Tailwind Conversion?

[Dandydog]

I just found this forum - I ran across a picture of your Hot Rod Wheelchair (Great rims and stance!), and followed it to your website.
I thoroughly agree with your assertions regarding the lack of innovation in the wheelchair industry, and I applaud your efforts to spur such change by building interesting and useful new devices. (Satisfying users' need for speed ain't bad, either. Do you have any 0-to-16 times for that thing?)
At present, I've got some practical problems that I could use some help with. My wife has used a Tailwind since her accident 12 years ago, but has recently developed some shoulder problems that make even the modest effort involved in propelling the T/W difficult and painful. So now she's crashing around the house in a 2-ton M300, and the dogs and I are dodging and diving out of her way. This has got to change.
I'd like to modify one of our Tailwinds (I've got an old iGlide and a newer version from their incarnation as Next) to be self-propelled (rather than assistive), with an armrest-mounted toggle control for each motor (and almost no other changes to the existing lightweight hardware.) The changes I'd like to make would involve reprogramming the CU, which in turn would necessitate either finding a way to read out the code from an exiting unit and then modifying that code, or finding a record of the original code.
Would you or one of your readers be interested in pursuing this project with me? (We would, of course, make our efforts and results available to this forum. And - if we're successful - we'll add cool wheels, paint and accessories.)
I'll look forward to hearing from you guys -
Neil Rose (Dandydog - the best Golden Retriever ever)

[Burgerman]

Tailwinds?

What is one? A power assisted manual chair?

I must say though that I never saw the point in power assisted manual chairs at least for a full time chair user that cannot stand or walk. They dont do a single thing better than a GOOD powerchair. Although thats "good" is hard to find. Apart from those that can walk, or stand and then the reduced weight makes them useful. Because otherwise they do everything the same or worse.

So I would like to ask why and what benefit you hope to achieve by trying to power a manual chair that isnt much better achieved with a good powerchair?

My wife has used a Tailwind since her accident 12 years ago, but has recently developed some shoulder problems that make even the modest effort involved in propelling the T/W difficult and painful.

Common.

So now she's crashing around the house in a 2-ton M300, and the dogs and I are dodging and diving out of her way. This has got to change.

As does every powerchair user with a stock programmed powerchair. It doesn't have to be that way.
http://www.wheelchairdriver.com/gopro/control.mp4 THIS is a stock knackered 20 year old chair, with old weedy 80A controller, TOTALLY knackered lead batteries, and yet its inch perfect with my 20 stone in it.

Even wheeling through doorways at 6mph just 2 inches wider than the chair. No way I will hit anything. (Apart from shoving the dog out of the way with my hand as I wheelyied through a doorway!) A good chair and I have a few, is much more accurate than this one. Watch my thumbs and fingers. Its accurate.

[woodygb]

As B.M. say's you should try reprogramming the Permobil.

Whose control system has it got make / model ...if you don't know post a pic of the joystick pod.

Oh! ...and could you please add your location to your profile as it will help the board to know where in the World you are.

[Dandydog]

Thanks for the quick response, Burgerman!

First, here's a link to information on the Tailwind: ClintonRiverMedical.com.
Next, a bit of background:
My wife was over fifty when she had the auto accident, so after rehab she decided to go with a power-assist chair to minimize wear and tear on her already-ancient shoulders (irony noted). We started with a Quickie and eMotion wheels but found the combination heavy and cumbersome. A year or so out, I lucked into an iGlide Tailwind on eBay, and Sandy liked it so much that we later upgraded to a newer model from Next Mobility. (Ownership of the rights to produce the Tailwind has passed through four companies in the past ten years, but the product - including the control software - has remained essentially the same.)

Sandy's use of the Tailwind is probably unusual: we travel by air a lot between our home in Denver and her home office in D.C., and we avoid the use of an aisle chair by running the T/W into the front galley of the plane and transferring directly to a front-row seat. And when we're at home, we often take drives to the mountains with Sandy's chair hanging off the back of my old BMW. The Tailwind's small footprint (~24"x36") and light weight (60 lbs.) make important contributions to our ability to live happily with Sandy's injury.

