US3026960A - Ladder dolly - Google Patents

Description

March 27, 1962 E. KOUTNlK LADDER DOLLY Filed July 15, 1960 Fig. 3

Fig. 2

JNVENTOR. E RNEST Kour/v/K rrqmvsr United States Patent 3,026,960 LADDER DOLLY Ernest Koutnik, 4475 Lowell Blvd., Denver, Colo. Filed July 15, 1960, Ser. No. 43,248 3 Claims. (Cl. 1s2-15 This invention relates to facilities freely shiftable from place to place to provide access to areas beyond normal upward reach of the user, and more particularly to means adapting conventional stepladders for expeditious shift and enhanced convenience of use with security to the user, and has as an object to provide a novel and improved shiftable ladder base of dolly type operatively coactable with ladder means of general availability to mount the latter in use positions stabilized as a consequence of their actual use.

A further object of the invention is to provide a novel and improved shiftable base of dolly type adapted for coaction with either fixed or separably associated stepladders as a mount susceptible of immobilization in reaction to use of the ladder.

A further object of the invention is to provide a novel and improved shiftable dolly and stepladder combination reactive to ladder use with security against inadvertent displacement.

A further object of the invention is to provide novel and improved means supplemental to conventional shiftable dollies effective to condition the latter as practical mounts for conventional stepl-adders.

A further object of the invention is to provide a novel and improved construction and operative organization of means constituting supplements applicable to condition conventional shiftable dollies for use as stepladder mounts.

With the foregoing and other objects in view, my invention consists in the construction, arrangement, and operative combination of elements as hereinafter set forth, pointed out in my claims, and illustrated by the accom' panying drawing, in which FIGURE 1 is a perspective view of a shiftable dolly and stepladder combination as organized in accordance with the principles of my invention ready for practical use.

FIGURE 2. is a longitudinal section, on a relativelyenlarged scale, taken through the dolly shown in FIGURE 1 on substantially the indicated line 2-2 of said view wit hthe position of the ladder legs indicated by broken lines.

FIGURE 3 is a vertical section, on a further-enlarged scale, taken substantially on the indicated line 3-3 of FIGURE 2; an alternative use position of relatively-movable elements being indicated by broken lines.

Stepladder units facilitative of access to elevated areas are commonplace in a diversity of sizes and structural particularity and shiftable dollies have long been extensively utilized for expedient translation of transient loads. Obviously, many occasions exist wherein a stepladder mounted upon a shiftable dolly would be advantageous and desirable to combine upward access with load-moving capability were it not for the insecurity of a wheeled mount for the ladder subject to use, hence the instant invention is directed to the provision of simple and practical means effective to condition such a dolly and ladder combination for efiicient use free from the hazard of base instability.

In accordance with and to give effect to the principles of the invention, the improvements hereinafter detailed are operatively associated with a conventional shiftable dolly, of any preferred construction, having a fiat, rigid platform rectangular in a size to receive and support the four legs of a conventional stepladder 11 which is translatably mounted, as is usual, on wheels 12, at least two of which are arranged to swivel on vertical axes, se-

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cured to and beneath the corners thereof. In all other respects conventional, the dolly typified by the platform 10 is conditioned for the attachments and reactions distingu-ishing the invention by the provision of two like slots 13 formed to spacedly and symmetrically intersect said platform in a size and disposition to receive and to freely pass the lower ends of the step legs 14 of the ladder 11 selected for association with the dolly, so that, when the ladder 11 is applied to the dolly, the brace legs 15 of the ladder rest upon the platform 10 to which they may be attached, if desired, by screws and clips 16 and the step legs 14 enter the slots 13 free from supporting engagement with the platform.

