US2551173A

US2551173A - Convertible straight and step ladder

Info

Publication number: US2551173A
Application number: US20128A
Authority: US
Inventors: Edward G Sheridan
Original assignee: Individual
Current assignee: Individual
Priority date: 1948-04-09
Filing date: 1948-04-09
Publication date: 1951-05-01
Anticipated expiration: 1968-05-01

Description

y 1, 1951 E. ca. SHERIDAN 2,551,173

CONVERTIBLE STRAIGHT AND STEP LADDER Filed April 9, 1948 swam kw Edwa rcZ G Sheridan cdfornev i atented May 1 1951 CONVERTIBLE STRAIGHT AND STEP LADDER Edward G. Sheridan, Worthington, Ohio Application April 9, 1948, Serial No. 20,128

The present invention relates to ladders, and has particular reference to ladders of the type which may be converted to either step ladders or straight ladders.

In the past, various types of convertible step and extension ladders have been proposed in the art, but in most instances, such ladders were characterized by inefficient and relatively cumbersome and complex hinge structures and braces which made possible the conversion of the ladder into either a step ladder or a, straight ladder.

It follows, therefore, that the primary objective of the present invention is to generally improve upon known and patented ladders of the character described through the provision of a novel and efficient hinge assembly which functions to rigidly hold the two ladder sections in either step ladder-forming positions, or in straight ladderforming positions as desired, and which additionally is structurally simple and of a lightweight nature, whereby the overall ladder structure may be easily transported by a single person, and may be readily adjusted by such person through the simple insertion of a plurality of stop pins within the hinge structures which function as braces for the separate ladder sections.

It is another object of this invention to provide a novel intermediate section for convertible ladders of the character outlined which functions as a hinge medium for the two ladder sections, and additionally as a common rung member which joins the two sections.

For a further and more detailed understanding of the present invention reference is made to the following description and the accompanying drawing wherein:

Fig. 1 is a perspective view of a ladder formed in accordance with the present invention;

Fig. 2 is an enlarged medial vertical sectional View taken through the upper portion of the ladder disclosed in Fig. 1;

Fig. 3 is a longitudinal vertical sectional view taken along the line 33 of Fig. 2; and V Fig. 4 is a fragmentary side elevational view of the intermediate section of the ladder showing the two ladder sections in longitudinally aligned relation.

Referring now to the drawing, the numeral 5 designates the base section of the present improved ladder, which base section is formed with a pair of transversely spaced and longitudinally extending side frames or legs 6 between which are carried, at longitudinally spaced intervals, a plurality of step-forming rungs 1. The present ladder is further provided with a complemental secondary section, generally indicated by the numeral 8, which secondary section is also formed with a pair of longitudinally extending side frames or legs 9, and a plurality of transversely disposed cylindrical rungs ill. Pivotally joining 3 Claims. (01. 228-23) the base and secondary sections of the ladder is an intermediate section, generally designated by the numeral H, which comprises a transversely disposed and relatively wide platform l2 which is carried between a pair of U-shaped channeled hinge brackets l3. The inner end portions of the side frames of the two ladder sections are pivotally mounted within the channels of the brackets I3 by means of separate pivot pins 14 which extend through transversely registering openings provided within the brackets, and within bearing openings I5 formed through the side frames of the sections. The pivot pins l4 may be screw threaded at their outer ends to receive fastening nuts IS, in order that the pins may be retained against accidental withdrawal or displacement from within the openings of the brackets l 3. As indicated in Figs. 2 and 3 of the drawing, the pin-receiving opening l5 formed through the side frames of the ladder sections may advantageously be provided with bearing sleeves I541, in order that a metal to metal contact and bearing surface may be had between the pivot pins l4 and the leg members of the ladder which, are preferably formed from wood. The upper portions of the

side frames

6 and 9 are mounted within the brackets l3 for separate pivotal swinging movement between positions substantially parallel to the plane of the platform member l2 and positions substantially perpendicularly thereto. Thus, the two separate sections of the ladder are relatively movable through an arc approximating 180, or between folded positions parallel to one another or extended positions in longitudinal alignment with one another.

To permit the separate side frame portions of the ladder sections to occupy substantially parallel positions with respect to the intermediate platform I2, and to obtain a flush fit upon longitudinal alignment of the two sections, the outer edge of each ofv the side frames is cut away, as at H, to provide recesses for the reception of the ends of the platform [2 when the two sections are positioned in longitudinally aligned relation. Further, the end portions of the side frames may be provided with metallic bands or straps t8 which serve to clamp the end portions of the side frames, and to reinforce the same against possible splitting or cracking which may be occasioned by undue strains or stresses placed upon the pivot points of the sections.

