I’m having a hard time finding information about the differences between a B30-7 and a C30-7… Can anyone explain them? Thank you.
Both are 3,000 hp (available to the main generator) locomotives. The significant difference is a B30-7 is four axle and the C30-7 six axle, and the C30-7 has to be longer to accommodate its two three-axle bogies. Mechanically they are essentially the same, and electrically the same other than the extra switchgear necessary to power six traction motors instead of four.
The “B” and “C” are codes for number of powered axles in a single bogie (aka a truck), which is common for diesel-electric, diesel-hydraulic, and electric locomotives.
A = 1 powered axle
B = 2 powered axles
C = 3 powered axles
D = 4 powered axles.
1, 2, 3, 4, etc. - unpowered axles.
Thus B-B is a locomotive with two bogies, each with two axles both powered (like a B30-7); A-1-A/A-1-A is a locomotive with two bogies, only the outside axles powered in each bogie (like an E9); B-B-B is a locomotive with three bogies, all axles powered (there are some electric locomotives so arranged); D-D is a locomotive with two bogies, four axles each, all powered (like a DDA40X), and so forth.
B30-7s were designed and typically assigned to through manifest freight and intermodal trains where the train is planned to have enough horsepower to maintain speeds of 20 mph or greater over the route, and average train speeds of 40-50 mph. C307-s were designed and typically assigned to drag freight and unit trains where the train is planned to have much less horsepower, and only be able to maintain speeds of 12-13 mph on upgrades, and average train speeds of 20-25 mph. The two extra axles and two extra traction motors enable the C30-7 to be able to put all of its horsepower onto the rail and do useful work at low speeds, whereas at low speeds the B30-7 will have to limit its horsepower output to in order to not exceed its ability to maintain adhesion to the rail. The extra axles and traction motors, and longer and heavier frame and bogies of the C30-7 not only cost significantly more
Thanks for the info! Not what I thought I would get, but definitely what I needed to know!