So: We're pretty satisfied with this chair, but I'd like to modify it to serve Sandy's current needs a little better. The changes I have in mind would involve minimal alterations to the hardware (replacing the wheel-rim switch that directs the power to each wheel with an armrest-mounted toggle.) More extensive changes would be required for the CU software (sort of like updating a Tesla's capacities, as opposed to swapping motors to get more horsepower, the way we used to do.)

These changes will satisfy Sandy's immediate needs, but I'll almost certainly go on to update the motors to brushless units, and the batteries to ones with more modern capabilities. I'd love to have help with every aspect of this project (especially the motor and battery updates, and the retrieval, decoding and modification of the CU program.) We'll post progress reports on this forum, and make details regarding the finished product available to other users.

Questions? Suggestions? Volunteers?
Thanks, guys!

[woodygb]

So you wish to convert from assistive drive to permanent drive?

MORE info is required but I suspect that the consensus of the board will be ...don't waste your time.

However.
What do you know?

The current motors are what ... brushed?
The battery is 24v NiMH 8.4 Ah or 5.6 Ah ?

Neither will last long as a permanent drive option.

[Burgerman]

As above. I think a non starter.

I also think you underestimate the complexity of what you want to do. And will need a different controller. And much more battery capacity. I also think that you will end up after lots of work and cost with something worse than a conventional powerchair, that has either totally inadequate range or proper batteries. Theres a reason that most powerchairs have massive heavy batteries! You will after a mountain of work eventually understand why powerchairs are how they are.

I also think you over estimate the size a powerchair has to be.
This is 26.2 wide. 35.0 long including footplate and anti tips. http://www.wheelchairdriver.com/BM-MK3- ... rchair.htm

With narrower tyres, like this, its 24.5 wide... download/file.php?id=4326&mode=view With a battery that gives 10x the range and a conventional controller. That once reprogrammed is as sharp and accurate as a knife. And its plan form is smaller than your tailwind.

And small lightweight lithium folding chairs are available cheaply too. But they are not as stable or as capable outdoors, or as comfortable, and dont have the same range or ability. And they are not smaller, just lighter.

[Gnomatic]

8gb RAM plenty and you will NEVER notice the difference between DDR3 1600 and 1866.

Don't worry about having to use a standard SATA SSD will still be a MASSIVE upgrade over the mechanical hard drive in your laptop currently

[Burgerman]

Err...

[ex-Gooserider]

link didn't come through, this is what I found...
https://www.clintonrivermedical.com/

I think it would be a definite problem to convert the chair to being controlled by something other than pushing, though it might not hurt to try contacting the manufacturer to see if they have any suggestions / solutions...

At the same time, I can see that the described use cases might be a problem for a full size power chair....

Fixing the programming on the Permobile will definitely help with around the house sort of uses, but still be awkward for some of the others.

It might be worth looking at some of the Chinese 'portable' chairs like the 'Foldawheel' mentioned in one of the other threads (there are several other brands of the same general design...)

ex-Gooserider

[Dandydog]

Hi Burgerman -

I understand your reservations about this project, and I appreciate your input. I hope that I've anticipated some of your concerns with the project development plan that I put together over the weekend (and which I'll detail below.)

First off, though, let me address the specific questions you asked:
The (single) batteries used in the Tailwind chairs are 24V, 5.64h NiMH units, and as such are virtually useless for long-range continuous propulsion.
The (dual) motors are equally ancient: brushed units with an integral step-down gearset that weigh in at 8 pounds (each)! (Overall, the propulsion unit [CU, motors, switch and battery] account for 26.0 pounds of the Tailwind's 60-pound weight.)
Clearly, there's room for improvement.

Last week, I sketched out this plan for achieving some of those improvements:

Feasibility Phase:
- Build project team
- Establish connection with Clinton River Medical personnel on both administrative and
technical levels
- Establish connection with brushless-motor resources
- Boosted(?)
- Determine and document capacities of current version of Tailwind
- determine reason for start-up delay (see note 1)
- software delay built in to switch on power only after wheels begin turning?
- hardware-based problem resulting from extent of gearing-down in gearset?
- similar problem for BB?
- Note: Tesla has no transmission
- Develop access to Tailwind CU code
- access thru CRM?
- dump program and decode?