Additionally, each of the brackets I3 are formed toward their outer and lower edge portions with sets of transversely registering openings l'9 for the removable reception of a like number of stop pins 20 which are carried at the ends of flexible chains 2| attached to the platform member l2. As particularly indicated in Fig. 2 of the drawing, the pin-receiving openings it formed in the brackets 13 are positioned so as to permit of insertion of the pins 20 toward the outer edge portions of the

side frames

6 and 9 when the latter are positioned in acutely angular relationship to one another, or upon the inner edge portions of the two side frames when the same are positioned in longitudinally aligned relation to one another. The detachable pins 20 provide stop devices for the separate sections of the ladder and function to hold the same in step ladderforming relation, or in straight ladder-forming relation. If desired, the separate side frames or legs may be formed with transverse openings for the reception of the stop pins 20, in which case the legs may be rigidly joined to the brackets, by the pins 20, rather than being held against swinging movement by abutting engagement with the pins. It will be understood, that the exact position of the openings 19 is immaterial so long as the pins function to selectively hold the separate sections of the ladder either in acutely angular relationship or in longitudinally aligned relationship.

In view of the foregoing, it will be seen that the present invention provides a relatively simple yet rugged hinge construction for dual purpose ladders of the character outlined, which construction makes possible the facile and fast conversion of the ladder from step ladder-forming configuration into straight ladder-forming configuration, and at the same time provides and insures rigid support of the separate ladder sections in either of their selective positions. Ladders formed in accordance with the present invention are further characterized by the fact that the intermediate section or platform dually functions as a top-forming member of the step ladder,

and as a common rung member between the two ections when the same occupy straight positions.

Ladders formed in accordance with the present invention are characterized by their mechanical strength and efiiciency, and constructional simplicity which renders the same economical in manufacture and maintenance.

While a present preferred embodiment of this invention has been disclosed in detail, it will be manifest that various modifications as to constructional details and design may be accomplished without departing from the spirit of the invention or the scope of the following claims.

I claim:

1. A ladder comprising a base section including a pair of spaced side frames and-a plurality of step-forming rungs carried between the side frames at longitudinally spaced intervals, a secondary section including side frames and stepforming rungs, a pair of channel brackets pivotally joining the side frames of said sections and providing for relative swinging movement thereof between folded parallel positions and longitudinally aligned positions, each of said brackets being formed with a plurality of transversely disposed pin-receiving openings arranged respectively to lie adjacent an edge of each of the side frames of said sections when the latter occupy relatively longitudinally aligned straight ladder-forming positions and acutely angularly related step ladder-forming positions, a plurality of stop pins insertable within the openings of said brackets for abutting engagement with an edge of each of the side frames of said sections to selectively hold the same in either relatively acutely angular relation or in longitudinally aligned relation, and a platform member rigidly carried between said brackets and providing a common rung between said sections when the same occupy longitudinally aligned positions and a ladder top when said sections occupy relatively acutely angular positions.

2. In a combination straight and step ladder atively spaced channel-forming brackets depend-- ing from one side of said platform member and arranged to receive an end portion of each of said first and second ladder-forming sections, means extending through said brackets and pivotally sccuring an end portion of each of said first and second ladder-forming sections to said brackets and providing for pivotal swinging movement of said first and second ladder-forming sections between relatively folded parallel positions and straight longitudinally aligned positions, each of said brackets being formed with a pair of pinreceiving openings arranged respectively to lie adjacent an edge of said first and second ladderforming sections when the latter occupy both a longitudinally aligned straight ladder-forming position and an acutely angularly related step ladder-forming position, and a plurality of stop pins insertable within the pin-receiving openings formed in said brackets for abutting engagement with an edge of each of said first and second ladder-forming sections and for holding said first and second ladder-forming sections in either relatively longitudinally aligned straight ladderforming positions or acutely angularly related step ladder-forming positions.

3. In a combination extension and step ladder of the type having separate base and secondary sections provided with spaced leg members and transverse rungs; a fiat platform member; a pair of relatively spaced channeled brackets; pivot pins extending through said brackets and the legs of said sections and providing for relative pivotal swinging movement of said sections between folded parallel and longitudinally aligned positions, each of said brackets being formed with sets of transversely registering pin-receiving openings positioned for close alignment with an edge of each leg of said sections when the latter occupy either longitudinally aligned extension ladder-forming positions or acutely angularly related step ladder-forming positions; and a plurality of stop pins insertable within the pinreceiving openings of said brackets for abutting engagement with an edge of each leg of said sections, said stop pins, when inserted within the pin-receiving openings of said brackets, serving to selectively lock said sections against pivotal swinging movement when thelatter occupy their longitudinally aligned positions or to prevent swinging movement of said sections past acutely angularly related positions when the latter occupy their folded parallel positions.

EDWARD G. SHERIDAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 719,450 Ferguson Feb. 3, 1903 1,685,632 Hammond et al. Sept. 25, 1928