claim is: 65 I. An air raid shelter COMPibiag a wall having an entrance opening formed therein, a door for closing said entrance opening, said door being arranged within the wall and having pivotal connections mounted in said wall in spaced relation 70 to said entrance opening, me=s for sealing the Joints betweeri the periphery, of raid door and the surfaces ol said entrance OPening, raeans carried bY said door,and engageable -with said wall for frictionally retarding the swinging move76 ment of- the door, p6 pluralitv of springs act-

2,350,981 5 ing against said retarding means for urging said retarding means into frictional engagement with said waR, and means for operating said retarding means for retaining said retarding means disengaged from said wall to permit free swinging 5 movement of the door when desired, said retard- , ing means being adapted, when blasts from exploding bombs strike the exposed surface of the door, to Permit said door to swing through a limited angle In the entrance opening without open- 10 ing the seal between the door and the walls of said entrance opening. 2. A building structure of the class described having an entrance opening formed therein, a door Jamb formed in said entrance opening, a 15 wall extending laterally from and substantially in alinement with said door Jamb, a cavity formed in said structure at the end of sgid lateral wall farthest from said entrance opening, a door extending across the entrance opening, the lateral 20 wall and the cavity and adapted to abut the door Jamb and the lateral wall to close the entrance opening, means disposed in said cavity for pivotally supportirig the door in the structure, and means carried -by said door and engageable with 25 the wall of said cavity for retarding the swinging movement of said door. 3. A building stracture of the class described having an entrance opening formed therein, a door jamb formed in said entrance opening, a wall extending laterally from said door Jamb, a 30 cavity formed in said structure at the end of said lateral wall farthest from said entrance opening, a door extending across the entrance opening, the lateral wall and the cavity and adapted to 35 abut the door jamb and the lateral wall t(> close the entrance opening, means disposed in said cavity for pivotally supporting the door in the structure, means carried by said door and engageable with the wall of said cavity for retarding 1( the swinging movement of said door, and mecha- ' nism for operating said retarding means for rendering the same inoperative. 4. A buuding structure of the class described having an entrance opening formed therein, a 5 door jamb formed in said entrance opening in 4 spaced relation to the outer end thereof, a wall extending laterally from and substantially in alinement with said dc>or jamb, a cavity formed in said structure at the end of said lateral wall 50 farthest from said entrance opening, said cavity having a vertical arcuate wall extending from said lateral wall to -a second wall arranged at an angle with respect to said lateral wall, a closure element for closing said entrance opening, said 5 closure element having pivotal connections ar- 5 ranged concentric with the vertical center of said cavity and adapted to lie along the face of said lateral wall and abut s9Ad door jamb wherx in position to close said entrance opening, and a plate hingedly connected to said closure element 130 and having an edge portion engageable with the wall of said cavity for retarding the swinging movement of said clo=e element. 5. A building structure of the class descrlbed having an entrance opening formed therein a (35 door Jamb formed in said entrance opening in spaced relation to the outer end thereof, a wall extending laterally from and substanti&Uy In alinement with said door jamb, a cavity formed in said structure at the end of said lateral wall TO farthest from said structure entrance opening, said cavity having a vertical arcuate wall extending from the inner end of s6,id lateral wall, a door for closing said entrance opening, Journals projecting from the bottorn and the top of said door and mounted in bearings disposed, respectively, in the center of curvature of the bottom and the top of said cav@@y for pivotally supporting said door at a point remote from the entrance opening in the structure, and means disposed witliin said cavity and pivotally mounted on said dogr in offset relationship to said.door journals and engageable with the wall of qaid cavity for retarding the