[GO/NG: At this point the project should be abandoned if 1) start-up problem appears to defy
solution, or 2) CU code is inaccessible.]

Phase 1 (Toggle Control):
- Software
- Develop ability to alter CU code
- Reprogram CU code
- eliminate start-up delay (if software-related)
- transfer user control from wheel-rim to toggle
- user will still 'pulse' power to wheels
- Hardware
- Design and build replacement armrests with incorporated toggle switches and wiring
- Eliminate start-up delay (if hardware-related)
- need to replace motors with brushless units in order to solve start-up problem?

[GO/NG point, based on availability of solution to start-up problem]

[At this juncture, we've either got a project that has foundered on the start-up problem, or we've solved that key problem and now have a prototype Tailwind 2.0 that has been converted to operate with armrest-mounted toggle switches. (Note that that's the only change we've made in the way the chair operates: the user still 'pulses' power to the wheels, and the power to each wheel is still controlled by a separate switch: consequently, the chair is still steered by directing power to one or another of the wheels. We haven't attempted to address any other problems - battery life, power, range, etc. - but we've created a Tailwind that the user can drive with her hands, rather than her arms and shoulders.)
If we've succeeded in solving that key problem, we're now free to move on to the fun part: purely developmental problems involving actual improvements to the Tailwind.]

Phase 2 (Brushless motors):
- Investigate 'pulsing' requirement for current motors (see note 2)
- CRM: overheating? current draw? battery limitation? other?
- Deconstruct existing motor/gearset
- CRM: tool for removing bolt?
- Research functionality and availability of brushless motors
- BB as resource?
- Replace brushed with brushless motors in prototype
- new housings required?
- print new housings or print adaptors and mounts for new motors
- change in power requirements?
- brushless motor power-draw way less than that of brushed motors?
- toy race car
[Do these changes eliminate the need to 'pulse' power to the wheels? I.e.: Have we achieved
a continuous-power Tailwind?
If so, we will need to change the controls to a single joy-stick, add a mode-selection switch
(assisted/power), and modify the CU code again.]

[This 2.1 version of the Tailwind will have the capacity to function 1) as a lightweight manual chair (power off); 2) as a power-assisted chair (with power-control either through the wheel rims or through armrest-mounted toggles; or 3) as a power chair, with power-control effected through a standard joy-stick. In power-chair mode it will have extremely limited range, because we haven't yet addressed the battery problems - but that's just a matter of project priorities, and we'll already have one hell of a product.]

Phase 3 (Batteries):
[CRM has this improvement in its project-development stream. Current difficulties include: Shipment of lithium batteries; customer concerns about same; regulatory issues.]

[All my information on battery development comes from the popular press, which leads me to believe that this will be the easiest part of the project. Battery technology has undergone quantum improvements since the Tailwind units were made, and equally great improvements in range, power, battery life and weight should be readily available. (The problems that CRM are citing should not affect production of prototypes.)
We'll research these developments at the same time that we investigate brushless motors, but I anticipate encountering few difficulties in either area.]


Note 1: The term 'start-up problem' refers to a characteristic of the Tailwind that is evident when a wheel-rim is first rotated: the motor activated by that wheel-rim does not turn on until the wheel itself has started to turn.
Note 2: The 'pulsing problem' refers to the fact that power is transmitted by the CU to the motors in bursts: rotating a wheel-rim causes power to be applied to that wheel for only a very short period - the wheel accelerates briefly, then coasts for ~5 seconds, gradually coming to a halt.


Again: Any thoughts, comments or advice will be welcomed.
Neil

[Dandydog]

I'm having problems with the Forum editing software.

[Dandydog]

Hi Burgerman -

I understand your reservations about this project, and I appreciate your input. I hope that I've anticipated some of your concerns with the project development plan that I put together over the weekend (and which I'll detail below.)

