US3915327A

US3915327A - Cargo container

Info

Publication number: US3915327A
Application number: US412997A
Authority: US
Inventors: John W Lovich; Frank C Morse; Oscar W Meller; Walter F Sprick
Original assignee: Goodyear Aerospace Corp
Current assignee: AAR Corp; Goodyear Aerospace Corp
Priority date: 1973-11-05
Filing date: 1973-11-05
Publication date: 1975-10-28
Anticipated expiration: 1992-10-28
Also published as: DE2449825A1; CA1028965A; BR7409103A; CH587773A5; ES431519A1; IT1021885B; JPS5073782A; FR2249809A1; IN138756B; NL7414013A; GB1467698A; BE821746A

Abstract

Disclosed is a unique igloo cargo container having three doors on the front thereof to allow complete and total access to the interior of the container. Two of the doors are interchangeable and enclose the side portions of the front of the container. A center door engages with the top and bottom of the cargo container and the side doors so as to complete the total enclosure. The center door is equipped with a latch having a bevelled wedge for engagement with a channel in the base of the container. The bevelled wedge, as it engages with the channel, causes sealing engagement among the three doors and the framework of the cargo container. There is also presented a slight variation on the unique latch primarily disclosed. The varied latch has an extended linkage rod so that the actuating arm of the latch may be positioned other than at that point on the center door where engagement is to be made with the cargo container framework.

Description

United States Patent 1191 Lovich et a].

[ Oct. 28, 1975 CARGO CONTAINER [73] Assignee: Goodyear Aerospace Corporation,

Akron, Ohio 22 Filed: Nov. 5, 1973 21 Appl. No.: 412,997

[52] US. Cl. 220/1.5; 217/62; 220/345 [51] Int. Cl. B65D 7/00; B65D 43/12 [58] Field of Search 220/l.5, 41, 345-347;

3,823,972 7/1974 Ramer 220/l.5 X

FOREIGN PATENTS OR APPLICATIONS 80,498 4/1920 Austria 217/62 Primary ExaminerJohn Petrakes Attorney, Agent, or Firm-Oldham & Oldham [5 7 ABSTRACT Disclosed is a unique igloo cargo container having three doors on the front thereof to allow complete and total access to the interior of the container. Two of the doors are interchangeable and enclose the side portions of the front of the container. A center door engages with the top and bottom of the cargo container and the side doors so as to complete the total enclosure. The center door is equipped with a latch having a bevelled wedge for engagement with a channel in the base of the container. The bevelled wedge, as it engages with the channel, causes sealing engagement among the three doors and the framework of the cargo container. There is also presented a slight variation on the unique latch primarily disclosed. The varied latch has an extended linkage rod so that the actuating arm of the latch may be positioned other than at that point on the center door where engagement is to be made with the cargo container framework.

11 Claims, 12 Drawing Figures U.S. Pat ent Oct. 28, 1975 Sheetl0f4 3,915,327

FIE-E US. Patent Oct. 28, 1975 Sheet 2 GM 3,915,327

US. Patent Oct.28,1975 Sheet3of4 3,915,327

U.S. Patent Oct. 28, 1975 Sheet4 of4 3,915,327

FIE5

FI5I1 FIE 1 Man! 1 CARGO CONTAINER BACKGROUND OF THE INVENTION Heretofore it has been known that various types of cargo containers have been utilized in the transportation industry. Most generally, these cargo containers are accessible by virtue of a single door on the cargo container or two doors, one on each side of the cargo container. In order to allow complete access to the interior of the cargo container these doors must generally be large in size and thus difficult to handle by a single operator. 7

Consequently, it is an object of the instant invention to present a cargo container which allows access to the total interior thereof by virtue of three separate and distinct doors, each of which is easily handled by a single operator.

A further object of the invention is to present a cargo container having three doors wherein each of the three doors interengages with another of the three doors and with the framework of the cargo container.

Yet another object of the invention is to present a cargo container having three doors wherein the middle door engages with each of two end doors and wherein the middle door has associated therewith a bevelled wedge-like latch member which affectuates sealing engagement among the doors by engagement with the base of the cargo container.

