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Buddy boards

Postby Irving » 19 Aug 2019, 05:05

shirley_hkg wrote:
youtu.be/F8fpUXcyr7s

We've been travelling in our Chinese way for 2 decades, 50_ish Km a day.


@Shirley _hkg Is it common to see partners riding buddy boards like that? I've never seen that here. Do you have some close up pics.
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Re: Buddy boards

Postby stevelawiw » 19 Aug 2019, 16:38

trolley.jpg
trolley.jpg (31.88 KiB) Viewed 4578 times

Made my own a few years back, no one I know will ride on it! A compete waste of time :roll:

Shirley I can see why having more top speed is so attractive to you, those completely flat, long straight roads must get boring if you're using them daily at 8.5 mph :problem:
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Re: Buddy boards

Postby Scooterman » 19 Aug 2019, 16:53

Your's is similar to this one http://www.epc-wheelchairs.co.uk/spares ... ry-trailer

I bet your one didn't cost 300 quid to make?
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Re: Buddy boards

Postby stevelawiw » 19 Aug 2019, 17:11

No but I did have to buy a kettle to make the mudguards and some springs to make it hold upright when not in use.
Oh and my box of ally offcuts took a hit :lol:
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Re: Buddy boards

Postby Scooterman » 19 Aug 2019, 17:23

Roller skates!

Small expense zero work. A win win solution ;)

PS Clever idea for the mudguards :thumbup:
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Re: Buddy boards

Postby flagman1776 » 19 Aug 2019, 17:27

Buddy boards have been discussed before. I think if I was going to do it, I'd mount it to spring loaded hingesS on the rear frame. For support, I'd use swivel casters.
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Re: Buddy boards

Postby flagman1776 » 19 Aug 2019, 17:38

no longer able to use my TravelScoots
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Re: Buddy boards

Postby shirley_hkg » 20 Aug 2019, 03:10

Irving wrote:@Shirley _hkg Is it common to see partners riding buddy boards like that? I've never seen that here. Do you have some close up pics.



It started as only two studs alongside with the anti-tippers for kids. Now they are practical attachment , allowing us finding joys as we suffer.

You have to get rid of the high pitched low magnitude vibrations from cracks of pavement. Otherwise it is not usable , because their feet will go numb in no time. The faster you go , the harder they feel.

I used to have the casters taken most of the load. However , the best way is to let the chair's pneumatic big wheels as shock absorbers. So I added the chain & shackle.
Casters land on the ground only at starts and pickups to stop wheelies. .
:dirtbike :dirtbike :dirtbike
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Re: Buddy boards

Postby flagman1776 » 20 Aug 2019, 04:00

Thanks Shirley. It's interesting about the vibrations.
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Re: Buddy boards

Postby shirley_hkg » 20 Aug 2019, 05:07

stevelawiw wrote:Made my own a few years back, no one I know will ride on it! A compete waste of time :roll:
:problem:

I knew that , of course . Must do shock absorption of some kind .

YOUR'S is too narrow, that their feet can't change position.
AB stands with their feet apart, not adhered together. Board should be as wide as you could take .

Fit axle doesn't seem right for wheels to maneuver freely.
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Re: Buddy boards

Postby flagman1776 » 20 Aug 2019, 18:24

Shirley, How is your center of gravity affected with a carer / rider on the back? DO you have to move your seating forward or was it not moved back like BM to start with? I see your assistant step was originally sprung... and that wasn't enough cushioning.
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Re: Buddy boards

Postby shirley_hkg » 21 Aug 2019, 04:33

I didn't alter my seat position. It doesn't bother me much. Buddy's caster is adjusted @½ an inch above ground when still. Weight will be transferred to its caster when chair starts to wheelie and just that . Simply adjust my driving attitude to a less aggressive manner, and will be all good from starts till going up inclines.

It does make difference , itsn't it ?
It's not the extra weight, but the higher CG of the person standing , instead of sitting. Adjust ourselves a bit , and will be alright.

My buddy is 120 lb. 5½ ft.
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Re: Buddy boards

Postby shirley_hkg » 21 Aug 2019, 04:46

flagman1776 wrote:Shirley, I see your assistant step was originally sprung... and that wasn't enough cushioning.

