Steam & Excursion > Air Compressor Questions

I have a brass model of a USRA 2-8-2 that has a Westinghouse cross compound air compressor under the fireman's side running board. There is one air reservoir on each side of the engine, a large one and a small one. I would like to move the compressor to the pilot deck, in the same manner as Frisco 2-10-0 #1630. This leads me to the following questions...

Is there a correlation between the number of compressors and the number or size of air reservoirs? If I wanted to toss in an extra small air reservoir to fill in the spot where the old compressor was, would that be realistic?

On the 1630 or any other engine with a similar compressor arrangement, is there a brace that holds the compressor in place, or at least a platform it sits upon? Does the location of the compressor have any effect on the number of pipes running to/from it?

For reference, you can go to http://www.irm.org/gallery/index.html and search for 1630 photos. I have looked for an online well-lit detailed shot of the front of 1630 but have met with little success.

Thanks for the help. Maybe after I get out of college I can start applying some of the technical things I learn on this board to an actual steam engine.

Flowing Wrote:
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<SNIP>
>
> Is there a correlation between the number of
> compressors and the number or size of air
> reservoirs? If I wanted to toss in an extra small
> air reservoir to fill in the spot where the old
> compressor was, would that be realistic?

There were several air brake systems in use on steam engines, from two suppliers of equipment: Westinghouse Air Brake, and New York Air Brake. Though there were some variations in details of some systems, parts from the two manufacturers are often interchangable.

The A-1 system was standard from about 1895 to 1905.

The 5-ET system was used on new systems from about 1905 to 1910.

The 6-ET system was the defacto standard from 1906 to 1957. Varients of the 6-ET system were used on electric and diesel locomotives: 14-EL, 6-DS, 6-BL, and 6-BLC. I may have missed some.

8-ET and 10-ET systems were introduced in the 1920's, I think, and installed until the end of steam.

24 systems were developed about 1930 and used into the diesel era.

In 1957 the 26-L system, and the 30-CDW system which is a variant of the 26, became defacto standard, and some steam locomotives in use today use modified 26 brakes.

Except for the A-1, all of these systems use two main reservoirs, regardless of the number or size of the pumps. It would generally be inappropriate to put in a third main reservoir (though I believe it has been done - DMIR mikados and 2-8-8-2's come to mind as possibly having 3, but I'll have to check some photos) but you could add another small reservoir for some other purpose, such as providing reserve storage capacity for a power reverse, or something like that.
>
> On the 1630 or any other engine with a similar
> compressor arrangement, is there a brace that
> holds the compressor in place, or at least a
> platform it sits upon? Does the location of the
> compressor have any effect on the number of pipes
> running to/from it?

Westinghouse and New York pumps ae mounted on a bracket attached to the backside of the pump. Pipe connections to each pump, and to the control and lubrication lines for the pump would not be affected by changing the mounting location.
>
> For reference, you can go to
> http://www.irm.org/gallery/index.html and search
> for 1630 photos. I have looked for an online
> well-lit detailed shot of the front of 1630 but
> have met with little success.
>
> Thanks for the help. Maybe after I get out of
> college I can start applying some of the technical
> things I learn on this board to an actual steam
> engine.

Here is the piping diagram for 6-ET brakes, which is undoubtedly what the USRA 2-8-2 and Frisco Russian decks were equipped with.

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Back in 1954, when DPM and Dr. Hastings visited the DM&IR for an installment in the "Smoke Over the Prairies" series, David remarked that "the Missabe must have been an appliance salesman's dream, for its power is loaded with extra air reservoir tanks, feedwater heaters, siphons, coal pushers, speed reccorders, and VHF space radio equipment." One suspects that holding 'em in check on Proctor Hill's 2.18 per cent may have accounted for those extra air tanks. One of Phil's shots depicts Mike 1303 with 2 or 3 tanks ( hard to tell which from the angle ) on top of the boiler, twixt stack and sand dome. In the Two Harbors shop there is a shot of what appears to be a 2-8-0, no. 1219, with round brackets between stack and sand dome, obviously for holding air tanks, which have been removed during the overhaul. What fascinating power DM&IR had!

Yeah, I've heard of the DMIR's power described as looking like a magnet dragged thru the parts shop.

But, then, if you were the engineer taking 8,000 tons of iron ore down 10 miles of 2.18 percent grade that dead-ends a quarter of a mile out over the largest, coldest, deepest lake in the western hemisphere - you might find some comfort in some of those extra parts.

Maybe those tanks on top were to keep the engine upright if it went in the water.

Here's one of the 2-8-8-2's showing her parts collection, and 3 reservoirs on the top of the boiler. Note that the original 1910 Baldwin separable boiler is still in place in 1952, though the feedwater portion has been supplanted with an Elesco feedwater heater in an innovative location.

http://members.lsol.net/mollyandmick/D202.htm

MTM--"A magnet dragged through a parts shop" That's priceless. I love it.

