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dc motor torque



Start torque and cruising torque must be taken into account for the choice of the dc-motor.

We have a force for the setting in motion then a force allowing to maintain the "regime" of cruising, which is weaker. 

Weight and friction occur: at start with the "initial friction" and at the cruising speed with the "residual friction".

We have to consider the slope to climb.

We reduce the problem to the calculation of a slope. 



Engine torque 5Kg.cm, Wheel radius 10cm, Wheel mass 1kg. 

Slope = ArcSin [deg] (Motor Torque [kg.cm] / (radius [cm] Mass [kilo])) = Arcsin (0.5) [deg] = 30 degrees. 

So if the slope is 25 degrees at startup there are 5 degrees for friction. 

We can estimate that in cruising speed the max slope will be between 30 and 35 degrees. 

The power is given by the motor because the torque is given at a speed of rotation. 

The electric power is also given by the example motor 12V - 8.5Watt Electric, 

with the torque and the speed of rotation 250rpm and the gearbox 1 / 34.02, 

I find 5.526 Watt mechanical Either a yield of 65%.