Stair-climbing wheel utilizing an involute curve configuration
First Claim
1. A wheel for use in transporting a load up and down a staircase constructed of a series of like stairsteps comprising:
- a plurality of lobes having two surfaces, each of said surfaces of said lobes comprising a portion of an involute curve which is defined by a circle of radius Rb, each of said plurality of lobes being symmetrical about a lobe center line, with the portions of the two involute curves making up the surfaces of a given lobe mirroring each other on opposite sides of the lobe center line and intersecting to form the lobe at the largest radii of the portions of the involute curves making up the surfaces of the lobe.
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Accused Products
Abstract
A wheel for use with a variety of devices for moving a load up or down a series of stairs is disclosed, which wheel is comprised of a plurality of lobes like teeth on a gear. Each lobe has two surfaces which are symmetrical around a lobe center line, with each surface being made up of a portion of an involute curve defined by a circle having a particular radius. The involute curves making up the surfaces of each lobe mirror each other on opposite sides of the center line and intersect to form the lobe at the largest radii of the portions of the involute curves making up the surfaces of the lobe. The wheel may be made to specifications allowing exact fit on a particular size stairstep and a properly fitting wheel will move in a close approximation of a straight line parallel to the staircase incline as it moves up a flight of stairs.
36 Citations
18 Claims
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1. A wheel for use in transporting a load up and down a staircase constructed of a series of like stairsteps comprising:
a plurality of lobes having two surfaces, each of said surfaces of said lobes comprising a portion of an involute curve which is defined by a circle of radius Rb, each of said plurality of lobes being symmetrical about a lobe center line, with the portions of the two involute curves making up the surfaces of a given lobe mirroring each other on opposite sides of the lobe center line and intersecting to form the lobe at the largest radii of the portions of the involute curves making up the surfaces of the lobe. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An improved design for a wheel to be used on stairs, comprising:
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a circle having a first radius Rb, said circle defining a plurality of involute curves; a plurality of lobes defining the outer surface of said wheel, each of which lobes has outer surfaces defined by two adjacent involute curves intersecting at the largest radii of the portions of the two involute curves defining the outer surfaces of each lobe, with the involute curves being defined by said circle; a beginning point for the portions of each of said involute curves defining the outer surfaces of each lobe, said beginning point being defined by a radius R1 and an angle b1, the radius R1 being a length referenced from the center of said circle, the angle b1 being referenced to the point at which the involute curves begin from the circle; and an ending point for the portions of each of said involute curves defining the outer surfaces of each lobe, said ending point being defined by a radius R2 and an angle b2, the radius R2 being a length referenced from the center of said circle, the angle b2 being referenced to the point at which the involute curves begin from the circle. - View Dependent Claims (11, 12, 13, 14)
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15. A device for transporting a load up or down a series of stairs defined by a rise height and a tread length, said device having a pair of lobed wheels, each of which comprises:
three lobes making up the outer surface of said wheel, said three lobes each having two surfaces, each of said surfaces of said lobes comprising a portion of an involute curve which is defined by a circle of a particular radius, each of said three lobes being symmetrical about a lobe center line, with the portions of the two involute curves making up the surfaces of a lobe mirroring each other on opposite sides of the lobe center line and intersecting to form the lobe at the largest radii of the portions of the involute curves making up the surfaces of the lobe, each of said portions of an involute curve having an angular measure of 60°
, with the arc length of each of said portions of an involute curve being equal to a length A'"'"' which is defined from the edge of a stairstep to a point, where the chord length of each of said portions of the involute curves making up the surfaces of the lobe is equal to the distance between said point and the edge of the next higher step.- View Dependent Claims (16, 17, 18)
Specification