Locomotive Performance and Tractive Effort Discussion

Maybe population density is something to do with it. If you were a volunteer, on average you would have to travel something like twice as far as someone in the UK. There is something missing though; you never see crowds of people at the lineside for steam specials, like you do in the UK.

 

Q. Oil Firing
For a Coal fired loco getting the draughting reasonably correct to give a suitable draw of air over / through the firebed is a key factor in performance and /or efficiency. Does a loco converted to oil firing need this to be adjusted significantly ?

 

I've never seen it mentioned on the engines converted over here in 1926 and post-WWII. There were no changes to the draughting of Middle East 8Fs converted to oil.

 

Given that there is no unburned fuel loss in an oil burner what does that do to efficiency and performance?

 

Union Pacific begs to differ!



Tom

 

Holcroft goes into a lot of detail of the system implemented on a small number of locos by the SECR, essentially as a learning exercise in case a wider role out was needed in a hurry (such as a coal strike).

The whole ethos seems to have been to prioritise cost of equipment and ease of fitting (understandable given the use case).

Two locos - an H class 0-4-4T and an E1 4-4-0 had a system based on that developed at Derby by the Midland Railway. There is detail in Holcroft’s book, but in essence fire bars, grate and ashpan were unaltered. The lower half of the firebox below the brick arch was lined with firebrick, and against the tube plate. The bars were covered with two layers of firebrick round the edges; the hole in the middle was then filled with broken firebrick and limestone. An oil tank was carried on the tender or bunker, with oil supply pipe, control valve and a steam supply (for atomising the oil) fed through the fire hole door.

Small amounts of coal were burnt in the back corners, which helped maintain firebox temperature when the burner was shut off (and also I think acted as an ignition source).

Apart from that, Holcroft doesn’t mention any other substantive changes. Air supply seems to have been primarily through the grate, ie primary air, drawn by smokebox vacuum in the normal way.

A single L class 4-4-0 was adapted using the “Scarab” system, which was all oil (no coal fire) and a slightly larger conversion, though still ultimately reversible. (From Holcroft’s description, and what I have seen of the “Big Boy”, it seems to me that they were not disssimilar). Of the two systems, the Derby one seems to have given less trouble in the fireboxes, presumably due to maintaining a more even temperature.

Holcroft dates that using the Derby system, if the parts were to hand then an engine could be converted in 48 hours at a cost of £110; and could be converted back to coal firing in 8 hours.

Subsequently a number of locos of other types were converted during the 1926 coal strike, using the knowledge gained by the SECR in 1921.

Tom

 

Suppose one difference is that a bed of coal burns faster / hotter when more air is being drawn through it with a slight lag between increased regulator and response in the fire box, the fireman is adding coal in anticipation of future demand as well as current consumption. With oil firing the amount of heat produced is more dependent on how open the tap is and calls for a different approach to ' firing'.

 

I was just about to say something similar myself. The draughting would need to be set up to produce enough heat to evaporate the required quantity of steam. I don't know whether a ton (for want of a suitable quantity!) of air would produce more heat when used to burn coal or oil.

 

Thats the difference - depends how much oil you are putting in... quite possible ( and possibly problematic) for the loco to be working very hard with an instaneous cut off of fuel, therefore heat.... aaargh lots of cool air rushing through the tubes. or for the loco to be steady but with the oil on too heavy maybe to get the boiler pressure up ( like that -photo above ?)

There must definitely be an art to it, just a slightly different one to coal firing...

 

Instructions from (probably) Ron Jarvis for oil firing an 8F.

 

Timely that the subject of oil firing should come up as the NYMR have recently announced that WD 3672 Dame Vera Lynn will be returned to service as an oil burner when its overhaul is complete. The railways's CME (Paul Middleton) having recently visited the U.S. to gain information and experience. 3672 has the advantage of a steel firebox and existing oil firing drawings. I've no idea whether it will be light or heavy oil that will be used. Oil firing is quite common with industrial boilers using package burners made by the likes of Nu-way and Riello. However, they have the advantage of having an electrical supply to both pump the oil through atomising nozzles and drive a fan for combustion air. Battery technology has come a long way in recent years; perhaps that may be the way ahead?

 

Precisely the reason that this subject came to mind...

 

This may be of interest then if we are discussing oil firing. Thanks to Chris Hext, formerly Swindon drawing office, for giving me this copy. As an anonymous company produced the document and 70 years are up copyright isn't an issue.

 

Thanks for this. From a quick glance it would seem that the equipment referred to in this and the document provided by LNS2968 are essentially the same. Certainly the drawing of the burner is identical.

 

Duplicate post deleted.

 

https://sugarexpress.com/faq/

This I’ve had an eye on for a while. Really interesting conversion.

 

what type of oil were they burning in BR days if it needed a heating coil in the tender and a pre heater? presumably something fairly viscous, what are the thoughts on the type of liquid fuel proposed to be used now, kerosene or a heavier oil?

 

There were 3 Tilbury tanks ,One each at Wellingboro'41966,Leicester 41938 (stored at the closed shed at Wigston )and Toton 419??.All taken away in the early 1950s and scrapped. I was told they were used for heating the oil for oil burning 8F s

 

Fairly sure it was pretty heavy stuff back then ... nowadays i think something like diesel or even recycled cooking oil perhaps ?

 

I think it was simple bunker oil, as used by ships.