swinging movement of said door. 6. A building structure of the class described having an entrance opening formed therein and including side walls, a t(>p, and a bottom, a d(>or jamb formed in said entrance opening in spaced relation to the outer end thereof and including a top higher than the top of the entrance opening, a bottom lower than the bottom of the en.trance opening, and laterally extending wars, one lateral wall having a width greater than the width of the other lateral wall, a cavity formed in said structure at the end of the lateral wall of greatest width, a door for closing said entrance opening, means disposed in said cavity for pivotauy supporting the door in said structure, said pivot means being located in spaced relation to an edge of said door in said cavity, and means disposed within said cavity and pivotally mounted on said door in offset i;elationship to said door pivot means and engageable with the wall of said cavity for retarding the swinging movement of said door. 7. A building structure of the class described having an entrance opening formed therein, a dgor jamb formed in said entrance opening in spaced relation to the outer end thereof, a wall extending laterally from and substantially in alinement with said door jamb, a cavity formed in said structure at the end of said lateral wall farthest from said entrance opening, a door extending across the entrance opening, the lateral wall and the cavity and adapted to abut the door jamb and the lateral waU to close the entrance opening, means disposed in said cavity for pivotally supporting the door in the structure, and a plate hingedly connected to said door and having an edge portion adapted to engage the wall of said cavity for retarding the swinging movement of said door. 8. In a structure of the class described, a wall having an entrance passageway formed therein, a cylindrical cavity formed vertically in said wall in spaced relation and affset with respect to said passageway, a ledge formed in said structure between th6 passageway and said cavity, a closur6 element for closing said entrance passageway, said closure element having pivotal connections with said wall arranged concentric with the vertical center of said cavity, said ledge limiting the swinging movement of said closute element in one direction, and a plate pivotally carried by said closure element and movable independently with respect to said closure element and having a pc>rtion engageable with the waU of said cavity for retarding the swinging movement of s@aid closure element. PALMER BESCHERER.

2 and the portion 27 of the floor may be substan. tially iin the same horizontal plane as the -floor of the building. The 4loor 27 should'be constructed as nearly flat as is possible, for a purpose to be hereinafter more fully described. @ I . Extending laterauy from the portion of the fravae 18 adiacent to the wall 15 is a vertically disposed waU I$. At the end of the wall 19 farthest from the opening 17, the structure I I bas forined therein a vertically disposed arcuate wall 20. The wall 28 extends into the concrete structure I 1. and the structure I I is comparatively thick so that the opening formed therein by the waU 28 wiD not be InJured by bomb explosions. .Tn order to construct the arcuate wall 20 In the concrete materiii used, in forming tlhe structure I 1, a shell 21 may be employed. The sheu 2 1 . formed from sheet metal of the desired gauge or thickness, is shaped to provide the excuate wall 20, and the'.vertical edges at each end of the sheet forming the shell 21 are bent to form flanges 22 and 23, respectively. The bottom of the sher 21 encircles a portion o,f a circular plate 24 which is set into the floor 27. 7be top of the shell 21 likewim encircles a portion of a circular plate 25, similar to the plate 24. The plates 24 and 25 are shown best In Flgs. 2 and 6, and the shell 21 is shown best In Mgs. 4 and 5. If so desired the exterior of the shell 21 may have a plurality of anchors 26.