Any wheelchair users here who are "all shook up" by caster shimmy?

Any wheelchair users here who are "all shook up" by caster shimmy?

Joined: May 12th, 2001, 1:29 pm

April 5th, 2012, 1:25 am #1

Anybody who's tried to take a standard manual wheelchair (e.g., by coasting downhill) much beyond a fast walking speed (i.e., 6 or 7mph), knows about (and hates with a passion) the annoying gyroscopic instability that creates caster shimmy. I know I do - and do.

Scholarly papers have been written about wheelchair caster shimmy.

http://www.rehab.research.va.gov/jour/8 ... larich.pdf
http://www.rehab.research.va.gov/jour/0 ... larich.pdf

But I've never been able to find a practical commercial product that addresses the problem. So here's a DIY one.

This simple gadget (actually a pair of them) totally and absolutely eliminates it. It consists of a nylon worm-drive hose clamp (McMasterCarr # 5471K1) threaded through a length of vinyl tubing (McMasterCarr # 5103K35), wrapped between the caster downtube and fork - one for each side of the chair.



Details on request. Wear a helmet.



Steve
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Joined: May 31st, 2002, 8:52 am

April 5th, 2012, 2:24 am #2

I know what you mean about caster shimmey. Before my dad died, he was using one of those rolling walkers with a seat and hand brakes. He was fine in the house but get rolling down the sidewalk the shimmey would almost make him loose directional control and you would have to grab the bar and make it go where pointed.
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Joined: April 25th, 2003, 11:35 pm

April 5th, 2012, 8:11 am #3

Anybody who's tried to take a standard manual wheelchair (e.g., by coasting downhill) much beyond a fast walking speed (i.e., 6 or 7mph), knows about (and hates with a passion) the annoying gyroscopic instability that creates caster shimmy. I know I do - and do.

Scholarly papers have been written about wheelchair caster shimmy.

http://www.rehab.research.va.gov/jour/8 ... larich.pdf
http://www.rehab.research.va.gov/jour/0 ... larich.pdf

But I've never been able to find a practical commercial product that addresses the problem. So here's a DIY one.

This simple gadget (actually a pair of them) totally and absolutely eliminates it. It consists of a nylon worm-drive hose clamp (McMasterCarr # 5471K1) threaded through a length of vinyl tubing (McMasterCarr # 5103K35), wrapped between the caster downtube and fork - one for each side of the chair.



Details on request. Wear a helmet.



Steve
get the info out there it will be much appreciated. it's the little things in life that drive you nuts with enough repetition.

small caliber joy
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Joined: February 11th, 2002, 6:01 pm

April 5th, 2012, 3:30 pm #4

Anybody who's tried to take a standard manual wheelchair (e.g., by coasting downhill) much beyond a fast walking speed (i.e., 6 or 7mph), knows about (and hates with a passion) the annoying gyroscopic instability that creates caster shimmy. I know I do - and do.

Scholarly papers have been written about wheelchair caster shimmy.

http://www.rehab.research.va.gov/jour/8 ... larich.pdf
http://www.rehab.research.va.gov/jour/0 ... larich.pdf

But I've never been able to find a practical commercial product that addresses the problem. So here's a DIY one.

This simple gadget (actually a pair of them) totally and absolutely eliminates it. It consists of a nylon worm-drive hose clamp (McMasterCarr # 5471K1) threaded through a length of vinyl tubing (McMasterCarr # 5103K35), wrapped between the caster downtube and fork - one for each side of the chair.



Details on request. Wear a helmet.



Steve
<p>at speed, and you dont notice the "drag" just tooling around the house?</p><p>cool.</p>

dr_subsonic's pneumatic research lab

the Lunatic Fringe of American Airgunning
Southwest Montana's headquarters for Airgunning Supremacy
Proud Sponsor of team_subsonic
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Joined: May 12th, 2001, 1:29 pm

April 5th, 2012, 3:59 pm #5

...you make when you adjust Tension/Friction.

One cool feature of the McMC hose clamps is they come with a convenient plastic key wrench for quick readjustment. This makes the small and lightweight "key" easy to carry with you for fine-tuning of the damping for for the specific riding situation - loose and easy for indoors, tighter and stiff for outdoors.

In fact, for outdoor use, you can dial the friction up so high that the chair resists turning so strongly that it has less of that annoying tendency to self-turn and follow the camber of the sidewalk or street. This avoids the fatiguing and efficiency-robbing practice of pushing on one rim while dragging on the other to keep the chair running straight.

Of course then it takes a definite effort at the rims to change direction.

Steve
Last edited by pneuguy on April 5th, 2012, 4:01 pm, edited 1 time in total.
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Joined: December 3rd, 2005, 3:06 pm

April 5th, 2012, 5:11 pm #6

When discharged from the Military, I spent more years in a Wheel Chair than I care to remember, They were the kind you have pictured.
If you are the one using the Wheel-Chair I would give this product some consideration, Especially in tight places.
http://www.iconwheelchairs.com/photos
They are many others but, The price is considerably higher. They provide for greater mobility both inside & outside of your residence.
I do know Government assistance is available in their purchase.
Check them out, You will be surprised on the advancements that have been made.
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Joined: May 12th, 2001, 1:29 pm

April 5th, 2012, 5:42 pm #7



Steve
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Joined: February 11th, 2002, 6:01 pm

April 5th, 2012, 7:32 pm #8

<p>_Your_ folding chair probably collapsed down to something that fits in small backpack, made of unobtainium for the lightest wieght possible and has speed sensors that will automatically put the brakes on when wheel rotation exceeds a certain RPM......</p><p>  </p>

dr_subsonic's pneumatic research lab

the Lunatic Fringe of American Airgunning
Southwest Montana's headquarters for Airgunning Supremacy
Proud Sponsor of team_subsonic
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Joined: May 12th, 2001, 1:29 pm

April 5th, 2012, 8:17 pm #9

...the ramjets on the handrims.



Steve
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Joined: February 11th, 2002, 6:01 pm

April 6th, 2012, 5:01 pm #10

<p>that your uphill power assist? </p><p>Or maybe yer out racing for pinks..... </p>

dr_subsonic's pneumatic research lab

the Lunatic Fringe of American Airgunning
Southwest Montana's headquarters for Airgunning Supremacy
Proud Sponsor of team_subsonic
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