US2895742A - Wheel chair shock absorber - Google Patents

Description

July 2l, 1959 F. H. JoHNsoN WHEEL CHAIR SHOCK ABSORBER Filed June 14, 1954 United States Patent WHEEL CHAIR SHOCK ABSORBER Franklyn H. Johnson, deceased, late of 'Los Angeles, Calif., by Robbie F. Johnson, executrix, Fresno, Calif.

Application June 14, 1954, Serial No. 436,452

3 Claims. (Cl. 280-124) My invention relates to shock absorbers, and it relates particularly to a shock absorber for a wheel chair or the like.

It is well known in the art to provide spring suspension means for increasing the riding comfort of the Wheel chairs.

However, it has long been a problem in the art to provide a wheel chair shock absorbing mechanism which does not interfere with the delicate alignment of the wheel chair.

It has also been a problem in the art to provide a wheel chair shock absorbing mechanism which may be readily applied to an ordinary wheel chair Without substantially altering the structure of the wheel chair.

It is therefore an object of my present invention to provide a wheel chair shock absorber which does not in any way interfere with the alignment of the wheel chair.

It is another object of my present invention to provide a wheel chair shock absorber which may be manufactured separately and installed easily on an ordinary wheel chair without substantial alteration of the Wheel chair structure, or which may alternatively be produced as a component part of the wheel chair when the wheel chair is initially constructed.

Another object of my present invention is to provide a wheel chair shock absorber which is adjustable for various weights.

A further object of my present invention is to provide a Wheel chair shock absorber adapted to be operatively associated with each rear wheel of a wheel chair, so that a pair of my shock absorbers mounted on a wheel chair may be equalized to provide balanced, uniform shock absorbing qualities to both sides of the wheel chair.

Other objects and advantages of my present invention will be apparent from the following description and claims, the novelty of my invention consisting in the features of construction, the combinations of parts, the novel relations of the members and the relative proportioning, disposition and operation thereof, all as is more completely described herein and as is more particularly pointed out in the appended claims.

In the accompanying drawings, forming a part of my present specification:

Figure l is a rear elevational view of a standard folding wheel chair employing my shock absorbers.

Figure 2 is a vertical section taken along the line 2-2 of Figure l.

Figure 3 is a horizontal section taken along the line 3-3 of Figure 2 showing further details of my shock absorber.

Referring to my drawings, in Figure 1 I yhave shown a folding wheel chair including vertical side frame posts 12 and 14, flexible chair back 16 suspended between frame posts 12 and 14, and rearwardly extending operating handles 18 integrally connected to the respective vertical side frame posts 12 and 14 at their upper ends.

A pair of crossed folding braces 20 are pivoted at central pivot 22.

A pair of rearwardly extending, generally horizontal frame legs 24 and 26 are integrally connected to the lower ends of vertical side frame posts 12 and 14, respectively, horizontal frame legs 24 and 26 facilitating manipulation of the wheel chair by a person who is pushing the wheel chair.

A pair of my shock absorber units 30 and 32 are operatively connected with the main wheels 34 and 36, respectively, of the wheel chair. While I have shown my shock absorber units 30 and 32 operatively positioned on a standard folding type of wheel chair, it is to be understood that my shock absorber units may be applied to any standard type of wheel chair.

Referring now to Figures 2 and 3 in which I have illustrated my shock absorber unit in detail, the wheel axle 38 is fitted into a counterbore 40 to be threadedly enga-ged in the thread bore 42 forming a continuation of counterbore 40, bores 40 and 42 being provided in the body portion 43 of U-shaped rocker arm 44. An adjustable lock screw 45 is threadedly engaged in the end portion of thread bore 42 to permit locking engagement of axle 38 with rocker arm 44 in a manner which exposes the proper amount of axle 38 to permit wheel 34 to freely rotate on axle 38.

