US3120290A

US3120290A - Ladder

Info

Publication number: US3120290A
Application number: US260978A
Authority: US
Inventors: George H Kamrath
Original assignee: Individual
Current assignee: Individual
Priority date: 1963-02-26
Filing date: 1963-02-26
Publication date: 1964-02-04
Anticipated expiration: 1981-02-04

Description

Feb. 4, 1964 G. H. KAMRATH LADDER Filed Feb. 26, 1963 INVENTOR Gearye H1? amroZ/z' ATTORNEYS United States Patent 3,126,298 LADDER George H. Kamrath, 2982 Ronaid t., Riverside, Calif. Filed Feb. 26, 1953, Ser. No. 26%,?73 6 Claims. (ill. 182-4139) The present invention relates generally to ladders and more particularly to a novel ladder adapted to be used in utility manholes.

The primary object of the present invention is to provide a ladder which may be conveniently installed in and removed from utility manholes and one which, when installed, is firm and stable and is readily accessible from outside the manhole.

it is a further object of the invention to provide a manhole ladder which the user can get on and on" of at street level, rather than at some point therebelow where he must suspend himself from the edges of the manhole.

Another object is to provide a manhole ladder which in itself establishes a Warning barricade for trafiic passing on the street above.

Still another object is to provide a ladder which is light in weight and readily foldable to a compact position for being transported.

It is also an object to provide a ladder which is simple in construction, economical to manufacture, and durable in use.

These and other objects will be apparent from the following description, when taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view illustrating a ladder constructed in accordance with the teachings of the present invention and installed as intended;

FIG. 2 is a fragmentary section taken on the line 22 of FIG. 1; and

FIG. 3 is a fragmentary section taken on the line 33 of FIG. 1.

Referring now more specifically to the embodiment of the invention disclosed in the drawings, the ladder is generally indicated by the numeral 1 and includes a spaced pair of vertical support members or risers 3, formed of any suitable material such as aluminum. A plurality of transverse rungs 5 are secured between risers 3 in the usual manner and in the instant embodiment are tubular in configuration.

A rear brace 7 is pivotally mounted at its upper end on the uppermost rung 5 and at its lowermost extremity is provided with a cap 9 having a ground-engaging point 11 thereon. A chain 13 is anchored at one end to an intermediate one of the rungs 5. A hook 15 secured along the length of brace 7 is adapted to be selectively and removably attached to one of the links at the links at the other end of chain 13 to adjustably limit the angle of inclination of the brace with respect to the ladder.

A pivot rod 17 extends through the uppermost one of the rungs 5 and through aligned openings in risers 3. A generally U-shaped front brace 19 comprises a pair of upstanding legs 21 pivotally mounted on the outer ends of rod 17 and secured in position by nuts 23 or the like. The legs 21 of brace 19 are bowed outwardly to provide clear access to the ladder as well as to the space immediately therebelow. An L-shaped bracket 24 is mounted centrally of the bight portion 25 of brace 19 to serve as an edge-engaging member as will be described hereinbelow.

3,lZb,Z% Patented Feb. 4, 196

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A pair of hanger elements 27 are mounted on the respective risers 3 and project rearwardly for approximately three or four inches. Elements 27 are provided With holes 2-9, and bolts 31, passing through these holes and selectively aligned ones of a series of holes 33 in risers 3 serve to adjustably mount the elements along the length of the risers. The position of adjustment of the hanger elements 27 is primarily determined by the diameter of the manhole, which is normally of a standard size Within any given locality. As this diameter increases the angle between brace 19 and risers 3 also increases and the hanger elements 27 must be raised accordingly to maintain the ladder at the desired angle.

In use, as shown in FIG. 1, the lower end of the ladder 1 is inserted into a manhole 35 with hanger elements 27 engaging the manhole frame 37 at the rear edge of the opening. The vertical risers 3 extend several feet above the opening and at least three of the rungs 5 are above street level so that a user can obtain a firm foothold and handhold when getting or or off the ladder. Rear brace 7 is inclined rearwardly and disposed at an angle of approximately 45 to 60 with respect to the ground. The chain 13 acts as a safety link and the point 11 is embedded in the ground, the ladder therefore being stabilized against rearward forces. At the same time brace 19 is inclined forwardly of the ladder to absorb forwardly directed forces. Brace 19 is secured in position by bracket 24 engaging the forward edge of frame 37, as clearly shown in FIG. 3.

