminal connectors. This figure also illustrates the manner in which a first prong of the circuit breaker is connected to the source bus and the manner in which a second prong is connected to the load terminal member.

Figure 3 is a top plan view of the panel board of my invention showing the bus bar assembly and load terminals to a cut-away portion of the top surface.

Figure 4 shows a top view of a second embodiment of my invention.

Figure 5 shows a front cross-sectional view of Figure 4 taken along the line 55.

Figure 6 shows a side view of a portion of Figure 4.

Referring now to the figures, the bus assembly comprises three main bus bars 22a, 22b and 220, each adapted to carry one phase of the three phase source A, B and C.

Bus bar 22a is located at the left, bus bar 220 is located at the right, and bus bar 2212 is located to the right of the longitudinal center line of the molding 29 and located between buses 22:: and 22c.

As best seen in Figures 1 and 3, the longitudinal bus bars 22 have transverse members or straps 24 attached thereto and extending toward and past the longitudinal center line of the mounting block 29. The transverse members 24a, 24b and 240 are in spaced relation and in parallel with each other. The transverse members 24 are rigidly attached at one end to the buses 22 by any suitable fastening means 30 such as screws or rivets. Each of the transverse members 24 has openings 27R and 271. at the other end thereof as seen in Figures 1 and 3 where letters R and L indicate cooperation with the right and left circuit breakers respectively. The openings are adapted to receive the spring ends 61 of the circuit breaker prongs 28 which are connected to the circuit breaker terminals 27 by screw means 73 within the openings 74.

As best seen in Figures 1 and 3, the holes 27a, 27b and 270 will lie in a vertical plane passed through the longitudinal center line of the mounting block 29.

It will be observed that if the three buses 22- are in a horizontal plane, it will be necessary that the transverse bar 24c be curved at 62c so that its left end at 27c is higher than its attached right end at 390. That is, since the bus bar 22b is in the same horizontal plane as bus bars 22a and 22c and located therebetween on the longitudinal center line of the molding 29, the transverse member 240 will have to be curved to enable it to pass above the bus bar 22b to ensure that it does not come into electrical contact therewith.

Since it is necessary to provide transverse member 240 with a curved section in order to permit it to pass above the bus bar 22b, it will also be necessary to provide transverse members 2441 and 2411 with similar curved sections to ensure that openings 27a, 27b and 270 are all located at the same vertical height. Hence, the openings 27 will not only be in the same longitudinal vertical plane, but will also be in spaced alignment along a longitudinal center line of the molding 29.

As best seen in Figure 1, molding 29' is molded with a series of spaced openings 23a, 23b and 230. These openings may be vertical cylindrical holes or any other appropriate type of opening with the cross-section of opening 23b best seen in Figure 1. These openings act as channels or guides for the connecting prongs 28 which are disconnect members for the plurality of removable circuit breakers 25, to permit the spring blades 61 of the prongs 28 to be inserted into the openings 27 and thereby make a positive electrical and mechanical connection between the bus bar transverse extension member 24 and the extension prongs 28 of the removable circuit breaker.

It will also be noted that appropriate recesses and grooves are provided within the molding 29 for the plurality of load terminal members 400.

In addition to the recesses or grooves needed to position and house the plurality of load terminal members 400, it is necessary to provide three openings within the molding block 29 for each load terminal.

For example, as seen in Figure 1, the vertical opening 406a in the molded block 29 communicates with the receiving. hole 403 in the terminal connector 4tl0La. Hence, when the circuit breaker 25L is mechanically and electrically connected to the panel board, the prong 28Ra will be in engagement with the receiving hole 27La of the strap 24a connected to the phase A, and the male prong 41L extending from the opposite terminal of the circuit breaker 25L will be guided through the opening 406La into mechanical and electrical engagement with the receiving hole 403 of the load terminal connector 400La.

The circuit breaker 25R is connected to the source at opening 27Rb and the load at receiving hole 406Ra of the load terminal 400Ra in the same manner as described in connection with circuit breaker 25L.

It will be noted that within each section two load terminals are associated with each phase. Thus, for exam ple, two load terminals are associated with phase A and are in transverse alignment with the openings 27La and 27Ra.

In like manner, load terminals are associated with phases B and C.