A pivot pin 46 is pivotally mounted in bearings 48 which are disposed in the respective leg portions of rocker arm 44. Vertical side frame posts 12 and 14 are provided with integral frame bosses 50 having lateral threaded `bores 52 adapted to receive axles 38 when the wheel chair is used without my shock absorbers. I mount my rocker arm 44 on frame boss 50 by placing the leg portions of rocker `arm 44 on opposite ends of boss 50 and then inserting pivot pin 46 through bearings 48 in the leg portions of rocker arm 44 and also through the threaded bore 52 of boss 50, the external threads on pivot pin 46 permitting pin 46 to be threaded into locking engagement in the threaded bore 52 of boss 50.

A set screw 54 is threadedly mounted in one of the legs of U-shaped rocker arm 44 to engage annular groove 56 in one end of pivot pin 46 to prevent any lateral movement of rocker arm 44 with respect to frame boss 50.

I provide an ear 58 which extends rearwardly from body portion 43 of U-shaped rocker arm 44, and ear 58 is pro-vided with an elongated opening or slot 60 which received the upper end of a rod 62.

Rod 62 is preferably provided in the form of a bolt, the head portion of which extends downwardly below slot 60 into shock absorber cylinder 64. The upper end of shock absorber cylinder 64 is closed, except for a vertical passage 65 which is centrally located in the upper end of cylinder 64 to receive rod 62. A plug 66 having a central bore to receive rod 62 may be provided in the upper end of cylinder 64 to prevent wear on passage 65 by reciprocation of rod 62, and to provide a base over which the upper end of cylinder 64 may be spun inwardly during production.

A helical compression spring 67 is disposed about rod 62 in shock absorber cylinder 64, with its upper end in abutment with plug 66 and its lower end abutting against a retainer 68 that is supported on the lower end of rod 62.

A washer 70 having an elongated opening therethrough is mounted on the upper end of rod 62 above ear 58, and a lock nut 72 is threadedly mounted on rod 62 above washer 70. The upper surface of washer 70 is an arcuate or cylindrical surface, the arc being aligned longitudinally with the wheel chair, and the lower surface of lock nut 72 is a similar arcuate or cylindrical surface having a larger diameter. This arcuate construction of -the upper surface of washer 70 and the lower surface of lock nut 72 provides a pivotal engaging surface between the shock absorber unit 30 and the U-shaped rocker arm 44, and also prevents lock nut 72 from unscrewing off of the end of rod 62.

If it is desired, a ball and socket type of joint may be provided between ear 58 and rod 62 instead of the arcuate washer and lock nut construction which I have shown and described.

A plug 76 is provided in the lower end of shock absorber cylinder 64, and is retained in its position by means of a laterally disposed pin 78 which extends through cylinder 64. A slot 80 is provided in plug 76 to accommodate the upper end of a link 82 which is pivotally mounted on pin 78, and the lower end of link 82 is pivotally connected, by means of a suitable bolt 84, to tube clamp 86 which is adapted to clamp tightly about one of the horizontal frame legs 24 or 26 by tightening of bolt 84.

Although my wheel chair shock absorber may be built into a wheel chair when the wheel chair is initially constructed, I prefer to provide my wheel chair shock absorber as a separate unit which may be quickly and easily installed on an ordinary wheel chair. In order to install my wheel chair shock absorber on a standard wheel chair which is produced without the shock absorber, al1 that is necessary is to unscrew and remove the axle 38 from the frame boss 50 on each side of the wheel chair and then attach one of my shock absorbers to each side of the wheel chair. The first step in this attachment is to set the rocker arm 44 around frame 'boss 50 in the manner shown in Figure 3 and to slip pivot pin 46 through bearings `48 in rocker arm 44 and into threaded engagement with the threaded bore inside of frame boss 50, locking rocker arm 44 against lateral motion with respect to frame boss 50 by engagement of set screw 54 in annular groove 56.

