This question appears to be off-subject matter. The customers who voted to shut gave this unique cause:"questions on the use of digital devices are off-subject matter as this web site is intended particularly for questions about electronics design." ?? laptop2d, derstrom8, dave tweed if this question may be reworded to in shape the rules in the assist center, please edit the question. One more factor to hold in thoughts is that the real working speed for a motor like that is determined by way of the weight. With the motor disconnected from the weight the velocity can be close to 1500 rpm regardless of the relationship. The weight will slow the motor down. The medium and low connections make the motor weaker so it slows down extra.