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Gauge 1 Steam, SNCF 232U1 (Gauge 1)

August 20, 2017

11/26/17: My friend Barry Coward visited from England and made this excellent narrated  (by your truly) video of this loco running.

9/9/17: I’ve just had a very fine run with 232U1. I have equipped her with radio control, on the regulator only. This makes running on my graded track much less fraught! The RC transmitter and receiver come from Peter Spoerer in England. The transmitter is a neat device that is purpose built for train control and fits neatly in the palm of one hand. I don’t like the usual big units that look like video game controllers.232U1 RC on Regulator


The RC installation is completely reversible, the servo bracket is clamped under two existing screws on the footplate. I tucked the battery pack in the gap between the fuel tank and the tender and the receiver simply lies on top of the tender inside the coal rave. I will make a shield to go over the servo for when I attempt coal firing. RC is not necessary on the blower (fortunately because there isn’t much room if I want to coal fire with RC fitted) because with the very soft blast of a compound, (I have found) it is necessary to run with the blower slightly open so there isn’t a concern about the flame popping back when she comes to a halt. The water usage is notably lower than that of the Merchant Navy however, fuel economy is comparable. I run both locos in full gear because it is easier and the reversers are too hot and fiddly to adjust once steam has been raised*. The fuel economy of 232U1 was terrible. I discovered that a previous owner had raised the burner screen about 3mm and cut higher wicks. I returned it to the original state and the economy improved a lot. What was happening was that the fuel was evaporating too fast for the available air supply so I had a fuel rich and thus relatively cool flame. I also put some silicone grease around the smokebox door, this resulted in the loco maintaining pressure with a much smaller blower opening, though the corrected burner will be helping this too. She does suffer the compound starting problem, not on the level or from cold, but on the gradient. The Merchant Navy has no problem restarting this train on the grade but 232U1 will not. This is because only the two smaller cylinders are available at starting. However, once she is moving and compounding (using all four cylinders) the pull is STRONG. I reckon she could pull perhaps double the weight up the grade.

* Also the run time with each, something over 30 minutes is quite enough for me. It’s time for tea after that!

Here’s the run:

8/20/17: The European 4-6-4 (or 232 using French nomenclature) is known as a Baltic,  and sometimes incorrectly as a Hudson. However, the 4-6-4 wheel arrangement first appeared in 1911 as du Bousquet’s last design, a 4 cylinder compound, and came to be known as a Baltic because the Nord Express served the Baltic coast. The 4-6-4 was introduced in America by New York Central in 1927, to haul crack passenger trains along the Hudson River valley and became known as Hudsons and fine they were too. Having digressed a little, back to the French story. SNCF 232U1 was the last of a batch of 8 Baltic locomotives commissioned just before WW2. Marc de Caso was the designer and the opportunity was taken once again to compare compound expansion with simple. 4 of the batch were built as 3 cylinder simples, 3 as 4 cylinder compounds having Dabeg rotary cam poppet valve gear. Whilst these compounds showed about a 12% savings on coal over the simples, the valve gear was not satisfactory. The last of the batch was not built until after the war and de Caso’s proposal to build the final one as a 4 cylinder compound having exceptionally long travel Walschaert’s gear with piston valves was accepted. (In full gear, the travel of the HP valves was 9.2″ and that of the LP valves, 11.7″, resulting in large valve openings at short cutoff settings.) The locomotive was successful, showing a further increase in coal economy of around 12% over the poppet valve compounds and able to sustain 3300HP at the drawbar. She was efficient and apparently easy to drive,  also having a mechanical stoker. Our British locos were too small for such to be of any real benefit, supposedly. Diesel and electric was coming and so 232U1 remained unique, nevertheless she racked up over a million km in 12 years, with no problems. She is preserved at the transport museum in Mulhouse and is perhaps the best indication of what steam technology could accomplish. I say best because while the French had other successful compounds, notably the Chapelon 242A1 that was also unique and somewhat more powerful, this one was perhaps the most rounded design, ready for a future that didn’t come. de Caso knew that 232U1 was the swan song for French steam locomotion and supposedly the streak along each side represented a swan and she became know as la Divine.

For some reason, British engineers never really made compound expansion work in the sense of coal economy. There were a couple of notable failed attempts, failed because the engineers involved tried to take too many steps at once. The French tend to be academically brilliant and able to translate theoretical predictions into measurable results. After all, the application of thermodynamics to heat engine cycle analysis originated with Msr Carnot and the French steam engineers took it seriously.

Moving on to the Aster Gauge 1 model. To me, the successful design of a proper compound expansion model in gauge 1 is an extraordinary accomplishment. Given the attitude of British engineers to compound expansion, it is ironic that the designer who made such models possible was a British citizen (J.T. van Riemsdijk). He was Mechanical Engineering curator of the science museum when I was little. I remember the apparently endless glass cases containing working loco models, each operable on compressed air by pressing a button (paradise for a little boy), many of which were 1 gauge!  Aster produced 4 compound models based on his work of which this specimen is 232U1 serial number 1! It is further notable in having a wet firebox capable of burning coal as well as spirit. The model comes with a grate and ash pan as well as a spirit burner. The spirit tank in the tender may be replaced with a coal bunker. Most fire tube models at this scale have a dry firebox and burn spirit only, as is the case with the superb Aster rebuilt Merchant Navy, that I described in an earlier post. A 1 Gauge luminary told me that the Rebuilt Merchant Navy is a museum quality model. I beg to demur, yes it is superb and an excellent performer, but museum quality it is not. The 232U1 on the other hand most certainly is of museum quality.