Reactive to and for support of the step legs 14 of the ladder as loosely received in the slots 13, a resilientlyextensible unit is secured to the underside of the platform 10 in obstructing relation with each slot 13, each of which identical units includes a tubular barrel 17 open at both ends and furnished with an annular flange, or collar, 18 fixed exteriorly of its upper end whereby it may be secured to the platform with its axis perpendicular thereto and substantially centered relative to the associated slot 13. The barrel 17 coaxially and reciprocably houses a cylindrical plunger 19 with a clearance sufiicient to accommodate thereabout a retractile coil spring 20 aflixed at its upper end to the barrel 17 and at its lower end to the plunger 19 in a manner effective to normally hold the latter retracted upwardly within the barrel to contact of the plunger upper end against the underside of the platform 10, as in the full line showing of FIGURE 3, and in a length approximating that of the barrel 17 said plunger 19 is furnished with a vacuum cup 21 secured to and depending from its lower end in opposition to the dolly support surface. Obviously, the downward extension of the fitting including the cup 21 from the platform 10 is slightly less than the elevation of the latter above a supporting surface provided by the wheels 12, whereby to provide for free shiftability of the dolly when the plunger 19 is spring-retracted within the barrel 17, and the tension of the spring 20 is such as to sustain the weight of the ladder step legs 14 imposed without load on the ladder and consequently maintain the retracted disposition of the plunger 19 with the ladder in use position on the dolly. As an aid to proper correlation of the lower ends of :the step legs 14 and with the plunger 19 of each fitting and as means for fixing said legs relative to the assembly, when desired, like, complementary fingers 22 fixedly upstand from the upper end of each plunger 19 through the associated slot 13 in a spacing such as to receive therebetween the thickness of the applied step leg 14, and apertures in the upper ends of said fingers are provided for the reception of fasteners, such as screws 23, effective to secure the step leg against unintended separation from its mounting.

Advantageous operation and use of the improvement should be manifest from the foregoing. Organized as shown and described with a ladder 1:1 mounted upon the platform 10 to engagement of the step leg 14 lower ends with the plungers 19 between the fingers 22, the ladder is shiftable with the dolly, with or without other load on the latter, to any desired location and position of ladder use, whereupon the weight of a user initially applied to the ladder extends the plungers 19 against the tension of the springs 20 and to coaction of the vacuum cups 21 with the dolly support surface, thereby effectively immobilizing the dolly while the ladder is in use and eliminating the hazard of a rollable base mounting. With the ladder relieved of user weight, the springs 20 retract the plungers 19 and lift the cups 21 away from the dolly support surface to again condition the assembly for ready shift.

aozaeso Since changes, variations, and modifications in the form, construction, and arrangement of the elements shown and described may be had without departing from the spirit of my invention, I wish to be understood as being limited solely by the scope of the appended claims, rather than by any details of the illustrative showing and foregoing description.

I claim as my invention:

1. In combination, a rigid, wheeled platform, a conventional stepladder unit having upwardly-convergent step and brace legs upstanding in use condition from said platform with the lower ends of the ladder step legs reciprocably accommodated therethrough, a barrel fixed beneath said platform in accommodating registration with each said step leg end, a plunger reciprocable in each said barrel in supporting relation with the associated step leg end, spring means normally biasing said plunger and the associated ladder element upwardly of the barrel, and a vacuum cup on the lower end of said plunger opposed to the surface engaged by the platform wheels and therewith coactable upon extension of the plunger downwardly of its "barrel against the influence of said spring.

2. An immobilizing adapter for a wheeled, platform dolly adapted to support a conventional stepladder unit having upwardly-convergent step and brace legs in use condition thereupon with the lower ends of the ladder step legs reciprocable therethrough, comprising a tubular barrel adapted to be secured beneath the platform in accommodating registration with each step leg end, a plunger reciprocable in said barrel for supporting engagement with the associated step leg end, a spring biasing said plunger upwardly of the barrel, and a vacuum cup on the lower end of the plunger normally spaced from and operatively opposed to the dolly support surface.

3. A rigid, wheeled platform adapted to support a conventional stepladder unit having upwardly-convergent step and brace legs in use condition thereupon, openings in said platform registrable with and for reciprocable accommodation of lower ends of the step legs of an associated ladder, and means resiliently extensible to platform-immobilizing coaction with a surface engaged by the platform wheels carried by said platform in obstructing relation with said openings for supporting coaction with the step leg ends received therethrough, wherein said means comprises a tubular barrel fixed beneath the platform, a plunger reciprocable in said barrel, spring means biasing said plunger to the upward limit of its travel in the barrel, and a vacuum cup on the lower end of said plunger operatively opposed to the subjacent surface.

References Cited in the file of this patent UNITED STATES PATENTS 2,398,812 Steil Apr. 23, 1946 2,712,366 Skupas July 5, 1955 2,851,126 Ward Sept. 9, 1958 2,897,910 Steely et a] Aug. 4, 1959

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