US2767897A

US2767897A - Ladder construction

Info

Publication number: US2767897A
Application number: US315170A
Authority: US
Inventors: Hoffman Cromer
Original assignee: Individual
Current assignee: Individual
Priority date: 1952-10-16
Filing date: 1952-10-16
Publication date: 1956-10-23
Anticipated expiration: 1973-10-23

Description

Oct. 23, 1956 c, HOFFMAN I 2,767,897

LADDER CONSTRUCTION Filed Oct. 16, 1952 3 Sheets-Sheet l lj v 6 t INVENTOR ATTORNEYS Oct. 23, 1956 c. HOFFMAN LADDER CONSTRUCTION 5 Sheets-Sheet 2 Filed Oct. 16, 1952 I INVENTOR Cromer Hoffman ATTORNEYS Oct. 23, 1956 c. HOFFMAN LADDER CONSTRUCTION 3 Sheets-Sheet 5 Filed Oct. 16, 1952,

/6 L 1 INVENTOR Cromer Ififfman ATTORNEY-5 United States Patent LADDER CONSTRUCTION Cromer Hoffman, Baldwin, N. Y.

Application October 16, 1952, Serial No. 315,170

2 Claims, (Cl. 228-17) ignated as a platform ladder in a generic sense as being applicable to any type of ladder; and whilethe following description and accompanying drawings refer specifically to a rung ladder, it will be understood that thisis merely by way of an illustrative embodiment and that the vconstruction may be accommodated to any type of ladder generally, and without any substantialchanges in structuralfeaturesa It may be said that one of theobjects of the present invention is to provide a platform ladder which maybe usediwithoutrrequiring detachment of the platform for any-purpose for whichgstandard rung laddersare commonly used; and;as;will become apparentas thedescription-vproceeds, .the improved construction may be used as a standard type of rung (straight) laddereither separately or asthe uppersection of that type of. extension ladder, or as-a platform ladder in. eitherof those applications.v

The present improved construction has for a further object thevprovjsion of an improvedplatform constructionwhich may be usedin any-standard ladder lengths, sincer the top of, the ladderabove. and including the platform has the same dimensions for any and all lengths of ladders. By way of exemplary illustration, the minimum useful length of the ladder might be approximately ten feet, at which-length the improved construction may-be usedto supplant vavstep-ladderrwherever used in an inclincd'positionsupported by a wall or otherstructures.

A still furtherobject of the present construction isto provide a platform ladder which. includes means for conveniently :re-leveling'the platform-as the ladder is shifted from .one location to another, the said means,-

together with associated locking devices, being operable by an operator while standing on the ladder.

Further objects and advantages of the present construetion'will become apparent as the description proceeds, and the features of novelty will become apparent as the description proceeds.

The improved construction willbe understood more readily from reference a to the accompanying drawings, which V Fig. 1 represents a front elevation of a ladder embodying the improved platform construction of thepresentinvention.

Fig.-2 is a rear view of the ladder.

Fig. 3 is alongitudinal sectional view, of the improved .laddergleaningly supported against a wall or similar structure,,with. the platform suspended inoperatively',

Fig, 4 isa side elevational view showingthetplatform and associated parts in level and locked operativeiposi- Fig; 5 is a top plan view of the platformitself, dissociated from the ladder. V

Fig. 6 is a bottom plan view of the platform. V

Fig. 7 is a longitudinalsection through the platform taken on the line 7-7 of Fig. 5 looking in the direction of the arrows.

Fig. 8 is a transverse longitudinal sectional ,view through the platform, the viewtbeing taken on the line 8-8 of Fig. 6, looking in the direction o'f the arrows.

It will, be understood as has been pointed out above that the improvements of the present invention-are applicable to any type of ladder, and are not limited to arungtype ladder as shown inthe drawings,and;in,the present specification and claims, the term tread elements? as employed may be considered to. be genericto bothrungs and steps, although the drawings illustrate these. elements as being rungs.