It is bearable at speed of 5--7 km an hour.
We used to go at over 16 , and long time .

I never broke a bearing in 15 years. Seems its robustness outweighed my anxiety .
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Re: Buddy boards

Postby Williamclark77 » 22 Aug 2019, 23:23

Here's one I made out of scrap. The larger pneumatic tires make the ride easier on the passenger. When we go places my younggun rides on it (she picked out the casters. A $5 Harbor Freight item). It hangs on the back of the chair from a clip on the crossbar. One day I'll stick a piece of aluminum plate on it for better foot support.

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Re: Buddy boards

Postby Williamclark77 » 22 Aug 2019, 23:23

Here's one I made out of scrap. The larger pneumatic tires make the ride easier on the passenger. When we go places my younggun rides on it (she picked out the casters. A $5 Harbor Freight item). It hangs on the back of the chair from a clip on the crossbar. One day I'll stick a piece of aluminum plate on it for better foot support.

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Re: Buddy boards

Postby stevelawiw » 23 Aug 2019, 10:43

I had pneumatics on mine to start with, but with the inner tubes being so small they didn't last long so mine are just solid now. I wanted the larger sized wheels to use it off road, we have a music festival here every year and I useually wear out anybody walking beside me after a day or two bless them :lol: But as I said before they never wanted to be on it while sober, and in any other state they would probably step off and possibly hurt themselves :roll:
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Re: Buddy boards

Postby Williamclark77 » 23 Aug 2019, 13:46

stevelawiw wrote: sober


That always makes a difference! drunk2
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Re: Buddy boards

Postby flagman1776 » 23 Aug 2019, 22:01

I was easily able to take a passenger on the rear bumper of my off-road Pride Wrangler. However the foldable arm-chair back is unstable and is lacking hand holds. I dare say passenger hand holds are critical.
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Re: Buddy boards

Postby shirley_hkg » 05 Jun 2021, 10:52

cheers
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Re: Buddy boards

Postby Rollin Positive » 08 Jun 2021, 00:09

I did one too back in 2015 but it really impacted battery drain and steering

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Re: Buddy boards

Postby Burgerman » 08 Jun 2021, 04:14

Well physics...

Weight is everything. If you double the weight of a user/chair combo then you absolutely need double the motor power (double the torque) at every speed, at every turn etc. And it may be that the chair itself cannot even do that. It also takes double the power out of the battery at every speed and at every manoever. And worse, the faster you take the power from the battery the less you get in total. Because of a gentleman called Peukert who was evil.

So double the weight will really give you only a 1/3rd the range. And need 2x the torque.


Exactly the same happens to me.

Given 2 identical chairs, you are light. Estimate 9 stone or less? I am 20+ stone. Total chair/user weight up by maybe 50%.
So I will get WAY less range from a lead battery than you do. Probably half as much when you also factor in peukert values.
So I would get 7 miles you might get 15.
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Re: Buddy boards

Postby Rollin Positive » 08 Jun 2021, 19:15

Did you notice too it was attached to a Pride chair...enough said

Mine popped up and out of the way when not being used so they people could jump on and off when needed but yeah good idea terrible when executed

Good idea for lithium battery users that can afford the extra running time
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Re: Buddy boards

Postby Fred005 » 16 Jun 2021, 20:42

Burgerman wrote:Well physics...

Weight is everything. If you double the weight of a user/chair combo then you absolutely need double the motor power (double the torque) at every speed, at every turn etc.


Wrong, weight does't affect max speed.
You'll need more time/distance/fuel, but independently of the vehicule weight the max speed will not be affected.
I ignore influence of tires crushing wich is nothing. And load is inside the vehicule not on top of the roof.


Burgerman wrote:Well physics...

.....It also takes double the power out of the battery at every speed and at every manoever. And worse, the faster you take the power from the battery the less you get in total.


Ok, for that.
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Re: Buddy boards

Postby Burgerman » 16 Jun 2021, 21:06

Weight is everything. If you double the weight of a user/chair combo then you absolutely need double the motor power (double the torque) at every speed, at every turn etc.


Wrong, weight does't affect max speed.


I never said it did. I said it doubles the power needed from your motors. And that happens. You draw much more amps, and do actually go slightly slower. Read again. I said current increases at every speed as mass increases. And that current increases at every speed with taller (faster) gearing too.

