Eight notches allowed reasonable control throughout the range of zero to everything. The concept also allowed MUing locomotives as only a few wires, energized in various combinations, could control the unmanned locomotives through the notches.
People Also Ask
The 4-6-2 locomotive became almost globally known as a Pacific type after a New Zealand locomotive that was shipped across the Pacific Ocean.
As wireless technologies advanced in the 1960s, freight railroads began adding extra locomotives to the rear of trains to give them enough power to climb steep hills. This is how distributed power was born.
Anyway, the reason for using two locomotives is pretty simple. Twice the number of locomotives means twice the power. This extra power boost is used for especially heavy loads or for trains going up steep grades.