- #1
constlurker
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So first of all, hello! I have a question - how much of a torque a car needs to produce that a wheels would start slipping? Let's say i have a car which weights 3200 kg, and has a wheel radius of 0.4394m. So I've been told that to calculate that, i need to do the following procedures(thats very basic):
1.) Calculate normal force:
F = 3200 * 9.81 = 31392 N
2) Multiply normal force by a friction coefficient(lets say its 1) and wheel radius:
T = 31392 * 1 * 0.4394 = 13793,64 Nm
3) Divide by number of wheels:
T/4 = 3448,41 Nm.
And we get the result - to slip a wheel you need to send to the wheel 3448,41 Nm of the torque. Is that true? How accurate is this method if its true? What about if a car has a rear wheel drive? A wheel will still slip if it reaches over calculated torque? Or you need 2x amount of that(for both wheels)? I'm just confused here..
I need that because I'm calculating a set of gears, and I've calculated that a car at it's peak can send a total amount of 9000 Nm(after all gearing), and that's just crazy amount of torque - gears will be just too big if i would try to calculate them to withstand that. So i know that a wheel will start slipping much earlier and a wheel will never reach 9000 Nm, and that's what i need to calculate - how much of a theoretical torque a wheel can get in a worst case scenario with an LSD differential(i've been told that theoretically in a worst case scenario, one rear wheel of a rear wheeled car with an LSD differential could get a full torque from an engine).
1.) Calculate normal force:
F = 3200 * 9.81 = 31392 N
2) Multiply normal force by a friction coefficient(lets say its 1) and wheel radius:
T = 31392 * 1 * 0.4394 = 13793,64 Nm
3) Divide by number of wheels:
T/4 = 3448,41 Nm.
And we get the result - to slip a wheel you need to send to the wheel 3448,41 Nm of the torque. Is that true? How accurate is this method if its true? What about if a car has a rear wheel drive? A wheel will still slip if it reaches over calculated torque? Or you need 2x amount of that(for both wheels)? I'm just confused here..
I need that because I'm calculating a set of gears, and I've calculated that a car at it's peak can send a total amount of 9000 Nm(after all gearing), and that's just crazy amount of torque - gears will be just too big if i would try to calculate them to withstand that. So i know that a wheel will start slipping much earlier and a wheel will never reach 9000 Nm, and that's what i need to calculate - how much of a theoretical torque a wheel can get in a worst case scenario with an LSD differential(i've been told that theoretically in a worst case scenario, one rear wheel of a rear wheeled car with an LSD differential could get a full torque from an engine).
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