# motor torque racing simulator

#### sason

Hi guys,
I am building a motion racing simulator.
i am trying to calc what are the characteristics of the motor that i need.

i want to raise 80 kg (160 lbs) with a servo motor
the motor is connected to a 8" (20cm) arm. the arm is connected to the weight, and needs to raise it 180 degrees from buttom to top.

i need it to achieve 2 g's and 75 rpm.

i thought using a planetary reducer, ratio 1:40 ,and a servo motor that turns at 3000 rpm
i calculated that a motor rated at 200w and 0.6nm (times 40 after reduction will give me more then enough torque) will suffice.
is that correct ?
can you show me the math ?
Thanks a lot !

#### oz93666

I think using power ratings of a motor may lead to inaccuracies . The input power (VxI) will not all be converted into torque , and the power and efficiency vary with revs ....

Some motors do have a torque rating ... e bike motors are a good example ,

This one "has a rated power of 250-750W, a reduction ratio of 1: 5 and a maximum torque of 80 N.m," (\$200)

That maximum torque is probably at zero revs . So if the lever arm connected to the motor was 1 meter , the force at the end of the arm is 80N ... It could hold a 8kg weight when the arm is horizontal ... more when not horizontal.

But your arm is 0.2 meter you have a 5:1 advantage . So the above motor could hold 40Kg horizontally.

If you want the same motor to accelerate the mass at the end of the lever , you must reduce it ... An acceleration of 2gs of the mass means , when horizontal , the mass experiences 1g from gravity and 2 g from acceleration = 3g

So the mass must be reduced threefold ...40/3 = 13.333Kg

This gives a rough indication of the power of motor need to do what you want ...Many KWs!!

Here's the torque chart for a bigger ebike motor .... this would be a brushless motor

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