US2834527A - Sectional ladder installation for large tanks - Google Patents

Description

May 13, 1958 T D. ALLER 2,834,527

SECTIONAL LADDER INSTALLATION FOR LARGE TANKS Filed Aug. 15, 1955 2 Sheets-Sheet 1 INVENTOR.

May 13, 1958 T D. ALLER 2,834,527

SECTIONAL LADDER INSTALLATION FOR LARGE TANKS Filed Aug. 15, 1955 2 Sheets-Sheet 2 7' DW/A T 44452 INVENTOR.

fie. 4. "fl Z Unite States Patent SECTIONAL LADDER INSTALLATION FOR LARGE TANKS T Dwight Aller, San Gabriel, Calif., assignor to Southwest Welding & Mfg. Company, a corporation of California Application August 15, 1955, Serial No. 528,251

12 Claims. (Cl. 228-23) This invention relates to a ladder installation to be used in large tanks such as are employed for confining large quantities of liquids such as gasoline and other petroleum derivatives or the like.

While the invention is applicable to any large tank, it is particularly so when applied Within a tank in which the height of the tank is relatively great as compared with its diameter. it is also applicable particularly to tanks such as referred to, in which a floating deck or roof is provided in the tank that floats on the liquids surface.

One of the objects of this invention is to provide a ladder, or ladder assembly, that will enable access to be had to the interior of the tank and to the floating deck regardless of the level of the liquid and the deck in the tank, as such a floating deck is located at a lower level when the tank is nearly empty, but at a high level at times; so one of the objects of the invention is to provide a construction for the ladder that will enable it to assume a folded position adjacent the upper edge of the tank when the deck is located quite near or at the upper edge of the tank.

Another object of the invention is to provide a ladder assembly such as referred to, composed of articulated sections, including an upper section supported adjacent the upper edge of the tank, while the lower section is disposed in an inclined position opposed to the inclination of the upper section, and supported on the upper side of the floating deck.

Another object of my invention is to provide a ladder installation such as described, with means whereby feaires of construction carried by the ladder or ladder-accessories, can cooperate with means on the tank wall to enable the installation to function also as an anti-rotating means for the floating deck. This is a desirable end in view of the fact that practically all tanks of this kind are provided with flexible sealing aprons to prevent the escape of vapors or gases from volatile liquids in the tank.

Another object of the invention is to provide a landing shelf supported at the point of articulation between the two ladder sections to facilitate a mans passing from one of the ladder sections to the other in going up or down the ladder; and at the same time to provide means for maintaining this shelf in a substantially horizontal plane regardless of the location of the floating deck, which, of course, occasions variations in the angle between the two ladder sections at the point of articulation between them.

In connection with the means for maintaining the landing shelf in a horizontal position, one of the objects of the invention is to provide a simple linkage for accomplishing this, that is constructed on the pantograph principle.

Another object of the invention is to provide means for steadying the, complete ladder assembly so that it will be maintained constantly in its proper vertical plane in which the ladder sections may move relatively to each other when their angle of articulation changes, and which it must do when the floating deck rises and descends.

One of the features of this ladder installation is that it includes a steadying frame, the upper end of which is connected to the ladder assembly adjacent the articulated point referred to, and to provide a simple construction whereby the lower end of the steadying frame carries means for guiding itself up and down on the inner face of the tank wall in an upright, or vertical direction; also to provide means on the steadying frame for maintaining contact with the tank wall at one or more laterally disposed points, thereby providing means for resisting any forces such as might act in a horizontal plane, for example, in a country subject to earthquakes.

Another object of the invention is to provide a simple and effective construction for connecting the lower end of the steadying frame to the edge of the floating ladder, and to include in thisconnection, means for effecting the guiding of this steadying frame on a guide provided on the inner face of the tank wall; also to provide this connection with features of construction that will prevent the steadying frame at this point from moving in a lateral direction off the guide, and also to provide means at this point for preventing the lower portion of the steadying frame from drawing away from the guide, and toward the vertical axis of the tank.

Further objects of the invention will be evident from a careful reading of the specification and a study of the accompanying drawing.

The invention consists in the novel parts and combinations of parts to be described hereinafter, all of which contribute to produce an eificient sectional ladder installation for large tanks.

A preferred embodiment of the invention is described in the following specification, while the broad scope of the invention is pointed out in the appended claims.