What did you mean by separable boiler?

John G

Isn't the "separable" boiler the one on which the forward portion was supposed to somehow function in the same way as a feedwater heater? I've read about this, but can't recall the details. Another attack of "Oldtimer's" disease.

john1082 Wrote:
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> What did you mean by separable boiler?
>
> John G


Though the separable boiler was pretty much obsolete by the time the 1922 Locomotive Cyclopedia was
published, they did include this definition: "A boiler composed of two units joined together in a
separable joint. The rear unit forms the boiler proper with firebox and tubes, while the forward unit
contains a superheater, re-heater, feedwater heater and smokebox. Used on Mallet locomotives."

Take another look at that DMIR 2-8-8-2. There is an 8" wide band around the jacket just ahead of those three air tanks, behind the cold water pump. This covers the joint where the two sections were bolted together. Behind this is a conventional firetube boiler with an large firebox, suitable for mounting on a large decapod. The boiler is attached to the saddle of the rear high pressure cylinders.

Ahead of this joint is another boiler-like section, with flues for the hot gasses to pass thru on its way to the smokebox. Superheater elements from the header in the smokebox passed thru some of these flues in the conventional manner. A single large flue, about 15 inches in diameter contained a reheater, which was a bundle of very small diameter tubes thru which exhaust steam from the high pressure cylinders would pass before moving on to the low pressure cylinders - sort of a second superheater for the low pressure cylinders.

A space of about a foot or so is accessable from a manhole in the top between the front tube sheet of the boiler and the rear tube sheet of the separable section.

No steam was generated in the separable portion. It was basically a feedwater heater. The delivery pipe from each injector went forward to a check valve on each side of the separable portion. Another pipe from the top center of the separable portion then led back to the conventional portion of the boiler and entered the boiler thru a check valve on the side of the boiler. This check valve is still visible on No 202 below the air reservoirs, and is now (1952) being used for the delivery pipe from the Elesco feedwater heater that has been installed as an afterthought, and the separable portion is no longer used.

After DM&N (later to be merged with D&IR to form DM&IR) discontinued use of the separable feedwater heaters they had to do something to offset the weight loss of all that water carried on the front engine, so they filled up the empty separable portion with scrap iron. When one of these engines had to be shopped, it reportedly took about three days for them to cool down to be worked on!

All engines with separable boilers were built by Baldwin. Other examples of engines with this boiler include SP MM-1 and MC-1 and MC-2 2-6-6-2 and 2-8-8-2 engines, and ATSF 4-4-6-2 and 2-6-6-2 designs.

A variation on the separable boiler, tried in several variations by the ATSF, was to attach the separable portion rigidly to the frame of the front engine, and put a huge ball joint or an accordian joint between the two sections of the boiler. Those engines gave new meaning to the term "Butt-Ugly", but maybe some ATSF fan out there can give us picture of 'em, huh?

MTM, Your wisdom is a benefit to us all. I believe I read in Model Railroader that their huge 2-10-10-2's also had this re-heater arrangement. Great drawings if you get the mag. It is from the May, 1989 issue.

Happy steaming to all, and thanks for all the great info.

Jim M.

3751_loony Wrote:
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> MTM, Your wisdom is a benefit to us all. I
> believe I read in Model Railroader that their huge
> 2-10-10-2's also had this re-heater arrangement.
> Great drawings if you get the mag. It is from the
> May, 1989 issue.
>
> Happy steaming to all, and thanks for all the
> great info.
>
> Jim M.
>

I really didn't have anything to add, at this point, but I jus wanted to see how the new sorting feature worked. <G>

I know I have drawings of the DMIR class M separable boilers somewhere, but I can't find 'em. But I'll look for the VGN 2-10-10-2 boiler drawings tonite. Maybe I can come up with something to illustrate this boilers unique features and post it tonite.

The reason for adding so much extra air reservoir capacity would be so that there is more air to release and recharge the brakes on the train. DM&IR probably needed this with 150-car trains, plus the added complication of cold weather which increases trainline recharging time. If you were coming down the hill and came to complete stop in the winter, it would take a lot more air to recharge the train than the typical 65-90 car freight train. Diesel locomotives conveniently solved this problem by having each main reservoir system train-lined to the lead unit, thus providing an abundance of air.

NRE973 Wrote:
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> If you were coming down the hill and came to
> complete stop in the winter, it would take a lot
> more air to recharge the train than the typical
> 65-90 car freight train.

DM&N / DM&IR steam engines didn't come down the hill in the winter with ore trains. With the lakes frozen, the road pretty much shut down after mid November. The Edmund Fitz went down on November 10, 1975, right near the end of the shipping season.