Recently looking at some photos of the nifty little USRA US Army 0-6-0's I noticed the sand domes on them to be different. Seems the Lima versions had one single, larger sand dome while the ALco versions had 2 smaller round ones. Is/was there any particular reason for this deviation in an otherwise identical locomotive?
Also many of both manufacturers seem to place the CC airpump on the left side of the boiler and others on the front pilot deck.
I don't seem to be able to find much on these engines other than specs and photos.
Thanks,
oldline1
i think the Army just liked to combine domes. They did it on 2-8-0's, too.
They tended to put air pumps up front; I think for clearance reasons.
The 2-8-0's were teeny little things, and cute. I would have bought one of the HO ones except they're expensive and don't appear to run that well.
Ed
7j43kThe 2-8-0's were teeny little things, and cute. I would have bought one of the HO ones except they're expensive and don't appear to run that well. Ed
I guess you're thinking of the S-160s. ROCO is the only one that has made one in HO RTR and they run extremely well. They have a tender drive system that's unusal by American standards but I understand this is common in Europe for their model steamers. The craftsman kit version by Model Loco also runs very smoothly. Both are expensive though.
As to the pumps being moved for clearance I don't buy that as there's ample side clearance on them and most engines, even considering the tighter European loading gauge, don't have that problem. I inderstand the front pump locations had more to do with weight distribution and sometimes they could cause cracking of the boiler shells.
I guess the Roco one I saw running was a lemon, then.
It would certainly be interesting to get the reasoning for the pump location from the horse's mouth.
My buddyand I both bought ROCOs when they were first brought out and they are smooth and nice. I'm not a fan of their sound system and will probably replace it. My friend pulled his out and installed a T2 and he's much happier with that.
I was told by an old Western Maryland Ry engineer they moved the side pumps to the front of the smokebox and were told by management it was to relieve stresses on the boiler shell. He said the Union told him it was to transfer weight to the front end off the drivers. Doesn't make sense to me to do that as they were used on the Thomas Subdivision and needed all the TE they could get to climb the Black Fork Grade. We'll probably never know.
FWIW, in 1963 I saw a whole pile of the S-160's at Fort Eustis, including one with a poppet valve conversion. There was also a triple-head run-by.
A superbly pleasant trip, including 112 MPH coming back (on the train, not in a car).
That's what inspired my interest when the Roco's were offered.
I saw them at Ft. Eustis a bit later. My first one was on the Reader RR with 1702. My wife and I spent most Saturdays in 1972-73 driving her with Mr. McBride and Jarrel the fireman. Great times. I have been following the S-160's and the Ma&Pa too for about 53 years. The Ma&Pa tested the 2628 (Ft. Eustis 611) when they converted her to the Franklin Rotary Poppet VG. She's alive after a horrible life since the Army. In Cumberland, MD and the owner hopes to make her run someday. I'm hopeful but very doubtful.
I purchased 4 of the Model Loco kits (DJH) many years ago and have one built so far. The others are not needed so will remain in their boxes. These kits are very easy to build in spite of their very many parts. The steam kits from the UK have all American steam kits beat so bad it's like comparing Tyco to brass imports. The kits assemble easy with very minimal hand tools and things actually fit!
My friend models the Ma&Pa so he actually did the conversion of the 2628 with the Franklin gear. It's pretty remarkble!
Glad your 112mph trip home wasn't on I-95!
Designed by col. Howard G hill, the S160 were designed to be fat boilered engines. Not intended for Europe but US base service. A war stop gap so diesel production could be freed up during war production. Big boilered for more steam capacity. They also have the unigue feature that the S100 and S160 were designed to have lead and trailing trucks added. for 2-6-0, 2-6-2 or oddly 0-6-2. The "s" was a classifiction by alco to denote thousands. The compressor is on the front for centerline weight distribution and stability. That fat boiler made them a little top heavy on the S160. The sand domes, was a builders prefference. both configureations had the same total sand capacity. At least 8 of these wee beasties still exist. #9 of new hope and ivy land now down at sms in southern NJ
Shane
A pessimist sees a dark tunnel
An optimist sees the light at the end of the tunnel
A realist sees a frieght train
An engineer sees three idiots standing on the tracks stairing blankly in space
NVSRR Designed by col. Howard G hill, the S160 were designed to be fat boilered engines. Not intended for Europe but US base service. A war stop gap so diesel production could be freed up during war production. Big boilered for more steam capacity.
