US3412509A

US3412509A - Retractable roof

Info

Publication number: US3412509A
Application number: US535084A
Authority: US
Inventors: Nicholas B Popil
Original assignee: NICHOLAS B POPIL
Current assignee: NICHOLAS B POPIL
Priority date: 1966-03-17
Filing date: 1966-03-17
Publication date: 1968-11-26
Anticipated expiration: 1985-11-26

Description

Nov. 26, 1968 RETRACTABLE ROOF Filed March 17, 1966 4 Shee ts-Sheet 1 INVENTOR. NICHOLAS B. POP/L N. POPIL 3,412,509

Nov. 26, 1968 N. B. POPIL 3,412,509

RETRACTABLE ROOF Filed March 17, 1966 4 Sheets-Sheet 2 11v- VENTOR. lvluoL A8 a. POP/l.

NOV. 26, 1968 POPlL 3,412,509

RETRACTABLE ROOF Filed March 17, 1966 4 Sheets-Sheet 5 ,1 I II 80 I III I I I INVENTOR. NICHOLAS a. POP/L Ii Q 78 BY I I f I H6. 7 a? QAMW/QY Nov. 26, 1968 N. B. POPIL 3,412,509

RETRACTABLE ROOF Filed March 17, 1966 4 Sheets-Sheet 4 IN VENTOR.

NICHOLAS B. POP/L United States Patent 3,412,509 RETRACTABLE ROOF Nicholas R. Pupil, 6945 W. Pleasant Valley Road, Cleveland, Ohio 44129 Filed Mar. 17, 1966, Ser. No. 535,084 9 Claims. (Cl. 52-2) ABSTRACT OF THE DISCLOSURE An overhead enclosure or cover for covering large areas such as stadiums, arenas, factories, etc., which comprises a cover member connected to a top portion of the structure at the opening and motive power means are connected to an opposite portion of the cover member for moving the cover back and forth across the opening to close the same. Sealing means are provided for sealing the peripheral edge of the cover member to the top portion of the structure in a relatively air-tight manner and means are provided for introducing air under pressure into the enclosure defined by the structure to extend the cover member preferably into a dome-like shape or into any other shape depending upon the fabrication of the cover member.

The present invention relates in general to a roof construction and more particularly to a roof construction which can be utilized for the purpose of covering large areas such as stadiums, arenas, or storage and manufacturing areas, which roof can be moved from an open position where the area is exposed to the weather elements to a closed position wherein the area is shielded from the weather elements.

As an example of the utility of the present invention one may take the case of large sports arenas such as those presently utilized by the major baseball leagues to play baseball and the major football leagues in the playing of professional football. Most of these stadiums comprise vertically extending wall structure which rise to a given vertical height which wall structure extends around and surrounds the playing field and in a conventional manner includes seating for spectators. The upper portion of the wall structure which extends around the playing field usually terminates in what is commonly referred to as a roof thereon, however, the large area between the generally annularly extending wall structure is exposed at all times to the weather elements.

Provision has been made in some prior art structures to provide a permanent closure or roof over this hereinbefore uncovered area and this permanent roof has included in some instances transparent portions in the nature of glass or plastic members, however, this construction is generally of a permanent nature. Many disadvantages have arisen with this type of structure such as glare from the sun resulting in players of a sport being momentarily blinded by the sun. When the transparent closures have been painted or otherwise treated to keep the sun out, difiiculties have been encountered in trying to keep the grass on the playing field from dying.

The prior art has also utilized in some instances a roof structure for this area which generally is of a permanent type construction but which can partially be uncovered by the rotation of various elements with respect to each other in a generally angular direction.

The present invention seeks to obviate the disadvantages in any of the hereinabove described prior art structures by providing a roof or closure member which can be readily opened and closed depending upon the Weather conditions exteriorly of the structure.

Another object of the present invention is to provide a cover construction for a stadium or other large uncov- 3,412,509 Patented Nov. 26, 1968 ered area which utilizes a means for drawing the covering between open and closed positions and sealing the cover member when closed, to the structure upon which it is mounted, and thereafter to cause air under pressure to be injected into the covered stadium to extend the cover member to a generally rounded or dome-like condition in covering the stadium.

Another object of the present invention is to provide a roof closure construction whereby the closure mechanism utilized includes cable means for drawing the cover member between open and closed position and also where rails are provided for drawing the cover member between open and closed positions.

