Hello all,

I’d just like to let you know about our new product the Nordigo wheelchair propulsion system. You can see the system on our website www.nordigo.ie.

The design has not been fully finalised so any input would be welcomed.

The Nordigo system is fitted directly to the wheelchairs frame allowing the wheels to be removed just like on a standard chair. It is very compact and light, at the moment it’s weighing in at 4kg, total.

Hi,

There is one point that I see maybe a drawback from the video on your website, and that is to go forwards, you have to pull the levers towards you.

For those who are higher paraplegics, and those with balance issues this may be a problem, as they have no trunk stability, so would just fall forwards.

It would be better if you had to push the lever away from the body to move forwards, as you could get more energy behind the levers as your back would be braced against the wheelchair back.

Regards

Simon.

It has come up. At the moment the Nordigo is very direct in the way it transfers the power to the wheels. We're looking into being able to push rather than pull and it would also opens the door to introducing gears.

At the moment we're keeping the design as simple as possible, we're trying to shave as much material off the brackets and arms as possible to keep weight down. The design is pretty straight forward at the moment so there's little that can actually go wrong and brake.

The other big benefit of keeping the design simple is of course it keeps the price down. I don't have a confirmed price but we will be competitive.

I'll second the point about reversing the thrust engagement. Balance is an issue for many SCIs. You get several benefits by having the power stroke going away from the user. One, better balance for the user. Two, more leverage and power with the user's back braced against the chair back with less energy expenditure.

Another point. If you put about a 10-15 degree bend in the levers just below the hand grip, the grips will be more vertical and give better leverage/power.

Just my opinion. As a quadriplegic, your device would be quite useful and be a power multiplier, especially on uphill grades. Keep up the good work.

Something like the red line in this photo?




We have done some experimentation with the arms,



There is the possibility for some customisation when it comes to the arms, we'll also need to add some sort of guard to the system which hopefully will also allow for more customisation as it would just be a cover. Personally I see allot of potential for customisation and even user customisation.

Are there any improvements that could be made to the website?

The design needs wheels with pins on the backs of the hubs. Fit slightly longer axle sleeves, one extra sleeve nut, and a low profile ratchet system, and it's done with just about as little weight, especially with the right alloy. This system is pretty heavy, which pretty much defeats the purpose of ultralight chairs...

Sorry I haven't responded sooner; been off the board for a bit. The bend would be most beneficial if the power stroke was changed to pushing away from the user's body instead of toward it. If you keep the power stroke as-is, the bend might be unnecessary.

OK so we're working on being able to push rather than pull, I'll post again when we've that done. Its a bit busy though at the moment so it may be a while. We have an otto bock, blizzard here that we'll attach it too.


What weight do you think we should aim for? I think we would be doing good to get it down to 3kg to be honest. I believe it's already the lightest system available.

From the design pictures, there is no mechanical power advantage, but rather a speed advantage. That would be great for somebody very strong. However, if you add 3kg weight to the chair, then you would need at least double that in power advantage in order to make the system feasible to begin with. That is where my concern with the weight lies- the lack of power advantage. Similar to the power advantage of the drivelines on sport motorcycles- small sprocket at the power source, and larger sprocket at the back wheel. From the look of the pictures here, the power advantage is going to be very slim. On the site, there is a listed benefit of "a natural rowing action." I don't see how it's natural as designed. Having to pull the levers is odd enough, but having to pull them up is slightly disturbing, as it can cause a lot of back problems. I may be incorrect (somebody tell me if I'm wrong), but I would think that people would want to avoid further stress on their backs. As well, adding that extra 3kg to the chair would make the chair that much more difficult to load and unload. I don't know how many others break down their chairs and load them in their vehicles, but I do when it rains. That extra 3kg and extra chair width would make it much more difficult to load/unload. Not trying to be too negative here, but if you're trying to sell these, please don't show the chairs being used and wheels being taken off by able bodied individuals only in your videos. I noticed the guy showing off the quick release wheels walking up to the chair and taking the wheel off. He even seemed to be working pretty hard at it when he was rolling around in the chair... Would probably do a LOT of good to have a few paras and quads try the system out to give you some real feedback. Maybe I'm wrong about your system, but I can't justify the extra weight and bulk.