Designed by col. Howard G hill, the S160 were designed to be fat boilered engines. Not intended for Europe but US base service. A war stop gap so diesel production could be freed up during war production. Big boilered for more steam capacity.
If they were designed for US base service, they would have been designed with typical US clearances.
A GN F-8 2-8-0 is a pretty typical sized 2-8-0. Overall height was 15'-4". Very typical. But the S160 was only 12'-10 1/2" tall--Two and a half feet shorter. For what?
Neither was the S160 "big boilered" by American standards. The F-8 had a boiler diameter of 74"--the "big boilered" S160 had a boiler diameter of about 71 1/2". Smaller. Not bigger.
No. These locomotives were designed for European clearances.
I have read (don't ask me where), that many of the US Army steam locomotives were built to operate, if needed, in foreign war zones. It was explained that this was the reason for some strange detail differences on US Army locomotives even those built to a "standard" design.
I have even heard that some could easily be "reguaged" if necessary.
-Kevin
Living the dream.
There are a few books out about the S-160 2-8-0s. They were built for use in the European Theatre so they were rather small engines and built to ensure they had clearance for any country in Europe they might be operated by. There were 2,200 of them made by Alco, Lima and Baldwin. They were not multi-gauge engines and were standard gauge. The multi-gauge engines mentioned were, I believe, some narrow gauge 2-8-2's similar to the Tweetsie or Dollywood engines.
The S-160 was definitely not a big boilered or even a big engine by any means. They were quite small and not top heavy. According to the books and information I have they were very efficient, ran well and gave good service in Europe and in the USA. The Brits had trouble with the water gauges as they weren't familiar with them which caused a few to blow up. Only a handful of them remained in the States and many are on the bottom of the Atlantic thanks to Hitler's U-Boat fleet.
Fortunately for those of us who are infatuated by the S-160s there are several in the UK that operate and soon to be a couple more in the US operating. Alaska RR 557 is nearing completion and the folks in Ohio are supposed to be getting the 612 operational. The Smokey Mountain (ex-Reader RR) 1702 has been running there for years. Not sure if it's out for maintenance or not at this time. The remaining Ft. Eustis engines are around but in various states of disrepair.
To the best of my reading and searching the S-160s they were never designed to be anything BUT 2-8-0s. Maybe you mean the USRA 0-6-0s? The Colorado Midland owned several and converted them to 2-6-0s. When sold to N&PBL they were converted back to 0-6-0 configuration. Not sure if that was before the sale or after. I don't think they were DESIGNED to be converted into 2-6-0 or 2-6-2 configurations. They were designed by the USRA as a light switcher. But who knows what went through a shop foreman's mind?
Class 155 - Eighty saturated USRA 0-6-0's for use domestically. Reason for one vs two domes is just a matter of of what the builder liked and had no operational reasons (Lima liked combining domes). The reason for the pilot deck mounted air compressor is the same as the reason that many modern locos had two of them mounted on the pilot deck on either side of the smoke box, to provide desirable front end weight. Here's a Lima built KCS 2-10-4 with both these features
68aa42b7c5ce555ff543ca44f41d477a.jpg (900×452) (pinimg.com)
BEAUSABRE The reason for the pilot deck mounted air compressor is the same as the reason that many modern locos had two of them mounted on the pilot deck on either side of the smoke box, to provide desirable front end weight.
Is front end weight desirable on a locomotive that does not have a pilot truck?
SeeYou190 BEAUSABRE The reason for the pilot deck mounted air compressor is the same as the reason that many modern locos had two of them mounted on the pilot deck on either side of the smoke box, to provide desirable front end weight. Is front end weight desirable on a locomotive that does not have a pilot truck? -Kevin
A Great Northern A-9 0-6-0, which did not have a front mounted compressor, had equal weight per axle of 47600 pounds.
Since its weight was evenly distributed on all axles, it's hard to see the advantage of moving the compressor forward.
It is not an atypical 0-6-0.
Therefore it appears that placing the pump in the forward position was not needed for better weight distribution.
7j43kA Great Northern A-9 0-6-0, which did not have a front mounted compressor, had equal weight per axle of 47600 pounds.
So on an 0-X-0 locomotive, would it be more desireable to have equal axle load rather than more weight on either the front or rear driver?