Another object of the present invention is to provide a convenient mechanism for providing a seal at the periph eral edge of the cover member once the cover has been moved to a closed position with respect to the area it is to cover.

Another object of the present invention is to provide a mechanism for folding the cover member when the cover member is moved to an open position in uncovering an area.

Another object of the present invention is to provide a cover member for covering a playing field or other large uncovered area which comprises a high strength plastic material which is translucent in nature and which is formed in a shape so that when fully extended by the air pressure utilized therewith it will assume a generally domelike shape.

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

FIGURE 1 is an isometric view of the exterior of a stadium showing the roof closure of the present invention in a closed condition;

FIGURE 2 is an elevational view of the stadium shown in FIGURE 1;

FIGURE 3 is a plan view of FIGURE 2 and showing the cover member in retracted position;

FIGURE 4 is an enlarged view taken generally along the line 4-4 of FIGURE 3 showing the fabric folding device;

FIGURE 5 is a view taken generally along the line 5-5 of FIGURE 4;

FIGURE 6 is an enlarged View of a portion of FIG- URE 4;

FIGURE 7 is an enlarged view taken generally along the line 7-7 of FIGURE 3;

FIGURE 8 is an enlarged view taken generally along the line 88 of FIGURE 3 showing the closing mechanism;

FIGURE 9 is a view taken along the line 99 of FIG- URE 8;

FIGURE 10 is a plan view of a stadium slightly different shaped than the one shown in FIGURES 1, 2 and 3 and illustrating a variation in the means utilized to move the cover member between open and closed positions;

FIGURE 11 is a somewhat diagrammatic representation of how the cover member shown in FIGURES 10 and 12 folds up as it is moved to open position;

FIGURE 12 is an enlarged isometric view illustrating the tracks shown in FIGURE 10 which move the cover member between open and closed positions;

FIGURE 13 is a plan view of the cover member and showing the pattern of reinforcing cables which extend therethrough to lend strength to the construction; and

FIGURE 14 is a view taken generally along the line 1414 of FIGURE 13.

As mentioned hereinabove, the present invention is susceptible of use in many applications wherein it is desired to cover a relatively large area. The embodiment illustrated in FIGURES 1, 2 and 3, to represent such a large uncovered area, is a stadium 20. The stadium includes a playing field 22 upon which many games can be played such as baseball and football. The stadium comprises a vertically extending wall structure 24 which extends to a given height and which extends around in what may be referred to as an annular direction, the playing field. In other words, the wall structure surrounds the playing field. The top of the vertically extending wall structure terminates in a fixed roof 26. As seen in FIGURE 3 the general pattern of the field assumes the configuration of an oval or might be said to be generally egg'shaped. The apparatus for covering the stadium or playing field includes a plurality of truss structures which are mounted on the fixed roof 26 and which extend all the way around the stadium roof. All of the truss structures 29 are conventioual in nature being generally triangular in configuration and having an uppermost vertical apex or point. For the sake of more case in describing the details of the present invention the stadium 20 may be said to have first and

second sides

31 and 32 respectively and first and

second ends

35 and 36 respectively. A first support member 38 is fixedly connected to the apex of the truss structures 29 on the first side 31 of the stadium and a second support member 40 is secured to the apex of the truss structure 29 on the second side 32 of the stadium and these two support members will be described in more detail hereinafter. Normally support member 38 would not be seen in FIGURE 3 because other structure would hide it from view but it has been indicated so as to more quickly illustrate its general position. A third support member 42 is secured to the apex of the truss structures 29 on the first end 35 of the stadium and a fourth support member 44 is secured to the apex of the truss structures 29 at the second end 36 of the stadium.

A first plurality of pulley means 46 (FIGURE 4) are supported by given truss structures 29 on the first side 31 of the stadium roof and a second plurality of pulley means 48 are supported by given truss structures 29 on the second side 32 of the stadium roof. For each of the pulley means on one side of the roof there is a corresponding pulley means on the other side of the roof. In the particular embodiment shown for example in FIGURE 3, there has been shown five cables numbered 50 through 54 and these cables are generally parallel with each other and extend across and over the playing field from the first to the second side of the stadium roof and each cable is continuous in nature as seen in FIGURES 4 and 8 and extends around a pulley of the first and second plurality.