It's I don't see it as negative, I appreciate what your saying and your right in a way. Many of the other systems on the market have been coming at the problem from that angle. Trying to make a device that will make it easier to push the chair around. But that is just one type of wheelchair user and there are products out there to carter for that. We're trying to get the Nordigo system to work for that type of user but it's design suits a more active wheelchair user.

I think that we should keep our focus on making the Nordigo system work as a wheelchair add on that brings added functionality to a standard wheelchair for those that want it. It should help increase the range of someone who would like to do more in their wheelchair.

That's why I'm out here asking questions, maybe we're completely wrong in focusing on a sporty set up, but from what I've seen around the internet there is a demand for it there.

The videos on the site are more a demonstration of the concept and features. We do have two guys touring Ireland and the UK visiting medical and rehab centres, sports teams and wheelchair distributors. The points you bring up about ease of use have come up. Again, we're talking about two completely different products (in my mind), I suppose the only way around it is with gears, it's just that's going to make it expensive.

Hey I got tho's same exact kenda tiers on my chair =]

Hi,

I have designed a lever drive wheelchair also. Most of the points raised in this topic have been addressed on my prototype.

1. Pushing or pulling the levers.
If you pull to go forwards then you pull your body forwards as well.
If you push to go forwards then you can tip also the pulling muscle group is far more efficient than pushing.
The solution is to drive while pushing AND pulling - push one lever away and pull the other back at the same time. This gives no forces on the body either forwards or backwards as the levers act as braces to push or pull against. If you drive when pushing and pulling there is no wasted effort re-setting the handles for another power stroke & gives a much smoother ride.

2. Gearing.
Any lever drive wheelchair must have a range of gears otherwise it will be too slow for stronger users or too dificult for weaker users. No two people are the same so a single gear is a poor compromise.
My solution is a continuously variable transmission with a 400% range, it will automatically select a lower gear when the pushing load increases.

3. Weight.
Although an increase in weight is not desirable it mainly affects the lifting of the wheelchair.
When travelling the increase in weight is not noticeable as a few kgs is a small percentage increase in the overall weight of the chair AND occupant. The extra weight gained is a small price to pay for the overall advantages gained.

4. Width.
Spaces are tight enough already & any increase in width should not be included in any design.

If you would like a detailed explanation please see the website:

http://jouleflow-water-features.com/page_1185858893451.html

There is also a video on youtube at:

http://www.youtube.com/watch?gl=GB&hl=...p;v=nM_L9ot2TFY

I hope these points are useful.

How does a person transfer into this chair? From the photo, it looks like the levers/fenders block both sides.

" From the design pictures, there is no [ 1. mechanical power advantage, ] but rather a speed advantage. That would be great for somebody very strong. However, if you add 3kg weight to the chair, then you would need at least double that in power advantage in order to make the system feasible to begin with. That is where my concern with the weight lies- the lack of power advantage. Similar to the power advantage of the drivelines on sport motorcycles- small sprocket at the power source, and larger sprocket at the back wheel. From the look of the pictures here, the power advantage is going to be very slim. "

1. Regarding the mechanical power advantage,
There is little to be gained mechanically unless the length of the drive lever is greater than the radius of the pushrim. A power advantage can be acheived if the system is geared down as suggested on motorcycles, but this will make the unit unreasonably slow. Without gears we have two choices.
a. Climb hills & travel slowly.
b. travel fast & struggle uphill.

The advantage with the lever drive system is the muscle groups used. By using larger & more efficient muscle groups more power can be delivered to the wheels. The lever drive system is a way of harnessing this power that is unavailable conventionally.

The best & most powerful set of muscles are for pulling. Although pushing can utilise the backrest as a brace, when pushing hard uphill the chair always wants to tip backwards. You then have to lean forwards to counteract this, eliminating the advantage of using the backrest as a brace. Pulling the levers in the same situation not only gives a power advantage but significantly helps to counteract tipping.

