No, not 2 inches ground clearance but ground clearace reduced by 2 inches to less than 1 inch!
See attached Permolock C3 manual. I know it is in Dutch, but the English language manual I have seen does not mention the F5.
Burgerman wrote:Speed... Not really the manufacturers problem.
On the face of it its EASY to make a chair faster. You just use taller gearing, or different motor windings. (Same result)
Burgerman wrote:A 6 MPH chair is a slight compromise. The main difference is that the gear ratio (or motor winding etc) takes 1.5x as much power from the controller, and the battery, at ALL TIMES. At every speed. Even if you never go faster than the 4mph chair. As such all else being equal, you will have around 1/3rd less torque, and 1/3rd less range. So now its 12 miles, and it wont go up a curb as easily. ***This is simple physics and there's no way around this. It also needs a 100 to 120 Amp controller to give adequate ramp, turning performance, and sucks more from the battery.
An 8 MPH chair, takes DOUBLE the battery power to travel at the exact same speeds, and double the power (Amps) at every turn, and on every slope or ramp, as a 4 MPH chair does.
This is because of its taller gearing, needed to reach 8mph at 24V. So it has HALF the battery range. It has HALF the torque (all else being equal, but often the motors are "bigger" to help, using yet more power). This chair is extremely hard on batteries, and these reach end of life much faster, and because of something called the Peukert effect, You actually get less Ah from the battery if you discharge it faster. So making range even worse. These chairs use a 100 to 120A controllers (usually the latter) and its not adequate. So torque suffers. But that's the biggest the industry has, and more than the batteries can provide easily.
I'm surprised by this as I would have thought the 'work being done' is the same. In a scientific side to side test of a 4mph, 6mph, and 8mph, all travelling at 4mph round the same track. At the end of say 10 laps wouldn't all three chairs have done the same amount of WORK?
Burgerman wrote:
Speed... Not really the manufacturers problem.
On the face of it its EASY to make a chair faster. You just use taller gearing, or different motor windings. (Same result)
Scooterman: Which option do manufacturers tend to choose?
Also why don't powerchairs/scooters use AC motors? Could you not then chop up the DC supply into a sine wave and control the speed of the chair by varying the frequency and not the voltage? I'm not saying you would gain anything apart from higher speed perhaps on flat smooth surfaces, or downhill if you're brave All without sacrifying torque at lower speeds? I've probably made some wrong assumptions/conclusions/theory but if you don't ask you'll never learn
I used a lightweight rigid frame manual chair for years (along with my scooters). I stuck with the 24" wheels on my chairs, a lot of manual WC users fit 25" or even 26". But my philosophy was my arms aren't very strong and (unlike a bicycle) most of the time is spent stopping and starting, and I thought the larger dia wheels will only make it harder to push off from a standstill,
In a powerchair, if you can avoid a short very steep hill (such as on my route home). And take the little bit further but more gentler incline, then it's got to be better for deep cycle lead acid batteries which aren't designed to provide very high currents.
And if you can't avoid a regular really steep hill, then a lead acid user might be better going with an AGM battery? So it's not just seating functionality a user has to consider, also the powertrain should be chosen to match the weight of the user and how they use the chair. But you've already said that here, and in the main pages, numerous times! Lol
Burgerman wrote:Theres no gearing involved. The push rim is the same distance from tyre regardless of wheel diameter. So the rim goes at road speed regardless. So its exactly the same speed/force required regardless of rim diameter.
Burgerman wrote:If you want average performance, long service life, and fast charging doesn't interest you as much, MK gel cannot be beaten. Esp on 6 mph chairs and with lightweight users. It can not cope as well with heavy currents.
Burgerman wrote:Sonnenschein gel A500 dryfit, were the first company to develop the starved electrolyte gel system model. They licensed this technology to MK.
However. MK offer a 74Ah gel. So more capacity, and so lower impedance and lower average discharge level and better range.
Sonnenschein changed they 500 cycle batteries to make them cheaper... So now only 450 cycles and higher impedance than MK.
And the ultramax and haze are both cheap junk in comparison. Especially the ultamax...
If it were me, I would but MK gel, or if it will fit, even better the odyssey PC1500. One of the few places you get what you pay for is batteries. And the best lead batteries are not really adequate for a powerchair.
Burgerman wrote:I used a lightweight rigid frame manual chair for years (along with my scooters). I stuck with the 24" wheels on my chairs, a lot of manual WC users fit 25" or even 26". But my philosophy was my arms aren't very strong and (unlike a bicycle) most of the time is spent stopping and starting, and I thought the larger dia wheels will only make it harder to push off from a standstill,
Theres no gearing involved. The push rim is the same distance from tyre regardless of wheel diameter. So the rim goes at road speed regardless. So its exactly the same speed/force required regardless of rim diameter.
The pushrims look about the same diameter as the ones on my manual chair, but the tires are MUCH larger in diameter... I'd estimate at least 6-12" larger than the rims... This would presumably mean needing a lot of effort per stroke, but getting a lot of speed for a given stroke rate...
Slight disagreement - the push rim stays the same distance from the tire, but it's distance from the AXLE changes... This means that at any given road speed, the user would be pushing (moving) his arms through a larger arc at a lower speed, and presumably needing less effort to do so... Think of the difference between using a screwdriver with a skinny handle and one with a fat handle...
Burgerman wrote:The pushrims look about the same diameter as the ones on my manual chair, but the tires are MUCH larger in diameter... I'd estimate at least 6-12" larger than the rims... This would presumably mean needing a lot of effort per stroke, but getting a lot of speed for a given stroke rate...
The pushrims being smaller than the wheel or tyre is the ONLY thing that changes the leverage or gearing. The diameter of the overall thing doesn't. The top of the wheel is always moving at the same speed in mph in relation to the chair you are in, as the chair is to the road. That does not change no matter what size the wheel is. The LENGTH of the stroke that you can push increases, so it can become easier (or harder if your arms are short). But gearing does not change unless the push rim is noticeably smaller than the wheel.Slight disagreement - the push rim stays the same distance from the tire, but it's distance from the AXLE changes... This means that at any given road speed, the user would be pushing (moving) his arms through a larger arc at a lower speed, and presumably needing less effort to do so... Think of the difference between using a screwdriver with a skinny handle and one with a fat handle...
Incorrect. Distance from the axle makes no difference here, as the push rim is near enough to the tyre to consider as the same thing. The tyre is always going at SAME road speed as the chair is moving. So same speed/torque as before. Although it can give a longer push on a longer pushrim if your arms are long enough.
But for the case where the pushrim is the same distance from the tire, I agree there is no gearing change between the pushrim and the tire, but if you look at it as an entire system from the user's shoulders to the road, then there is an effective gearing difference with different diameter rims, as the 'crankshaft' length is different -
just as if you have different size cranks on a hand-winch - as long as the effort is reasonable it takes more effort to turn a short crank, but you can crank faster... A longer crank is easier to turn, but has a limit on how fast it is comfortable to turn it...
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