US2778719A - Balancing or stabilizing mechanism for vertically movable tank roofs - Google Patents

Description

Jan. 22, 1957 J. H. wlGGlNs 2,778,719

BALANCING OR STABILIZING MECHANISM FOR VERTICALLY MOVABLE TANK ROOFS Filed June 12, 1952 /2 5 la TA/VEN TOR,

/ 6 ATTORNEY.

BALANCING R STABILIZING MECHANISM FOR VERTCALLY MOVABLE TANK ROOFS John H. Wiggins, Chicago, lll.

Application June 12, 1952, Serial No. 293,071

4 Claims. (Cl. 48-176) This invention relates to mechanisms ot the kind that are used for balancing or stabilizing vertically movable tank roofs which rise and fall in response to variations in the pressure of a gas or vapor on the underside of the roof.

VThe objects of my invention are to reduce the cost and number of parts, and simplify the installation and inspection of tank root` balancing mechanisms of the particular type that employ or are equipped with a vertically movable guide means attached to the roof at the center of same and arranged in sliding engagement with a coacting, vertically disposed, stationary guide means located at the center of the tank.

To this end l have devised a tank roof balancing mechanism of the general type above referred to, that has the following essential and distinguishing characteristics:

(a) The stationary guide means at the center of the tank consists of a vertically disposed member that projects upwardly through an opening in the' roof and terminates at a level high enough to ensure that it will coact properly with a guide means carried by the roof even when the roof is in its highest position.

(b) The roofis provided with a housing means that encases the upper end portion of said stationary center guide member in all positions of the roof, and

(c)` The roof carries a guide means that coacts with said stationary guide member and which is so arranged that it is accessible from the top side of the roof.

Other features Vof my improved mechanism that are advantageous but not essential to its successfuloperation, are that the plates of which the roof is constructed are utilized to constitute part of the balancing mechanism for the roof, and the framing-on which the roof rests when it is in its lowest position is utilized to constitute part of the roof balancing mechanism.

Figure l of the drawings is a transverse vertical sectional view illustrating a roof balancing or stabilizing mechanism constructed in accordance with my invention.

Figure 2 is a top plan view of the roof showing certain parts of the balancing mechanism in horizontal section on the line 2 2 of Figure 1, and Figure 3 is a vertical sectional view illustrating another way of constructing the guide means that is located above or on the top side of the roof.

In the drawings the reference character 5 designates a tank that is provided with a vertically movable roof 1, herein illustrated as a lifter type roof equipped with a depending skirt 2 that surrounds and is arranged in spaced relation with the tank side wall, the lower end of said skirt being reinforced and strengthened by a stitener or equivalent means 3. vAny suitable means can be used to seal theV annular space'between said skirt and the tank side wall such as a conventional liquid seal or a curtain type seal formed by a gas tight flexible element 13 attached to the skirt on the roof and to the tank side wall, said sealing element being so designed as to permit the roof to move vertically from its extreme low position shown in full lines in Figure l, into its extreme high nited States Patent O position shown in broken lines in said figure, in response to variations in the internal pressure of the gas or vapor space on the under side of the roof.

The preferred form of my improved balancing mechanism herein illustrated, briefly described, consists of a stationary, vertically disposed guide member arranged at the center of the tank with its upper end portion projecting upwardly through an opening in the roof, a guide means carried bythe roof and accessible from the top side of same and constructed in such a manner that when the roof tilts or goes out of balance said guide means will exert a lateral thrust on the portion of said stationary guide members located above the roof a housing on the roof for encasing the portion of said stationary center guide which projects above the roof, a load member of relatively great weight arranged in telescoped relation with the stationary, vertically disposed guide member at the center of the'tank, a group of radially disposed pull down devices formed by cable, chains or rods that suspend said load member from the underside of the peripheral portion of the roof and maintain said loa-d member in Widely spaced, vertical relation with the previously mentioned guide means mounted on or adjacent the top v an annular weight 7 that surrounds the stationary guide l member 15, said Weight being suspended from the roof side of the roof, a circular beam attached to the periphery of the roof and extending circumferentially around the same, and a group of radially disposed roof rafters attached at their outer ends to the top edge of the side wall of the tank and attached at their inner ends to the stationary vertically disposed guide member in the tank. When the roof tilts or goes out of balance the load member suspended from the roof exerts a lateral thrust on the stationary guide member in a direction diametrically opposite to the lateral thrust exerted on said stationary guide member by the guide means carried by and accessible from the top sideV of the roof. For convenience kI Will refer to the guide means accessible from the top side of the roof, as the top guide, and l will refer to lthe load member which is suspended from the underside of the roof as the weight i In the form of my invention herein illustrated, the