(see Figs. I and.2) mounted thereon, which anchor-s @ may be embedded in the concrete of the structure II in weH known manner so as to retain the shell in position In said structure. The adjoining edges of the sher 21 and the plates 24 and 25 may be connected by welding, so as to provide a unitary structure. With the center of the plates 24, 25 as a center and with a radius extending from the center of said plates to the far end of the wall I 8, the opening or entrance 33 is formed with a vertical arcuate side wall 28. The wall 28 extends from the wall IS inwardly of the structure II in the er shown in FU. 7. The wall 28 forms one side of a passageway, Of which the other side is formed by a wall 29. The wall 29 extends from the flange 23, inwardly of the structure I I for a suitable distance, and terminates in a wall 30 which is arrangedsubstantially in pararel relationship with the wall 15, but which is Gffcet with respect to said wall. 15. The inner end of the wall 28 terminates at a point distant from the wall 30 an amount approximately equal to the distance between the waus 14, 15, and extending inwardiy from the Inner end of the wall 28, is a wall 31 which parallels the wall 30. Betwieen the walls 30 and 31 there is a passage-waY 32 which extends Into the interior of the structure It. As shown in Fig 7, the inner passageway 32 is offset with respect to the -outer passageway 17, and said Inner and outer passageways are connected by the intermediate passageway 33 having the arcuate wall 2 B. The waus 94 and 15 are disposed at an angle of appro3dmately 120 degrees with respect to the wall 29. In other words, between the inner edges of the flanges 22, 23, the sheb 21 has an opening extending thrgugh an are of approxiWhen moved from closed to open podtion and vice versa, the door can be swung thmugh the above referred to angle. of approiLW@ately 120 degrees. The center 6f curvature of the shell 21 and 'the center of curvature of-the plates 24 and 25 is,.the center of the pivotal connection of the door with the structure. The door is preferably constructed of metal 10 and the door proper consists of a rectangular. sheet of steel of suiitable tbickness, indicated by the reference numeral 38. The outside periphery of the door on three sides, that is to say, the dimensions of the door 15 are such that the upper edge 37, the outer edge 38, and the bottom edge 39 are owed- a sught distance from the walls 34, 28 and 27, respectively, as shown In Plgs. 2, 3 and 8. However,. when the door Is in closed position, as shown in 20 Figs. 1 and 8, the peripheral edges of said door abut against the jam or abutment I S. I . IThe outer face of the door 36 Is formed around the periphery with a ftishing strip 40 and the inner face of the door bas a similar finishing ss strip. I around its periphery (see Figs. 2, 3 and 8). For the purpose of rotatably supporting the door 36 so that'the same, can swing about the vertical axis, the portion of the door which is 30 disPOsed witbin 'the circular cavity 45 provided bY the arcuate waU 20, is formed in the manner to be hereinafter described. At the pivotal side or Inner vertical edge of the door there are three pigtes 42, 43 and 44. 35 The inner vertical side edge of the-door plate 38 Is dispo-sed, whell the door is in the clos@d Position shown In Fig. 1, at a@point approximately midway the breadth of the wall 19. Forming a continuation of the plate 36 and ex-. 40 tending into the circular cavity 45, is the plate 42. The Jplate 43 is disposed on the outer face of the plates 36 and 42, and extends from the waU 15, when the door is in the closed position shown 46 in Mg. 4, to a point a suitable d&.ance within the cavity 45. A portion of the plate 43 which is disposed within the cavity 45 is bent along a vertical line at an angle away from the outer face of the plate 42, as indicated at 46, Flg. 4. 50 ' Likewise, one face of the plate 44 abuts the Inner faces of the plates 36 and 42, and said plate 44 extends from a point in allnement with the wall 15, into the cavity 45. The portion of the Piate 44 which Is disposed within the cavity 55 45 is bent along a vertical line so that said plate has a portion 49 disposed at an angle With respect to the plate 42. The construction is such that the plates 36 and 42 are clamped between a portion of the plates 60 43 and 44, and the several plates MaY be United together to form a unitary structure by any suitable means, such as by welding or by means of screws, bolts, or other suitable fastening elements, not shown. or, Pivotally connected to the inner vertical edge of the portion 46 of the plate 43, by means of hinges or similar pivoting elements, 47, is a plate 48. As shown In Mg. 6, the height of the portion 70 49 of the plate 44 is somewhat greater than the height of the plate 48. Extending outwardly from both sides of the plate 42 at points adjacent to the upper and lower edges of the plate 48, are upper and lower horimately one-tliird the circumfere"ce p@f #ip )ip1l.. To ;ontauy disposed plates 50, 51, 52 and 58.

