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# How do I calculate the torque required for linear motion?

## How do I calculate the torque required for linear motion?

(OP)
Hello everyone,
I need a motor for my project, but I´m not quite sure if my calculations are correct.

I need a motor to move a 500 kg horizontally (linear motion), where the friction constant is 0.8. The speed should be around 0.3 m/s

To calculate the force required to move the object:

F = m * g *u , F = force, m = mass of object, g = gravity constant, u = friction.

F = 500 kg * 9,82m/s2 * 0.8
F = 3924 N to overcome the frictional forces.

Calculating the motors torque:
T = F * d, where T = torque, F = force, d = radius of wheel
T = 3924 N * 0.101 m
T = 396.324 Nm

Are my calculations alright? Since the torque calculated is the torque that will be needed to overcome friction i will obviously need a little higher torque to account for acceleration.
Will selecting a motor of 420 Nm be alright? with 4 motors I would need 105 Nm motor for each wheel.

Do i need to use a gearbox motor for this purpose? Kindly correct me if I did any mistakes in the previous steps, and how to approach this forward as well. TIA

Kind Regards,
Khuzaim Khan

### RE: How do I calculate the torque required for linear motion?

Your friction estimate is ridiculous. That's roughly what you'd get by scraping a block of rubber on concrete. I'd guess you are using wheels?

Cheers

Greg Locock

New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

### RE: How do I calculate the torque required for linear motion?

I'd never bother calculating this stuff but would instead use a spring scale to measure it. Then add %50 to the prototype to get the show on the road.

Keith Cress
kcress - http://www.flaminsystems.com

### RE: How do I calculate the torque required for linear motion?

Did you account for the inertia of the motor and wheel(s)? Also, your excess torque drives the acceleration, so how quickly do you need to accelerate to speed?

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

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