So as to gain access to the load terminals 400', it IS seen in Figure 1 that openings 411 are provided in the molding 29 which openings are individually aligned with the load terminals. A second series of clearance openngs 407 are then provided in molding 29 which are aligned with openings 411, openings 407 providing access to a fastening means such as a screw which could be a part of connector 400 and serves to fasten electrical wiring inserted through openings 411 to its cooperating terminal.

By way of example, a screw fitting in opening 407Lb would serve to fasten a load lead wire inserted through opening 411Lb to its associated terminal block.

Thus, it should now be apparent that there is no exposed conducting material of the bus arrangement extending beyond the upper surface 26 of the molding support 29. That is, the bus bars 22 and their associated transverse members 24 are completely imbedded within the molding 29 so that access to the openings 27 and 403 is only achieved by passing prongs 28 and 41 through the vertical openings 23 and 406 respectively.

It will be noted that the mounting block 29 may have appropriate passageway and recess cut or molded into the uper surface 26 to receive the bus arrangement of Figure 1. With this modification, the bus arrangement can be sealed off by means of insulating compound, leaving appropriate openings only for the prong receiving holes 27 and 403.

As may be best in Figure 2, the removable CIIC UIlZ breakers are placed on the top surface 26 of the molding 29 and may be fastened thereto in any desired manner.

As best seen in Figures 1 and 3, the main mountlng block 29 is provided with a longitudinal extension 10, which may either be an integral part of mounting block 29 or a separate portion attached thereto as hereinafter more fully described. The bus bars 22 have integral extensions 11 which pass through the side of the mounting 29. An insulating sheet 35 is securedly bolted to the molding extension by means of securing screw 36 and 27. Thus, the bus bar extensions 11 extend through the side of molding 29 and over the insulating surface 35 on extension molding 10. Terminal connectors 31 are securely fastened to the ends of the bus bars extension 11 to provide means for connecting the power leads from a source to the bus bars 22. It will be noted that if the three terminal connectors 31 are to be equally spaced, it is necessary to provide an L-shaped connection 33-11b, connected to bus bar 2211 by means of bolt or screw 46, to ensure that the connector 31b will be located along the center line of molding 29. The terminal connectors 31 may be of any standard make. In the connector illustrated, the power leads are inserted into the opening of the connector 31 and secured thereto by means of screw 32.

The longitudinal extension 10 may be an integral part of the molding 29 as seen in Figure 1, when the panel board is made by the method of molding the support 29 around the bus arrangement. If the panel board is made by placing the bus arrangement in grooves and recesses of the premolded support 29 then the member 10 may be a molded or sheet of insulation material attached to the support by any desired means.

Itwill be noted that the mounting block 29 can be a single piece adapted to support any number of circuit breakers or can be a series of segments to support three of six circuit breakers.

It will be apparent to those skilled in the art that one section of the panel board of my present invention can be used for mounting one or two three-phase circuit breakers, three single phase breakers, a series of two pole breakers or any other desired type of circuit breaker. It will be further noted that a series of sections, as noted in Figure 3 by I and II, can be added together to form a panel board for a plurality of one or three phase removable circuit breakers or the panel board can be molded in a single unit to accommodate any number of circuit breakers.

Panel boards having the arrangement of my present invention have the advantage of distributing the load evenly among all the phases when single phase loads are connected thereto. Thus, if all loads of a motor nature are connected to the phases of section 1, each phase, a, b and 0, will carry a similar load. Section II can have single phase loads of pure resistance connected thereto to propperly distribute these loads between the three phases.

It will be further noted that my invention is not limited to a unitary support for source bus bar. Thus, if the panel board is to be used for single phase connection, a neutral bus bar may be imbedded in the molding 29 along with the source bar 22. Also, it should be noted that the panel board is not restricted to either three phase or single phase use. One section, such as I, can be used to mount a three phase load, whereas section II can be used to mount three singlephase loads.

Accordingly, my present invention as seen in Figures 1, 2 and 3, results in a panel board arrangement which has no exposed connecting material except where the bus at the end of the panel board extends out the end of the molding for connection to the source of power, is readily adaptable to a plurality of different types of connections, has all the advantages of the panel boards of the prior art, and eliminates all the undesirable features of these umts.