A one-piece translucent plastic cover member 56 is provided and is constructed and formed to assume generally the surface of a portion of a sphere when fully extended. The particular construction of the cover member may be varied substantially, however, the fabric might be constructed of nylon and/or Dacron covered with for example vinyl or a neoprene rubber. For the sake of example the cover member should have a comparatively high tensile strength preferably over 200 pounds per square inch and should be as mentioned before, translucent. The material should have a low moisture absorption factor preferably less than 5% of the fabric weight and should comply with the cold snap test when used in northern climates to 40 F. The construction should also include anti-ozone compounds for protection from the ultra-violet rays of the sun and the material should be comparatively light weight, for example it should Weigh in the range of from 10 to 70 ounces per square yard. The material should be fire-resistant to meet Federal Regulation CCT-l9lB Method 5910. FIGURES 13 and 14 show some detail of the cover member. FIGURE 13 shows a plan view of the cover member which shows a pattern of cables 57 extending therethrough. The cables extend through a piece of plastic pipe material 58 (FIGURE 4) which is held in position by fabric pieces 61 held by a suitable adhesive.

The plastic cover member in any event has a peripheral edge which generally assumes the configuration defined by the

members

38, 40, 42 and 44 as viewed in FIGURE 3. A portion 59 of the peripheral edge of the cover member is fixedly secured to the first support member 38 as seen in FIGURES 4 and 6 in a generally permanent and air-tight manner and means are provided for securing or connecting the opposite peripheral edge portion 60 of the cover member or that portion of the peripheral of the cover member which is to be connected with the second support member 40 to each of the cables through 54. FIGURES 4 and 8 illustrate this means of connecting the second peripheral edge of the cover member to each of the cables 50 through 54. This means includes a bracket 62 fixedly secured to each of the cables 50 through 54. This means includes a bracket 62 fixedly secured to the cable at one portion and having another portion fixedly secured to the material of the cover member. A drive motor 64 (FIG- URE 8) is provided for driving each of the cables 50 through 54 and each of the drive motors is mounted by means of a bracket 65 to a truss structure 29. As shown in FIGURE 8 the drive motor drives the pulley 48 of the second plurality by way of a belt 66, however, it will be readily appreciated that this drive might be a gear drive or other equivalent means. The drive motors 64 are all reversible so as to drive the cables in both first and second directions back and forth across and above the playing field. The motors are also synchronized with respect to each other so as to drive their respective cables at a speed which is proportionate to the complete distance that must be traversed so that the complete edge portion 60 arrives at the second side at the same time. Simply for the sake of example if We assume that the cable 52 must span 500 feet and that the cable 50 must span 400 feet, in order to have the second peripheral edge 60 of the cover member carried by cable 52 arrive at the second side 32 at the same time that the second peripheral edge of the cover member carried by cable 50 arrives at the second side 32, the cable 50 must be driven at a linear rate of speed which is four-fifths of the linear speed of cable 52. In other words, the motors must be synchronized so that the second peripheral edge of the cover member arrives at the first and

second support members

38 and 40 at the same time when the cover member is traveling between open and closed positions.

As mentioned hereinabove, the first peripheral edge portion 59 is secured to the first support member 38 in a fixed and relatively air-tight manner. It is also necessary that the second peripheral edge 60 of the cover member be sealed when it arrives at the second side 32 of the roof member in contact with the second support member 40. This will be best understood from referring to FIGURE 8 where it will be seen that the bracket 62 carried by the cable 52 is formed at 68 (also see FIGURE 4) so as to conform to the outer cylindrical contour of the second support member 40. Although they have not been shown, suitable limit switches have been provided at both sides of the roof 26 to be engaged by either the cables or the bracket 62 so as to de-energize the drive motors 64 when the cover member has traversed the given distance. When the cover member has moved to the position shown in FIGURE 8 the peripheral edge is fixedly secured to the support member 40 by means of a sealing lever 70 which has a portion 71 which clampingly engages the peripheral edge of the cover member when a hydraulic piston and cylinder arrangement 72 is actuated. When actuated the sealing lever 70 is caused to pivot about its pivotal mounting 73 causing it to move from the dot-dash position 75 to the full line position whereat the peripheral edge of the cover member is sealed in contact with the support member 40. When the piston and cylinder arrangement is deactuated the sealing lever is returned to the dot-dash position by means of a spring 76.