2,350,981 3 Me -plates 11, II 52 and 13 constitute horizon. tai webs, which in plan are of triangular &ape, as shown In Plg. 4, and in order to further i-iin. force the structure and to also ietain the end oor. tions of said,plates in position, use is made of a 5 pair of vertically arranged angle =6mbers 54 and 55. The angle.member 54 -has a side waR I$ which lies against tbe.,.face of.the plate 42..and a side waR 57 which. is arranged substantiAllyL -iLt right 10 angles to t . he side 'wall 51 and eiftnds o@utwardly to the portion 49 of the plate 44. 7-be angle member 55 hai@ a side wall 58 which Res agaiiiit the foice of tiie plite 42 and a side wall 59 which is arranged substantially at right 15 angles to the side wall 51 and extends outwardly to the outer angularl-y disposed edge portions of the webs 51 and 53. 7be angle member 54 may be rigidly secured to the plates 42, 49, 51 and 52, by weldink, or bY 20 any other suitable means. The angle -member @ 55 should I)e rigidly, secured'to the plates 42, 51 and 53. Tti,6 member 48 ii not secured to the -edges'df the plates 0'4, '53. n6r is said member secured 25 to the edge of the side iall 59 of the angle member 55. F'rom -the foregoing it wtH be noted that the portion @pf the door 'whiih is disposed within the cavity 45 includes splayed plates, which are ar- 30 ranged as shovm In INgs. I and 4 somewhat In the form of a fish tail. As shown In Pig. 6, the center of the bottom plate 24 Is formed with an opening 61, and disPosed on the-underside of said plate and having a 35 vertical bore 12 arranged In alinement with the opening II, Is a block 63. The block or- member 13 constitutes a 4ournal for a trunnion 84 carried by the bottom portion of the door structilre. the lower end of: said trun- 40 nion being mounted in a thrust bearing 65 disposed in the bor6 @li. Mounted in'the opening 81 and suriounding the trunnion 14, is a packing 68 adapted,to prevent dirt and other foreign matter from enterin L' 45 g the b@re 62 a"nd the bearing 55 momted therein. The trunnidn 44 may be detachably secured to the bottom poiiion 6i the door structure by means of screws, bolt@, or other suitable fast'ening meons, lndleated at 67, Plg. 6. 50 IAke,wise, the center of the top plate 25 Is forined With an opening.$$ and mounted on top of the plate 25 and having a vertical bore 69 disposed in vertical axial alinement with the opening 60, is a block 70.,, The blo6k or member 78 constitutes a journal for a trunnion 71 carried by the uppbr portion of the door structure. The trunnion, 71 Is deby means of screws, bolts, or the jike 72. Since the blocks 63 and 70@ are embedded In the concrete which forms the wall structure II... said blocks will be. rigidly anchored in-place and the plates 24 and 25, provide means for protecting said block's ftom'being damaged. By providing the Vertically disposed trunnions 64, 7 1, the door will be.free to swing fr6m closed to open position axid vice versa, and by locating the trunnioxxs at a point remote fromthe -do6r, 70 opening 17, the likelihood of said trunnions coming damaged as the result of,blasti- from elploding bombs wiU be reduce4. to a ftilnimilm stupe the thinnions are protected. by a d portion of the wall structure 1 75 AnAnged i;OUnd the Periph6ry of the door, is a gasket or ge3dble sealft strip 75. 7be wwing strip or gasket 75 m&Y be mounted on the Ainiabing strip 41, being sect;rely fastened thereto bY meam of a binding strip 76 which _.may be attached to the periphery OfL the door by means of screws 77-, as shown in Plg. 3. The se&Uno strip or gasket 75 Is adapted to bear at all thnes against the awacei provided by the waus 11, $4, tl,'and 21, so as to thoroughly seal the joints between the structure I I and the door, In order to @ preient gases and other obnoxious fumes, etc., from entering the shiiter or building. Due to the manner In which the gasket I or sealing st rip 75' IS operatively associated with the structure I 1, i slight frictional resistance of the movement of the door wfll be had. However, this frictional resisiance to the free swinging movement of the door wfll not be excessive, and any @person can readily awing the door by grasping either the handle 79 on the outside of the door or the handle 71 on the inside of the door. In order to provide means for locking tfie