US3438459A - Portable scaffold - Google Patents

Description

April 15, 1969 E. J. MAGEE 3,438,459

PORTABLE S CAFFOLD Filed Nov. 30 1966 Sheet of 2 EUGENE J. M4655 zdwz MM 2104/ az w ww Affvrn e 98 Filed Nov. 30, 1966 [)VVHVTOR. Euesms J. M4655 zwdumaw uw United States Patent US. Cl. 182-119 6 Claims ABSTRACT OF THE DISCLOSURE A scaffold which is characterized by two extension ladders having work planks disposed therebetween. The work planks are associated with the upper part of the extension ladders and raised and lowered electrically. Special fittings leads to extreme versatility insofar as length, width and height of the scaffold.

Background of the invention This invention relates to scaffolds and more particularly relates to a scaffold which is readily adjustable and further which is readily assembled and dismantled.

While a number of scaffolds depending on ladders have been disclosed in the prior art, there has long been a need for a scaffold which is readily adjustable for width, height and length, and which further may be assembled and dismantled with relative ease. The present invention provides such a scaffold by providing means for automatical- 1y raising and lowering the scaffold and by further providing quick-hitch fittings and length guide means.

Summary of the invention One embodiment of a scaffold in accord with the present invention includes two extension ladders set edgeways. The bottom ladders are set in carriages which include locking casters with legs adjustable to adapt to the terrain and which are clamped to the ladders by hook bolts which reach through the carriage and around the rails of the ladder.

The ladders are held in a vertical position with runners and braces adapted for quick adjustment, assembly or dismantling. The ladders are secured to a building; surface with bumpers and props. The bumpers further serve to splice two sections of the scaffold together if a wider scaffold is desired.

The horizontal work planks can be used either resting on the rungs when the raising or lowering of the scaffold is not important, or resting on shelves which are attached to the upper part of the extension ladders and raised or lowered electrically or by a hand crank.

The extension ladders may be of wood, metal or any other suitable material and may be of any height, from six to sixty feet being the normal range. The work planks may be either of wood or metal or any other suitable material, and of any length desired, although six feet is normally as short as is desirable.

Therefore, it is an object of the present invention to provide an improved scaffold characterized by its versatility.

Brief description of drawings The full nature of the invention will be understood from the accompanying drawings and the following description and claims.

FIG. 1 is a side view of a scaffold in accord with the present invention.

FIGQ'Z is an end view of the scaffold of FIG. 1.

FIG. 3 is a perspective view of a bracket adapted to be secured to a ladder rail and having a mounting flange adapted to receive a quick-hitch fitting.

FIG. 4 is an exploded view of a quick-hitch assembly fitting from the braces and ladder rails.

FIG. 5 is a section View of the assembled quick-hitch fitting of FIG. 4.

FIG. 6 is a perspective view of a quick-hitch washer for the above fitting.

FIG. 7 is a perspective view of the bracket fittings for the runners.

Description of the preferred embodiment Referring more particularly to the drawings, one embodiment of the scaffold in accord with the present invention is shown generally at 10. The scaffold includes two extension ladders shown generally at 11 which have a bottom ladder 12 and a top ladder 13. The ladders are held in position by an arrangement of horizontal runners 14 and diagonal braces 15. The runners and braces are received in quick-hitch fittings shown generally at 16 and 17, respectively.

Fittings 17 are permanently bolted to the ends of each brace (indicated by dotted lines). Each fitting is a substantially H-shaped member. The end of the brace abuts the inner surface of the end wall 18 of the fitting. The brace is secured within the fitting via bolts (not shown) which are received through apertures 19 in the fitting side walls 20 and 21. The upstanding arm 21A extends outwardly beyond end wall 18 to form a mounting tongue. The mounting tongue shown in the illustrative embodiment is tapered at its distal end so as to conform to the configuration of the ends of the bracket members shown generally at 22.

The fitting shown generally at 16 serves to mount the braces and runners to the ladder rails (dotted line). Side wall 23 engages a side wall of a bumper or runner. Wall 24 engages the inner side surface of the ladder rail and mounting flange 25 is adapted to be removably coupled to fittings 17 and 46.

