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| Line 10: |
Line 10: |
| | **When no power is applied, a spring closes the brakes | | **When no power is applied, a spring closes the brakes |
| | ***A manual clutch can disengage the brakes entirely | | ***A manual clutch can disengage the brakes entirely |
| | + | * Doing the math, each motor is approximately 1/5 HP (Thank you Mark!) |
| | | | |
| | =Motor Requirements= | | =Motor Requirements= |
| Line 34: |
Line 35: |
| | *100 Just in case | | *100 Just in case |
| | Total planned weight capacity: 1000 lbs (450 kg) | | Total planned weight capacity: 1000 lbs (450 kg) |
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| − | ==The Numbers==
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| − | Once we have the above, we need to calculate the required horsepower, torque, RPMs, etc. Please, if you find an error below, contact me or correct it; I'm a decent mathematician, but I am NOT an engineer! (I can do the math, but I don't really understand the numbers.)
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| − | *r = wheel radius = d/2 = 13in
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| − | *c = circumference = 2 * PI * r = 81.68in
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| − | *v = velocity = 10 mph = 880 ft/min = 10560 in/min
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| − | *speed = v/c = 129.28 RPMs
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| − | *T = torque on wheel = torque on motor
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| − | **T = rF or F=T/r
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| − | *F = Force on wheel ~= (safety factor) * weight = 2 * 1000 lbs = 2000 lbs
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| − | **For the moment, using a 2x safety factor. Some sources have recommended 5x.
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| − | I've plugged these in to some formulas, and gotten back a requirement of 53.333 HP, but since the current chair is probably 1/3 to 1/2 HP, I'm guessing that there's an error somewhere.
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| − | Of course, some of the error may be the fact that the numbers represent the amount of power required to ''lift'' the chair, not roll it, but that still seems out of line. Considering I can push the chair at 3 mph fairly easily, and I'm certainly not as strong as the average horse...
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| − | Would anyone like to take a crack at this?
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