At any convenient time, the same axle 38 which was removed from its initial operative engagement with frame boss 50, or a new axle 38 if desired, is slipped through the wheel 34 or 36 and is threadedly engaged in thread bore 42 through body portion 43 of rocker arm 44. When axle 38 has been threaded into bore 42 the correct amount to provide the necessary clearance for wheel 34 or 36, the lock screw 45 is tightened against the end of axle 38 to lock axle 38 in this operative position.

Then the upper end of rod 62 which protrudes upwardly from the top of shock absorber cylinder 64 is moved upwardly through slot 60 in ear 58, washer 70 is slid down onto the top of rod 62 and lock nut 72 is engaged on the upper end of rod 62.

All that remains to complete the installation of my shock absorber on the wheel chair is to engage tube clamp 86 on horizontal frame leg 24 or 26 in the manner shown in Figure 2.

Itis obvious that lthe above installation steps may occur in any desired order, the only step being required in any particular order being the removal of axle 38 from its normal operative engagement in frame boss 50 before my shock absorber is installed.

Once my shock absorber is installed, it may be adjusted by the adjustment of lock nut 72 to accommodate persons of dilerent weight, lock nut 72 being moved downwardly on rod 62 for a heavier person, or upwardly on rod 62 for a lighter person. Proper adjustment of my shock absorber units on each side of the wheel chair in this manner will permit the shock absorbing action on both sides of the wheel chair to be equalized, so that my shock absorbers do not in any way interfere with the perfect balance and alignment of the wheel chair.

The weight of the person sitting in the wheel chair is applied to the shock absorber through horizontal frame leg 24 or 26, a sudden downward jolt of the chair moving frame leg 24 or 26 downwardly to pull the entire shock absorber cylinder 64 downwardly relative to rod 62 which is suspended from the wheel 34 or 36 because of the attachment of both rod 62 and wheel axle 38 to rocker arm 44. This causes compression of spring 67, thus taking up the shock. Y

As relative movement thus occurs between cylinder 64 and rod 62, a twisting movement will occur between rod 62 and ear 58 of rocker arm 44. 'Ihe elongated shaping of slot 60 in ear 58 and washer 70 permits this twisting movement to occur, and the bearing for accommodating this twisting action is the curved surface connection between the upper surface of washer 70 and the lower surface of lock nut 72.

The rotatable mounting of rocker arm 44 on pivot pin 46 permits rocker arm 44, and hence the wheel 34 or 36 to swing freely in an arc about pivot pin 46.

Although I have illustrated a shock absorber unit 30 or 32 consisting of a spring loaded cylinder, in which the wheel chair is supported on spring compression, it is to be understood that any other suitable shock absorber unit may be substituted for the unit described in detail hereinabove. Thus, a spring tension type of shock absorber unit may be used, or a pneumatic or a hydraulic type of shock absorber unit may be used if it is desired.

Another change which may be made without departing from the spirit of my invention is the substitution of a ball and socket join for my preferred washer and lock nut engagement at 74.

My wheel chair shock absorber introduces an entirely new element in the wheel chair suspension art, namely, my U-shaped rocker arm 44 which is adapted to be pivotally mounted on the wheel chair frame boss that originally accommodated the axle, and that is also adapted to suppport the wheel chair axle in spaced relationship to its original position on the wheel chair.

Another entirely new element in the Wheel chair suspension art is my adjustable feature which permits the adjustment of my shock absorbers to accommodate varying weights, and particularly to equalize the shock absorbers on both sides of the wheel chair so that the perfect alignment of the wheel chair is not disturbed.

These new elements, together with their new functions and modes of operation, produce the surprisingly new results of permitting an ordinary wheel chair to be transformed into a wheel chair with shock absorber mounting swiftly and with very little effort, and also of permitting Vaccurate wheel chair alignment and shock absorber adjustment.

