US2959245A - Extension and straight knockdown ladder - Google Patents

Description

Nov. 8, 1960 'r. J. O'KEEFE EXTENSION AND STRAIGHT xuocxnown LADDER 2 Sheets-Sheet 1 Filed May 9, 1956 22 .1. @NVENTOR Nov. 8, 1960 'r. J. O'KEEFE 2,959,245

EXTENSION AND STRAIGHT KNOCKDOWN LADDER Filed May 9, 1956 ZSImets-Sheet 2 iii ATTOR 5.

United States Patent EXTENSION AND STRAIGHT KNOCKDOWN LADDER Thomas J. OKeefe, 28 Mansfield St., Bethel, Conn.

Filed May 9, 1956, Ser. No. 583,751

3 Claims. (Cl. 182-151) This invention relates to ladders, and particularly to a ladder which may be used as an extension or a straight knockdown ladder, and has for an object to provide an improved and simplified construction which may be shipped in a knockdown self-contained package for easy final assembly by the user, to thus greatly reduce the shipping space required, and also the cost of shipping.

Another object is to provide a construction which will be of light weight but which will be of a strong, rigid construction, and in which the side rails may be made of extruded aluminum or magnesium alloys, the rails of both the upper and lower sections of the ladder being the same, and the side rails of the two sections can be disconnected, and the rungs can be disconnected from the side rails, and placed in a package in a knockdown condition, requiring a minimum of space in proportion to the weight for shipping purposes.

Another object is to provide an improved connection for fastening the rungs to the side rails which may be readily connected or disconnected and with a simple construction will provide a strong, rigid connection between the nungs and the rails.

With the foregoing and other objects in view, I have devised the construction illustrated in the accompanying drawings forming a part of this specification. It is, however, to be understood the invention is not limited to the specific details of construction and arrangement shown, but may embody various changes and modifications within the scope of the invention.

In this drawing:

Fig. l is a front view of the ladder partially extended;

Fig. 2 is a view looking toward the inner side of the side rails and showing a stop hook in elevation and two adjacent rungs in section, the section being substantially on line 22 of Fig. 3;

Fig. 3 is a transverse section looking toward the bottom of Fig. 2 with an end portion of one of the rungs and the improved connector for fastening to the side rails shown in section;

Fig. 3a is an end view of a portion of one of the rungs;

Fig. 4 is a side view of the lower ends of the side rails of the upper and lower sections in the collapsed condition;

Fig. 5 is an end view looking from the left of Fig. 4;

Fig. 6 is a section similar to Fig. 4 of the upper end of the side rails;

Fig. 7 is an end view looking from the right of Fig. 6;

Fig. 8 is a perspective view illustrating how the parts of a knockdown ladder may be assembled for shipping purposes, certain parts being omitted and others shown in section;

Fig. 9 is a perspective view of one end portion of this package with a portion of the enclosing end protector or make a knockdown extension ladder of light weight but 2,959,245 Patented Nov. 8, 1960 strong, rigid construction, in which the side rails can be made of extruded aluminum or magnesium alloy, the rails of both the upper and lower sections of the ladder being the same, and they are so arranged that the side rails of the two sections can be disconnected and the rungs can be disconnected from the side rails and all the parts placed in a package in the knockdown condition, requiring a minimum of space in proportion to the weight for shipping purposes. One objection to the ordinary ladders, both straight and extension, is that in shipping them a large space is required in proportion to the weight involved, making shipping costs very high. This ladder in the knockdown condition can be placed in a package requiring minimum shipping space and can be readily assembled by the purchaser.