It will be understood furtherthat, when the auxiliary ladder section is used otherthan as the uppersection of an extension ladder, the distance between the side rails of the main sectiontwhich are equidistant wat all points as shown in Fig. 2) optionally maybe increased gradually, proportionately withthe increased over-all length of the ladder, beginning at or below the ninth rung downward from the .-ladder-,top, as shown in Fig. 2 and'continuing to the ground level end thereof.

Referring more particularly to the drawings, the improved ladder construction of the present-invention comprises; amain. ladder-sectien ,A, and an auxiliary section B'. The main sectionAcomprisesgside railsl interconnected by equally spaced rungs Z, theendsof which are secured ,in; any lusual ,rnanuerv in the side rails 1-.

The auxiliarydadder section B includesside rails .3 interconnectedby rungs fl, the spacing betweenwhich is equal to the ;spacing between the rungs 2.. .The side, rails 3 of the auxiliarysection Btsnuglynfit between side rails 1 of the main section, the auXiIiary-LsectiomB being hingedly suspended. from a selected upperrung, preferably the first top rung or the second rung of. the section A, the side-rails 3 of the auxiliarysec'tionzB being provided with elongated closed end slots ,5 intolwhich is. inserted the suspending rung of the section A, and.-.which maybe secured by lock nuts on its ends, if said rung is ofmetal or pins through the endssif of wood, thelength of the slotsr5 permittingan amount-of longitudinal movement of the auxiliary section relative to the section A of the ladder so that the-open-ended slots 6 provided in the lower end of the side rails 3' of the auxiliary section may be positioned vover an adjacent rung of section A for securingithe auxiliary section B in position flush with'said section'A. and with side rails 3 of the auxiliary section intermediate the side rails 1 of the main section A.

Freely suspended from eye-bolts 7 securedin the side rails 1 of section A adjacent the-lower end ofthe auxiliary section is the platform "8, there being eye-hooks 9 at the upper corners of the platform 8 received permanently in the eye-bolts 7, and providing freely flexible connection therewithw .The'respective bolts 7 extend through thevside rails l at an angle so as to position the eyes of the -bolts directly to the rear of and in alignment with the adjacent rungof the main section A, the platform 8 therefore freely hangs, from the eye-bolts 7 when not'in use, and it lies flush with the rails 1, when the ladder is placed in horizontal position, so that there, are no protruding parts to interfere with easy storage or transportation of the ladder. The width of the rectangular platform 8 is equal to the inside lengthof the rungs plus behind the main section A in a manner similar to that described in connection with the eye-hook 9.

The platform 8 comprises a body 10, which may be provided with anti-skid tread surface member 10', the body 10 being received in angle members 11 applied and secured to the body 10 by bolts 12 held by nuts 13. The angle members 11 have upstanding portions 14 extending along the edges of the platform body and are provided with bottom flanges 14 through which the ends of the bolts 12 project and which receive the nuts 13. The free or lower end of the platform body is extended into lateral projections 15 through which is passed a supporting bar or rod 16 that is mounted permanently in these projections 15, and extends through upstanding portions 14. The bar 16 is adapted to be received in the corresponding leveling grooves 17 provided in the side rails 3 of the auxiliary section B. A plurality of these leveling grooves is provided in each of the side rails 3 so that the platform may be re-leveled to correspond to the amount of angular displacement between the main section A and the auxiliary section B when the ladder is tilted against a wall or similar surface as shown in Figs. 3 and 4. The leveling grooves 17 are inclined inwardly and downwardly relative to the side rails 3 for minimizing accidental displacement of the supporting bar 16 from the grooves 17, this accidental displacement being absolutely prevented by providing locking rods 18 on the inner surface of the side rails 3, these rods being retained in loop members 19, the rods 18 being removably adjustable therein so that they are adapted to extend below the bottom pair of leveling grooves for holding the platform supporting bar 16 in any pair of these leveling grooves which may be selected to maintain the platform 8 in substantially level position when in service. The bent top ends 20 of the locking rods provide handles and prevent the rods from slipping out of their retaining loops 19. It will be apparent that the auxiliary section B can swing backwardly away from the main section A, but it is prevented from swinging forwardly all the way between the side rails 1 by engagement of the lower end of the auxiliary section with and behind a corresponding rung of the section A. However, moving the auxiliary section B upwardly for the length of the slots 5 will enable the slots 6 to be slipped over a rung of section A for securing the auxiliary section flush with the side rails 1 of the section A, the platform 8 having been released from the leveling grooves or notches 17.