First off, though, let me address the specific questions you asked:
The (single) batteries used in the Tailwind chairs are 24V, 5.64h NiMH units, and as such are virtually useless for long-range continuous propulsion.
The (dual) motors are equally ancient: brushed units with an integral step-down gearset that weigh in at 8 pounds (each)! (Overall, the propulsion unit [CU, motors, switch and battery] account for 26.0 pounds of the Tailwind's 60-pound weight.)
Clearly, there's room for improvement.

Last week, I sketched out this plan for achieving some of those improvements:

Feasibility Phase:
------- Build project team
--------Establish connection with Clinton River Medical (CRM) personnel on both administrative and
------------------technical levels
--------Establish connection with brushless-motor resources
------------------Boosted boards (BB)?
--------Determine and document capacities of current version of Tailwind
------------------determine reason for start-up delay (SEE NOTE 1)
-------------------------software delay built in to switch on power only after wheels begin turning?
-------------------------hardware-based problem resulting from extent of gearing-down in gearset?
-------------------------similar problem for BB?
-------------------------note: Tesla has no transmission
--------Develop access to Tailwind CU code
------------------access thru CRM?
------------------dump program and decode?
-
[GO/NG: At this point - about a week in, with almost no money spent - the project should be abandoned if
----------------1) the start-up problem appears to defy solution, or 2) CU code is inaccessible.]
-
Phase 1 (Toggle Control):
--------Software:
------------------Develop ability to alter CU code
------------------Reprogram CU code
--------------------------eliminate start-up delay (if software-related)
--------------------------transfer user control from wheel-rim to toggle
----------------------------------user will still 'pulse' power to wheels
--------Hardware:
------------------Design and build replacement armrests with incorporated toggle switches and wiring
------------------Eliminate start-up delay (if hardware-related)
------------------------need to replace motors with brushless units in order to solve start-up problem?
-
[GO/NG point, depending on solution of the start-up problem]
-
[At this juncture, we've either got a project that has foundered on the start-up problem, or we've solved that key problem and now have a prototype Tailwind 2.0 that has been converted to operate with armrest-mounted toggle switches. (Note that that's the ONLY change we've made in the way the chair operates: the user still 'pulses' power to the wheels, and the power to each wheel is still controlled by a separate switch: consequently, the chair is still steered by directing power to one or another of the wheels. We haven't attempted to address any other problems - battery life, power, range, etc. - but we've created a Tailwind that the user can drive with her hands, rather than her arms and shoulders.)
If we've succeeded in solving that key problem, we're now free to move on to the fun part: purely developmental problems involving actual improvements to the Tailwind.]
-
Phase 2 (Brushless motors):
--------Investigate 'pulsing' requirement for current motors (SEE NOTE 2)
------------------CRM: overheating? current draw? battery limitation? other?
--------Deconstruct existing motor/gearset
------------------CRM: tool for removing bolt?
--------Research functionality and availability of brushless motors
------------------BB as resource?
--------Replace brushed with brushless motors in prototype
------------------new housings required?
------------------------print new housings or print adaptors and mounts for new motors
------------------change in power requirements?
------------------------brushless motor power-draw way less than that of brushed motors?
------------------------------toy race car
-----[Do these changes eliminate the need to 'pulse' power to the wheels? I.e.: Have we achieved
------a continuous-power Tailwind?
------If so, we will need to change the controls to a single joy-stick, add a mode-selection switch
------(assisted/power), and modify the CU code again.]
-
[This 2.1 version of the Tailwind will have the capacity to function 1) as a lightweight manual chair (power off); 2) as a power-assisted chair (with power-control either through the wheel rims or through armrest-mounted toggles; or 3) as a power chair, with power-control effected through a standard joy-stick. In power-chair mode it will have extremely limited range, because we haven't yet addressed the battery problems - but that's just a matter of project priorities, and we'll already have one hell of a product.]
-
Phase 3 (Batteries):
[CRM has this improvement in its project-development stream. Current difficulties include: Shipment of lithium batteries; customer concerns about same; regulatory issues.]
-
[All my information on battery development comes from the popular press, which leads me to believe that this will be the easiest part of the project. Battery technology has undergone quantum improvements since the Tailwind units were made, and equally great improvements in range, power, battery life and weight should be readily available. (The problems that CRM are citing should not affect production of prototypes.)
We'll research these developments at the same time that we investigate brushless motors, but I anticipate encountering few difficulties in either area.]
-
-
Note 1: The term 'start-up problem' refers to a characteristic of the Tailwind that is evident when a wheel-rim is first rotated: the motor activated by that wheel-rim does not turn on UNTIL THE WHEEL ITSELF HAS STARTED TO TURN.
Note 2: The 'pulsing problem' refers to the fact that power is transmitted by the CU to the motors in bursts: rotating a wheel-rim causes power to be applied to that wheel for only a very short period - the wheel accelerates briefly, then coasts for ~5 seconds, gradually coming to a halt if the wheel-rim switch is not re-activated.
-
-
Again: Any thoughts, comments or advice will be welcomed.
Neil