In the drawing:

Figure 1 is a vertical section through a tank, and illustrates a ladder installation embodying my invention, and also showing a portion of the steadying frame in section. This view shows the ladder sections in an extended position such as they would assume when the floating deck is near the bottom of the tank, and also illustrates in dotted lines the floating deck disposed substantially at the upper end of the tank, where the ladder 7 sections are disposed in their maximum folded relation,

that is to say, with the smallest minimum angle that they assume with relation to each other.

Figure 2 is a plan of the tank and the installation shown in Figure l, with the lateral portions of the tank broken away so as to present a medial transverse zone extending across the tank.

Figure 3 is a view similar to Figure 2 with certain partsbroken away and showing the tank wall in section. In this view the upper ladder section is omitted so as to illustrate details of the steadying frame and the means for articulating the ladder sections to each other; and also illustrating the linkage employed, and operating on the pantograph principle for maintaining the floating deck in its proper horizontal plane; at the same time, allowing for its movement to and fro in accordance with the horizontal components of the movements of the articulating pivot pin or shaft that connects the two ladder sections to each other.

Figure 4 is a detailed vertical section taken about on the line 4-4 of Figure 1, shown on a larger scale, and further illustrating details of the ladder sections at their point of articulation. The view also shows the upper portion of the steadying frame.

Figure 5 is also upon an enlarged scale and is a detailed section taken about on the line 5-5 of Figure 1.

Referring more particularly to the parts, and especially to Figures 1 and 2, the ladder assembly includes two ladder sections 1 and 2, which, if the level 3 of the liquid 4 is low, might be disposed at substantially the angle and inclination indicated in Figure l.

The upper ladder section 1 is preferably supported from above by hinge connection 5 at a point elevated above the upper edge 6 of the tank 7. In order to do this a superstructure framing 8 may be employed, the upper portion of which also supports a platform 9 having a safety hand railing 11 around its edge. However, this railing should be omitted at one edge of the platform such as indicated at to facilitate a mans gaining access to the platform 9 by means of a ladder (not illustrated) resting against the tank wall.

As shown, the upper ladder section 1 inclines downwardly toward the interior of the tank, and the lower section 2 inclines in the opposite direction, the two sections being articulated together by a hinge joint 12. This may involve the use of a long pivot pin or cross shaft 13. The ladder sections, as illustrated in Figure 2, are offset with respect to each other. Each ladder section has two side bars or stringers 14 connected by rungs 14a which operate as steps for ascending or descending the ladder sections. The stringers 14 are preferably of angle iron.

This shaft 13 is not continuous, but includes two aligning sections, including a section 13a that connects the side bars 14 of the lower ladder section, and another extension 13b that connects at its ends to two slippers 15, respectively, the purpose of which wll presently appear.

Steadying means is provided for the ladder assembly preferably in the form of a boom 16, and in order to connect this boom to the ladder assembly the extension 13!) of the pivot shaft 13 preferably passes through the upper end of the boom (see Figure 3) to facilitate the functioning of the steadying means.

This steadying frame includes two diverging bars 17 and 18, the former of which extends down in an inclined direction and at its lower end is connected to a bracket 19 (see Figure 1). The base of this bracket is secured to the upper wall 20 of the floating deck or roof 21. Its connection to the bracket 19 includes a shackle 22 mounted between two fork plates 23 (see Figure 5), that have flanges 24 riveted or welded to the end 25 of the leg or bar 17.

Between the side plates of the shackle 22 roller-means is provided including a broad faced roller 26 that rolls on the double flange 27 of a T-shaped guide-bar 28. The edge of the web of this flange bar is welded at 29 to the inner face of the side wall 30 of the tank 7.

This guide-bar 28 of course, extends in an upright direction and should be substantially vertical to facilitate the guiding of the roller 26 as it moves up and down with the rising and descending deck 21.

The ends of the rollers 26 are formed with stub flanges 31 which lap the edges of the double flange 27 to prevent the roller from shifting laterally off the guide-bar; and in order to prevent the bar end 25 of the steadying frame from shifting inwardly, and away from the guide 28, the forks of the shackle 22 are provided with inwardly extending flanges 32.

It is preferable to employ a lost motion connection 231: such as a pin-and-slot between the yoke at 23 and the shackle 22 in casethe deck gets out of its proper horizontal position.