As shown in Fig. 3, the side rails of the ladder comprising the rails 10 of the upper section and 11 of the lower section are of the same extruded cross section, preferably of the aluminum or magnesium alloy, comprising a channel shape including a connecting web 12 and opposite edge flanges 13 and 14 at the opposite edges of the web extending laterally in the same direction from this web at substantially right angles thereto, with shorter edge flanges 15 and 16 extending inwardly from the outer edges of the flanges 13 and 14, so that the shorter flanges 15 and 16 extend inwardly toward each other spaced from and parallel to the web 12, providing an open-sided channel section. The rails of the two upper and lower sections are reversed, as shown in Fig. 3, the rails 10 of the upper section having their open sides facing outwardly, while the rails 11 of the lower section have their open sides facing inwardly toward each other. The lower flanges 14- of the rails of the upper section and the upper flanges 13 of the rails of the lower section are overlapped, as shown in Fig. 3, to connect the rails of the two sections for relative longitudinal sliding movement for lengthening or extension and shortening or contracting purposes, and the short flanges 15, 16 of these wider flanges are also overlapped as shown in Fig. 3, to interlock against lateral separation. This section makes a strong, rigid construction in proportion to the amount of metal required for the section, and the overlapping flanges provide a novel interlocking connection between the rails of the upper and lower sections of the ladder to permit ready longitudinal sliding movements between them for extension and retracting purposes, while providing an effective interlocking arrangement between them to prevent them from separating during these movements and while the ladder is in use.

The side rails of the two sections are connected by transverse tubular rungs 17 and 18 connected at their opposite ends to the connecting webs 12 of the rails by an improved fastening means which can be readily assembled by the purchaser of the ladder in the knockdown condition, and form a strong, rigid connection between the rungs and the side rails. This novel and improved connection is shown in section in Fig. 3. The rungs 17 and 18 are tubular sections, preferably extruded tubu-lar sections, provided with a roughened or ribbed outer surface, as shown in Fig. 3a, a series of longitudinal ribs 19 providing a series of spaced sharp edges preventing slipping of the foot of the person stepping on the rung. The wall thickness of the rungs is sufficient to permit internal screw threading, as indicated at 20, to receive the fastener 21. This is a cylindrical member having an outer threaded surface 22 adapted to be screwed into the internally threaded end of the rung and provided with a flange 23 at its outer end of a larger diameter than the threaded body portion so as to engage the end of the rung. It is provided with wrenching surfaces, such, for example, as a hexagonal shape to permit use of a wrench in threading this fastener into the end of the rung. It is also internally mit the rung to enter this recess.

threaded at 24 throughout its length to receive a fastening screw 25 or bolt which may pass through an opening in the web 12 of the side rail and has wrenching. surfaces on its outer edge such, for example, as a hex head 26 for applying it to the fastener and setting it up tight in connecting the rung to the side rail, preferably with a suitable washer 27 between the head and the outer surface of the rail, and the flange 23 between the end of the rung and the inner side of the web. This makes a very simple and rigid connecting means for securing the opposite ends of the rungs to the rails, requiring merely screwing the fastener into the end of the rung, after which the ends of the rung may be hit a blow with a hammer at the flats of the flange 23 to form a fin or burr over the flat to prevent the fastener from unscrewing or loosening up in the rung, and then the bolt 25 may be applied through suitably spaced openings in the side rails to complete the connection of the rungs to the rails. The rungs are normally spaced on twelve inch center to center distances. In the bottom section the first rung is twelve inches from the bottom of the ladder, but the top rung is only eleven inches from the top. In the top section the first rung is eleven inches from the bottom and the top rung is twelve inches from the top. This arrangement permits two short ladder sections to be extended the same distance as con-- ventional ladders.

The rungs 18 of the lower section are so located as to support the lower flanges 14 of the side rails of the upper section and maintain this lower flange and the upper flange and the lower rail, as well as the short flanges and 16, in overlapped or interlocking relation. The lower flanges 14 of the rails of the upper section thus run on the rungs of the lower section, doing away with the requirement of separate rollers or other supports for the upper section.