As has been mentioned above, in practice the width of the platform 8 is equal to the inside length of the rungs of the main section A plus the thickness of the two side rails 1, it being desirable for reasons of convenience in storage or transportation of the ladder that the sides of the platform do not project beyond the limits of the side rails 1. In the present instance, the length of the platform, exclusive of the rear-end supporting bar 16, is approximately eighteen inches, so that the platform size is ample for safety and comfort. It is understood that the size of the platform may be varied in accordance with different sizes of ladders.

Also, it will be evident that an operator is enabled to relevel the platform, as the shifting of the ladder from one location to another changes its pitch, by merely raising the locking rods 18, resetting the platform supporting bar into a different pair of notches 17 and returning the locking rods 18 to locking position. These manipulations may be effected while the operator is standing on the ladder. The swing-back feature of the auxiliary section B makes it possible for the operator to walk in between the outer side rails 1 of the ladder, thereby bringing the operator closer to the wall or object against which the ladder is leaning, and affords the additional protection of the side rails 1, which will be on either side of the operator's hips when standing on the platform, and, while standing with both feet on the platform, the operator has unhampered use of both hands,

and therefore, the operator can safely work faster and more efficiently, and ladder fatigue is reduced correspondingly.

All the rungs of both sections are spaced equally throughout, this being important for safety reasons, and therefore the front edge of the platform is fixed securely at the rung level, so that the steps up to it or down from it do not require a conscious effort. The rungs in the auxiliary section B, when this section is swung back to support the platform 8, provide a convenience to the operator for hanging tools, paint pails, or the like, currently being used on a given job.

It is found in practice to be preferable to suspend the auxiliary section B from the top rung of the main section A of the ladder instead of the second rung from the top, and correspondingly moving the platform up from the seventh to the sixth rung from the ladder top. Under the above circumstances the maximum distance between the platform and the ladder top is six feet, if the platform could be extended and leveled in that position. As the slope angle of the ladder increases, the vertical distance between the extended platform and the top of the ladder decreases, and the horizontal distance between the rear of the platform and the object against which the ladder is inclined increases. The platform when in extended and locked position is continuously rigid and is strongly mounted thereby eliminating factors of hazard to an operator.

In conclusion, it might be well to state that while the auxiliary ladder section B and platform 8 may be constructed of any suitable material, the side rail members of the auxiliary ladder section B and the platform 8 (including angle members 11 and the reinforcing bar 16 thereof) are preferably constructed of aluminum, or light metal alloys such as the aluminum-magnesium alloy known to the trade as magnalium. The rungs and all other parts may be made of suitable wood.

From the above it is apparent that I have provided a platform ladder device comprising parts adapted to be readily applied to a conventional ladder with only slight modification, for converting said ladder into a platform ladder, said parts being foldable with respect to the ladder into a substantially flat compact unit and without materially affecting the portability of the ladder, said device being simple in construction, easily assembled, manufacturable at minimum cost and efficient for the purposes intended.

Although in practice it has been found that the form of the invention illustrated in the accompanying drawings and referred to in the above description as the preferred embodiment is the most efficient and practical, yet realizing that conditions concurrent with the adoption of the invention will necessarily vary, it is well to emphasize that various minor changes in details of construction, proportion and arrangement of parts, may be resorted to within the scope of the appended claims without departing from or sacrificing any of the principles of the invention.