[woodygb]

Buy a 2nd hand VSi ( All In One control ) and connect it to your motors.
http://www.ebay.com/bhp/vsi-joystick

This should be fairly straight forward and easy conversion..8 wires ..2 for the battery ..2 for each motor and 2 for the brake ...you can trick the pods brake detection with a suitable resistor.

I can almost guarantee that there will be insufficient torque to move the chair from a standstill.

[woodygb]

The (single) batteries used in the Tailwind chairs are 24V, 5.64h NiMH units, and as such are virtually useless for long-range continuous propulsion.
The (dual) motors are equally ancient: brushed units with an integral step-down gearset that weigh in at 8 pounds (each)! (Overall, the propulsion unit [CU, motors, switch and battery] account for 26.0 pounds of the Tailwind's 60-pound weight.)
Clearly, there's room for improvement.

Such as ?
If your anticipating massive weight saving then I suggest that you think again!

[woodygb]

There are some real world facts that you CANNOT escape ...
You need a drive that can move the chair independently of the user on a decent slope ...say 8 degrees.

Do some math and see what sort of Energy you need to do this ...you then need a battery that is able to supply this energy.

The battery needs to be sized according to the distance that you want the chair to travel on a regular basis ...taking into account the peak and average energy requirements of your drive.

Note that brushed motors are not very efficient and brushed motors can have problems with low starting torque.



You might want to look here...THIS IS NOT A RECOMMENDATION OF THE PRODUCT.
https://www.goldenmotor.com/wheelchair.htm

https://www.goldenmotor.com/

[Dandydog]

Woodygb -
One of my favorite Far Side cartoons (Do you guys get The Far Side over there? Come to think of it: Do British people laugh?) has two beavers chewing on the wooden leg of a sleeping pirate. The caption reads, "Hey! These guys are edible! This changes everything!"
Thanks for referring me to GoldenMotor.com.
I'll get back on the forum page with revisions to this project in a few days.
Neil

[Burgerman]

(Do you guys get The Far Side over there? Come to think of it: Do British people laugh?)

The simpler they are the more they laugh.

[Sully]

Laughing is good for you!
Being able to laugh at yourself is really great for your health, mental and physical.

[Dandydog]

Hey, guys -
I took a couple of weeks off from the forum to incorporate the Golden Motor info into my project. (I'd had no idea that such conversion kits existed; I thought I was going to have to learn all about brushless motors - along with 3D printing - to get to prototype stage.)

[Woodygb passed the Golden Motor information along with the caveat, "THIS DOES NOT CONSTITUTE AN ENDORSEMENT." Has anyone had experience with this company and/or its products? My contacts with them have been productive, but I haven't had any hands-on experience with their products or found a functional US dealer.]

[Woodygb also observed in a previous post that he didn't think that "the board" would approve of my project. Could I ask: What's that about? Is this site something other than an arena for an interchange of ideas?]

With the knowledge that bolt-on kits were available to power a wheelchair (if not from Golden, then from some other supplier), my project objectives have changed. What do you guys think about the idea of developing a bolt-on kit that could be used to convert ANY wheelchair from manual/assistive to power? The direct advantages of such a product would include: Universality - the kit would bolt onto any popular model wheelchair, and a user could retain his original chair; Economy - $1000 - $1500, compared to ? for used power chair; Flexibility - the kit would be easily removable when or if the for power assistance was no longer needed; Light Weight - the kit would add under 50 pounds to the weight of the chair. Incidental benefits would include those accruing to what amounts to a basic redesign of the suspension system of any wheelchair.