An improved form of stop hook 28 is provided for holding the upper section in any extended position. It comprises a body portion 29, one for each side rail, located at the inner side thereof and pivotally connected to the web of the rail by the shouldered bolt 30 adjacent the upper rung 17, as shown in Fig. 2, and provided with an opensided hook or recess 31 to seat over any rung 18 of the lower section. The bolt 30 is shouldered to space the hook from the side rail for proper clearance. The body portion has an elongated opening or slot 32 through which the rung 17 passes, and the opposite ends of which by engaging this rung limit the swinging movements of the hook. This also permits the use of a rung at the hook location, while in usual ladder constructions this rung is omitted, forming a gap in the rung arrangement. outer end the hook is provided with a curved cam surface 33 adapted to cooperate with the rungs of the lower ladder section in the extension or contracting operation, and pivoted at 34 to the lower body portion of the hook is a toggle 35 having a weighted lower end portion 36 and an upper portion 37 offset laterally from the portion 36, as indicated at 38, Fig. 3, to permit the portion 37 to lie in the same plane as the outer portion of the hook and to engage the opposite end 39 at the opposite side of the recess 31 to close this recess, as shown in Fig. 2. The open or retracted position of the hook is shown in broken lines, Fig. 2, this movement being limited by the lower end 40 of elongated slot 32 engaging the rung 17, and its movement in the opposite or closed position is limited by the opposite end 41 of this slot engaging this rung, as shown in full lines. As the upper section comprising the rails 10 is shifted upwardly, cam surface 33 may engage rungs 18 on the lower section to swing it to the left or broken line position to permit the hook to pass by the rungs 18, but if it is desired to have this hook engage any particular rung to have the rung seat in recess 31, the operator may cause the rung to engage the projecting end 42 of the toggle arm 37 to swing this arm downwardly and uncover the open side of the recess 31 to per- Downward' swinging At its movements of this arm of the toggle are limited by the free end of the weighted portion 36 engaging the rung 17, as indicated in dotted lines in Fig. 2. When the toggle arm is across or opposing the open side of the recess 31 it will permit the upper section of the ladder to be slid downwardly on the lower section in the contracting operation, without permitting the hook or recess 31 to engage any of the rungs 18 in the lower section of the ladder, this arm 37 of the toggle thus having a camming action on the rungs to throw the hook to the left or counterclockwise to the position indicated in broken lines and to permit the hook to pass the rungs. This hook is specifically described and claimed in my copending application Serial No. 583,752, filed of even date herewith, now Patent No. 2,895,660, issued July 21, 1959.

At the lower ends of the rails 10 and 11 are inserted wooden blocks 43 and 44 to project from the ends of the rails, and are secured therein by suitable bolts 45. The lower block 44 may extend for the full width of the rail 11, but the upper block 43 is of less width than the rail, as shown in Figs. 4 and 5, to provide room for the top flange 13 of the lower rail to pass in the relative sliding movements between the upper and lower sections. These wooden blocks form feet for the lower ends of the rails to rest on the ground when the ladder is being used. Similar blocks 46 and 47 may be inserted in the upper ends of the rails to rest against the sides of the house or other object against which the ladder may be placed in use, to prevent marring of these surfaces. As shown in Figs. 6 and 7, the upper block 46 extends the full width of the upper rail, while the lower block 47 is somewhat narrower than the rail to provide clearance for the lower flange 14 of the upper rail.

For shipping purposes, the four side rails of the two sections may be arranged as shown in Figs. 8 and 9, with two side rails arranged vertically and laterally spaced but with their open sides facing each other, and they may be either the upper rails 10 or the lower rails 11, but for the purposes of illustration they are indicated as comprising the upper rails 10. Similarly the other rails, in this case the rails 11, are arranged in the horizontal position vertically spaced with their open sides facing each other, and with their edge flanges 13 and 14 between the short flanges 15 and 16 of the rails 10, and these four rails are maintained in this rectangular or box arrangement by suitable spacing blocks 48, which may be wooden blocks of the proper width and length to engage the webs of the rails 10 at their opposite ends and lie between the short flanges 15 and 16 of the rails 11, thus making a rectangular package. The space between the rails when in this arrangement may be used to enclose the other elements of the knockdown ladder. Thus, as shown in Fig. 8, it may enclose the hooks 28 and a carton 49 containing the fasteners 21, the blocks 43 to 47, a bag 50 containing the bolts 25, the rungs 17 and 18, and the adjusting rope 51. After so assembled, the opposite ends of these rails and package may each be enclosed in a carton 52, preferably of some fibrous material, such, for example, as a corrugated paper construction, of a proper shape to receive and slip over the assembled ends of the rails, as indicated in Fig. 9, the outer end being closed, as shown at 53, to close the open end. of the space between the rails, with the opposite end open as shown at 54 to slide over the ends of the assembled rails. This carton may be of any length desired, but a length of about six inches is preferred, as this is sufficient to enclose and protect the ends of the rails. At its open end the corners are recessed, as indicated at 55, to expose the corners of the assembled rails, and secured in this position over the ends of the rails by wrapping around it a strip of so-called industrial tape 56, which is a strong adhesive tape which fastens itself securely to both the carton and the rails to thus hold the rails in the assembled position and the carton in position over the ends of the assembled rails. Other spacing blocks 48 may be applied at any desired intermediate positions within the assembled rail package, and also these adhesive industrial tapes 56 may be applied at any number of intermeidate positions desired to maintain the package and keep it from opening during the shipping operation. After being delivered to its destination the package may be readily separated and the parts assembled to form the sections of the ladder, as previously described, for either use as such for straight ladders or for assembling to form an extension ladder.

