US 2588959 A
Description (OCR text may contain errors)
March 11, 1952 L, CAMPBELL 2,588,959
EXTENSION LADDER AND HOIST THEREFOR Filed Jan. 18, 1947 2- SHEETS-SHEET 1 INVENTOR. Har
H. L. CAMPBELL EXTENSION LADDER AND HOIST THERFOR March l1, 19.52
Filed Jan. 18, y1947 2 SHEETS--SHEET 2 Patented Mar. 1l, 1952 EXTENSION LADDER AND HOIST THEREFOR Harry L. Campbell, Wilmette, Ill.
Application January 18, 1947, Serial N o. 722,947
' 2 Claims. l
The present invention relates generally to ladders, but more particularly to a novel and improved construction of an extension ladder and a hoist attachment associated therewith.
One of the primary objects of the present invention is to provide a novel and improved, as well as compact form of extension ladder in which the side rails of the main ladder section and extension telescopically connect with one another so as to form a light weight and simplied structure of ladder construction.
A further object of the invention is to provide a novel and improved construction of ladder in which the side rails of the ladder sections are of channel formation and telescopically mounted within one another in combination with an elevating platform which has rollers supported in the channel-formed rails so as to form in effect tracks for the elevating and hoisting platform.
A still further object of the invention is to provide a novel and simplified construction of extension ladder in which the side rails of the respective sections are telescopically mounted, with the rungs of the ladder of the respective sections welded to the side rails and in which the side rails form the tracks for maintaining and elevating the platform in operative position on the ladder.
These and other objects are accomplished by providing a construction and an arrangement of the various parts in the manner hereinafter described and particularly pointed out in the appended claims.
Referring to the drawings:
Fig. 1 is a side elevational view of my improved ladder construction showing the manner in which the hoisting platform is supported therefrom;
Fig. 2 is an enlarged cross-sectional view taken on the line 2 2 in Fig. 1;
Fig. 3 is a similar cross-sectional view taken on the line 3-3 in Fig. 2;
Fig. 4 is an enlarged side elevational view of the curved portion of the upper section of the ladder;
Fig. 5 is a similar view showing the elevating Vplatform in position at the delivery point on the curved extension; and
Fig. 6 is a cross-sectional view taken on the line 6-6 in Fig. 5.
My novel invention comprises a main ladder section and an extension section, generally indicated respectively by the reference characters I 0 and II. The main section comprises oppositely disposed side rails I2, which are preferably made from at sheet metal such, for example, as aluminum or magnesium alloy so as to be light in weight and of suicient gauge to provide the necessary strength for the ladder construction. Each of these side rails I2 are of 'channel-like formation, but preferably in the form of the letter C in cross-section, as. shown at I3. The lower portion of each of the side rails I2 has a lower extension of the C-shaped cross section in the form of an inwardly turned flange so as to form an L-shaped portion, indicated by the reference character I4. Secured at the usual uniform intervals, by means of welding, as shown at I5, are tubular rungs I6. Telescopically mounted within each of the channel or C-shaped side rails `I2 of the main section I0, are complementary channel or C-shaped side rails I'I of the extension section II. Secured at suitable uniform intervals by the means of welding IB to each of the side rails I1 are suitable tubular rungs I9. It will be obvious from the above description that the extension II and particularly the side rails thereof, are telescopically mounted within the complementary side rails of the main section I0 and the construction provided thereby not only affords a rigid and compact ladder extension construction, but that the C-shaped rails I3 and Il' afford a track for supporting thereon a traveling or elevating platform of a construction hereinafter more fully described.
The upper end of the extension Il? has each of the side rails arcuately curved as shown at 20. The upper ends of the curved track or side rails is braced by a transverse angle member 2l. Secured to the upper ends of the opposite curved side rails 20 is a transverse shaft 22. Journaled on the shaft 22 in the center between the side rails is a sheave or pulley 23. In a similar manner, centrally located pulleys 24, 25, 26 and 2'I are journaled on the respective shafts: 28, 29, 30 and 3|, which, in turn, have their opposite ends secured to the opposite side rails of the curved side rails 20. Another pulley 32 is journaled on a shaft 33 which, in turn, has its opposite ends secured to the underside of the extension rails II by a bracket 34.
My improved elevating platform and the manner in which carriage wheels thereof are supported in the channel or C-shaped side rails of the respective ladder sections will next be described.