SeeYou190 7j43k A Great Northern A-9 0-6-0, which did not have a front mounted compressor, had equal weight per axle of 47600 pounds. So on an 0-X-0 locomotive, would it be more desireable to have equal axle load rather than more weight on either the front or rear driver? -Kevin
7j43k A Great Northern A-9 0-6-0, which did not have a front mounted compressor, had equal weight per axle of 47600 pounds.
I don't know if it matters if the weight distribution is uneven. But considering that 0-X-0's were bi-directional, I'm not sure what the point would be to do it intentionally.
My impression was that BEAUSABRE was asserting that by moving the compressor to the front, it would allow for an even distribution of weight on the axles of the Army 0-6-0's. I pointed out that this goal was accomplished without doing so, on the GN locomotives.
I'm just asking questions trying to get a basic understanding of locomotive design.
SeeYou190 I'm just asking questions trying to get a basic understanding of locomotive design. -Kevin
Great!
Pulling power is proportional to overall weight on drivers (leaving out booster engines, etc). For a locomotive with only drivers, repositioning weighty elements should have no effect on pulling ability--the overall weight on drivers remains the same.
Some people may believe that having an equal weight on all drivers make the locomotive pull more (or perhaps less) than an unequal weight distribution. This may have been tested in the real world, and I would be very happy to read an article describing this event.
One good reason to have equal weight distribution is that higher axle loading produces greater stress on track. Even if it's only one axle. So there IS an incentive to have an equal weight on the axles.
Another is that wear will be increased for the bearings related to the heavy axle. THAT might be non-linear, in a bad way.
Adding lead and trailing trucks complicates things a bit, but we were only talking switchers.
Linn Westcott in Kalmbach's Model Railroader Cyclopedia Vol. 1 Steam Locomotives, says the reason the air pumps/compressors were moved to the front of the smokebox (or mounted on the pilot) was to provide better balance: those things were heavy.
BEAUSABRE Linn Westcott in Kalmbach's Model Railroader Cyclopedia Vol. 1 Steam Locomotives, says the reason the air pumps/compressors were moved to the front of the smokebox (or mounted on the pilot) was to provide better balance: those things were heavy.
Perhaps the S-155 0-6-0's were designed unbalanced, and moving the compressor corrected that. Or perhaps they WERE designed balanced, and someone wanted to change that.
What the move will NOT do is change the weight on the drivers. And, subject to my earlier comments, it's the weight on the drivers that determines the amount of tractive effort possible. And that is a key element of a switching locomotive.
Would changing the spring force on driver axles adjust the load on each driver?
On class 8 spread-axle flatbed trailers the pressure in the suspension air bags is altered to keep axle loads the same.
Just thinking...
SeeYou190 Would changing the spring force on driver axles adjust the load on each driver?
Here's a drawing showing some of the elements of springing and equalizing on a steam locomotive:
You can follow the linkage down the row to see the equalizing action. Push up at one location, and everything moves to keep the wheels on the rails.
As to your question, the "bolts" going through the holes in the ends of the springs have nuts to lock onto those springs. And they can be moved. Hence the spring force on an axle can be changed. Of course, the leaves can be changed out, too. If the equalizing arrangement is designed to not include some or all of the adjusters, one is left with doing it only with spring changes.
"All" steam locomotives in the US used a three point suspension. In the case of an 0-6-0, the front axle would NOT be equalized to the others. It would be sprung however. This would provide the forward central support for the locomotive. The other two axles would have equalization on each side. That would provide the two rear supports for the locomotive.
You had essentially a tripod, with the rear two legs going directly to the rails, and the front to a loose pivot.
A 4-4-0 is perhaps the simplest to envision. The drivers have, on each side, a simple equalizing bar above/below each of the two journal boxes. That creates the rear legs of the tripod. The front truck pivots about a center pin. That's the front leg.
Increasing polar moment of inertia might improve issues with reciprocating augment on an engine with no lead truck...
SeeYou190I'm just asking questions trying to get a basic understanding of locomotive design.
Mr. Meador here gives a very informative walk around explaining some frame and steam chest design criteria for the PRR 1361 in Altoona:
A very worthwhile seven-and-a-half minutes.
Regards, Ed
gmpullmanA very worthwhile seven-and-a-half minutes.
Time well spent indeed.
Thank you for posting the video. There sure is a lot to a steam locomotive frame.
I'm really glad I asked the question about sand domes on the USRA 0-6-0's! Thanks for the HELP!