Hope this is useful.

That is an interesting project webby. Being able to use constant drive (pushing and pulling) is a major benefit. I wouldn't agree about the weight issue at all though. Having a heavier wheelchair will make it harder to push. You don't see race car drivers striping out their cars for no reason. Obviously your drive system makes it allot easier to propel the wheelchair but that metal transmission looks heavy. Perhaps this is just down to it being a prototype and much more weight could be saved with good manufacturing techniques.

Can the system be attached to any chair?

Of course the most important question is price. Having all these features is great until you realise the cost is so high it prices itself out of the market. You can try and build the system to last but then a system with so many moving parts is more prone to failure.

An update on our own system: We've shaved a little bit more weight off the system, but the main focus has been on gearing and we think we've made a big improvement in ease of use without sacrificing to much speed. I'll get a video up as soon as possible demonstrating the difference between the two gearings.

Hi Nordigo,

thankyou for your comments, I appreciate that you recognise that the way forward is with push & pull driving. No wasted effort in re-setting the handles & having driven several systems over the years it is definitely a much smoother ride.

There are a lot of different opinions regarding weight as I have said a few kilos extra in my experience does not seem to make pushing harder. A bag of sugar on your lap to me felt no harder than without.

My feeling is that lightweight wheelchairs tend to be better engineered with higher quality bearings & better balance & these contribute more to the sportiness than the odd half kilo. The biggest effort required is to move the occupant as this is the most weight by far compared to the wheelchair.

I design & manufacture these prototypes myself on a shoestring budget so I need to build them strong enough to work first time to prove the principles. Once the principles have been proved & tested then large manufacturers can refine the design & save weight.

The new unit can be fitted to most chairs but will not work with folding chairs. I could follow standard design conventions & split the drive either side but this will add width to the chair. I set out a list of features that I believe are required & adding no width at all was a very important issue.

There are a lot of moving parts but they are engineered from first principles & are proven techniques that work together.

I am not too concerned about price, this is research that demonstrates what can be acheived.

There is a natural tendency to relate these "sporty" lever wheelchairs to younger fitter occupants, I believe that they can also add independence to people who may be considering a power chair. There are huge health benefits to keeping active & a lever wheelchair may extend this activity longer before changing to a power chair. This system also gives more independence over a power chair as it can still be lifted into a car.

Just a quick final point. If I fit both brake levers on one drive lever then the system can be used with one arm only. So hopefully it will benefit another group of people that do not seem to have many choices of propulsion.

Please post again if you need further infomation.

p.s.
I am really struggling to get my prototype ready for the Kemble show, I have an old steel wheelchair that I may have to use unless anyone out there has one I can borrow please...

I think there's more to the weight issue than just being able to propel the chair, there's also dealing with the chair on a daily basis. Getting it into and out of vehicles, breaking it down. The lighter it is the easier it will be to deal with on a daily basis. Sometimes a chair may need to be lifted up at arms length. Once you go over 10 kilos it's extremely difficult to easily move that weight around while not sitting in the chair.

Hi,

yes you are right there is more to weight issues other than moving forward. My post #12 item 3 refers to the lifting of the unit.

There are two issues with weight:
Propulsion & lifting.

I appreciate that lifting the disassembled unit does indeed become more difficult when it is heavier.
I was replying to the comment on propulsion "stripping out race cars" a little extra weight does not have a great effect on this. If you are racing then you must indeed do all you can to gain even the slightest advantage.

It seems that there is a lot of thought going into weight reduction & little research into width reduction.
Generally the total width of a wheelchair is 7" to 8" wider than the seat width.
For example an 18" seat width wheelchair will be around 18+8= 26" in total width. Standard house door apertures that I have measured are usually around 29" this will give 1.5" a side clearance for the example above. This leaves little room to add lever drives without making it impossible to go through a standard house door.

The thinnest lever drive I have found is the Wijit it only adds 1" to the overall width by using specially designed wheels.
Another type, the Nudrive adds total of 2.8" to the original wheelchair width. These will still go through a 29" door if fitted to the example above. Both sizes are with 0 degree camber.

