In a typical brushless motor, the torque is proportional to the magnetic field from the rotor times the current in the stator (non-rotating part). The best conv

In a typical brushless motor, the torque is proportional to the magnetic field from the rotor times the current in the stator (non-rotating part). The best conventional magnets and conductors (neodymium-iron-boron and copper) can only generate a certain amount of torque without overheating due to the I^2R loss in the copper. This isn't nearly enough for most applications from driving vehicle wheels to robot joints, so motors need a step-down gearbox. For something like a walking robot knee joint, it needs around 15:1 torque multiplication. This makes it move "robotically", and not be able to absorb the impacts of running and jumping. A superconductor can handle much larger amounts of current than copper, and maybe also generate a higher magnetic field in the rotor, so you could get much higher torques directly from the motor. Superconductors still aren't ideal -- they stop being super in really high magnetic fields, perhaps because the electrons are moving in curves rather than straight and the complicated quantum effect that causes superconductivity doesn't work. But plausible superconductors could give great results.