Fire escape – ladder – or scaffold – Unitary foldable – rigid scaffold or ladder – Collapsible ladder
Reexamination Certificate
2000-06-12
2001-11-20
Ley, Bruce A. (Department: 3634)
Fire escape, ladder, or scaffold
Unitary foldable, rigid scaffold or ladder
Collapsible ladder
C182S156000, C182S159000, C182S163000
Reexamination Certificate
active
06318498
ABSTRACT:
CROSS-REFERENCES
There are no applications related to this application filed in this or any foreign country.
BACKGROUND
This invention relates to a foldable or “collapsible” ladder. In general, emergency ladders of the types used in fire escapes are rather bulky or do not provide the stability of steps and side rails present in conventional ladders. Moreover, such ladders are not always readily transformed from a storage or folded condition to an extended or use condition.
As a result, foldable or collapsible ladders are known. Such ladders comprise segments which fold flat against each other when not in use, and which assume a three-dimensional form when extended for use.
What is needed is a collapsible ladder which comprises segments which fold flat against each other when in storage, which are easily manufactured and which provide the structures required to cause the side elements in each segment to be held in the proper relative position, and which provides the required overall strength.
SUMMARY
The present invention is directed to an apparatus that satisfies the above needs. A novel collapsible ladder includes some or all of the following structures.
(A) A collapsible ladder is formed of a plurality of segments, each segment having a single rung and a side rail on either side of the rung. Each segment is movable between a flat storage position and an in-use position wherein the elements forming the side rails on opposed sides of the rung are oriented in a substantially U-shaped cross-section.
(B) A pair of generally vertically oriented inside elements support a generally horizontally oriented rung between them.
(C) A middle element is pivotally carried by each inside element, and movable about a hinge between an orientation wherein the middle element is in the same plane as the adjacent inside element to an orientation wherein the middle element is perpendicular to the inside element.
(D) An outside element is pivotally carried by each middle element, and movable about a hinge between an orientation wherein the outside element is in the same plane as the adjacent middle element to an orientation wherein the outside element is perpendicular to the middle element.
(E) A pair of springs bias the inside and outside elements into a 90-degree relationship with the adjacent middle element, thereby assuming the in-use configuration having a U-shaped cross-section. The springs are arrayed in an X-configuration when viewed from the end of the ladder. Each spring is attached to an outer element on one side of the rung and an inner element on the other side of the rung. The springs cross midway between the siderails. It is therefore a primary advantage of the present invention to provide a novel collapsible ladder having segments, wherein each segment is formed of a rung flanked on both the left and right by inside, middle and outside elements, and wherein the angle between the inside and middle elements, and between the middle and outside elements, is fixed at 90 degrees when the ladder is in the extended or use position.
Another advantage of the present invention is to provide a collapsible ladder having segments comprising inside, middle and outside elements, each of which carried a plurality of reinforcements.
Another advantage of the present invention is to provide a collapsible ladder wherein the rung is located closer to one end of the inside elements supporting it, and which therefore allows adjacent rungs to be separated sufficiently when the ladder is folded for storage to allow the rungs to be thicker than the inside, middle and outside elements, and to therefore result in a collapsible ladder which is stronger than known collapsible ladders.
A still further advantage of the present invention is to provide a collapsible ladder wherein in a preferred version the rung of each segment is extruded from aluminum stock, but wherein the inside, middle and outside elements are formed of cast aluminum, thereby combining the best qualities of different materials for a preferred overall combination.
Other objectives, advantages and novel features of the invention will become apparent to those skilled in the art upon examination of the invention and the accompanying drawings.
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Ley Bruce A.
Thompson David S.
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