The divergence of the two bars or legs 17 and 18 of the steadying frame, is most advantageous because the bar 18 functions as a lateral brace to prevent the free end of the steadying frame from moving toward the side on which this arm is located, and in this connection, its functioning is cooperating with the shackle 22 whose flanges 32 engage the inner sides of the double flange 27 to prevent the bar 17 from pulling away from the guide bar 28 (see Figure 5). In order to adapt the bar 18 to this purpose I prefer to provide its tip with a roller or wheel 35 the periphery of which rolls against the inner face of the tank wall 30. A strut brace 13c connects the upper ends of the bars 17 and 18.

In order to supplement the steadying action of this bar 18 and prevent the ladder assembly and the steadying frame from swinging in the other direction, I prefer to provide a cross-bar or brace 36 (see Figure 3). This brace is attached at 37 to the side of the lower end of the bar 18, and at 38 to the underside of the bar 17, and it extends over a considerable distance beyond the bar 17 and then bends toward the wall of the tank at a straight extension 39. The end of this extension also carries a roller 40 which may be similar to the roller 35, and rolls on the tank wall. This extension 39 is preferably disposed in a radial direction from the axis of the tank so that the plane of the roller, which, as illustrated, is of disc form, is normal to the concave face of the tank wall 30. The roller or disc 40 is preferably at substantially the same distance from the guide-bar 28 as the other roller 35.

The roller 26 is mounted on a pin 33 that is held in place by split pins 34. The pin 33 is carried in the forks 23 which constitute a yoke. At about the level of the joint 12 between the laddersections a landing shelf 41 is provided. It lies in a substantially horizontal plane and is maintained in that plane regardless of the degree of the angle 42 that lies between the two ladder sections.

In order to accomplish this I prefer to make the two slippers 15, already referred to, in the form of two sleeves as shown in Figure 4. They receive, and slide on, two horizontal parallel bars 43. These bars are maintained in a horizontal position through the agency of a linkage, the parts of which are connected up on the pantographic principle. This relation, as shown in Figure 3, shows the bars 43 as being of considerable length and extending back to a joint connection 44 (see Figure 1). This connection 44 involves the use of a cross-bar or shaft 45 (see Figure 3) one end of which passes through an eye 46 on the end of an inclined link 47; and at both its ends it passes through similar eyes on the horizontal bars 43. In addition to this, there is another hub or eye 48 pivoting on one end of the bar 45; this eye 48 is on the upper end of a link 53. This link is parallel to link 47 (see Figure l); and it and the link 47 extend down and their lower ends are attached on a pivot pin connection 49 to the side- bars 17 and 18 of the steadying frame 16.

This pivotal connection at 49 includes a cross-bar 50 substantially similar to the cross bar 45 and parallel to it and the outer end of this cross bar 50 carries an eye or hub 51 through which the cross bar 50 passes and beyond which this cross bar is attached to the inner face of the outer bar 18 of the steadying frame. This connection is made at 52 as shown in Figure 3, and through the eye 51 formed on the end of a link 53 that is parallel to the link 47, and extends upwardly; its upper end is pivotally attached to the cross-bar 45 at the rear end of the outer parallel bar 43.

In addition to this the pantographic linkage includes two parallel upper links 55 disposed in an inclined position, their lower ends being pivotally attached to the cross bar 45 and their upper ends attached pivotally on a gusset bracket 56 secured to the side bar of the upper ladder section.

With this arrangement of linkage just described, it will be evident that, regardless of what the degree of angle 42 becomes, the pivot point or joint 44 will always be maintained in this same horizontal plane as the joint 12. This, of course, insures that the parallel bars 43 will always be maintained in a horizontal plane regardless of whether the sleeves 15 and the shelf 41, supported on the sleeves, move forward or back on the horizontal bars 43.

Referring again to the lower ladder section 2, the side angle bars 14 may be reinforced on their outer sides by strap. metal bars 57 that extend along the outer sides of the iron bars and unite with them to form side stringers for the ladder section.

Both the ladder sections are provided with a hand-rail 58 on each side of the ladder body but these hand-rails are omitted in Figures 2 and 3, so as not to interfere with the showing of more important details. A handrail 59 is also preferably provided on the outer end of the landing shelf 41 and also on its outer side edge 60.

