1. Field of the Invention
This invention pertains generally to the field of body support devices for the infirm or handicapped person and more particularly relates to improvements in the construction and assembly of height adjustable tubular crutches.
2. State of the Prior Art
Height adjustable crutches of various designs have been in use for many years. In one particular form, the height adjustment has been accomplished by providing an orificed tubular carrier member secured between parallel lower extremities of two crutch bows. A tubular foot member telescopically carried within the carrier tube has a radially outwardly spring biased detent adapted to project outwardly through any of a series of longitudinally spaced orifices in the carrier tube. By manually pushing the detent inwardly of the carrier tube, the leg member may be slid to a desired degree of extension relative to the carrier tube and secured at that extension by allowing the detent to project radially into the nearest carrier tube oriface.
Various methods of assembling such a crutch, and in particular of securing the lower bow extremities to the carrier tube have been adopted in the past. In one type of adjustable crutch disclosed in this applicant's U.S. Pat. No. 4,509,741, the bows of the crutch are maintained in a normal tubular condition of substantially constant circular cross-section. In particular, the tubular bows retain a normal, undeformed cross-section along the parallel lower extremities between which is supported the carrier tube. The bow members are held to the carrier tube by means of an upper rivet which extends diametrically through the carrier tube and both bow members at a location above the carrier tube orifaces, and also by an end fitting which is encompasses and snugly receives the lower bow ends and the carrier tube so as to hold these three elements in adjacent parallel relationship. The end fitting is riveted to each of the bow ends so as to fix it axially against sliding movement therealong.
While this crutch construction has been found strong and to work well, the lower extremities of the bows terminate in blunt cylindrical ends on each side of the carrier tube. Such blunt cylindrical ends, unless provided with suitably shaped end caps or fittings, define corners which have a tendency to catch on staircase step edges and pose a risk of injury if not used carefully while descending or ascending staircases. This difficulty can be overcome by crushing the lower ends of the bows to a substantially flattened condition and then riveting the crushed bow ends to the carrier tube. The result is a more streamlined crutch construction which tapers smoothly through the transition from the bow ends to lower end of the carrier tube.
This general type of construction, i.e. flattening the bow ends, is already known from a crutch marketed by the Preco Company as their underarm crutch models 6000 and 6050. This prior art crutch is illustrated in FIGS. 1 and 2 of the drawings. As may be seen from these illustrations, the bows in the prior art crutch undergo an abrupt transition from a normal cylindrical tubular state along their upper portions to a fully flattened condition along the full length of their parallel lower extremities laterally adjacent to the carrier tube. The carrier tube is secured by an upper rivet which passes through the flattened bow portions immediately adjacent the transistion between the normal tubular and flattened portions of the bows and by two lower rivets to each of the flattened bow ends. The bows are also bent at or immediately adjacent to this transition. The strength of this crutch is compromised by the combination of the abrupt transition to a fully flattened state, and by both bending and riveting of the bow tubes immediately adjacent to this transition point.
A continuing need therefore exists for an improved detent adjustable crutch with flattened bow ends but without the aforementioned shortcomings.