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# design of a motor

## design of a motor

(OP)
i have to design a motor(power) driving a mass of 450kg(car) at 30km/hr,any ideas of formulas giving power & losses ,which i have to take into consideration

### RE: design of a motor

Here are some ideas that I hope will help. Determine a torque at the wheels based on the weight x a rolling coefficient of friction (Mark's HB has values like .02 for this). Next, determine the rpm of the wheels based on the speed you want to move the load at. Now, the horsepower would equal T x rpm/63000. Also, take into account any losses due to powertrain efficiency. For example, if you are driving through a gearbox, the efficiency can be as low as 70%.

### RE: design of a motor

Firstly you have to specify either if you want to pull the weight over a straight or inclind surface as the pull force will be changed depending on the slope angle.

once you you find the pull force [F]which is equal to friction force[mass x g x cos (slope angle)x friction coefficiet]plus horizontal component of the weight parallel to inclind surface [mass x g x sin( slope angle)]

Motor power (kW) = F (kN) x Speed (m\s)

You have to multiply by sfety factor to compensate the motor efficiency.

I hope the above is helpful,
best regards,

Khaled Muhsen

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