A second embodiment of my novel invention may be seen in Figures 4, 5 and 6 which show a panel board which is adapted to be completely wired to a line and a load and is further adapted to receive a plug-in type of circuit breaker. Clearly the same advantages would obtain in the case of the panel board of Figures 4, S and 6 as did in the case of Figures 1, 2 and 3 for it is only necessary now to wire the panel board and external connectlons need not be made to the circuit breaker terminals when the circuit breaker is mechanically connected to the panel board.

Referring now to Figures 4, 5 and 6, and more specifically to Figure 5, the line or source buses 100, 101 and 102 are seen to be supported within an insulating and supporting block 103. The insulating block 103 as well as the insulating blocks 104 and 105 which will be seen hereinafter to carry the load terminals are then supported in any desired manner from a frame or support structure for the panel board.

Buses 100, 101 and 102 are then provided with connecting straps 106, 107 and 108 as can be seen most clearly in Figure 4, these connecting straps having protruslons or studs 109 and 110, 111 and 112, and 113 and 114 respectively. Studs 109 and 110, 113 and 114, may be connected to their associated jumpers 106 and 108 respectively in any desired manner while studs 111 and 112 are connected as seen most clearly in Figure 5 to have a connecting member 115 completing the current carrying connection from strap 107 to bus 101 since bus 101 is in a plane lying beneath the plane of buses 100 and 102. It is essential to note that each of the studs 109, 111 and 113, and 110, 112 and 114 lie along a common center line.

The insulating block 103 is further provided with a threaded aperture 116. therein which serves to receive a fastening screw from a circuit breaker cooperating with that portion of the panel as will be seen more fully herelnafter. Blocks 104 and 105, as has been mentioned above, are adapted to carry the load terminals such as load terminals 117. In the case of Figure 4 in which the panel board is shown as being capable of receiving at least four three-phase circuit breakers, there are four sets of load terminals 117, each corresponding to one circuit breaker position.

Each of terminals 117 is constructed as may be best seen in the cross-sectional portion at the right hand of Figure so as to have a connection to a connectingv strap 118 which is supported to the moldings such as molding 105 of Figure 5 by the connecting screw 119.

A current carrying stud 120 is also in electrical connection with the strap 118 and could be an integral part of the strap if desired. Thus reference to Figure 4 shows that current carrying studs 120', 121 and 122 protrude from the surface of the panel board in the same manner as do current carrying studs 112, 110 and 114 of the panel board portion adapted to mount one circuit breaker. In alike manner, source protruding studs and line. protruding studs are provided for each of the other circuit breaker mounting portions of the panel board of Figures 4 and 5.

Referring now to circuit breaker 123 of Figure 5, it is seen that the line and load, terminals for one phase of this circuit breaker are formed of studs 124 and 125 respectively which are adapted to have spring- type connectors 126 and 127 connected thereto. The spring- type connectors 126 and 127 are further adapted to receive studs 120 and 112 so as to interconnect the circuit breaker terminals 124 and 125 therewith. This type of tulip clip contact structure may be more fully seen in Figure 3 of US. Patent 2,606,233 to W. H. Schymik, entitled Switchboard, issued August 5, 1952, and assigned to the assignee of the instant application.

Hence it is now clear that a panel board construction is provided wherein complete wiring is accomplished for both load and source connections at terminals 117 and the terminals of buses 180, 101, 102 respectively within the panel board itself. Circuit interrupting equipment may then be connected to the. panel board so as to interconnect a load with the source by merely connecting the disconnect contacts between the circuit breaker and its cooperating panel board portion in the absence of any additional required Wiring for the circuit breaker. After electrical connection of the circuit breaker, it may be securely fastened to the panel board in. a manner such as the manner shown in Figure 5 wherein the. circuit breaker 128 has a screw means 129 and 130 associated therewith which cooperate with the threaded openings 116 of the block 103 and 131 of the block 164. Further connections may be had as is seen in Figure 4 on the other side of circuit breaker 128 by the screws 132 and 133.

As may be further seen in Figures 4 and 5 and more specifically in Figure 6, the terminals indicated generally as terminals 117 are comprised of ring shaped protrusions 134 which could be an integral part of member 118 wherein a threaded stud 135 is attached to the top of ring shaped protrusion 134. A slotted clamping means 136 is then movably positioned over the threaded stud 135 and a locking nuts arrangement comprised of nuts 137 and 138 is then threaded on the stud 135.

