Fuel Tenders

That isn't ignorance. It's a good question.

A tank car / fuel tender coupled between locomotives in an MU consist is subject to pulling, pushing, and braking from both locomotives. The bigger the car / tender, the more force affects it.

A tank car coupled behind a locomotive is subject to forces in the train - not from a powered unit behind it.

A big car like the one on the photo has to be beefed up to deal with 4400 hp from each unit.

If railroads start using LNG to reduce fuel costs, some sort of fuel tender will be required. That will have to be beefed up, too.

A tank car in front of a pusher at the train doesn't have a powered unit in front, so the same applies there.

Fuel tenders between locomotives are back, for liquified natural gas (LNG) powered consists.  This time, they are designed from the beginning for their specific task and position in the consist, rather than being modified tank cars.

If you Google "BNSF LNG TENDER" you'll get lots of pictures and info.

Thanks for the info ReadingFan and The GN Man.  Now, I have to find one for my layout.

I thought your topic was very interesting, but I could find nothing on the reasons for their demise. That left me to assume that the reasons for their need were resolved with modern diesels.

This website, MountainWestRail, with detail on the Burlington Northern, hints at various issues, including frame stress, but, seems to indicate in 2002 that they (diesel fuel tenders) were returned to service for certain uses.

Canadian Northern, BNSF and UP are testing duel fuel engines with LNG cars. You can find examples of these and some of the manufacturer's information while searching. Technology advances to allow the equipment that returns the LNG to CNG has improved and is now on the fuel tender and advances in the engine design are making this attractive along with significant fuel cost savings, of course.

A closer look at LNG  

Fuel Storage-LNG locomotive tender car

The common link for these, as most railroad equipment, is cost. The fuel tenders also address the convenience of nearby supply(or lack thereof).

Did you have a link to an article that discussed the forces imparted to rail cars?

Ok, I found your article UP fuel tenders

"UP had four tank cars converted to serve as diesel fuel tenders 1995. The cars were numbered as UPT 5 to UPT 8, numbered following the four LNG tenders (UPT 1 to UPT 4). The diesel fuel tender program was initiated in late 1995, placing a single  fuel tender between two new General Electric C44ACs. The combination of a fuel tender connected between two locomotives was usually assigned to unit coal trains coming out of the Powder River Basin in Wyoming. The fuel tender program came to an end due to wear and tear on the fuel tenders themselves, since tank car frames are not designed to take the buffeting and differing longitudinal loads that locomotives are designed for. The tank cars used were standard tank cars, which are also not designed to take the high mileage of being coupled between locomotives (approximately 90,000 miles per year, about four times what a standard tank car would see). The   program was in operation during  from approximately July 1996 through May 1998 (date range supported by dated photos of fuel tenders in service). All of the fuel tenders were out of service by April 2000, and stored at Council Bluffs at UP's Fox Park passenger facility. They were still there as late as June 2002. (part from Trainorders.com, January 26, 2006; see also an article by Michael McGowen in "Union Pacific Modeler", Volume 3, pages 84-91)