DC Motors can be made to turn either clockwise or counter-clockwise by changing the polarity of the voltage applied to their terminals. The torque that is generated at the output shaft can be scaled up or scaled down by using a gear train.
What is torque? In simple words, torque is a quantity that decribes the ‘strength’ of a motor. A motor torque of 50 kgcm means that lifting a 50kg weight at 1 cm could be achieved with that motor. By the law of moments, lifting 50 kg at a distance of 1 cm is equivalent to ……
Lifting 500 kg at 0.1 cm
OR Lifting 5 kg at 10 cm
OR Lifting 0.5 kg at 100 cm
In most motors, like the one shown below, the gear train scales up the torque of the motor by using a reduction gearing that outputs a much higher torque (albeit at the cost of a much reduced output RPM).