GM EMD SD40-2

One of the problems with the popular "carbody" units was that the strength lies in the shell itself with it's stressed and re-inforced walls; rather than in a rigid underframe. If you take the sides off an f-unit, it will fall apart, making it difficult to undertake major repairs on the locomotives.

The introduction of the GP7, the first "road switcher" in 1949, marked the beginning of the end for the attractive carbody units that were critical to EMD's early success.

With experience in diesel operation came better understanding of the problems of diesel maintenance; and it became clear that the most attractive scenario involves using the smallest number of the largest possible locomotives to achieve the required power.

This thinking inspired a demand for locmotives in the order of 3000hp, double the output of the famed f series; and in 1965 EMD issued a contender with it's new 645 cid prime mover. The 645 2 stroke v engine, available in several configurations, would eventually become something of an industry standard.

A battle ensued over the next few years that saw the developement of a range of locos by various manufacturers, including the 4 axled GP40 and the 6 axled SD40, SD for Special Duty.

The SD40-2 was a result of a series of revisions in this fiercely competitive climate, and from 1972, began to take it's place as the best selling US locomotive ever - sales approaching 4000 by the end of the 70's. The largest orders for SD40-2s were placed by Burlington Northern, whose roster of 900 units comprised a quarter of the total fleet.

This is considered the world's most reliable and cost-effective diesel electric; and is a favourite among crews and railfans alike.

Resources

General Data

SD40-2 Gallery - Northeast Railfan.Net - EMD diesel trains