Steam & Excursion > A Cab Forward Puzzlement

A photo posted today by Fiftyfooter shows one of those SP Cab Forwards leading into the photo from the left.  https://www.trainorders.com/discussion/read.php?11,5172303

I'm noticing the condensation lines on the side of the tender, and see that the tender has a well defined interior slope sheet for a coal space into which a form-fitting oil bunker had apparently been inserted.

With a probability of somewhere close to zero that these locomotives would ever be converted to coal, why would the designers have not simply incorporated an oil tank into the tender design, as they did with early oil tenders such as the whalebacks?

-LD

 

For what it's worth, pretty much ALL of those oil bunkers where shaped like that, since the bunker receiving area of the tender was designed that way. Regardless whether it could ever have been converted to coal, that seemed to be the "standard design", which also provided for maximum water capacity.

If you look at the SP Vanderbuilt tenders they have an angled rear sheet in the oil bunkers too.  Why did they do it that way?  I don't know.  Maybe it was because the engineers designing the tenders lived in the east and as far as they were concerned all of the tenders were designed that way.  Probably a better reason is that it would funnel the oil to the drain hole.  Luckily I never went into the oil tank to see what it looked like on the inside.  The water tank has baffels in it to keep the water ftrom surging back and forth.  Maybe having the oil tank angled plus the higher viscosity of the oil kept the oil from surging.

The oil tank had steam heat coils to heat the oil so it would flow. The heaters and the oil outlet were at the bottom of the tank.
The sloped surfaces formed a sump at the bottom of the tank to do this.

wingomann Wrote:
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> If you look at the SP Vanderbuilt tenders they
> have an angled rear sheet in the oil bunkers
> too.  Why did they do it that way?  I don't
> know. 

Sure, on a tender that may conceveably be converted to coal someday.  But, on a cab forward?

-LD

LarryDoyle Wrote:
-------------------------------------------------------
> wingomann Wrote:
> --------------------------------------------------
> -----
> > If you look at the SP Vanderbuilt tenders they
> > have an angled rear sheet in the oil bunkers
> > too.  Why did they do it that way?  I don't
> > know. 
>
> Sure, on a tender that may conceveably be
> converted to coal someday.  But, on a cab
> forward?
>
> -LD

You still need a sump at the bottom of the tank so that the pick up is always covered by fuel oil.
Otherwise you'll suck air and lose suction.

Or anywhere in the West?
Coal was long gone...

Bill Deaver
Tehachapi, CA

GUYS......The SP burned bunker C, a thick oil that had to be heated to flow from the ternder to the boiler and was the bottom of the barrel of oil...

Advantage of seperate drop-in oil fuel tanks on :

- If it leaks, say at a rivet that connects the oil bunker and water compartment, fuel oil it can't get into the water. 

- Can remove bunker occasionally to clean out gravel and other heavy fuel oil contaiminants. (SP 2472's fuel oil bunker had about 2" of this gooey graveley crud at the bottom. The S.P. had set the oil burner pointing towards one corner of the firebox to compensate for it being partially clogged with this crud. Long before the first fire-up after restoration, we had H&H Ship Service steam clean the bunker and vacuum out the heated gooey crud.)

- Fuel oil bunker is thermally isolated from the water tank, so a cold load of fuel oil will heat up faster when the fireman turns on steam to the heating pipes inside the bunker. (Bunker C should be heated above body temp to flow well and burn cleanly. Fog-temperature Bunker C flows (or more correctly doesn't flow) like cold molasses.)

- Doug Debs

LarryDoyle Wrote:
-------------------------------------------------------
> A photo posted today by Fiftyfooter shows one of
> those SP Cab Forwards leading into the photo from
> the left. 
> https://www.trainorders.com/discussion/read.php?11
> ,5172303
>
> I'm noticing the condensation lines on the side of
> the tender, and see that the tender has a well
> defined interior slope sheet for a coal space into
> which a form-fitting oil bunker had apparently
> been inserted.
>
> With a probability of somewhere close to zero that
> these locomotives would ever be converted to coal,
> why would the designers have not simply
> incorporated an oil tank into the tender design,
> as they did with early oil tenders such as the
> whalebacks?

While cab forwards used a pressurized oil delivery system, it is important to realize the shape limits sloshing effects on fuel flow when level is low and helps with head pressure on both pressurized and non pressurized systems. Also heated oil tanks need to be insulated from the water sections of the tender or the boiler feed systems may have trouble operating.  It is also important to realize that the SP did not always keep the same tender on the same locomotive for a locomotive's life.  The 2-8-0's were always getting different tenders as their assignments changed.  The tenders could be assigned to other locomotives latter if managment decided to make changes.  Toward the end of steam on the SP you did see larger tenders for certain classes of larger power and their older tender passed down.

Dreamer




>
> -LD
>
>