above mentioned stationary, vertically disposed guide memberis formed by a tubular post 15 Whose lower end is securely anchored to the bottom 6 of the tank 5 and whose upper end portion 14 projects upwardly through an opening at the center of the roof 1. The roof is prolvided with a top guide illustrated on Figures 1 and 2 as being formed by a plurality of rollers 10 that are rotatably mounted on brackets 11 carried by a housing member 12 which is rigidly attached to the top side of the roof 1 so as to surround the center opening in the roof through which the stationary guide member l5 projects upwardly, the yrollers l0 being so arranged that when the roof tilts or goes out'of balance there will be .some portion of the guide means on the top side of the roof that exerts lateral pressure on a portion of the stationary center guide member which is located above the roof, this being true both when the roof is in its extreme low position shown in full lines in Figure l, and in its ex' relation with the roof is provided with a removable cap or top portion 4 so as to facilitate the installation, inspection and servicing of the rollers l0.

The previously mentioned load member suspended from the roof, is herein illustrated as being formed by by a plurality of radially disposed pull down devices or tension members, formed by chains or cables or by rods 8 attached at their lower ends to the weight 7 and leading upwardly and outwardly from same to the periph- Patented Jan, 22, 1957V` eral portion of the roof to which the upper ends of said rods are attached by lugs on the underside of the roof located some distance inwardly from the peripheral edge of the roof.

The upper end portion of the side wall of the tank is reinforced and strengthened preferably by means of a curb 18 that extends circumferentially around the top edge of said side wall, and the stationary center guide member 15 is anchored to the tank side wall by radially disposed roof rafters 9 disposed so as to serve as a supporting structure for the roof when the roof is in its extreme low position. As shown in Figure l, the roof is provided at its peripheral edge with a reinforcing member 19 that coacts with the roof plates and with the skirt 2 of the roof to form an annular beam which extends circumferentially around the roof.

When the roof is supported by the rafters 9 or by gases confined in the tank, and the roof is subjected to no forces such as wind pressure or a snow load that tips the roof or throws it out of balance, all of the rods 8 have the same tension. The horizontal components of these tensions at the upper ends of said rods are directed to the center of the roof and these are all equal and are balanced through the circular beam 19 at the periphery of the roof. Hence it is not necessary that the rollers lil or equivalent top guide of the roof be in direct bearing engagement with the upper end portion 14 of the stationary guide member 15 at such times, as they perform no function in stabilizing or balancing the roof. Also under the condition mentioned the horizontal components of the tensions at the lower ends of the rods 8 are all equal and are balanced through the weight 7, with the result that the weight 7 is maintained in such relation with the stationary guide member 15 that said weight exerts no side pressure or lateral thrusts on said stationary guide member. When a foreign load, such for example as a snow load designated by the reference character 16, is applied to the left side of the roof, then the rods 8 at the right hand side of the tank pull harder than normal and the rods 8 at the left hand side of the tank pull less than normal. This gives an increased horizontal force component at the right side, directed towards the center as indicated by the large arrow 17 in Figure l. This load passes around the peripheral portion of the roof, which acts as a circular beam and compression member, t a point which is near the foreign load 16 on the roof, as indicated by the smaller arrows 17 in Figure 2. Then this same load passes in tension, designated by the arrows 2b in Figure 2, through the roof plates to the center of the roof and this same load 17 is then applied to the roller 10 on the right side of the top portion 14 of the stationary guide member 15. This exerts a lateral thrust on the portion 14 of the stationary center guide member which tends to push said portion 14 to the left. However, as the stationary center guide member is prevented by the roof rafters 19 from moving laterally, this same load 17 is then carried into the top curb member 1S at the top edge of the tank side wall. At the same time there is a horizontal component directed as shown by the arrow 21 in Figure l. This is resisted by the stationary center guide Whose lower end is securely anchored to the bottom of the tank.

In Figure 3 I have illustrated another Structure that may be used to constitute the top guide on the roof. In said structure the upper end portion 14 of the stationary center guide member is provided at its top with a plurality of rollers lila which are adapted to engage or bear against a housing member 12a rigidly attached to the top side of the roof and projecting upwardly from same, said housing member 12a being preferably provided with a removable cap 4a.

From the foregoing it will be understood that in my improved structure substantially the total top portion of the roof guiding means of the mechanism, is located above the top side of the roof, and is formed by a portion of the stationary center guide that projects upwardly through the roof, coacting guide rollers that are accessible from the top side of the roof, and a housing on the top side of the roof that encases the portion of the center guide member projecting above the roof and which, in whole or in part, is formed by a member rigidly attached to the roof. Also in my mechanism the metal plates of which the roof is constructed and the rafters on whichthe roof rests when it is in its lowest position, are utilized to constitute part of the mechanism relied upon to restore the roof to its normal position in the event it tips or becomes unbalanced. Hence l reduce the parts necessary for a roof balancing mechanism to a very minimum and accordingly reduce tremendously the cost of the structure.