The length of the ladder depends largely upon the manner of use inasmuch as it may be designed to extend entirely to the bottom of the manhole having a given epth or, more commonly, would only be of sufiicient length to be used in connection with pro-existing manhole steps.

it will be readily understood that the construction described above has fully achieved the stated objectives. While only one embodiment has been disclosed, numerous changes and modifications will occur to those skilled in the art without departing from the spirit of the invention or the scope of the annexed claims.

I claim:

1. A ladder, comprising: at least one vertical supporting member; a plurality of spaced transverse rungs secured to said member; a first brace member secured at its upper end adjacent the upper end of said supporting member and inclined rearwardly therefrom for a distance substantially smaller than the length of said supporting member; a second brace member secured at its upper end adjacent the upper end of said supporting member and inclined forwardly therefrom for a distance substantially smaller than the length of said supporting member, where by said ladder can be inserted into an opening in a supporting surface with the lower extremities of said braces engaging said supporting surface in front of and behind said opening and said supporting member extending a substantial distance through said opening from a point thereabove, and means to inhibit movement of said ladder relative to said opening secured to at least one of said members at approximately the same level as that of said lower extremities and engaging said opening.

2. A ladder as defined in claim 1 wherein said inhibiting means includes at least one hanger element secured along the length of said supporting member at approximately the same level as that of said lower extremities.

3. A ladder as defined in claim 2 wherein said hanger element is adjustably secured along the length of said supporting member.

4. A ladder as defined in claim 1 wherein said second brace member includes a pair of legs pivotally secured at their upper ends, and said legs being bowed outwardly intermediate their respective lengths to provide clear access to the front of said ladder.

5. A ladder as defined in claim 1 wherein said brace members are pivota'lly secured adjacent the upper end of said supporting member and additional means are provided to limit the outward pivotal movement of said brace members.

References Cited in the file of this patent UNITED STATES PATENTS 530,374 Wilkins Dec. 4, 1894 767,257 Banks Aug. 9, 1904 1,248,189 Smith Nov. 27, 1917

Claims

1. A LADDER, COMPRISING: AT LEAST ONE VERTICAL SUPPORTING MEMBER; A PLURALITY OF SPACED TRANSVERSE RUNGS SECURED TO SAID MEMBER; A FIRST BRACE MEMBER SECURED AT ITS UPPER END ADJACENT THE UPPER END OF SAID SUPPORTING MEMBER AND INCLINED REARWARDLY THEREFROM FOR A DISTANCE SUBSTANTIALLY SMALLER THAN THE LENGTH OF SAID SUPPORTING MEMBER; A SECOND BRACE MEMBER SECURED AT ITS UPPER END ADJACENT THE UPPER END OF SAID SUPPORTING MEMBER AND INCLINED FORWARDLY THEREFROM FOR A DISTANCE SUBSTANTIALLY SMALLER THAN THE LENGTH OF SAID SUPPORTING MEMBER, WHEREBY SAID LADDER CAN BE INSERTED INTO AN OPENING IN A SUPPORTING SURFACE WITH THE LOWER EXTREMITIES OF SAID BRACES ENGAGING SAID SUPPORTING SURFACE IN FRONT OF AND BEHIND SAID OPENING AND SAID SUPPORTING MEMBER EXTENDING A SUBSTANTIAL DISTANCE THROUGH SAID OPENING FROM A POINT THEREABOVE, AND MEANS TO INHIBIT MOVEMENT OF SAID LADDER RELATIVE TO SAID OPENING SECURED TO AT LEAST ONE OF SAID MEMBERS AT APPROXIMATELY THE SAME LEVEL AS THAT OF SAID LOWER EXTREMITIES AND ENGAGING SAID OPENING.