Having thus described my invention, what I desire protected by Letters Patent is as set forth in the following claims:

l. A ladder structure comprising a main section including a pair of side rails interconnected by equally spaced tread elements and having an upper end and a lower end, a top rung connecting the side rails and adjacent to the upper end, and an auxiliary section hingedlysuspended from the top rung of the main section, the auxiliary section including side rails interconnected by equally spaced tread elements, the spacing betweenthe tread elements of the auxiliary section being equal to the space between the tread elements of the main section, the side rails of the auxiliary section abutting against rear portions of successive tread elements of the main section, the auxiliary section being freely displaceable rearwardly of the main section when the ladder is tiltably supported against a supporting surface, the side rails of the auxiliary section being so spaced as to assume a fully nested position within the main section and intermediate the side rails of the main section and flush with the main section when the ladder structure is lying in a flat recumbent position, a

platform member secured to the main section, the side rails of the auxiliary section are provided with a plurality of parallel locking slots extending inwardly from the surface of the side rails opposite to the main section of the ladder, a reinforcing bar on the platform member, adapted to be received in the locking slots, locking rods slidably mounted on inner surfaces of the side rails of the auxiliary section and having a length adapted to extend over the reinforcing rod when the latter is received in the parallel slots for releasably locking the reinforcing rod in a selected pair of the parallel slots, and suspension means for the platform member mounted on the side rails of the main section enabling the platform to be shifted from a freely depending position behind the main section to a substantially horizontal extended position rigidly bracing the auxiliary section in a selected angularly displaced position relative to the main section and behind said main section.

2. A ladder structure comprising a main section including a pair of spaced side rails interconnected by equally spaced tread elements and having opposite top and bottom ends when the ladder is in elevated position, a top rung interconnecting the side rails adjacent to said upper end, and an auxiliary section suspended from the top rung of the main section, hinge means connecting said auxiliary section and selected tread element, the auxiliary section including side rails interconnected by equally spaced tread elements, and the spacing between which side rails being less than the spacing between the side rails of the main section, the side rails of the auxiliary section having elongated slots with closed ends formed therein adjacent to their upper ends through which the selected suspension tread element is passed, the said slots enabling longitudinal movement throughout their length of said suspension tread element, the side rails of the auxiliary section are formed at their lower free ends with corresponding elongated open ended slots adapted to receive and fit over an adjacent locking tread element of the main section for interlocking the auxiliary section nested be tween the side rails of the main section, the auxiliary section being releasable by longitudinal movement sufficiently to clear the open-ended slots with respect to the locking tread element, the auxiliary section being displaceable rearwardly relative to the main section responsively to the ladder being tiltably engageable with a supporting surface, a platform freely suspended from the main section, cooperating means on the auxiliary section and on the platform for securing the platform to the auxiliary section when the platform is extended rearwardly relative to the main section into substantial horizontal operative position, the side rails of the auxiliary section being provided with a plurality of parallel corresponding pairs of locking slots adjacent to the open-ended slots, and which are inclined downwardly and inwardly from the surface of the side rails, opposite to the main section of the ladder, the platform including a supporting and reinforcing bar or rod adapted to be received in a selected pair of said slots for maintaining the platform substantially horizontal independently of the amount of angular displacement between the auxiliary and main sections, and locking rods slidably mounted on the inner surfaces of the side rails of the auxiliary section and having a length adapted to extend over the rod in the said parallel slots for releasably locking the supporting and reinforcing rod of the platform in the selected pair of the parallel slots.

References Cited in the file of this patent UNITED STATES PATENTS 93,323 Malbone Aug. 3, 1869 567,755 Stillman Sept. 15, 1896 606,763 Lukens July 5, 1898 960,565 Levander June 7, 1910 2,245,661 Fieroh June 17, 1941 2,530,452 Duffey Nov. 21, 1950 2,563,436 Toth Aug. 7, 1951 2,584,197 Garner Feb. 5, 1952 FOREIGN PATENTS 103,207 Germany May 18, 1899