Hope you find the information informative.

I have different figures for the widths, according to their website.

The wijit adds 1.5" per side so that's a total of 3"
The Nu-Drive adds 1.4" per side, that's a total of 2.8"
Ours is currently the widest at 3.6" but there is scope to reduce the width a bit further we should be able to get below 2.8".

The problem with both those systems is there adding that width to the outside of the wheels, so your hands move further out. If your going to catch your knuckles pushing the rims, your definitely going to catch your knuckle using either of those systems that attach to the outside of the wheels.

This is not an issue with both our systems as the attachment is inside the wheels meaning your hand position is actually narrower and further away from any obstacles.

So far we haven't had a problem with getting in or out of doors but it seems the standard doorway in Ireland is 30" and we have chamber on every chair we've put out.

Hi,

sorry for the confusion regarding the wijit width.

I have looked again at the wijit site & there are two different widths given.
On the features page under "advanced ergonomic wheel design" it states that the wijit adds 1" to the overall width. However under the faq section it states that it adds 1.5" per side. I guess that the 1" refers to the width addition when the camber is around three degrees, or perhaps it means that just the wheel increases by1".

It is difficult to find an image of the wijit looking directly at the front to see how far in the handles come in at the top compared to the widest part at the wheel hub crown. You can just see from some images that the grip part of the handle is slightly inboard of the hub crown, giving a little clearance. They seem to acheive the handle clearance by adding a camber to the wheels. The wheels are tilted in at the top so that the ouside of the bottom of the wheel is directly below the hub crown. By doing this they do not increase the width. By adding this amount of camber & not passing outboard of the hub crown, (which is the widest part) they acheive an angled drive lever. This set up naturally brings the gripping part of the handles further inboard giving more "knuckle" room.

The Nudrive seems to have the same approach, because the levers are perpendicular to the axle whenever a camber angle is added then the top of the lever moves inboard.

There comes a point with both of these systems where the lever drive no longer adds width. If you take a standard wheelchair setup with a very large camber angle it becomes much wider at the base. By adding either of the two systems described above, the lever assemblies then lie completely inboard of the widest part of the wheelchair.

I have double checked my door widths & my doors are 30" wide but the door aperture has 1/2" of wood either side for the door to close against reducing the aperture to 29". One doorway for some reason is only 27" but an 18" seat width standard wheelchair would still go through at a total of 26" wide.

Maybe the "advanced ergonomic wheel" is an addition that can be purchased separately. It's hard to tell from the website if the wheel is part of the package, or an optional extra. It looks like what their saying is if you use this special wheel with the wijit it will only add 1" of additional width to the wheelchair.

I'd assume that camber is completely adjustable as it is in our system.

You can see on this page, http://www.nu-drive.com/nudrive/technical-specification/ that there is a little picture at the bottom right that shows the nudrive with a slight camber but on the wijits website http://www.wijit.com/gallery/ the 5th picture from the left (top row) shows an almost straight on picture of the wijit, in that picture there is quite a bit of camber on the wheels but the arms come straight up. In our system the wheel is parralel with the wheel and camber is added to both when mounting the bracket.




Well that would be quite a bit of camber probably more than is workable in the real world.

Hi,

I have looked at the images suggested & the handles do not seem to come in very far on those models. I reckon that 9 degrees of camber will negate a 1" additional width & around 11 degrees for 1.5". The larger cambered wheelchairs I was thinking of are the sport chairs that go up to 20 degrees.

The handmaster company seem to have made significant developments recently including a range of gears & even a form of ABS braking. They have managed to put all their mechanism inside the hub & offer a wide range of wheelchair types.

There is a full description at:

http://www.mycycle.si/My_html/Dodatki/Pdf/...GB_navodila.pdf

Just starting to assemble my "drive blade" system I will soon know if my continuously variable automatic transmission works. It will probably require several trials with different spring strengths to get a useable system. Still no luck finding a lightweight rigid wheelchair.

Will keep you posted.

