US2229987A - Ladder construction - Google Patents

Description

Jan. 28, 1941. a H PHELPS LADDER CONSTRUCTION Filed April 8, 1938 2 Sheets-Sheet 1 w Y 2% W MW A m w 6 Jan. 28, 1941. s. H. PHELPS LADDER CONSTRUCTION Filed April 8, 1938 2 Sheets-Sheet 2 INVENTOR George/7! PheJas av v ATTORNEY Patented Jan. 28, 1941- UNITED STATES PATENT OFFICE LADDER CONSTRUCTION George H. Phelps, Floral Park, N. Y., assignor to Metropolitan Device Corporation, a corporation of New York Application April 8, 1938, Serial No. 200,815

3 Claims.

The invention herein disclosed relates to a portable ladder construction of the type that is carried by a vehicle and utilized for servicing street lights, for tree trimming and the like.

The primary object of this invention is to provide a portable ladder construction with which the ladder may be readily and easily raised, lowcred and positioned by a single person and which is provided with means for reliably securing the ladder in various angular positions.

The foregoing and other objects which will hereinafter appear are embodied in the ladder disclosed in the accompanying drawings in which:

Fig. 1 is a rear elevation of an automobile truck having a portable ladder mounted thereon;

Fig. 1a is the upper portion of the ladder having a platform thereon;

Fig. 2 is an enlarged fragmentary elevation of the lower portion of the ladder;

Fig. 3 is a section taken on the line 33 of Fig. 2;

Fig. 4 is an enlarged, fragmentary elevation of a section of the ladder, illustrating the rung construction; and

a Fig. 5 is a section of the same taken on the line 5-5 of Fig. 4.

The ladder illustrated in the drawings is mounted upon an automobile truck I. Preferably there is provided a steel bedplate 2 that is secured to the platform of the truck and upon which the ladder is mounted. The ladder is mounted on a horizontal rotatable platform 3 that rotates about a pivot-pin 4 extending through the platform 3, the bedplate 2 and the platform of the truck. On this rotatable platform 3, which may desirably consist of a single casting having four radial arms, the frame for supporting the ladder is mounted. This frame consists of two spaced, vertical, parallel channel irons 5, and two channel irons 6 inclined to the horizontal. Each of the vertical channel irons is secured at one end to the rotatable platform and extends substantially perpendicularly from the plane thereof. Each inclined channel iron 6 is secured at one end to the horizontal platform and at the other end to the upper end of a vertical channel iron 5. These channel irons form a pair of spaced, rigid, triangular uprights between which the ladder is pivotally mounted.

The ladder may be of the adjustable, extension type having two sections I and 8, the section 8 being slidable on the section I in the usual manner. The lower section I of the ladder is mounted on a pivot 9 extending through'the side rails l and II of the section and through the frame uprights at the point where the elements and 6 are joined together. For a substantial distance on either side of the pivotal connection of the section of the ladder to the frame, the side 5 rails l0 and I are reinforced by metal plates l2.

At the lower end of the section I of the ladder, there are mounted counterweights I3 and I4, one secured to the lower end of each of the side rails l0 and II. The counterweight I3 is 10 secured to the side rail H] by bolts l5 and It. The counterweight I4 is similarly secured to the side rail H by bolts I1 and Hi. In the counterweight l3, there is slidably mounted a bolt I9 that extends perpendicularly to the plane of the side rail H). A similar bolt 23 is slidably mounted in the counterweight l4. These bolts cooperate with angularly disposed, spaced frame members 2| and 22 that are secured to the rotatable platform. The lower end of the ladder swings be-. tween these two frame elements. Each of the frame elements 2| and 22 has a series of openings 2|a therethrough disposed in an arc concentric with the axis about which the ladder pivots. The holes 2|a through the frame elements 25 are of a diameter to receive the bolts l9 and 20. When the bolts extend into aligned openings 2|a in the frame elements 2| and 22, the ladder is positioned in one of several angular positions and is secured in that position by the interengagement of the bolts and the frame elements 2| and 22.

The bolts I9 and 20 are spring-pressed in opposite directions so that each bolt is urged in a direction to enter the openings 2|a in the frame elements 2| and 22. For this purpose, there is provided a cylindrical element 23 that extends between and that is rigidly fastened to the counterweights. The bolts l9 and 20 extend into the cylindrical element 23. A spring 24 within the element 23 presses on the ends of the bolts within the cylindrical element 23. Tubular sleeves 25 and 26 are slidably mounted on the element 23. A pin 21 extends through the bolt l9, diametrical, longitudinal slots in the element 23 and into the sleeve 25, and a pin 28 extends through the bolt 20, slots provided therefor in the element 23 and into the sleeve 26. The slots in the element 23 through which the pins 21 and 28 extend are of sufiicient length to permit the bolts to 5 be moved toward each other a distance to disengage them from the openings in the frame elements 2| and 22, the sleeves 25 and 26 forming hand-grips for this purpose. The pins also limit, by abutment with the ends of the slots, the outward movement of the bolts. From the description of this construction it will be seen that when it is desired to position the ladder the operator grasps the sleeves 25 and 26 and draws them inwardly until the bolts are free of any openings in the frame elements 2! and 22. With the bolts thus retracted, the ladder is moved about its pivotal connection to the desired position when the bolts are released and the ladder moved slightly until the bolts, by virtue of the action of the spring, move into the nearest pair of openings through the frame elements 2| and 22. The ladder is thus positioned and it is secured in position. It will be apparent that with this construction, the bolts l9 and 20 and the spring 24 can be removed for inspection, cleaning and greasing.