Having thus described my invention, that l claim as new and desire to secure by Letters Patent is:

l. In a tank having its upper end closed by a disclike roof that is vertically movable with respect to the tank in order to vary the internal Volume of the tank beneath the roof, the combination comprising, an upstandingsubstantially rigid vertical guide post fixed at its lower end at the center of the tank and having its upper end portion extending through an opening in the center of the roof, roller means for guiding said roof upon said post for articulate tilting movements with respect thereto and also for guided vertical movements along said post, said roller means being so constructed and arranged as freely to accommodate tilting movement of said roof with respect to said post and with respect to the horizontal when an unbalancing off-center load is applied to said roof, an upwardly extending housing hermetically covering said opening in said root and containing said roller means, said upper portion of said post extending upwardly into said housing, and an annular balancing weight for said roof encompassing said post and arranged for guided vertical sliding movements thereon, said annular balancing weight being of substantial mass and being suspended beneath said roof solely from the peripheral portion thereof by a plurality of substantially equally spaced flexible suspension members having their respective upper ends secured to said peripheral portion of said roof at circumferentially spaced locations thereon and having their lower ends secured to said weight, the mass `of said balancing weight tending to maintain said roof in a horizontal attitude and causing said roof to return to said horizontal attitude when an unbalancing off-center load is removed from said roof.

2. The combination set forth in claim l, wherein said roller meansincludes a plurality of rollers mounted upon the interior Wall of said housing for rolling contact with said upper portion of said post.

3. The combination set forth in claim 1, wherein said roller means comprises a plurality of rollers mounted upon said upper portion of said post for rolling contact with the interior wall of said housing.

4. The combination set forth in claim l, wherein said housing is provided with a doorway permitting ready access to said roller means.

References Cited in the le of this patent UNITED STATES PATENTS 628,868 Strom Iuly 11, 1899 666,598 Bryan Jan. 22, 1901 2,194,581 Weichsel Mar. 26, 1940 2,360,692 Larsen Oct. 17, 1944 2,452,146 Plummer Oct. 26, 1948 2,497,851 Allen Feb. 21, 1950

Claims (1)

1. IN A TANK HAVING ITS UPPER END CLOSED BY A DISCLIKE ROOF THAT IS VERTICALLY MOVABLE WITH RESPECT TO THE TANK IN ORDER TO VARY THE INTERNAL VOLUME OF THE TANK BENEATH THE ROOF, THE COMBINATION COMPRISING, AN UPSTANDING SUBSTANTIALLY RIDID VERTICAL GUIDE POST FIXED AT ITS LOWER END AT THE CENTER OF THE TANK AND HAVING ITS UPPER END PORTION EXTENDING THROUGH AN OPENING IN THE CENTER OF THE ROOF, ROLLER MEANS FOR GUIDING SAID ROOF UPON SAID POST FOR ARTICULATE TILTING MOVEMENTS WITH RESPECT THERETO AND ALSO FOR GUIDED VERTICAL MOVEMENTS ALONG SAID POST, SAID ROLLER MEANS BEING SO CONSTRUCTED AND ARRANGED AS FREELY TO ACCOMMODATE TILTING MOVEMENT OF SAID ROOF WITH RESPECT TO SAID POST AND WITH RESPECT TO THE HORIZONTAL WHEN AN UNBALANCING OFF-CENTER LOAD IS APPLIED TO SAID ROOF, AN UPWARDLY EXTENDING HOUSING HERMETICALLY COVERING SAID OPENING IN SAID ROOF AND CONTAINING SAID ROLLER MEANS, SAID UPPER PORTION OF SAID POST EXTENDING UPWARDLY INTO SAID HOUSING, AND AN ANNULAR BALANCING WEIGHT FOR SAID ROOF ENCOMPASSING SAID POST AND ARRANGED FOR GUIDED VERTICAL SLIDING MOVEMENTS THEREON, SAID ANNULAR BALANCING WEIGHT BEING OF SUBSTANTIAL MASS AND BEING SUSPENDED BENEATH SAID ROOF SOLELY FROM THE PERIPHERAL PORTION THEREOF BY A PLURALITY OF SUBSTANTIALLY EQUALLY SPACED FLEXIBLE SUSPENSION MEMBERS HAVING THEIR RESPECTIVE UPPER ENDS SECURED TO SAID PERIPHERAL PORTION OF SAID ROOF AT CIRCUMFERENTIALLY SPACED LOCATIONS THEREON AND HAVING THEIR LOWER ENDS SECURED TO SAID WEIGHT, THE MASS OF SAID BALANCING WEIGHT TENDING TO MAINTAIN SAID ROOF IN A HORIZONTAL ATTITUDE AND CAUSING SAID ROOF TO RETURN TO SAID HORIZONTAL ATTITUDE WHEN AN UNBALANCING OFF-CENTER LOAD IS REMOVED FROM SAID ROOF.

Images