These objects and other objects which will become apparent as the detailed description proceeds are achieved by a cargo container having a basic structure of a base and a top, two end panels interconnecting the base and top, and a back panel connected tothe top, base, and end panels thus defining an open container, further comprising verticle door frame channel members attached to each of the end panels; a header interconnecting the door frame channel members and attached to the top; two side doors slidin'gly engaged among the header, base, and door frame channel members; and center door removably engaged among the header, base, and side doors; and a latch assembly positioned on the center door adaptable to make gripping engagement with the base thus affectuating interlocking engagement between the two side doors and the center door.

For a true understanding of the invention in its preferred embodiment, reference should be'had to the detailed description and accompanying drawings wherein:

FIG. 1 is a plan view of the cargo container of the invention;

FIG. 2 is a plan view of the cargo container having the doors thereof removed;

FIG. 3 is a cut-away frontal view of the cargo container;

FIG. 4 is a sectional view of the cargo container taken along the line 44 of FIG. 3;

FIG. 5 is a sectional view taken along the line 5-5 of FIG. 3 and shows the engagement of a side door with I the vertical framework of the container,

FIG. 6 is a sectional view taken along the line 6-6 of FIG. 3 showing the engagement ofthe center front door with the center of the cargo container;

FIG. 7 is a sectional view taken along the line 7--7 of FIG. 3;

FIG. 8 is a sectional view taken along the line 88 of FIG. 3 showing the engagement of the center door with the base of the cargo container;

FIG. 9 is a frontal view of the latch of the cargo container;

FIG. 10 is a sectional view taken along the line 10-10 of FIG. 9 and the latch in its latched position;

FIG. 11 is a sectional view taken along the line ll11 of FIG. 3 showing the interengagement of the center door with a side door; and

FIG. 12 is a frontal view of a latch assembly for use with the cargo container and having a linkage rod attached thereto.

Referring now to the drawings, and more particularly FIG. 1, an appreciation of the exterior structural design of the invention may be had. Here it can been seen that the cargo container, designated generally by the numeral 10, comprises a top 22 connected to a back member 11 and right and

left end panels

18, 20. Each of the

end panels

18, 20 are preferably of 0.040 inch thick aluminum stiffeners 13 attached thereto for rigidity. The back panel 11 is similarly constructed with six equally spaced vertical channel stiffeners connected thereto. The top of the bach panel has an aluminum angle riveted to the top of the back panel 11 which is drilled to provide for screw attachment with the top 22. As can be seen, the

end panels

18, 20 are angled into the top 22, that angle preferable being approximately 30 from the vertical. The engagement of the angled portions of the

end panels

18, 20 with the top 22 is facilitated by means of the channel angle members 32 which are appropriately affixed to the top and the end panels. The back 11, and

end panels

18, 20 are fixedly attached to a base 24 in a manner which will become apparent hereinafter.

Door

frame channel members

34, 36 are respectively attached to the

end panels

18, 20 and to a header 38 which is in turn attached to the top 22. Engagement between the

door frame channels

34, 36 with the header 38 is made by means of the angled clips 40 lying flush with and attached to the respective door frame channels and header. The combination of the front portion of the base 24, the header 38, and the door

frame channel members

34, 36 provides for the basic frontal design of the cargo container. v

As can further be seen in FIGS. 1 and 2, there are provided three doors, a center door 12 and side doors l4 and 16 which make engagement between the header 38, the base 24, and the

door frame members

34, 36. The

doors

14 and 16, as will be apparent hereinafter, are interchangeable. Each of the door members is characterized by the presence of fabric handles 28 affixedly attached thereto for purposes of facilitating the handling of the respective doors. The center door 12 is further characterized by the presence of a latch assembly 26 at the bottom thereof for purposes of achieving interlocking engagements among the doors, the base 24, the header 38, and the door

frame channel members

34, 36. Each of the

end panels

18, 20 has attached thereto a strap 30 to facilitate the movability of the cargo container 10.

Referring now to FIG. 3, a more detailed showing of the structure of the invention may be seen. Here it can be specifically noted that the header 38 is connected to the respective door

frame channel members

34, 36 by means of the clips 40, one on each side of the joint formed between the header and door frame members.

It should be noted that clips 40 are preferably interconnected by means of bolts 41 passing therethrough so that dismanteling of the cargo container may be readily achieved with ordinary hand tools. It can be further noted from the cut-away portion of the drawingthat the back panel 11 is strengthened by means of the vertical channel members 42 equally spaced therealong. Although not shown, the top 22 is constructed and strengthened in a manner similar to that of the back panel 11. Further detailed description of the structure of the cargo container will now be had by reference to sectional views taken from FIG. 3.

