D51 steam locomotive trivia

[bikkuri bahn]

While looking at Tenshodo's die cast HO scale D51:

 

http://item.rakuten.co.jp/tenshodo/10771005/

 

I noticed the quite large boxy structure on the tender.  It reminded me somewhat of the head brakeman shanty or "doghouse" found on the tenders of many steam locomotives such as those that operated in the state of Texas. However, in this case I found out this box was an auxiliary tank containing heavy fuel oil (apparently in this model, a type "B" tank, 3000 liter capacity).  This further piqued my curiosity- why is a coal burning locomotive carrying a good amount of fuel oil?  Well, after some searching the net, it seems the fuel oil injection was a modification used to provide additional power (a "boost" like water injection for jet engines) on heavily graded lines. Also, another function of oil injection was to reduce soot when running through long tunnels. D51 types equipped with this feature were common in Tohoku, I suppose due to the particularly mountainous nature of the region.  

 

This was the first time I heard of this practice, does anyone know if this was done on railway systems in other countries?

 

 

prototype picture of said tender and auxiliary fuel oil tank:

 

http://niigata1116.com/sl/uetsu/1971/d515121-1.jpg

 

detail of the piping connections (in this case a smaller version on a C62 type, but I assume similar layout):

 

http://eagle.blue.coocan.jp/C62_EVO/C62_photos2/C62P2_tc623/09r.jpg

 

video of a triple headed freight in the Tohoku region- all three D51's have the auxiliary fuel tanks (starts around 5:15):

 

http://www.youtube.com/watch?v=Fd2h-qeuhNA&feature=related

[westfalen]

I think I've read of British steam locos being dual coal/oil fired during a lengthy coal miners strike and the resulting shortage of coal, but this is the first I've heard of it being done on a regular basis for this purpose. Very interesting, you learn something new every day.

 

BTW interesting video. I think whatever the engines were burning the cab of the third one would not have been the most pleasant place to be going through tunnels. When I travel round Japan I often think how difficult some of the lines would have been to work in steam days.

[Triplex]

Dual firing was used on German class 45 2-10-2s and on many Romanian engines.

[marknewton]

Does anyone know if this was done on railway systems in other countries?

 

Yes, it was fairly common around the world - railroads in Europe, the USA, South America and Australia all used coal-oil firing at different times.

 

Having said that, there are two distinct methods of dual-firing. One is the method used by JNR, where the coal fire is the primary source of "hot", and the oil is used to increase the firing rate beyond what is possible with coal alone, at times of high demand.

 

The other method is where the oil fire is the primary fire, and the coal fire is fairly small, and is mainly to enable a quick relight of the oil burner if needed.

 

Cheers,

 

Mark.