door In 6]osed position without -employing the usual lodkixig bolts, latches, or the like fastening elements, the member 48, along its vertical outer edge portion I 1, is formed with a gasket or flexible strip 82; as shown best In 1PIgs. 4 and 5. . The gasket 82 is arranged on the outer faoe of the member 48, being secured to said member b* means of a binding strip 83 in a manner similar to. the manner in which the binding strip 76 retains the gasket 75 on to the door. The gasket 75, as weU as the gasket 82, may be constiucted of swtable flekible material, such.as rubber composition, or any other material found suitable for us@ as fiexible gafkets. However, the body, of the gasket 82 should be somewhat thicker than the body of the gasket 75 In order to withstand hard usage and heavy strains. 7be gasket 82 constitutes a pad which is adapted to be moved into engagement with the wall of the arcuate shell 21 so as to provide means by which rotation of the door on its trunnions 64 I .7 1, Is retarded. In other. words, when the member 48 Is disposed In the@.posi in which the pad 82 engages the wall.of the shell 2 1, means are provided for braking the rotative movement of the door, irrespective of the position of the door in the passageway. Constituting a part of the braking means for retarding the rotation of the door, is a plurality of expansible coil springs, 85. As shown In Fig. 2, the springs 85 are suitably spaced apart and as shown -in Mgs. 4 and 5, said springs are io@ated adjacent to the angle membergg. One end of each spring 85 bears against a block 86 carried Py the plate 42, and the other end of. member 48. The springs 85 normally urge the member 48 away from the stops provided by the horizontal, webs 91 and $3. In orde, i@ position the plate 48 so that the pad 82 wffl not enga rfa ge with the su ce of the shell 2 1.@ that is to say, i;x order to release the braki g n meang so that the doorwfll be free to swing on the pivots.provided by the trutinions 64, 71, an actuator 8.7 ii provided. 7be actuator 87 comprises a rod having a portion thereof fdrmed with screw'threads 88, which screw threaded portion is mounted in a bli)ck Is @@secured -in the door structure, 42, 49, -and having a bore 11 fgrmed with s6rew threads. On e end of the actuator rod 87 is provided with tachably connected to the. door members 42, 49, 6o each spring bear3 agginst the inner face of the

4 a hand wli6el 9 1, . which hand wheel is located on the lmide bf the door, so that when the door Is In the closed position shown in Mg. 1: the hand wheel wiU be conveniently disposed, for ready manipul4lon by'an air raid warden or operator, in order to.effect movement of the actuator so as to apply, the braking means, as will be hereinafter more fully described. The actuator rod 87 also extends through an elongated opening 92 formed in the member 48 and also formed in a boss 93 on the outer face of said member. At its outer end, the rod 87 Is formed with an enlarged portion or head 94 having an opening 95 formed therein for a purpose to be hereinafter descritted. The head 94 of the actuator rod 87 bears against a shoiilder or abutment 96 provided by the outer surface of the boss 93 and in doing so retains the member 48 from swinging outwardly as the result of forces exerted by the expansible coil springs 85 against the opposite fkce of said member, which forces urge the member 48 to swing on the hinges 47 in a dirertion away from the plate 42. Mounted on the outer face of the member 48, in a position adjacent-to the boss 93, Is a bracket 97 having an opening formed therein for receivIng the shank of @ headed pin or rod 98, as shown best.in Mg. 2...... When the door Is not in use, the actuator 87 retains th6 plate or member 48 in the position shown in Flg. 4, in which position the member 48 lies against the horizonta,l webs 51, 53. The springs 85 are thus compressed. With the member 48 thus positioned, the pad 82 will be disengaged from the shell 21, thereby enabling the door to freely rotate on its trunnions @except for the slight frictional resistance of the engagement of the gasket 75 with the walls 21, 28, the cehing 34, and the floor 27. Assuming that the door Is installed at an opening In an air raid shelter and an air raid waming signal has been sounded, the door is placed in the