FIG. 4 is a cross sectional view of the right end portion of the cargo container 10 taken along the line 4-4. Here it can be seen that hat channel members 44 are provided along the top 11 in a manner parallel to the header 38. It can further be seen that hat channel members 46 are provided in a transverse manner to the vertical channel members 42 to further increase the rigidity of the back panel 11. Along the entire length of the back panel 11 and attached thereto is a cap 48 having a groove 49 formed therein. A T-shaped interlocking member 52 is connected to the base 24 so as to engage with a groove 53 contained within an attached edge member 50 which is similarly connected to the base 24. As can be seen, the T-shaped interlocking member 52 is fixedly attached to the base 24 and the edge member 50 by bolts 54 and is further connected to the member 50 by the tongue and groove engagement as shown at 55. A second portion of the T-shaped interlocking member 52 engages in a groove 49 of the cap 48 so as to achieve a total weather-seal engagement between the back panel 11 and the base 24. It should be noted that the engagement between the back 11 and the base 24 is moveable by virtue of the slidable engagement between the T-shaped member 52 and the groove 49 of the cap 48. Thus, compression on the top of the cargo container will allow some movement of the back 11 with respect to the base 24 before deformation of the back 11 will be realized.

The header 38 is fixedly attached to the top 22 at the front edge of the cargo container. The header 38 is characterized by the presence of a top track 56 extruded or formed therein. The

side doors

14, 16 are characterized by a slide 58 fixedly attached along the top edges of the doors. The slides 58 are formed so as to mate with the top tracks 56 formed within the header 38 along the respective side portions thereof. The front edge portion of the base 24 in the areas of the side doors l4, 16 are characterized by the presence of a front extruded channel member 60 attached thereto, the channel member 60 being characterized by the presence of a bottom track 62 extruded or otherwise formed therein. The bottoms of the

side doors

14, 16 have attached thereto slides 64 designed so as to slidingly engage with the track 62.

As can be seen in FIG. 5, which is a cross sectional view taken along the line 5-5 of FIG. 3, the door frame channel member 34 is formed so as to have a receptacle 66 defined thereby. The edges of the

side doors

14, 16 have a door edge member 68 fixedly attached thereto, the member 68 making sealing engagement with the receptacle 66. Thus, it can be seen that the

side doors

14, 16 may he slid along the bottom track 62 and the top track 56 into sealing engagement with the receptacle 66 formed in the vertical door frames.

Attached to one of the bottom corners of each of the

side doors

14, 16 there is a triangular shaped doubler 76 as shown in FIGS. 3 and 7. The triangular doubler 76 is applied to each side of the

doors

14, 16 so as to strengthen that portion of the door. The doubler 76 and the door 16 are then capped at the bottom thereof with a channel member 74 which is continuous from and similar in nature to the slide 64. The channel 74 and doubler 76 are fixedly attached to the door 16 by means of bolts 78 or other appropriate means. The channel 74 has received in the bottom thereof a plurality of channel nuts and bolts 73. The bolt heads are circular in nature and of such size as to be receivingly engaged in the bottom track 62. It should be noted that the head 75 is slidingly received in the track 62 and is not removable therefrom except by sliding. On the contrary, the slide 64 is slidingly received in the bottom track 62 but is removable therefrom by vertical motion of the doors l4, 16. Thus it can be seen that the channel nut and bolt assembly along the triangular doubler portion of the doors provides for engagement between the

side doors

14, 16 with the bottom tracl 62 such that disengagement between the

doors

14, 16 and the track 62 is prohibited.

FIG. 6 is a sectional view taken along the line 6-6 of FIG. 3 and shows the cross sectional characteristic of the header 38 at that portion thereof where the center door 12 will be placed. Here again it can be seen that the header 38 is characterized by the presence of a track 70, the depth of which is substantially less than that of the track 56 due to the presence of the cutaway portion 72. The track 70 is of sufficient depth that when the bottom of the door 12 is appropriately engaged with a track in the base 24 the track 70 will engage with the top edge cap 77 which is fixedly attached atop the door 12.