In a car or a fast bike where the primary force you are fighting is aerodynamic drag it takes 4x the power in watts or horsepower to double the speed. Because thats the square law of speed/drag.
In a slow thing like a 6mph wheelchair where we never travel fast enough to make aerodynamic drag a big part of the equation it absolutely does take more power as you increase the mass. The primary force that stops us traveling at our low speeds with zero amps (or zero power) is drag from tyres. No tyre friction or losses and we would have infinite range. And we have very little... Tyre losses increase pretty much in line with mass. Thats why its damned hard work to push your low pressure tyre'd chair manually. It takes power! Its also much harder to push it faster. The mass on those tyres absolutely increases the rolling resistance. As well as the amps required to move it at a given speed. And its the main retardation force at low speed.

So no I am not wrong. Dont believe me? Measure Amps when you drive your chair.Then try that again when its being driven by RC as I already have. All my chairs are RC capable and its something I already did test long ago. An empty chair draws many less amps at constant speed than one with my fat 20 stone sat in it. Typically half. And because of that I need a profile with a lower motor load compensation or its jerky to drive. And it also draws more proportionally with me in it (MUCH more) at every turn, every manoever, every transverse slope. As well as at any/all speeds.

You'll need more time/distance/fuel, but independently of the vehicule weight the max speed will not be affected.
I ignore influence of tires crushing wich is nothing. And load is inside the vehicule not on top of the roof.

Wrong. Tyre rolling resistance is a huge part of the frictional load in a slow moving device. Its the largest one at 6mph probably 90% or more of the total frictional losses. Now in a fast moving vehicle like a car, its top speed is almost unaffected by weight. It just slows acceleration. Inthis case the largest resistance to speed is the air you are forcing yourself through and accounts for almost all the engines power. THAT doesent care (much) about mass. The tyres make only a very small addition to the total drag, which is mainly the huge air drag at the top speed. That doesent really come into things at the speeds we go in wheelchairs. At 6mph its barely measurable. So tyre rolling resistance is everything. And it increases with mass like 20 stone of me sat on top of it. Pretty much proportionally. If you were powered by a fixed output petrol engine then the heavy chair would be slower. DC motors dont work that way. They draw more current as you load them up. So you draw more amps, and go only a tiny bit slower. Because more Amps x 24V = MORE POWER.
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Re: Buddy boards

Postby Burgerman » 16 Jun 2021, 21:18

Calculating rolling resistance

This equation is used to calculate the force of rolling resistance from each tyre:

FRR = CRR x weight

FRR is the rolling resistance force.
CRR is the coefficient of rolling resistance (a number used to rate each tyre at a given pressure),
weight is the force due to gravity being exerted on each tyre (= mass (kilograms) x 9.8).

The type of tyre and the mass of the bike plus rider are the only two variables.
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Re: Buddy boards

Postby Fred005 » 16 Jun 2021, 22:07

About tires, I don't agree with you.
Except if you over load tires.
But if you stay in the manufacturer specifications (weight vs pressure), gross weight will not affect tires efficiency (not sure of my english, sorry !!!).
But fore sure, in a perfect world, without the need of tires/wheels, it'll be better for everybody.
Even if wheel is a good invention !!!
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Re: Buddy boards

Postby Burgerman » 16 Jun 2021, 22:28

No.Tyre rolling resistance is very well understood. Not only tyres. ANY rolling surface. Any materieals. It is directly related to the mass it carries. Same formulas even work on rails. A loaded train takes much, much more power (torque) to maintain a constant speed. In the case of rubber which makes heat as it is deformed internally this is siple to understand. But in the case of steel wheels and steel rails you may find it harder to comprehend. But its still true that double the mass = double the rolling resistance. Applies to all rolling systems.
In the case of a heavy train. It deforms the wheels, deforms the rails as its mass increases. In the same way that a tyre deforms. And the road surface moves under the vehicle weight. EVERYTHING double when the mass boubles. That gives twice the loses and twice the rolling resistance. This isnt noticed in fast vehicles only because it makes up maybe 2 or 3% of the total drag/resistance. But it IS noticed when there IS no air resistance. Or very little as in a 6mph chair.
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