Again: Comments (pro or con)? Constructive criticism? Just plain carping?
Thanks -
Neil Rose

[woodygb]

The board has seen this sort project before and your initial concept of taking a Tailwind and modifying it was almost certainly going to fail for a plethora of reasons.

The board simply passed on this judgement to you .


Your NEW project may work and the board WILL help if you have a specific question....but please give us enough HARD DATA to work with.

[Burgerman]

What do you guys think about the idea of developing a bolt-on kit that could be used to convert ANY wheelchair from manual/assistive to power?

For a full time chair user, that cant just get up and walk, theres quite literally zero advantages of an add-on power assist to a manual chair. The only sensible reason to use a manual chair at all is if you can get out, and so throw it into the car easily. At which point light is more important than power.

Theres nothing else that a power assisted manual chair does better. Its basically got all the disadvantages of a manual chair, and a powerchair rolled into one. The only sort of people that keep on trying to power a manual chair tend to be the ones that went through the sausage machine. They come out of hospital knowing they dont "need" a powerchair. And refuse point blank to try one... The system brainwashes them into thinking that they will lose something. In fact you just gain everything.

Once you start adding power you will see the shortcomings of an unstable manual chair, with tiny jam into every hole casters, skinny tyres. Lack of speed (stability, ride, safety) lack of range (thats why they have 70Ah batteries to move your lard all day) etc. Once you start trying to improve all this stuff you will end up with a powerchair...

Tell me, once finished, what does it do better than a GOOD powerchair? Remembering that its now heavy, less stable. And limited in range, control, and gives a horrid ride. And less comfortable seating, and tiny skinny wheels? Fix those issues, and you have a powerchair.

Thats my take, and I am not trying to piss you off! But I tried all this 20 years ago. Then my programming wore off.

[Dandydog]

Burgerman -
Can you please tell me a little more about how this site functions?
I'm used to the interchange of information and advice among enthusiasts that occurs on automotive forums in the US (and have successfully diagnosed and corrected a number of problems on my e30 with the help of other forum members), but I have no experience with anything else.
Who or what is "the board"? What assistance can they provide to users? What criteria are used to decide which projects/questions should be supported/answered? Have I been abusing forum regulations by trying to elicit suggestions and contributions from other members?
If I've inadvertently transgressed, I apologize - and I'll be glad to abide by any rules/restrictions your organization maintains, as soon as I understand them.
Thanks for your help -
Neil

[woodygb]

[Burgerman]

You asked:

What do you guys think about the idea of developing a bolt-on kit that could be used to convert ANY wheelchair from manual/assistive to power?

And I replied in depth.

Thats my take, and I am not trying to piss you off! But I tried all this 20 years ago. Then my programming wore off.

You are doing nothing wrong, its just that there are o lot of people that have seen it all before, and can tell you before you waste your time why it wont work, or work badly. The real problem is that even the manufacturers started off this way, many years ago. And after years of trying to make stuff more useful ended up with a normal powerchair we see today. Adding power to a manual chair is fundamentally flawed for many reasons. Which is my take, and thats what you asked for.

If you ask a technical question there are many that will help. But we will need a bit of info to work with.

[Dandydog]

Guys -
Could you please tell me a little bit about how this forum is organized?
My only other experience with online collaborative problem-solving is on automotive forums in the US. On the ones I've used, anyone with a problem can post a request for assistance or information, and anyone with experience and/or time on his hands can respond, with a sort of caveat emptor vibe to the whole system.
From several of your responses, I get the impression that your site is managed more actively, and that I'm not really reaching a significant population of wheelchair users with a wide range of experience. Is this the case? (If so, isn't that sort of like setting up a Suicide Prevention Hotline, and then screening the calls? [No offense intended.])
I'm very interested in being an active participant in your forum, and I'll look forward to hearing from you again.
Neil

[Burgerman]

Just a bunch of users, a couple of manufacturers, some chair tech guys, and so on. Anyone interested can reply, as I did.