The construction of the rungs and their connection to the ladder are illustrated in Figs. 1 and 5. From these figures it will be seen that the rung 29 extends between the side rails l and H but does not enter the side rails. A gusset-plate is provided at each end of the rung for securing the rung to the ladder. i'he gusset-plate 3E], securing one end of the rung 29 to the side rail I0, is made from a single piece of metal and consists of a tubular section 36a having an in ternal flange 3ll'a at the end thereof and a fiat section 301) extending from the tubular section, at one end thereof, perpendicularly to the axis and along the side of the side rail iii. The section 30b consists of a pair of flanges 35c and Std. It will be seen from Fig. 5 that the gusset-plate is formed by bending these flanges and bending the plate to form the tubular section sea. The blank forming the gusset-plate is cut diagonally and a triangular section 386 consisting of two thicknesses of the metal spot-welded together extends between the section ?dib and the tubular section 39a. This section 3Ele constitutes a reinforcement for holding weight placed upon the rungs of the ladder. The lower portion of the gusset-plate is secured to the side rail by a bolt 3| which extends through a boss 39] formed in the gusset-plate and a reinforcing plate 32 on the opposite side of the side rail It. A similar gusset-plate 33 is provided for securing the opposite end of the rung 29 to the side rail H. Through bolts 84 and 35 extend between and through the side rails If! and H. These bolts extend through the socket sections of the gussetplates and 33 and are received in longitudinal recesses formed on diametrically opposite sides of the rung 29. The bolts 34 and 35 also extend through the plate 32 and a similar plate 36 on the side rail II and serve to hold the side rails in contact with the ends of the rungs. All of the rungs of the ladder, with the exception of the rung 9 about which the ladder pivots, and a rung about which a platform pivots, are

mounted in this manner and the construction greatly stiffens and steadies the ladder against lateral sway and side strains.

From the foregoing description of the construction of the ladder disclosed in the drawings it will be seen that by this invention there is provided a ladder that is simple in construction and which provides a ladder of great strength, and one that is readily moved into any of the several inclined positions in which such ladders are used.

It will be obvious that various changes may be made by those skilled in the art in the details of the construction of the ladder disclosed in the drawings and described above within the principle and scope of the invention as expressed in the appended claims.

I claim:

1. A portable ladder construction comprising a frame, a ladder having side rails and rungs pivotally mounted in the frame, a counterweight attached to each side rail at one end thereof and cooperating inter-engaging means carried by the frame and the ladder for securing the ladder in various angular positions including parallel, angularly disposed frame elements, one on each side of the ladder, having a series of aligned openings therethrough disposed about an arc concentric with the axis of the pivotal connection of the ladder and the frame, a pair of aligned bolts one extending through each counterweight and slidably mounted therein, the bolts being positioned to be aligned with the openings through the angularly disposed frame members upon pivotal movement of the ladder, and resilient means between the bolts for urging the bolts in opposite directions.

2. A portable ladder construction comprising a frame, a ladder having side rails and rungs pivotally mounted in the frame, a counterweight attached to each side rail at one end thereof and cooperating inter-engaging means carried by the frame and the ladder for securing the ladder in various angular positions including parallel, angularly disposed frame elements, one on each side of the ladder, having a series of aligned openings therethrcugh disposed about an arc concentric with the axis of the pivotal connection of the ladder and the frame, a'pair of aligned bolts one extending through each counterweight and slidably mounted therein, the bolts being positioned to be aligned with the openings through the angularly disposed frame members upon pivotal movement of the ladder, hollow end sections on adjacent ends of the bolts and a spring extending between the bolts and received in the hollow end sections.

3. A portable ladder construction comprising in combination a frame, a ladder having side rails and rungs pivotally mounted in the frame, and cooperating interengaging means carried by the frame and the ladder for securing the ladder in various angular positions including parallel, angularly disposed frame elements, one on each side of the ladder, having a series of aligned openings therethrough disposed about an arc concentric with the axis of the pivotal connection of the ladder and the frame, a pair of aligned, slidably mounted bolts on the ladder extending transversely of the ladder and positioned to be aligned with the openings through the angularly disposed frame members upon pivotal movement of the ladder, resilient means between the bolts and acting thereon to urge the bolts in opposite directions, and a hand grip connected with each bolt for manual movement of the bolts against the action of said resilient means.

GEORGE H. PHELPS.

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