The quick-change fittings consist of a T-head bolt 30, a shoulder washer 31, a tension washer 32, a lock nut 33 and a wing nut 34. This can be adjusted so the exact tension can be held on a T-head bolt to hold it in the slot 36 in the mounting flange 25.

A quick-hitch washer 37 has a central aperture 38 which is aligned with slot 36 of the mounting flange. The quick-hitch washer has a plurality of spaced fingers 39 which extend outwardly from and are perpendicular to the face of the washer. The width and spacing of the fingers correspond to the width of the substantially rectangular apertures 40 located on either side of slot 36. The outer edge 39A of the fingers are concave and of such a length that they protrude through the mounting flange 25. When the bolt is in place as shown in FIG. 5, the head 30A is seated on the concave surface of the fingers. When the assembly is pushed in, the T-head is moved out of engagement with the concave surfaces of the fingers. By turning the bolt and aligning the T-head of the bolt with the slot 36, the entire assembly can be removed. By reversing the procedure, the entire assembly can be easily assembled. Therefore, a quickhitch fitting which is extremely convenient and easy to manipulate has been provided. It will be noted that the mounting flange has two slots 36, one adjacent the top of the flange and one adjacent the bottom of the flange. Thus, flexibility in the positioning of the brace is provided. It is obvious that a series of intermediate slots could be provided for even greater flexibility.

The braces are afiixed to the runners via brackets 22. The brackets shown generally at 22 have a flat bracket member 45 which fits flush against the runner and a bracket member 46 which is substantially C-shaped to fit over the side of the runner and which has mounting flanges 46A which interfit with the member 45. Two

bracket members 46 may be used facing each other instead of the combination of bracket members and 46 when it is necessary to splice two runners together to obtain a longer scaffold. Brackets 22 and fittings 17 are joined by means of a conventional bolt, nut and washer.

It will be noted that each of the runners have a plurality of spaced holes 51 therein. The holes are drilled in pairs at predetermined intervals. Bracket member 46 has an aperture 46B which is adapted to be aligned with apertures 51. Thus, by loosening bracket 22 and sliding the bracket to the appropriate position, the length of the scaffold is readily adjusted. This arrangement greatly simplifies the task of squaring off the scaffold. The workmen only have to remember to use the pair of holes selected, the ones nearest the end of the runner for the bottom part of the ladder and the holes of the pairs nearest the center for the upper part of the ladder. With this pair arrangement the runners are interchangeable between the upper and lower ladders by changing bracket member 46 to the proper holes.

In order to brace the scaffold, a bumper is mounted to the top part of the lower extension ladder. The bumper is placed perpendicular with respect to the vertical work surface so that the scaffold will be held solidly between the prop 61 and the building to be worked on. Similar bumpers can be used as high as sixty feet or more, so that the top parts of the ladders can be tied securely against buildings, and be released when the work is completed. The bumpers serve to hold the scaffold solidly to the building and still provide working space. If the scaffold should be used in a large interior space, the bumper which is normally two by four could be extended as long as twenty-four feet and two sections of the scaffold locked together. In this instance, the prop 61 would not be needed. The props are connected with universal swivel joints 62 which allow the props to be folded back flush with the rest of the scaffolding when the scaffolding is moved through gates and other narrow areas. The work planks rest on shelves 71. The work planks are seated on the shelves which hook over the ladder rungs so that they can be mounted at various places on the ladder.

The runners above each work plank on the upper ladder are used as protective back rails as well as functioning in connection with the braces to strengthen and stabilize the upper part of the ladder. Each of the bottom ladders has a plate which is mounted to the lower end of each of the bottom ladders. Each plate has two slots 81 which allow for differences in widths of various ladders. Each of the plates have an inturned bottom flange 82 on which the ends of the ladder rails seat against.