It is likewise necessary to seal the portion of the peripheral edge of the cover member which is located adjacent the

support members

42 and 44. This is accomplished by means of the structure which is illustrated in FIGURE 7. It will be seen that the

cables

50 and 54 are located closely adjacent the

support members

42 and 44 and a portion of the peripheral edge of the cover member is reinforced and in its unsealed condition travels in a position because of its weight slightly below the

support members

42 and 44. When the second peripheral edge 60 has arrived at the second support member 40 or in other words has traversed the playing field, a pinion gear 78 is actuated by drive means not shown which services to drive a rack gear 79 which carries at its top a sealing portion 80 which moves the peripheral edge of the cover member into contact with the support member 42 at the one end and a similar construction is used to move the other portion into sealing engagement with the support member 44. In most instances it is desirable when the cover member has been moved to its closed condition to have a workman or operator of the device check the peripheral edges of the cover member adjacent the

support members

40, 42 and 44 to assure that the peripheral edge will be properly located against its respective support member before the sealing mechanisms are actuated.

It is also desirable to have mechanism for folding the cover member 56 when the playing field is to be uncovered and the cover member is moved from the second side 32 of the stadium roof back to the first side 31. To accomplish this there is provided five folding mechanisms id :ntified by the reference numerals 82 through 86 (FIG- URE 3). Each of the folding mechanisms is provided with a drive motor 88 which by way of a pulley 89 drives four shafts upon each of which are mounted sheaves or pulleys 91 which in turn drives and contains fold cables 92 through 95. As will be seen from reviewing FIGURES 3 and 4, each of the fold cables 92 through 95 of a given folding mechanism is attached to respective portions of the cover member at proportionate distances across the playing field from the first to the second side thereof. In other words, referring to FIGURES 3 and 4, if one were to assume a span of 400 feet for the cover member at cable 50, the fold cable 92 would be attached to the cover member 80 feet from the first support member 38, the fold cable 93 would be attached 160 feet and so on in 80 foot intervals until the last fold cable 95 would be attached 80 feet from the second peripheral edge 60 which would be located 320 feet away from the first support member. In the folding mechanism 84 if one were to assume the span of the field at this point to be 500 feet the fold cables would be attached to the cover member at 100 foot intervals.

In operation when the cover member is to be opened the drive motors 88 are all actuated and these drive motors are synchronized so that the entire length of the second peripheral edge 60 of the cover member will arrive at the first side 31 of the stadium roof at the same time. The drive motors 64 are also synchronized with the drive motors 88 to accomplish this desired end result. It will be seen that the folding mechanism is contained in a covered enclosure defined by a wall 98 and each of the cables 92 through 95 travel through an opening in this wall. As the cables 92 through 95 are Wound upon their respective pulleys it will be seen that cable 92 where attached to the cover member will engage the wall 98 which prevents further winding of cable 92. This is permitted because of a clutch construction between the shaft and the pulley for the fold cable 92 which enables the shaft to keep turning without further turning of the pulley. The next cable to be wound is cable 93, etc., through cable 95, with resultant folding of the cover member 56 as illustrated in FIG- URE 4. Either the main cables or the fold cables may have means attached thereto to de-energize both the drive motors 88 and the drive motors 64 upon complete retraction of the cover member to the first side 31 of the stadium roof. When it is desired to close the cover member the drive motors 64 perform this function by way of cables 50-54 and the cables 92-95 associated with folding mechanisms 82-86 are simply unwound from their respective pulleys. The general position of the longest cables when the cover member is closed are shown in FIGURE 1.

The particular pattern or assemblage of the various pieces to make up the entire cover member have not been illustrated in this particular embodiment however the as sembly is made by a series of separate pieces suitably connected together in a manner similar to that illustrated in FIGURE 14.

It is understood that the remainder of the stadium proper has previously been rendered relatively air-tight by closing all apertures etc., and personnel or vehicles which are to enter or leave the stadium may pass through an air lock which is in principle a double door or something on the order of a rotating door so as not to lose pressure within the confines ot the stadium.

Centrifugal blowers 111 are mounted on the stadium roof between the truss structures and after the cover member has been moved to its closed position and sealed, the centrifugal blowers are actuated to in effect inflate the cover member so as to hold it in the position shown in FIGURES 1 and 2. The inflation pressure under normal conditions would preferably be on the order of about .25 pound per square inch, however, this pressure may be increased by the centrifugal blowers utilized, by means of suitable control mechanism which is not de scribed in any detail herein. Safety valves 113 are also provided to insure that the air pressure does not exceed a predetermined level which condition could arrive under certain conditions for example, by excessive warming or heating of the air contained in the closed stadium. If desired, prior to a game or immediately after one, the inflation pressure might be dispensed with resulting in the cover member in effect resting on the cables 50-54. This would expedite the entrance and exit of people from the structure which would be more time consuming if the air lock were maintained. The cover member could again be inflated after the entrance or exit of the spectators.

