Were/are SD-7s used frequently on branchline small trains in addition to being good for switching large tonnage? I read somewhere that supposedly three axle diesel locos work better on lightly used track. Were there any railroads that bought them just for branchlines?
Yes, besides the normal duties any high horsepower CC would still hold to this day, they were often used on branchlines and as heavy switchers and were bought by some customers for those purposes.
Union Pacific's 10 examples are an excellent example. They were bought for the purpose of hauling heavy iron ore trains, heavy switching, and to replace steamers and Alco RSC-2's on branches with light rail and bridges.
They're idealy suited for light branchlines due to their lower axle loading due to spreading the weight of the unit across two additional axles. It's not much different then standing on thin ice that might break under you but is more then able to support you if you were laying down and spreading your weight across a larger area.
And if you had exceptionally light rail, a poor roadbed, and lightly built bridges, in years past you might've even purchased an A1A unit (Such as a GMD1 or Alco's various RSC models). That way the weight of the unit is even lighter due to having two less traction motors while also still spreading the weight of the unit across 6 axles.
Yes, some railroads bought their SD7s ballasted relatively heavy (for the time), while others bought theirs unballasted and with small fuel tanks to operate on branchlines with lightweight rail.
Examples of heavy SD7s were those bought by GN, B&LE, B&O, and PRR. Lightweight SD7s were bought by C&NW, and MILW. But even lightweight SD7s weighed more than their counterpart GP7s and so made better "heavy" switch engines.
beaulieu Yes, some railroads bought their SD7s ballasted relatively heavy (for the time), while others bought theirs unballasted and with small fuel tanks to operate on branchlines with lightweight rail. Examples of heavy SD7s were those bought by GN, B&LE, B&O, and PRR. Lightweight SD7s were bought by C&NW, and MILW. But even lightweight SD7s weighed more than their counterpart GP7s and so made better "heavy" switch engines.
On another thread in the "General Discussion" forum a poster raised the question on 4 axle versus "lighter"6 axle power for shortlines...I pointed out that there are not that many light 6 axles available on the used locomotive market.
That got me thinking about Southern Pacific and their large fleets of SD7s and (especially) SD9s, many of which remained in service well into the 1990's...was Espee's preference for 6 axle early EMD's largely for the way the units performed on branch line trackage?
"I Often Dream of Trains"-From the Album of the Same Name by Robyn Hitchcock
ndbprrAll the PRR SD7 engines were relatively stock with the exception of the induction trainphone antennas. Two were purchased for the 5.98% MAdison ncline in Madison Indiana. Those engines had frames almost double in thickness to help.adhesion on the grade. The PRR stock engines were used primarily in transfer service.
PRR had only two SD7's, purchased specifically for Madison Hill and were heavily ballasted, equipped with dynamic brake and rail washers but were not equipped with MU. One of them later turned up on TRRA. PRR also had 25 more conventionally equipped SD9's.
Oregon has a large number of SD'9's still in use.Portland and Western has a handfull with some in SP paint that are used daily.The Port of tillamook bay railroad in Oregon has many ex BN SD'9 that were still in their colors.They were used daily with some trains having 3 or 4 SD'9s on the train.A few years ago a river flooded and took out some track connecting the POTB to the outside world leaving the locomotives stuck in Tillamook bay with no where to go.The railroad has ceased operations but will probably repair the track and get back to business one day.
I believe BNSF still uses a few SD'9s in yard service.Seattle had one or two still kicking around.There is many other SD'9s and SD'7s still in service all over America.If you buy the offical roster of locomotives book(which is printed every year) that little book will tell you every locomotive on every railroad in America.You can narrow down what model you are looking for by skimming the information listed under the names of the various railroads.
Our community is FREE to join. To participate you must either login or register for an account.