It will be evident from this structure that from the possibility of the parts being placed in a package, as shown in Fig. 8, greatly reduced space is required for shipping purposes. Thus, for example, where a 20' extension ladder as a shipping package will measure approximately 2% x 4% x 116 /2 inches containing about 1262 cubic inches and weighing about 26 /2 pounds, the same ladder assembled would measure 4% x 15%; x 120 inches and occupy about 8868 cubic inches.

Thus approximately seven knockdown ladders can be shipped in the space required for one assembled ladder and therefore the shipping rate will be proportionately reduced.

Having thus set forth the nature of my invention, .1 claim:

1. An extension and knockdown ladder comprising side rails having upright webs provided with openings therethrough, rungs connecting said rails and internally threaded at the ends, a fastener connecting the ends of each rung to the rails comprising an externally threaded shank provided with a threaded inner longitudinal passage and also provided with an external flange at one. end, said shank being screwed into the threaded end of the rung with the flange seated against the end of the rung, and a headed bolt passing through an opening in the web and screwed into the inner passage in the fastener with the flanged end of the fastener clamped against the inner side of the web and the head of the bolt against the op posite side of the web.

2. An extension and knockdown ladder including a side rail and a series of rungs, said side rail including a web provided with openings therethrough, means fastening the rungs to the rail comprising a tubular fastener having an external flange at one end and an externally threaded shank provided with a longitudinal internal threaded passage, the end of the rung being internally threaded, the fastener being screwed into the rung with its flange seated against the end thereof, and a headed bolt passing through an opening in the rail and screwed into the fastener with the flange clamped against the inner side of the rail between the end of the rung and the rail and the head of the bolt against the opposite side of the rail.

3. An extension and knockdown ladder comprising two sections each including a pair of laterally spaced side rails, a series of rungs for each section extending between the rails thereof, and means for detachably securing the ends of the rungs to the rails, said rails comprising open sided channel sections including a substantially flat web and laterally extending flanges at the opposite edges of and at right angles to the web with inwardly extending flanges extending toward each other at the outer edges of the first flanges, said rails being arranged with two rails laterally spaced in an upright position with their open sides opposed and the other two rails in vertically spaced horizontal positions between the inwardly extending flanges of the first rails and their open sides opposed, spacing blocks between and abutting the inwardly extending flanges of the second pair of rails and the webs of the first pair retaining the four rails in a rectangular hollow bundle providing a hollow space between them, said space enclosing the rungs and their securing means, cartons of protective material enclosing the opposite ends of the bundle, and securing tape wrapped around the rails and the cartons retaining them in the bundle arrangement.

References Cited in the file of this patent UNITED STATES PATENTS 467,081 Church Jan. 12, 1892 934,736 Koch Sept. 21, 1909 1,213,599 Dow Jan. 23, 1917 1,732,827 Adam Oct. 22, 1929 1,967,063 Pielstick July 17, 1934 2,340,387 Hummel Feb. 1, 1944 2,594,561 Huck Apr. 29, 1952 2,721,060 Morain Oct. 18, 1955 2,727,672 Luca Dec. 20, 1955 FOREIGN PATENTS 140,391 Australia Mar. 5, 1951

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