As can be seen in FIG. 8, the center of the door 12 has attached thereto at the bottom thereof an extruded edge member characterized by the presence of a tongue 80 at the bottom thereof. Along the central portion of the base 24 where the center door 12 will be properly engaged, a groove 82 is provided in the extruded edge member. The groove 82 is of such nature as to make sealing engagement with the tongue 80 but is readily removable therefrom by merely lifting the door 12 in an upward and outward manner so as to disengage the tongue and groove engagement achieved by the

elements

80, 82.

FIG. 9 is a detailed showing of the latch assembly 26 which is attached to the center door 12. As can be see, the latch assembly 26 comprises a handle 84 rotatable about a pivotal pin 86, the pivotal pin 86 being mounted on a block 88. As should be apparent from cross sectional views of the

doors

12, 14, 16, and the base 24 of the cargo container 10, these elements are all constructed of aluminum clad balsa wood. Thin aluminum skins are provided with end-grain balsa wood therebetween thus presenting a sturdy lightweight element. The latch assembly 26 of the instant invention is recessed within the front of the center door 12. The recess is created by removing the front aluminum skin of the door and the balsa wood lying directly thereunder. The recess is bounded by the line 90 with the area between the

lines

90, 92 being arcuate in nature. The recess provides a means for protecting the handle and allows the front face of the cargo container to be planar in nature with no protruding elements. For purposes of strengthening the inner skin 94 of the door 12 which is exposed by the recess, a reinforcing plate 96 is fixedly attached to the back of the inner skin 94. The block 88 is fixedly attached to the inner skin 94 and reinforcing plate 96 by means of the spacers 89 which hold the handle 84 at a predetermined distance from the skin 94. A plunger 98 is movably contained within a housing 100 such that the plunger 98 rests on the base 24. The handle 84 has a head 102 at one end thereof and a wedge 104 with a bevelled portion 105 perpendicular to the length of the handle 84. The handle 84 further has a hole 108 at one end thereof, the hole 108 securing the handle by engagement with an eye bolt 106 fixedly attached to the skin and reinforcing

plate

94, 96. Security wire may be passed through the eye bolt 106 and hole 108 to secure the handle in its closed position. An arcuate portion 109 is fixedly retained within the recess, the arcuate portion providing means for engagement with the hole 108 of the handle 84 when the handle 84 is pivoted about the pin 86 to release the latch. A protrusion 110 is contained upon the arcuate portion 109, the protrusion 110 providing means for engagement with the edge of the hole 108 so as to retain the handle 84 in an open position.

With a basic understanding of the door and latch assemblies of the invention, specific notice will now be given to the operation of the same. As is best shown in FIG. 2, a side door, for example 14, may be placed so that the bolt heads 75 are received within the milled slots 59 in the base 24. At this point the slide 58 at the top of the door passes through the cut-away portion 72 in the header 38 at the center thereof, the slide 64 making engagement with the bottom track 62. With the side door so positioned, it may be slid to the right, for the righthand door 14, or the left, for the lefthand door 16, such that the slide 58 will make engagement with the top track 56 and such that the bolt heads 75 will make within the receptacle 66, this door is sealing ly held by the top track 56 interacting with the slide 58 and the bottom track 62 in engagement with the bolt head 75. At this time the left door 16 may be similarly placed into the milled out slots 59 and the cut-away portion 72 and slid to the left to make similar engagements with the header 38, left door frame 36 and the base 74.

With the side door so engaged, the center door 12 may be readily positioned by first shoving the upper edge thereof into the track 70, as shown in FIG. 1, and then placing the bottom edge 80 of the center door 12 into the appropriate groove in the extruded edge member of the base 24. The tongue 80 on the bottom edge of the center door 12 is then forced into engagement with the groove 82 in the extruded edge member of the base 24 by the downward motion of the handle 84 of the latch assembly 26. It should of course be understood that while engaging the center door 12 with the cargo container and the other doors, the latch assembly 26 has the handle thereof restrained on the protrusion 110 of the arcuate portion 109. The downward motion of the wedge 104, beginning with the bevelled edge 105 within the groove in the extruded edge member, forces the tongue 80 into the groove 82 to effectuate interlocking engagement therebetween. As can be seen, the aggregate width of the wedge 104 and the tongue 80 is such that it substantially fills the groove within the extruded edge member on the base 24 so that a tight engagement is made between the tongue and the groove 82.

