Common carrier. A common carrier in common law countries (corresponding to a public carrier in civil law systems, usually called simply a carrier) is a person or company that transports goods or people for any person or company and that is responsible for any possible loss of the goods during transport.
Best Answer: Torque is a twisting force. It is the power output of an engine at one specific point in time. The first number, 200 in your expample, is the amount of torque. In America is is measured in foot/pounds. The second number, 400 in your example, is the RPM where that torque number occurs.
In that sense the RPM limit is down to how well the engine is made and what it's made of rather than any fundamental EM properties. The torque is dependant on how large a magnet field the engine generates, and this is mostly dependant on the current it draws and the number of turns in the coil.