Probably the greatest diiculty in connection with prior art wheel chair shock absorbing mechanisms was the alignment problem. I have completely eliminated this problem not only by my adjusting feature which permits the relative adjustment of the shock absorbers on both sides of a wheel chair, but also by my novel axle mounting structure. While my axle 38 is movably suspended with respect to the wheel chair frame, it is prevented from any lateral shifting whatsoever by the pivotal engagement of my U-shaped rocker arm 44 on frame boss 50, and is at all times kept substantially parallel to the bore 52 in frame boss 50 by my rocker arm mounting.

Another surprisingly new result of my invention is that it displaces the wheels of the wheel chair rearwardly from their original positions relative to the wheel chair frame, thus preventing a wheel chair embodying my invention from tipping over backwards.

It is to be understood that the form of my invention herein shown and described is my preferred embodiment and that various changes in the shape, size and arrangement of parts may be resorted to without departing from the spirit of my invention, or the scope of my appended claims.

What is claimed is: j

1. Apparatus for converting a conventional wheel chair of the type having a frame with a pair of spaced frame members that have substantially horizontal wheel axlereceiving passages therethrough into a spring supported wheel chair; including a pivot pin engageable in each of said wheel chair axle-receiving passages, each of said pins extending fromV both sides of its respective said axlereceiving passage, a bifurcated rocker arm having a body portion and a pair of spaced legs pivotally mounted on each of said pins, the spaced legs of -each of said rocker arms being pivotally mounted on the respective said pin on opposite sides of the respective said wheel chair axle-receiving passage, a substantially horizontal axle-receiving passage in said body portion of each of said rocker arms for carrying the respective wheel axles, and spring means operatively engageable between each of said rocker arms and said wheel chair frame.

2. Apparatus for converting a conventional wheel chair of the type having a frame with a pair of spaced, substantially vertical frame members that have substantially horizontal wheel axle-receiving passages therethrough and a pair of substantially horizontal frame members attached to the respective said vertical frame members into a spring supported wheel chair; including a pivot pin engageable in each of said wheel chair axle-receiving passages, each of 'said pins extending from both sides of its respective said axle-receiving passage, a bifurcated rocker arm having a body portion and a pair of spaced legs pivotally mounted on each ofv said pins, the spaced legs on each of said rocker arms being pivotally mounted on the respective said pin on opposite sides of the respective said wheel chair axle-receiving passage, a substantially horizontal axle-receiving passage in said body portion of each of said rocker arms in horizontally spaced relation to the respective said pins for carrying the respective wheel axles, and spring means operatively engageable between each of said rocker arms at a point horizontally spaced from the respective said pins and the respective said horizontal frame members.

3. Apparatus for converting a conventional Wheel chair of the type having a frame with a pair of spaced, substantially vertical frame members that have substantially horizontal wheel axle-receiving passages therethrough and a pair of substantially horizontal frame members attached to the respective said vertical frame members below said axle-receiving passages into a spring supported wheel chair; including a pivot pin engageable in each of said wheel chair axle-receiving passages, each of said pins extending from both sides of its respective said axle-receiving passage, a bifurcated rocker arm having a body portion and a pair of spaced legs pivotally mounted on each of said pins, the spaced legs of each of said rocker arms being pivotally mounted on the respective said pin on opposite sides of the respective said wheel chair axlereceiving passage and with said body portion of each of said rocker arms horizontally spaced from the respective said substantially vertical frame members, a substantially horizontal axle-receiving passage in said body portion of each of said rocker arms for carrying the respective wheel axles, and extensible spring means operatively engageable between said body portion of each of said rocker arms and the respective said horizontal frame members.

References Cited in the file of this patent UNITED STATES PATENTS 1,577,233 Hotto Mar. 16, 1926 2,090,141 Newton Aug. 17, 1937 2,181,546 Bradshaw Nov. 28, 1939 2,632,655 King et al Mar. 24, 1953 2,675,057 Glass Apr. 13, 1954 FOREIGN PATENTS 626,556 Great Britain July 18, 1949 640,765 Great Britain July 26, 1950 816,796 Germany Oct. 11, 1951

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