With reference now to FIG. 11, a sectional view of the interengagement between the center door 12 and the side door 16 may be seen. As is readily noted from reference to the Figure the side door 16 is capped along the vertical edge thereof by a T-shaped edge member 112. It should of course be understood that the edge of the side door 114 is similarly capped. The center door 112 on each of the vertical edges thereof is capped by an L-shaped edge member. With the

side doors

14, 16 positioned as described hereinabove and shown in FIG. 2, the center door, when placed into its proper upper and lower tracks, causes engagement between the T- shaped edge members 112 and the L-shaped edge members 114. When the latch assembly 26 is actuated so as to secure the center door 112, the

side doors

14, 16 are tightly secured by the engagement between the

members

112 and 114. It should of course be noted that the T-shaped members 112 result in a reversibility or interchangeability between the

doors

14 and 16.

With reference now to FIG. 12, a slight variation on the theme of the cargo container latch assembly 26 may be seen. It should of course be understood that with the latch assembly heretofore discussed the operator must bend substantially to the ground in order to engage or disengage the latch. In order to facilitate such engagement and disengagement, the instant invention may adapt the use of the latch assembly 121 as shown in FIG. 12. As can be seen, such a latch assembly teaches that a handle 124 be pivotally mounted about a pivotal pin 128 and connected at one end thereof to a linkage rod 126. The linkage rod is in turn connected to a bevelled blade 130 and a head 131 respectively similar to the bevelled blade 104, and head 102 of the latch assembly 26. The bevelled blade 130 is adaptable to make the sealing engagement between the tongue 80 and the groove 82 as described hereinabove. The bevelled blade 130 and the head 131 are pivotally about a pivotal pin 133. When the handle 124 is pivoted about the pivotal pin 128 to a position substantially horizontal with respect to the. base 24, the bevelled blade 130 is engaged so as to cause the engagement between the tongue 80 and the groove 82. When the handle 124 is lifted upward and pivoted about the pin 128, the linkage rod 126 is forced downward pivoting the head 131 about the pivotal pin 133 and causing engagement with the plunger 132 contained within the housing 134. Again, this actuation is similar to that described with reference to the plunger 98 of the latch assembly 26. As the handle 124 is lifted the bevelled blade 130 is disengaged from the groove in which it has been retained and frees the tongue 80 from the groove 82 such that the plunger will lift the door upward and rock the tongue 80 out of the groove 82. It should of course be understood that the linkage rod 128 is contained within a recess 116 and a handle 124 within a recess similar to the recess described with reference to latch 26. A reinforcing pin 118 strengthends the recessed area and there is of course provided an arcuate portion 122 for purposes of protecting the handle 124.

Thus it can be seen that the objects of the invention have been achieved by the apparatus presented hereinabove. While in accordance with the Patent Statutes only the preferr'e'ti embodiment and best mode contemplated by the inventor for carrying out the invention have been presented and described in detail, it is to be understood that the inventin is not limited thereto or thereby. Consequently, for an appreciation of the scope and breadth of the invention reference should be had to the appended claims.

What is claimed is:

1. A cargo container having a basic structure of a base and a top, two end panels interconnecting the base and top, and a back panel connected to the top, base, and end panels thus defining an open container, further comprising:

verticle door frame channel members attached to each of the end panels;

a header interconnecting the door frame channel members and attached to the top;

two side doors slidingly engaged among the header,

base and door frame channel members;

a center door removably engaged among the header,

base and side doors;

a latch assembly positioned on the center door adaptable to make gripping engagement with the thus affectuating interlocking engagement between the two side doors and the center door; and

wherein the header and base have tracks therein for slidingly receiving the side doors and are further characterized by insertion means in the center thereof for receiving theside doors into said tracks, the center door being engaged at said insertion means.

2. The cargo container as recited in claim 1 wherein the door frame channel members are characterized by the presence of verticle recesses therealong and wherein one side edge of each of the side doors has a cap thereon complementary to the recesses such that sealing engagement may be affectuated between the tWO.

3. The cargo container as recited in claim 2 wherein the other side edge of each of the side doors is capped with a T-shaped edge member and wherein the side edges of the center door are capped with L-shaped edge members, the T-shaped and L-shaped edge members being adaptable to interlockingly engage each other.

