How many box cars can a train pull?

Question

The most I ever counted was 245 cars. Seven engines were pulling it (not sure if all were working). Anyone know how many a single engine can pull?

Answer 1

It all depends on the locomotive used.... some are more powerful than others..... and the weight of the freight wagons.

For instance, the British Class 59 Diesel loco (based on a US SD40-2), as far as I'm aware still holds the record for heaviest load pulled by a single locomotive in the UK - it managed in a test to pull 40 x 100tonne Hopper wagons (despite the tracks being coated in wallpaper paste to simulate poor adhesion conditions), recording a maximum tractive of 114,000lbs.

A week or so later the same loco managed to pull 4,300tonnes while at the sametime pushing a pair of Class 56 diesel locomotives (which weigh about 126tonnes each)..... before that, the previous most powerful UK Diesel locomotive was the Class56, which had a maximum pulling capacity of 2,300tones (23x100tonne wagons).

Answer 2

to add on to tom-sj's answer.

The most powerful locomotives in use today are 6,000 hp weighing well over 200 tons.

the 1 ton/1 hp is usually only true going UP HILL.  You need far less to get a train moving on level ground.  Many trains can maintain speed or gain speed going up a 1% grade at about .7-.9 hpt.  

As for the BNSF railroad, as long as you are within .5 of the scheduled HPT you should be able to make any of the hills on that particular territory.

BTW  it would depend on the cars... whether they are loads or emptys.  An empty car weighs approx 30 tons, and a load weighs anywhere from 70 tons to 143 tons.

Answer 3

To move cars in a switching yard, not a lot power is required because a single locomotive basically drags a single car, which then pulls its neighbor, and so on all the way down the string of cars.  In a yard, when a switch engine moves a string of cars with all the slack in, the effect is like crack the whip as you hear the movement from the start to the end of the train.

To move a train of cars a long distance up and down grades, the story is different.

In the US, a rule of thumb for mostly level track is 1 horsepower per 1 ton of freight.   A 100-ton coal car (among the heaviest loads) would require a 100 HP locomotive to move.   Therefore, a 100-car train of 100-ton coal hoppers would require 10,000 horsepower of locomotives.    

The most powerful diesel-electric locomotives (SD-70 or AC-4400) these days can provide up to 4,400 HP in a single unit - so one of those could conceivably pull 44  100-ton coal hoppers for a long distance on mostly level track.

Going up hills, a locomotive's pulling power is significantly derated.  Other folks such as Hoghead can tell you exactly what are the derating factors, which are limited by the ruling grade percentage in the particular territory.