The elevating platform comprises a substantially flat base 33 and a right angularly projecting rear wall 36. Secured to the forward and rearward portions and to the opposite sides of the at member 35, are depending brackets 3l.
Y transverse rod 41.
are provided with offset portions, as shown at 48,
3 Formed integrally with these brackets are hub portions 38 in which are secured stub shafts 3S. Journaled on the inner ends of each of these shafts 39 are carriage wheels 4U. I'he carriage wheels of the elevating platform, as clearly disclosed in the drawings, are adapted to travel within the C-shaped tracks or side rails of each of the ladder sections so that the platform is free to move thereon in conveying and elevating material from the lower portion of the main section to the curved extension or to a point, for example, adjacent the roof of, a building, generally indicated by the reference character 4I in Fig. 1 of the drawings. l The platform may be connected to one end of a cable 42, which is attached to the front end of the platform and is trained aboutl the pulley 23 and 32 with the lower end thereof connected to a crank operated winch, generally indicated by the reference character 43; The winch in this instance, may be power operated or manually operated and may be attached to the lower or main section of the ladder for convenient operation or control by the operator on the ground.
In order to actuate the platform 35 in its return Vtravel after the material has been delivered therefrom, I have provided a novel arrangement and construction which includes a spring 44. The lower end of the spring is attached as shown at 45, to a transverse angle 46, which has its opposite ends secured to the opposite brace members 2|. The upper end of the spring 44 is connected to the center of a The opposite ends of the rod so that the outer ends thereof, as shown at 49, seat in upwardly extending hooks 50 secured to the inner side of the opposite curved track 20. These outwardly projecting portions 49 are parallel to the main portionof the rod 41 and lie in the path of and are adapted to be engaged by oppositely disposed hooks 5l secured tothe lower side of the platform 35.
Y From the above description it will be observed that as the elevatingv platform 35 reaches the curved portion ofthe extensionV I l, the hook portions 5I will engage the outwardly projecting portions 49 ofthe rod 41 and thereby extend or expand the spring from the position shown in Fig. 4 to that shown in Fig. 5 of the drawings, in which case the extended spring will be trained aboutthe pulley 25. After the material has been removed from the platform and the tension on the lifting cable released from the winch, the spring will actuate the platform 35 from the full line position to the dotted line position shown in Fig 5 of the drawings and from that point on,
gravity will convey the platform to its lowermostl position or the position shown in Fig. 1 of the drawings.
Ysummarizing the advantages,V and function of operation of my improved extension ladder and conveying platform, it will be observed that'by forming the side rails of the main and extension sections of the ladder in channel shape or preferably ink C-shaped cross-section, that I have not only increased the strength by such cross-section, but have also afforded a simple telescopic connection between the two sections of the ladder and at the same time, provided a track for supporting the wheels of the traveling platform therein and thereby reduce to a minimum not only the number of parts heretofore required, but by such conguration and formation, have compactly arranged the parts and reduced the overall weight to a minimum.
While in the above specification I have described one embodiment which my invention may assumein practice, it will, of course, be understood that the same is capable of modification and that modification may .be made vwithout departing from the spirit and scope of the invention as expressed in the following claims.
What I. claim as my invention and desire to secure by Letters Patentis:
1. An extension ladder comprising a main section having side rails and spaced apart' rungs, anv extension section having side rails telescopically mounted in the side railsof said main section, spaced apart rungs carried by said extension section, a curved extension formed integrally .with said extension section, an elevating platform mounted on said ladder, an'extension spring having one end attached at a point adjacent said curved extension, a transverse rod" connected to the other end of said spring, hooks carried by said extension for supporting said rod in one position, and hoo-ks carried by said4 platform for engaging the opposite ends of said rod asv the platform'moves upwardly oversaid curved extension.
2. An extension ladder comprising a main section having side rails and spaced apart rungs, an extension section having side rails telescopically mounted in the side rails of said main section, spaced apart rungs carried. by said extension section, a curved extension formed integrally with said extension section, an elevating .platform l curved extension, a transverse rod connected'to YNumber Y Y VName Date 1,924,751 WPc`)rter Aug; 29,- 19-33 2,198,071 Artini Apr.23, 1940 2,394,148 Campbell Feb. 5,@ 1946