I wonder what’s in this case?20170815_145416

Aha! A warning, this is NOT a toy!20170815_143611

Inner lid:20170815_143706

Under the lid, assembly and operation manual and book of exploded assembly drawings:20170815_143622

Now to the loco and tender, still in the original (and slightly oily) tissue. The tool laying on top is the flue brush.20170815_144036

Tender first!20170815_14445320170815_144604

The loco has outside Walschaerts valve gear. Rocking levers transmit the motion to the valve for each inside cylinder. The original did have inside combination levers though.20170815_170137

Four cylinders, inside high pressure, outside low pressure. These are cast bronze, I think.20170815_165819

Leading crank axle for inside cylinders. 20170815_165840

The eccentric on the middle axle drives the boiler feed pump. What I can’t show is that the suspension has equalization beams, another technique that was eschewed by British Engineers. I can’t help think that if the Bullied Pacifics has been so equipped, they would have an entirely different reputation! I have described the equalisation of the front truck further down.20170815_165852

At the front is the Roscoe displacement lubricator. The leading truck not only has compensated suspension but the proper swing link system to guide the loco smoothly into turns. As the truck moves off centre, it causes the front of the loco to lift a little, the lifting force causes a turning moment that will cause the front of the loco to move in the direction of the curve, smoothly following the truck (or bogie).20170815_145721

Here’s the swing links either side of the pivot bearing. Each axle box is sprung. The force from each pair of boxes is coupled to the truck by a beam that is pivoted at the centre, thereby providing load equalization.20170815_170001

Here’s the rear truck with the spirit burner affixed, also showing drag/control links.20170815_170431

There is a link each side that connects the truck to the loco such that as the truck moves from side to side, it also turns slightly to follow any turn radius the loco is traversing. The links also couple the pull to the truck, the link at the back is the draw bar so the pull of the loco is coupled through the side links via the truck to the draw bar. There are side bolsters that support the weight of the back end of the loco on the truck.20170815_170444

Detail view of left side drag/control link:20170816_140749

And now to a very special feature of a small model, the wet leg firebox complete with crown sheet and stays. The hot end of the five flues are visible. The two large flues contain superheater elements. As the label in the lid states, this is NOT a toy!20170815_165913

Here is the grate and ashpan in place: The four screws engage in keyholes in the side bolsters of the truck, making the truck easy to remove for changing the burner or cleaning the grate and firebox.20170815_170534

Here I’m holding one of the sprung loaded ash hopper doors open:20170815_170910

Speaking of flues, here’s a view through the firedoor into the smokebox:20170815_171516

Here’s the backhead. Clockwise from top left, whistle, regulator, gauge glass, pressure gauge, screw reverser and blower. Tucked down in the left corner is the control rod handle for the LP cylinder drain cocks. At the bottom right is the feed water bypass valve. The reason for the feed water bypass is that the maximum capacity of the feed pump is designed to keep ahead of the steaming rate. There is a pump bypass valve that can be adjusted to balance the feed, the excess being returned to the tender20170815_170957

Another view of the backhead and cab:20170815_172809

At the front end, here’s the appropriately filthy inside of the smokebox!20170815_171714

Double chimney:20170815_171738

Top of boiler showing nicely detailed access flaps, presumably, some would have been for sand. The front one has been used to cover the boiler fill plug. Two safety valves (4.5bar) at the right.20170815_171813

And back to the tender, it is hefty!20170816_200745

Detail view of the steps showing the catenary warning!20170816_20080620170816_201025

Hatches showing water tank and hand pump, again superb detail:20170816_200827

And finally the tender front showing the water bypass return, spirit connection and water feed connection. 20170816_200907

I will close with the words of John van Riemsdijk written in 1997 and taken verbatim from the Gauge 1 Model Railway Association book “Modelling in Gauge 1 Book 2”:

“The latest, and perhaps last, compound was the French streamlined Baltic, SNCF no 232U1. Baltic, not Hudson: the first 4-6-4 tender engines were also built for the French Nord main line, and in 1911, and were called “Baltics” because that was where the trains they were meant for ended up. 16 years later, the Americans took up the 4-6-4 wheel arrangement and called it a Hudson, but U1 is definitely a Baltic. The real engine proved one of the greatest locomotives of all time, and is on view with one of the original Baltics in the museum in Mulhouse. The model is unsurpassed and perhaps unsurpassable. It has only two sets of valve gear, but this is extremely robust and closely copies the same arrangement on the real engine. As compared with the Chapelon Pacific, the cylinder sizes are the same, but the greater weight of the coal-fired boiler improves the adhesion and allows higher working pressure to be used effectively. There are drain cocks on the L.P. cylinders, but I find that it clears itself without their use. In fact you can tie it onto a very heavy train, then raise steam, and when at full pressure the engine will quietly move off with its load, the puff only becoming audible when the cylinders warm up.”

Please Note: If an official of the G1MRA feels that I have appropriated these words err, inappropriately, notify me and I will (reluctantly) remove them.



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