4. The cargo container as recited in claim 1 wherein the header contains a top track therealong, the side doors having slides along the top edges thereof making sliding interlocking engagement with the top track, and wherein the base has a bottom track therein, the side doors having slides along the bottom edges thereof to make sliding interlocking engagement with the bottom track, the top track-slide engagement restricting downward vertical movement of the doors and the bottom track-slide engagement restricting upward vertical movement of the side doors.

5. The cargo container as recited in claim 1 wherein the latch assembly is housed within a recess in the center door and comprises a handle pivotally mounted to the door, the handle having a head at one end thereof and a wedge attached to the handle perpendicular to the length thereof, and wherein a plunger rests upon the base and opposite head such that contact of the head upon the plunger affectuates separating motion between the center door and the base.

6. The cargo container as recited in claim 5 wherein the bottom edge of the center door has a tongue therealong, the base below the center door has a groove therealong, and the wedge of the latch assembly is bevelled and positioned such that actuating movement of the latch handle forces the bevelled wedge into the groove below the center door and forces the tongue into the groove in tight interlocking engagement.

7. A cargo container, comprising:

a front framework of a header and base separated by and interconnected with vertical door frame elements;

first and second side doors having slides at the top and bottom thereof, the slides respectively engaging with tracks in the header and base of the container;

a center door engaging with the header, base, and two side doors thus completely enclosing the front framework;

a latch assembly positioned on the center door and operatively engaging the base, such engagement inhibiting the interpositional movement of the first and second side doors and the center door; and

wherein said base and header have receiving slots therein at the centers thereof, said slots receiving said side doors therein for engagement with said tracks, said center door engaging the base and header at said slots.

8. The cargo container as recited in claim 7 wherein the two said doors are interchangeable as to their positional relationship with the center door.

9. The cargo container as recited in claim 8 wherein the side doors have T-shaped elements along one vertical edge thereof and the center door has L-shaped elements along both vertical edges thereof, the T-shaped elements of the side doors lockingly interengaging with the L-shaped elements of the center door.

10. The cargo container as recited in claim 9 wherein each of the side doors has a reinforcing plate thereon with protrusions extending therefrom in vertical interlocking and horizontal sliding engagement with the track in the base of the container and wherein the top of each side door is capped with a T-shaped element in vertical locking and horizontal sliding relation with the track in the header.

11. The cargo container as recited in claim 7 wherein the latch assembly is positioned in a recess centrally located in the center door and comprises,

a handle pivotally mounted to the door;

a linkage rod operatively connected to one end of the handle; and

a bevelled blade and head combination pivotally connected to the center door at the bottom thereof and further connected to the linkage rod opposite the handle, the bevelled blade and head making en-' gagement with the base to sealinglyengage and disengage the center door therewith.

Claims

1. A cargo container having a basic structure of a base and a top, two end panels interconnecting the base and top, and a back panel connected to the top, base, and end panels thus defining an open container, further comprising: verticle door frame channel members attached to each of the end panels; a header interconnecting the door frame channel members and attached to the top; two side doors slidingly engaged among the header, base and door frame channel members; a center door removably engaged among the header, base and side doors; a latch assembly positioned on the center door adaptable to make gripping engagement with the base thus affectuating interlocking engagement between the two side doors and the center door; and wherein the header and base have tracks therein for slidingly receiving the side doors and are further characterized by insertion means in the center thereof for receiving the side doors into said tracks, the center door being engaged at said insertion means.

7. A cargo container, comprising: a front framework of a header and base separated by and interconnected with vertical door frame elements; first and second side doors having slides at the top and bottom thereof, the slides respectively engaging with tracks in the header and base of the container; a center door engaging with the header, base, and two side doors thus completely enclosing the front framework; a latch assembly positioned on the center door and operatively engaging the base, such engagement inhibiting the interpositional movement of the first and second side doors and the center door; and wherein said base and header have receiving slots therein at the centers thereof, said slots receiving said side doors therein for engagement with said tracks, said center door engaging the base and header at said slots.

11. The cargo container as recited in claim 7 wherein the latch assembly is positioned in a recess centrally located in the center door and comprises, a handle pivotally mounted to the door; a linkage rod operatively connected to one end of the handle; and a bevelled blade and head combination pivotally connected to the center door at the bottom thereof and further connected to the linkage rod opposite the handle, the bevelled blade and head making engagement with the base to Sealingly engage and disengage the center door therewith.