FIGURES 10, l1 and 12 illustrate a modification of the structure which is disclosed in FIGURES 1 through 9. In this embodiment a slightly different shaped stadium 116 is disclosed which also extends around a playing field and comprises vertically extending wall structure terminating at the top in a fixed roof 118. Positioned on the roof are a plurality of truss structures 119 and secured to the top of the truss structures along each of two sides of the stadium roof are support members 122 which take a cylindrical form and are preferably constructed from pipe. Also secured to the truss structures just outside the support members are

tracks

124 and 125 and a plurality of sliders 127 are positioned on track 124 and a plurality of sliders 128 are positioned on track 125. A plurality of cables 129 extend between respective sliders 127 and sliders 128 and each are secured to a cover member 131 which is of the same basic construction as the cover member 56 he'reinabove described. The cover member at the end 134 of the stadium roof is permanently anchored in position and the other end of the cover member is adapted to travel back and forth to the other end 135 of the roof between open and closed positions. To accomplish this result there are provided drive motors 136 and 137 located at the respective ends of track 124 and drive

motors

138 and 139 are located at the respective ends of track 125. A cable 140 extends through an opening in each of the plurality of sliders 127 and is connected at one end to a pulley driven motor 136 and at the other end is attached to a pulley driven by motor 137. The cable 140 is attached only to the slider closest to drive motor 137 and is freely slidable through the openings through which it extends in each of the other sliders. It will thus be seen that as the drive motors are actuated in a given direction, that since cable 140 is attached only to the slider adjacent drive motor 137, this will facilitate movement of all of the sliders upon opening movement of the cover member or in a downward direction as viewed in FIGURE 10 since one slider will engage the next and so on until the cover member has been opened. In movng the cover member to closed position the reverse is true in that the slider which is attached to cable 140 serves to move all of the sliders to an extended position with respect to each other until the cover member is closed. This same construction is repeated with respect to sliders 128 on track 125 wherein a similar cable is driven by

drive motors

138 and 139 and is attached only to the slider adjacent drive motor 139. FIGURE 11 is a representation of approximately how the cover member 131 folds as it is moved to an open position and the general position of the sliders.

After the cover member 131 has been moved to its closed position it is necessary that .a substantially air tight seal be obtained between the support members 122 and the peripheral edge of the cover member. This is accomplished with a mechanism such as that shown in FIGURE 12 and it will be understood that it is necessary to seal the cover member along its peripheral edge between each of the cables 129. However, since this mechanism is the same in all instances, only one has been shown. In order to accomplish this end result there has been provided a lever 142 pivoted to the rail which is located adjacent at 143 and secured to the end of the lever 142 is an arcuately shaped sealing member 144 which is adapted to forceably hold the peripheral edge of the cover member to a corresponding portion of a support member. The lever 142 is moved between operative and inoperative positions by means of a hydraulically actuated piston and cylinder arrangement 145 which is connected by a pivot 146 to the lever.

The cover member is also sealed along the

ends

134 and 135 of the stadium roof in a like manner. However, at these ends one or two mechanisms covering the entire extent of this end might be utilized since it is not necessary to provide a seal between obstructing cables 129.

Centrifugal blowers 150 are positioned on the stadium roof and are adapted to introduce air under pressure after the cover member has been moved to its closed and sealed position in a manner similar to that disclosed in the stadium described in conjunction with FIGURES 1 through 9. Also not shown are suitable safety valves to assure that the pressure in the stadium does not rise above a predetermined value. Likewise as in the previous stadium described it is also necessary that the remainder of the conventional stadium structure be rendered relatively air tight before .air pressure is introduced.

Obviously when it is desired to uncover the stadium it is necessary to move the sealing levers 142 to inoperative position and actuate drive motors 136 through 139 all of which are synchronized with each other so as to move the cables 140 pulling the extreme sliders located

adjacent drive motors

136 and 139 downwardly as viewed in FIG- URE 10 and as a result moving the cover member to uncovered position with the cover member folding generally as shown in FIGURE 11.

It will thus be seen from reviewing the foregoing that the primary object of conveniently covering a large area such as a stadium has been accomplished in an economical and inventive manner.

