I have a motor attached to a shaft with four gears. If I run the motor, I can stop the shaft moving by applying a torque opposite to the torque supplied from the motor. This is the thing. If the torque I apply is opposite to the shaft direction, I get a certain amount of friction. But if the torque I apply is so great that the motor runs in the opposite direction, then the friction from the gears is much greater! How can one explain this?