Conventional two-way locking casters 83 are mounted in the plate. The height of the casters is adjusted by telescoping square or tubular members 34. The ends of plate 81 have apertures 85 drilled therein. The height adjusting members 84 also have spaced apertures 86 drilled therein. By adjusting the position of the telescoping member 84 with respect to the plate, the height of the scaffold may be adjusted. This is particularly important where the ter: rain is uneven, or where the scaffold is to be set up on steps. It is a simple matter to square off the scaffold by adjusting the position of the members 84 with the plate. Once again, the workmen only have to match up the corresponding holes on each member to square off the scaffold. Thus, the scaffold is readily moved from one position to another and is readily adjusted for differences in the terrain or floor area.

The height of the scaffold is electrically adjusted by a motor and winch arrangement shown generally at 90 and indicated by dotted lines in FIG. 1. The cable (not shown) runs underneath the work plank. The cable 92 is placed around a pulley 93 as shown in FIG. 2 and strung between the rungs of two ladders up to a pulley 94 suspended between the two top rungs of the bottom ladder. The cable goes down and is attached to the bottom rung 95 of the top ladder. The motor operates two drums. Thus, in order to adjust the height of the scaffold, the upper ladder is moved electrically with respect to the lower ladder. Any number of pulley arrangements may be utilized.

One arrangement includes a drive pulley mounted on one of the shelves as indicated in the drawing. A trolley pulley is associated with the drive pulley. A first cable travels under the trolley pulley and upwardly between the rungs of the lower ladder and the rungs of the upper ladder, over a return pulley which is mounted adjacent the rungs of the ladder and under the work plank and finally anchored at the opposite end of the work plank. A second cable is run over the trolley pulley and from there to the opposite end of the scaffold. There is a first trolley pulley and a second trolley pulley mounted to the shelf means at the opposite end of the scaffold. The second cable travels over the first trolley pulley, under the second trolley pulley, upwardly through the openings between the rungs of the upper ladder and the rungs of the lower ladder and around the return pulley, which is mounted near the rungs of the ladder as indicated by numeral 94. The cable then returns downwardly through the openings between the rungs of the upper and lower ladder and is anchored under the work plank.

It is obvious that the ladders may be also adjusted by hand, that is, the pulley system may be operated manually. However, with the electric arrangement, the workmen on a work plank need only activate the electric motor until the proper height has been attained and then deactivate the motor. The entire structure provides for numerous combinations of sizes and heights of the scaffold.

While the invention has been disclosed and described in some detail in the drawings and foregoing description, they are to be considered as illustrative and not restrictive in character, as other modifications may readily suggest themselves to persons skilled in this art and within the broad scope of the invention, reference being had to the appended claims.

The invention claimed is:

1. In a scaffold, the combination comprising:

first and second scaffold members; a first bracket on said first scaffold member and having a portion with slot therein for receiving a head of a T-shaped bolt, and having first and second apertures on opposite sides of said slot; a fitting mounted to said second scaffold member and having a portion with an aperture therein disposed in registry with said slot; a washer having an aperture for receiving the neck portion of said T-shaped bolt therethrough, and having a pair of fingers disposed on opposite sides of said aperture and spaced to correspond to said apertures of said bracket and received therein, said fingers being generally perpendicular to a face of said washer and said fingers having cavitied end surfaces for seating said bolt head therein; a nut threadedly received on the neck of said bolt, with said apertured portion of said fitting and the slotted portion of said bracket being disposed between said bolt head and said nut; resilient loading means disposed on the neck of said bolt between said nut and said fitting portion and urging the bolt head into said cavitied ends of said fingers to hold said fitting and bracket portions together; said loading means being adapted to accommodate intentional release of said bolt head from said cavitied finger ends for turning and removal of said bolt head through said slot for quick separation of said bracket portion from said fitting portion.