Of course, as the floating deck rises and descends with the liquid level the roller 61 supports the lower end of the lower ladder section, moving without sliding friction, to and fro on the upper wall 20 of the floating deck. Here I prefer to provide two rollers 61 of disc-form that roll on. strong-back rails 62 to prevent the rollers from buckling the plating. The discs 61 also have end flanges 63 that lap the sides of the rails 62 so as to keep the lower end of the lower ladder section moving in a straight line.

One of the incidental objects and advantages of applicants invention is that the ladder assembly is so constructed that each ladder section includes no structural parts projecting beyond its side edges. Hence, the space at the sides is unobstructed, which results in the establishment of a clear unobstructed path for an attendant in passing on the shelf or platform 41 from one ladder section to the other.

Many other embodiments of this invention may be resorted to without departing from the spirit of the in vention.

I claim and desire to secure by Letters Patent:

1. In a ladder installation for liquid tanks, or the like, having a floating deck therein, the combination of upright guide-means on the inner face of the tank wall, a fioating deck on the surface of the liquid in the tank and having means for engaging the said guide means, a ladder comprising two sections located at different levels, with a flexible connection between the same, the lower ladder section having its lower end guided to move in a trans verse direction on the upper side of thedeck when the deck rises and falls with the surface of the liquid in the tank, the upper section of the ladder having its upper end supported adjacent the upper end of said tank, said ladder sections being offset laterally from each other, and having a transverse landing shelf supported at about the level of the said joint; and means for maintaining said landing shelf in a substantially horizontal position as the said joint flexes with the rise and fall of the said floating deck.

2. A ladder installation for liquid tanks or the like, according to claim 1, including a steadying frame connected at its upper end to the joint between the ladder extensions and inclining downwardly toward the location of said guide means, and guided at its lower end on the guide-means, said steadying frame having a lateral extension adjacent its lower end, said lateral extension having means for engaging the inner face of the tank wall at a point removed laterally from the said guide-means to maintain the ladder in a substantially fixed upright plane as it rises and falls with said deck.

3. A ladder installation for liquid tanks, or the like, according to claim 2, including a flanged roller mounted at the lower end of the steadying frame and running on the said guide-means for preventing lateral movement of the lower end of the steadying frame with respect to the guide-means.

4. A ladder installation for liquid tanks, or the like, according to claim 2, in which the lower end of the lower ladder section is connected to the edge portion of the floating deck adjacent to the guide-means; and including a flanged roller running on the said guide-means.

5. A ladder installation for tanks having a high ratio of vertical height to their diameter, in accordance with claim 1, in which the lower section of the ladder is disposed in an offset position with respect to the upper section of the ladder, and in which the said ladder sections incline in opposite directions;

a joint connecting the upper portion of the upper ladder section to a point adjacent the upper edge of the tank; an anti-friction connection between the lower end of the lower ladder section and the upper side of the floating deck; and in which the said steadying frame has a lost motion connection to the upper side of the floating deck adjacent said guidingmeans.

6. A ladder installation for a tank having a vertical height of a relative high ratio to its diameter, and constructed according to claim 5, including a shackle carried at the lower end of the said steadying frame, said shackle and said guide means having a correlated form cooperating to prevent the lower portion of said steadying frame from drawing away from the guide-means.

7. A ladder installation according to claim 1, in which the said flexible connection includes a substantially horizontal transverse pivot pin, a slipper connected to each end of said pivot pin, a steadying frame for the ladder including two downwardly inclined frame bars connected to said pivot pin, diverging from each other and inclining downwardly to a point at about the level of the deck, roller means on one of said bars rolling on the said guidemeans; and roller means on the lower end of the other of said bars to roll up and down adjacent the inner face of the tank wall; a pair of parallel bars on which the,

said slippers slide, said landing shelf supported on said slippers; and a pair of links pivotally attached to said divergent bars, and to each other, and to said parallel bars on a common pivot; and including a pair of links connected at one end to said common pivot, and at their upper ends connected pivotally to the under side of the upper ladder section, all of said links and parallel bars functioning to maintain said parallel bars in a horizontal position, and to enable said slippers and the said shelf to slide to and fro on the parallel bars as the said deck rises and descends with the surface of the liquid in the tank.