[woodygb]

As B.M. say's this forum is just a bunch of users with a general leaning toward improving power wheelchairs for their own/others benefit.

When you have some hard data present it to the board / forum and we WILL attempt to HELP...

Please note that negative comments ...with an explanation to as why they are negative ...is HELP.

I'm able bodied and just have an interest in this and building Robots / Battlebots .

[Dandydog]

Borg Guys -
Okay - assimilation will be great, so long as my yielding will help produce some actionable ideas.

Here's where I went after you showed me the Golden Motor kits:
Assuming that Golden (or another company like that) is producing a useable propulsion system (wheel/motor units, CU, controller and battery pack), then all I've got to do is work out a mechanical system for attaching those components to a manual wheelchair.
I had an old iGlide in the garage, so I stripped off the assistive-power components, ending up with a wonderfully light frame/seat/front caster unit. The iGlide frame has no rear cross-member, so I fabricated a brace and mounted it to the frame about 2" above and 7" in front of the center of the old drive wheels (that's where it fit most easily).Then I built a couple of trailing arms and hinged them to the new cross-member; I attached new drive wheels - 8" spares from my parts bin, standing in for the motorized wheel-units that I'll order if this mule seems to work - on the trailing arms about 18" from the pivot point, so that the footprint of the chair remained the same as it had been originally (i.e., the rear edges of the new 8" drive wheels lie in the same plane as the rear edges of the old 24" wheels.) Finally, I added a pair of ~5" braces between the frame and the trailing arms, so that the ride height and dump were the same as the original (18" seat height at the rear).
At this point, the chair looks weird: it's got a long wheel-base (over 30" from the front contact patch to the rear), and the trailing arms are nearly horizontal - I'm guessing about a 20-degree inclination from horizontal (but the plane of the arms runs right through the original drive-wheel center, by design.) Ungainly-looking as it is, the rig is adjustable as hell, and I'm happy with it as a test mule: I'm on the verge of biting the bullet and ordering a $900 power system. (That's why I'd like to get input from forum members who may have had experience with Golden Motor.)

As to why I'm working on this project: A standard power chair simply does not work well for our circumstances, and I can't imagine modifications that would make one suitable for our particular preferences. We live in an old house with narrow doorways; we travel a lot, and we can take Sandy's narrow Tailwind right into the aircraft cabin to transfer into bulkhead seats, and the chair is light enough to be carried down the aircraft's access stairs to the baggage compartment; we normally use a ramp-equipped van to get around, but whenever we want to really enjoy the Rockies we can sling her chair off the back of my e30 BMW and take a trip with the top down; and when it snows heavily - which it does often up here - I haven't even been able to get the M300 out of the garage.
We won't be able to use a power-assist chair forever, but Sandy would like to stay in the Tailwind as long as she can, and I can extend that period by equipping the chair with an easily-removeable full-power system. (Right now, she's had an operation on her left hand and can't use the regular wheels easily: anticipation of this condition is what started this project.)

As I mentioned, I'm pretty satisfied with the mule, but I'd still appreciate some help: I'd like to hear from forum members about their experiences with Golden Motor, or get referrals to other companies with similar products; I'd like to hear ideas on how to jury-rig the mule to test it under power without laying out a grand for the Golden motors; I'd like references to detailed documention for similar projects (successful or not-so-much) that I can use to enhance my understanding of the feasibility of this project; etc.

The mule is out in my garage right now, waiting for something to power its rear wheels.
It's snowing like a bandit, with about a foot on the ground already.
We're headed out - with Sandy in her Tailwind - to a movie.
Please let me know what you think of the project -
Neil

[woodygb]

Upload some photo's of the "mule".

I doubt very much that anyone on this forum has experience with Golden Motor's wheelchair products.... we can however probably extrapolate possible performance from the motor specs.

Have you considered a complete chair from Golden?

https://www.youtube.com/watch?v=B4dvs5uv6_Y

https://www.youtube.com/watch?v=CvTuIi8-zZI

[steves1977uk]

https://www.clintonrivermedical.com/tailwind-features Some info on the Tailwind... Personally I'd look for a lightweight powerchair from China.

Steve