Tubular crutch construction
AssigneeGuardian Products, Inc.
InventorNathan L. Ellena
Life of this patent
Estimating the term…
Abstract
A crutch of tubular construction has two crutch bows with straight parallel lower ends, between which is a leg carrier tube held by an upper fastener and lower rivets, and a crutch leg telescoped in the carrier tube. Weak points are avoided by gradually flattening the bows from a cylindrical cross section at the upper fastener through intermediate partially flattened bow portions to fully flattened bow ends at the lower rivets.
Claims7
In a crutch of the type having a pair of tubular bow members, said bow members having upper ends connected by an underarm support, said bow members having spaced apart upper portions, angled sections between two bend points and parallel lower portions each terminating in a lower end, a carrier tube supported between said lower portions by fastener means spaced along said carrier tube, a crutch leg telescopable within said carrier tube, and means for releasably locking said leg to said carrier tube at a selected relative extension therefrom, the improvement wherein said lower portions are progressively crushed along said lower portions between said upper and lower carrier tube ends from a cylindrical tubular shape through one or more intermediate partially crushed sections to a substantially fully flattened double walled state, said fastener means including upper fastener means securing said carrier tube to each of said bow members at a location significantly upwardly of both said partially crushed and fully flattened sections, and lower fastener means securing said carrier tube to each of said fully crushed lower ends;
- said lower fastener means consisting of two lower rivets, each rivet passing through both said walls of one of said crushed lower end and the wall of said carrier tube, said lower rivets each having a substantially flat rounded rivet head external to said fully crushed lower ends such that the lower portions of the bows are substantially protected against catching on staircase edges and the like.
In a crutch of the type having a pair of cylindrical tubular bow members having upper ends connected by an underarm support and each having a lower portions terminating in a lower end, a cylindrical carrier tube supported between said lower portions, a crutch leg telescopable within said carrier tube, and means releasably locking said leg to said carrier tube at a selected relative extension thereform, the improvement wherein said lower portions are progressively crushed from an undeformed normal tubular state through a transitional segment of partially crushed cross-section tapering to a substantially fully flattened double-walled state at said lower ends, said carrier tube being secured to each of said bow members by an upper rivet passing diametrically through said bow members through undeformed portions of said bow members, each of said flattened lower ends being secured to said carrier tube by at least one lower rivet passing through both said walls and the wall of said carrier tube, each said lower rivet having a rivet head internal to said carrier tube and said crutch leg being longitudinally dimpled to accommodate each said internal rivet head while making a snug sliding fit with said carrier tube, each said lower rivet further having a substantially flat rounded rivet head external to said fully crushed lower ends such that the lower portions of the bows are substantially protected against catching on staircase edges and the like.
Dependencies are inferred from the claim text.