8. In a ladder installation for a relatively tall tank, the combination of two ladder sections, located at different levels, the upper ladder section having means for hingedly supporting the same adjacent the upper edge of the tank, a floating deck supported on the surface of the liquid in the tank, said ladder section being inclined in opposite directions, means including a transverse pivot pin connecting the side bars at the lower end of the upper ladder section to the side bars at the upper end of the lower ladder sections, a steadying frame for the ladder including two diverging bars with their upper ends connected to said transverse pivot pins; roller means carried by the lower end of said lower ladder section for rolling on the said deck to support the same; roller means carried by the lower ends of the said bars of the steadying frame for rolling up and down adjacent the inner face of the side wall of the tank, means connecting one of said bars of the steadying frame to the said floating deck, including a lost motion connection; a landing shelf located at said transverse pivot pin; and a pantographic framing connected between said steadying frame and the upper ladder section; and means cooperating with the pantographic framing for maintaining the said landing deck in a substantially horizontal position.

9. A ladder installation according to claim 8, in which the means cooperating with the pantographic frame to maintain the landing shelf horizontal includes a pair of horizontal bars connected into the pantograph framing, and sleeves connected to the said pivot pin, and mounted to slide to and fro on the said parallel bars.

10. In a ladder installation for a tank including a ladder and a steadying frame for maintaining the ladder inclined in its proper place, the combination of a tank having an upright guide bar on its inner wall, a floating deck within the tank, a shackle mounted on the edge of the deck having means engaging the guide bar to prevent the steadying frame from drawing away from the tank wall, a roller carried by the shackle riding to and fro on the guide bar, and a lost motion connection between the shackle and the adjacent end of-the steadying frame.

11. In a folding ladder installation for a tank holding a liquid and havinga floating deck supported on the same, the combination of a pair of articulated ladder sections including an upper section with means for hingedly articulating its upper end to the upper portion of the tank and at the edge thereof, the other ladder section being hingedly articulated to the lower end of the upper ladder section, a steadying frame articulated to the ladder sections at their point of connection, so as to rotate on the same axis on which the ladder sections are articulated to each other, said steadying frame extending downwardly in an inclined direction with its lower end disposed adjacent to the wall of the tank below and in line with the said upper articulated connection to the upper portion of the tank, roller means carried by the lower end of the steadying frame for running up and down on the inner side of the tank wall, a pair of links parallel to the steadying frame pivotally attached to the under side of the upper ladder section, and a second pair of links parallel to each other and pivotally attached to the upper side of the steadying frame, and also pivotally connected to said first pair of parallel links at about the same level as the articulated connection between the two ladder sections, a landing shelf between the two ladder sections located at the level of the articulation between the same, and including guide members extending substantially parallel to the plane in which said shelf lies to swing on their articulated joint; and substantially horizontal bars pivotally attached on the pivotal connection between the said pairs of links and guided to slide through said guides as the floating deck rises and falls with the liquid level for maintaining the shelf in a horizontal position in any relative position assumed by the ladder sections.

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12. In a sectional ladder assembly for the interior of 'a tank holding a liquid, and having a floating deck supported on the surface of the liquid, the combination of a pair of articulated ladder sections consisting of an upper ladder section having means for hingedly supporting its upper. portion on the side wall of the tank at about the level of its upper edge, a lower ladder section hingedly articulated to the side of the lower end of the upper ladder section, each ladder section consisting of two side stringers with rungs connecting the same, pantographic frame-means located at the articulated connection between the two ladder sections, a landing shelf supported by the pantographic frame-means in a substantially horizontal position in any angular relations the ladder sections may assume, steadying means for the ladder sections including a boom which is hingedly attached to one of the ladder sections at a point adjacent its articulated connection to the other ladder section, and with the lower end of said boom supported on the upper side of the roof; and means for guiding the lower end of the boom up anddown on the tank wall, all of said parts cooperating so as to leave the outer side edges of said ladder sections clear and unobstructed, thereby establishing a clear and unobstructed path for an attendant in passing on the shelf from either ladder section to the other.

References Cited in the file of this patent UNITED STATES PATENTS 878,863 Brazill Feb. 11, 1908 1,636,963 Jagschitz July 26, 1927 1,944,159 Bailey Jan. 23, 1934 2,341,890 Wiggins Feb. 15, 1944 2,708,064 McGowen May 10, 1955 2,728,512 La Spina Dec. 27, 1955

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