Thus, as is seen in, Figures 4 and 5, a current carrying conductor is inserted within the aperture 139 of ring shaped protrusion 134 whereupon the slotted clamping means 136 is clamped down and held by nuts 137 and 138 to place the external conductor in rigid mechanical and electrical connection with respect to the terminal 118. This construction, while being illustrated here for the load terminals, could also be utilized for the line terminals and provides the advantage of placing all wiring connections'at an angle. Thus, a minimum ofwire bending is required torun the wires to the end of an enclosure. It is to be noted that when wire connections are made to the circuit breaker as was the case in the past, that the wire connections can not be placed at an angle since they would be inaccessible or would reduce electrical surface creepage distance.

Although I have described preferred embodiments of my novel invention, many variations and modifications will now be obvious to those skilled in the art. I prefer, therefore, to be limited not by the specific disclosure herein, but only by the appended claims.

I claim:

1. A panel board comprising a unitary molding for a plurality of removable circuit breakers, said panel board being constructed to be connectible to load lines immediately adjacent the boundary of said panel board, a plurality of bus bars and load terminals imbedded in said molding, openings in said molding extending from the upper surface of said molding to each of said bus bars and said load terminals, each of said openings adapted to receive prongs from one of said removable circuit breakers to enable said prongs to make electrical contact with said bus bars and said load terminals; said load terminals including portions adapted to removably secure load lines; said molding including side openings to receive load lines for connection to said load terminal portions.

2. A panel board comprising a molding for a plurality of removable circuit breakers, said panel board being constructed to be connectible to load lines immediately adjacent the boundary of said panel board, a plurality of bus bars and load terminals imbedded in said molding, said bus bars and load terminals adapted to receive prongs from said removable circuit breaker, openings in said molding at regular intervals extending from the upper surface of said molding to each of said bus bars and load terminals to permit the said bus bars and load terminals to receive prongs from said removable circuit breaker, said panel board having no exposed electrical conducting members other than the input conducting member from a source; said load terminals including portions adapted to removably secure load lines; said molding including side openings to receive load lines for connection to said load terminal portions.

3. A panel board constructed to be connectible to load lines immediately adjacent the boundary of said panel board, said panel board comprising a unitary molding with a first, second and third bus bar and a first, second and third load terminal imbedded therein; a first and second plurality of openings in said molding; said first plurality of openings extending from the upper surface of said panel board to openings in said first, second and third bus bars; said second plurality of openings extending from the upper surface of said panel board to said load terminals; said load terminals including portions adapted to removably secure load lines; said molding including side openings to receive load lines for connection to said load terminal portions.

4. A panel board constructed to be connectible to load lines immediately adjacent the boundary of said panel board, said panel board comprising a unitary molding with a first, second, and third bus bar and a first, second, and third load terminal imbedded therein; a plurality of openings in said molding, straps connected to said first and third bus bars and extending perpendicular thereto in the direction toward said second bus bar, a first, second, and third of said openings extending from the upper surface of said panel board to a hole in the strap of said' first, second, and third bus bar respectively; a fourth, fifth and sixth of said openings extending from the upper surface of said panel board to said first, second, and third load terminals respectively, said first, second and third openings adapted to receive a first, second, and third prong respectively, from a removable circuit breaker and to guide said first, second, and third prongs into said hole of the strap for said first bus bar, the second bus bar and the strap for said third bus bar; said fourth, fifth, and sixth openings adapted to receive a fourth, fifth, and sixth prong respectively from said removable circuit breaker to guide said fourth, fifth, and sixth prongs into said first, second, and third load terminals; said load terminals including portions adapted to removably secure load lines; said molding including side openings to receive load lines for connection to said load terminal portions.

433,770 Cunnington Aug. 5, 1890 10 Chase Nov. 7, 1916 Jirka Feb. 7, 1933 Williams Dec. 5, 1933 Koehler July 6, 1937 Graves May 11, 1948 Page May 3, 1955 Norden Mar. 20, 1956 Edmunds Oct. 9, 1956 FOREIGN PATENTS Great Britain Apr. 7, 1949

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