by Jay Potter
I wouldn't say that the other traction motors remain at "full power". I'd say that the reduction of power to one motor does not automatically cause a reduction in power to the other motors. For example, if a GE AC unit pulling upgrade encounters grease, the wheels on its number one axle will lose adhesion; and whatever power level is going to that traction motor will be reduced in an effort to regain adhesion. When the wheels on number two axle reach the grease, the power to that traction motor will be reduced, but only in the amount that is necessary to compensate for its wheels' loss of adhesion due to whatever grease still remains on the rail. The power reduction to number two axle should be less than the power reduction to number one axle had been because the passage of the first set of wheels will have conditioned the rail to some extent. This progression will continue, axle by axle, with the traction motor on each successive axle needing less of a power reduction than the preceding traction motor had needed. In other words, if you consider the aggregate power reduction for all six motors, there will be less of a reduction with single-axle control than there would have been if each axle had not been independently controlled.