I have put the lever project on hold for a few weeks as I am concentrating on a collapsible wheelchair that fits into a small flight case.

Please see website at http://www.jouleflow-water-features.com/pa...5812068108.html

Or Youtube video at http://www.youtube.com/watch?v=IEImgEHMHtA

Any feedback or questions welcome.

Greg.

Great idea, but where do you stow the case when you get back in the wheelchair?

Thanks for the reply,

the case is for storage & transportation if required.
In our testing for everyday use we just remove the wheels & pass them over to the passenger seat in a car. Then we retract the footrest & casters making the unit around 43cm long. The wheelchair can also be easily passed over to the passenger seat as well as it only weighs just over 8.5kg.

Greg.

Hi Greg,

As you've designed it to go in a flight locker, I was thinking more about air travel.

Presumably, when the plane lands, the chair would immediately be needed to get the owner off the plane. This requires two hands, so no hands left to carry the case and no stowage facility for it on the chair.

In which case (no pun intended) why bother with the case at all for in-flight stowage?
Obviously the answer is that the chair, as designed, when not assembled is a collection of disconnected bits that need a container to keep them together.

Wouldn't the chair be more practical if it broke down into fewer parts, or just folded up small enough to go in a cabin locker?

certainly looks good for travel, but the chair itself doesnt look like it'd be very comfortable for everyday use (although i could well be wrong, never having seen it in the flesh) but good idea in theory for travelling with limited space to store chair, would be interesting to see it

Forgive my ignorance guys regarding the propulsion system, but hasn't this already been done (much better) by Nudrive?

Or am I missing something?

http://www.nu-drive.com/nudrive/

edit - ok sorry just noticed in some of your previous posts that you mentioned the Nudrive!

Click to view attachment

Hi greybeard,

sorry for the delay in responding & thankyou for your comments.
Is is unfortunate that the case I used was called a flight case & perhaps gave the impression that the use was purely for aircraft transport. Anyway after more research & prototype building the ultralight collapsible wheelchair is now ready for production. Please have a look at the new website & see what you think.

www.jouleflowdesigns.com

Best regards,

Greg.

That is an awesome looking chair,, and a dramatic departure from current designs. I am intrigued by the disassembly possible.

But,, and there is always a but,,, it appears that this might not be the machine for those of us on the ,,, large,, size, who use their chairs,, shall we say, strenuously. What I'm trying to say is that I'm fat and I beat the hell out of my chairs. How heavy was the durability testing,, or is this more of a "dress" chair,, more useful for more sedate pastimes?

I have to admit,, this is a chair I wouldn't mind being seen in.
ed

looks good, price seems good until you realise it doesnt come with the rear wheels and pins, ok if your good at sorting wheels out yourself but my last attempt seemed to be fine until i lost a rear wheel going over the threshold of my friends door, if it hadnt been for the quick reactions of my assistance dog i'd have gone over backwards off the side of the ramp, so i for one wont be adjusting my own pins again!!

Hi wheelywendy,

thanks for your comments regarding supplying the wheelchair with wheels.
It was a tricky decision, we could supply cheap wheels to keep the price down but it would spoil the design of the product. If we supplied top end wheels then the price would be far too high & negate our efforts to produce an affordable wheelchair with so many features.

There is a youtube video at: http://www.youtube.com/watch?v=kEL8gX3rGco

Greg.

Hi Nordigo your website doesn't seem to work, as I can't fill out the Contact Form to contact you guys?

Do you have a e-mail?

Hi Bart,

Sorry about that problem, the website is back up and running again.

My email in mick@nordigo.ie

Hi Nordigo.

just a quick response to your initial post asking for input & suggestions.

Would you consider a variable gear system whereby the start of the stroke is in a low ratio & the gearing gets higher as you reach the end of the stroke. This will help when starting from a standstill & when cruising a higher gear will be more appropriate.
So; if ascending a slope then shorter pulls at the beginning will have easier effort.
When already moving then shorter pulls at the top end of the stroke will give a higher speed.
The gearing could then be set to suit the individual depending where the ratio starts.

Hope this helps with your development.

Greg.