2. In a scaffold, the combination comprising:

(a) a pair of extension ladders, each of said extension ladders having a top ladder and a bottom ladder;

(b) a first runner bridging said top ladders of said extension ladders, a second runner bridging said bottom ladders, each of said runners having a first end and a second end;

(c) coupling means cooperatively associated with each of said first and second ends of said first and second runners for coupling each of said ends to said ladders;

(d) receiver means cooperatively associated with said ladders for receiving said coupling means associated with said runners;

(e) means for bracing said runners, said bracing means having a first end cooperatively associated with a ladder and a second end cooperatively associated with a runner;

(f) means for coupling said first end of said bracing means with said runners, said runners having complementary coupling means;

(g) fitting means for coupling said second end of said bracing means with said ladders, said ladders having complementary coupling means;

(h) a first work plank bridging said top ladders;

(i) means for coupling said work plank to said ladders;

(j) means for adjusting the height of said first work plank cooperatively associated with said extension ladders; and

(k) means for maintaining said scaffold in a fixed position in relation to a work area, said means being cooperatively associated with said extension ladder;

said complementary coupling means of paragraph (g) for coupling said second end of said bracing means with said ladders comprising a bracket means aflixed to an inside wall of a ladder rail, said bracket means having a mounting flange extending outwardly therefrom, said mounting flange having a slot for receiving a head of a T-shaped bolt, a first substantially rectangular aperture on one side of said slot and a second substantially rectangular aperture on the other side of said slot; a quick-hitch washer disposed between said mounting flange of said bracket means and a mounting tongue of said fitting means; said quickhitch washer having a centrally located aperture for receiving the neck portion of said T-shaped bolt therethrough, said mounting tongue having a corresponding aperture, said quick-hitch washer additionally having a plurality of fingers disposed about said centrally located aperture and spaced to correspond to said first and second substantially rectangular tapertures of said mounting flange, said fingers being perpendicular to the surface of said quick-hitch washer; said fingers having concave end surfaces for seating said bolt head thereon; a wing nut threadedly received on said neck of said T-shaped bolt, tension adjusting means disposed about said bolt neck between said mounting tongue and said wing nut, washer means disposed about said bolt between tension adjusting means and said wing nut, and a locking nut disposed about said bolt at its outer end, said locking nut abutting said wing nut, said coupling means adapted to be removable when pressure is exerted on said wing nut so as to compress said tension adjusting means whereupon said bolt head is movable out of engagement with said concave surfaces of said fingers, and whereupon by rotating said wing bolt about said head is aligned with said slot and said bolt is removable from said mounting flange.

3. In a scaffold in accord with claim 1, said first work plank being disposed below said first runner, said first runner additionally serving as a safety rail for a workman; said means for coupling said work plank to said ladders being shelf means adapted to removably engage a ladder rung and be supported thereby, said work plank having a shelf means associated at each end thereof.

4. In a scaffold in accord with claim 3, said height adjusting means being an electric motor means operable to raise and lower said top ladder, thereby raising and lowering said first work plank.

5. In a scaffold in accord with claim 4, the combination additionally comprising a second work plank bridging a bottom part of said top ladders, shelf means removably engaged over the rungs of said top ladders, the ends of said work plank seated on said shelves.

6. In a scaffold in accord with claim 5, said scaffold additionally comprising caster means afiixed to the lower end of each of said bottom ladders, said caster means being adjustable so as to compensate for uneven terrain.

References Cited UNITED STATES PATENTS 1,692,664 11/1928 Kirsc-h 182-208 2,933,150 4/1960 Balogh 182-208 2,951,549 9/1960 Holan et al 182-208 506,561 10/1893 Smith 182-119 711,384 10/1902. Carman 182-119 734,321 7/1903 Hagan 182-118 771,878 10/1904 Laughlin 182-118 1,351,053 8/1920 Macklem 182-119 1,549,270 8/1925 Laber 182-118 3,071,206 1/1963 Kristen 182-119 REINALDO P. MACHADO, Primary Examiner.

US. Cl. X.R. 182-179 U.S. DEPARTMENT OF COMMERCE PATENT OFFICE Washington, 0.0. 20231 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,438,459 April 15 196' Eugene J. Magee It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 6, line 12, the claim reference numeral "1" should read 2 signed and sealed this 14th day of April 1970.

(SEAL) Attest:

WILLIAM E. SCHUYLER, JR.

Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer

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