dotted line position shown in Mg. 7, SO that the passageway or entrance to the air raid shelter Is unobstructed. After persons seek slielter in the building, the air raid-warden or other per@on in charge, moves the door from the open position shown by the dotted lines in Mg. 7 to the closed position shown in Flg. 1. The hand wheel 9 1, which is now disposed in a readily aec sible. position at the mouth of the cavity 45, as shown best in Figs. 4 and 5, is turned in the direction in which the headed end 94 of the rod 87 is moved outwardly or away from the boss 93. Since the member 48 is bingedly mounted on the door structure, the springs 85 force said member 48 outwardly in a direction away from the plate 42. The hand wbeel 91 should thus be operated so as to permit the springs 85 to move the member 48,a distance sufficient for the pad 82 to bear tightly against the shell 2 1. When this operatiori has been completed the frictional engagement of the elongated pad 82 with the surface of the shell 21 will retain the door firmly in its closed position. Due to the constructi6n of the door and the manner in which said door is arranged in the passageway, when a blast from a bomb or other explosive element occurs at some place on the exterior of the building, the forces expended by the blast against the exposed surface of the door deflned by the outer passage@way 17, upon striking the door ma@y force the door to swing Inwardly again# the frictional, resistance provided by the e.ngagement of the Pad 82 with the waU of the shell 21. However, since the wall 28 presents a surface of considerable breadth,. the door can r) be forced by blasts to swing through an are of approximeitely 90 degrees without breaking the seai of the gasket 75 with the surfaces of the pgssagaway In which the door Is disposed. It WHI thus b@e noted that although the brak10 ing means provided by the engagement of the pad 82 with the wall of the -shell 21 may offer a resistance sufficient to prevent swinging movements being imparted to the door by ordinary force,@, when heavy blasts from bombs or other 15 explosive elements strike the surface of the door exposed to siftch blasts, the braking means are flexible enough to permit the door to swing on its trtmnions without damaging or otherwise disrupting the pivotal mounting of the door in the 20 structure 11'. Due to the nianner in which the door Is pivotally mounted In the buflding I 1, and also due to the arrangement of the hand wheel 9 1, should the door be swung to a position in which the 25 hand wheel Of Is inaccessibly disposed In the cavity 45, the pin or rod 98 can be removed from the bracket 97 and inserted in the opening go of the head 94. The rod 98 can then be used to rotate the actuator rod 87 so as to disengage the 30 pad 82 from the shell 21, thereby releasing the braking means, so that the door can be readily moved. The constiuction hereinbefore described provides improved means by wmch, during bom35 bardments In tiine of wari the door of an air raid shelter or the like, can be retained in closed position I under pies;ures sufficient for the door to resist average blasts without movement. In the event of close or extremely heavy blasts, the 40 blast pressure on the door will compress the springs 85 sufficiently for the door to mcve, rather than for the door or Its hinges to be damaged. This spring prefture is adapted to brake t@e inward swing of the door and check such swinging 45 movement within a predeterniined are of safety (compare Fig. 1 with Elg. 7)@ After which the spring brake may be released by turning the hand wheel 9 1, the door moved back to Its closed position, and the brake again applied In the manner ro heretofore described. In addition to being applicable for Installation in bomb and gas resisting shelters, the improved door herein described is susceptible for use In other types of buildings and structures, such as r,5 in chemical plants, refilgeration and packing Plants, fortifications, explosive@ manufacturing plants, etc., In some of its applications the door may be installed in the walls of bufldings so as to Prevent fumes, gases, or other fluids from readily passing from one room to another room, or from passing from the lnterlor of a building to the exterior ,hereof. Having thus described my invention, what I