It will be observed from FIGURE 2 that a guard 105 has been disposed on the truss structures slightly below the top of the same for the purpose of preventing high winds from hitting the cover member at its connection with the support members. In this view the guard 105 has been shown only on the back side of the stadium so as not to interfere with the illustration of the other structure, but it will be understood that the guard extends completely around the stadium. This construction also is applicable to the stadium shown in FIGURE 10.

Although this 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 cover for an opening in an enclosure defined by wall means including in combination a cover member, a first portion of said cover member being relatively permanently connected to a portion of the wall means at the opening in a relatively air tight manner, motive power means connected to a second portion of said cover member for moving same laterally back and forth across the opening to open and close the opening, releasable sealing means for sealing said cover member to said wall means around said opening in a relatively air tight manner in the closed position of said cover member and for unsealing said cover member so that it may be moved across said opening to open position, and means for introducing air under pressure into the enclosure to extend said cover member in its closed position.

2. A cover as claimed in claim 1 wherein said cover member is constructed of translucent plastic material and has a generally dome-like shape in extended position.

3. A cover as claimed in claim 1 wherein said motive power means comprises pulley means on opposed sides of the opening with cables extending therebetween and a second portion of said cover member is connected to said cables whereby said cover member is opened and closed in the direction of said cables when said cables are moved back and forth between said pulley means.

4. Apparatus for covering an open area defined by vertically extending Wall structure which extends at least partially around the open area including in combination a first plurality of pulley members mounted on the top portion of the wall structure at a first side thereof, a second plurality of pulley members mounted on the top portion of the wall structure at a second side thereof and being oppositely disposed with respect to the pulley members of said first plurality, cable members extending between respective pulley members of said first and second plurality, a cover member having a first side portion fixedly secured to the top portion of the wall structure at said first side thereof and having a second side portion secured to said cable members, drive means for moving said cable members to move said second side portion of said cover member back and forth between said first and second side portions of the wall structure to open and closed positions respectively, sealing means for sealing said cover member around its peripheral edge portion to the top portion of the wall structure in a relatively air tight manner, said sealing means comprising first and second members, means for moving said members relative to each other to entrap said peripheral edge portion in said closed position of said cover member and to release said peripheral edge portion whereby said drive means may move said cover member to said open position, and means for introducing air under pressure into the open area after said second side portion of said cover member has been moved closed to said second side portion of the wall structure and said first and second members having entrapped said peripheral edge portion of said cover member.

5. Apparatus as claimed in claim 4 wherein said cover member is constructed of translucent plastic material and has a generally dome-like shape when extended by the introduction of air under pressure into the open area.

6. Apparatus as claimed in claim 4 wherein folding means are located at said first side portion of said wall structure to fold said cover member when same is moved to an open condition, said folding means arranging increments of said cover member generally horizontally and in a vertically extending stack.

7. Apparatus for covering an open area defined by vertically extending wall structure which extends at least partially around the open area including in combination, first and second tracks mounted on the top portion of the wall structure at first and second sides thereof respectively, a plurality of slide members mounted on each of said first and second tracks, a cover member, 'a plurality of cables extending between corresponding slide members on said first and second tracks and each being connected to said cover member, means fixedly securing one end of said cover member to the top portion of the wall structure between a first end of said tracks, drive means for moving said slide members back and forth on said tracks between said first end thereof and a second end thereof to open and closed positions respectively, means for sealing said cover member to the wall structure along said first and second sides and at said second end, said sealing means comprising first and second members, means for moving said members relative to each other to entrap said sides and said second end of said cover member in said closed position of said cover memher and to release said sides and said second end of said cover member whereby said drive means may move said cover member to said open position, and means for introducing air under pressure into said open area when said cover member has been closed and said first and second members have entrapped said sides and said second end of said cover member.

8. Apparatus as claimed in claim 7 wherein said cover member is constructed of translucent plastic material.

9. Apparatus as claimed in claim 7 wherein said cover member has a generally dome-like shape when extended by the introduction of air under pressure into the open area.

References Cited UNITED STATES PATENTS 2,754,899 7/ 1956 Karobonink 160-23 2,898,607 8/ 1959 McGuire 160-23 2,958,083 11/ 1960 Shook 160-26 3,050,743 8/ 1962 Lamb 160-310 3,051,232 8/1962 Lamb 160-273 3,277,615 10/ 1966 Marquez 52-2 REINALDO P. MACHADO, Primary Examiner.