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Offline Token  
#1 Posted : 18 February 2015 11:43:13(UTC)
Token

Australia   
Joined: 25/01/2009(UTC)
Posts: 300
Location: Sydney, NSW
Having failed to find a picture of an s2/5 hauling a train for Kimball, I stumbled on a fascinating image of an early German/Prussian prototype for cab forward design. The image and extract is copied from Wikipedia.de

S 9 Altona 561
S 9 Altona 561

S 9 Altona 562
S 9 Altona 562

Roughly translated

Built between 1904-1907, the S 9 Altona (Altona 561 and 562) of the Prussian state railways were experimental, for fast express engines with the axle configuration 2'B2 '.

These locomotives were the result of a tender put out by the Association of German Engineers from the year 1902/1903 which specified a locomotive to be built, capable of hauling 120-ton train at 120 km / h to 150 km / h.

They were the world's first locomotives with the rare axle configuration 2'B2 '. Altona 561 was a complete streamlined full fairing while both machines also had front driver's cabs because of the need for improved vision at the desired high speeds.

The locomotives were given an unusual three-cylinder compound engine, with all three cylinders having the same diameter. The first axle driven from the central high-pressure cylinder, the second from the outer low-pressure cylinders.

The Tender of the two machines were unique with the one attached to Altona 561 maintaining continuous streamline as the locomotive and a passage from the cab to the train.

During the high-speed tests on the section Marienfelde-Zossen (Royal Prussian Military Railway) in1904, S 9 Altona 561 with a 109-ton train - made up of three D-train cars - achieved a speed of 137 km / h at a maximum of 1,400 bhp. They thus fell short of the expectations placed in this large, complex design and overall, were considered inferior to the smaller S 4 design (which achieved 136 km / h in similar trials).

The locomotives were ultimately considered a poor design and did not go into production. Experts assume that the dimensions of the three-cylinder compound engine were not sufficient. Provided with a more careful design, the machine could achieve an output of about 1600 hp. In addition, there were problems with the mass balance, as the two outer cylinders worked without crank offset. By 1914, the front driver's cabs removed to along with much of the streamlining and put into regular express service until 1918 in Hannover.

More successful was in 1907, the Bavarian S 2/6, reaching 154 km / h with the same wheel arrangement and the same driving wheel diameter of 2,200 mm.

However, the S 2/6 was less suitable for everyday use due to the low friction load, and overall very few locomotives were built with this wheel arrangement around the world. The main disadvantage was the low traction achieved with only two of the six axles powered.

In the US, only five 2'B2 ' were built. One was scrapped after a short time, the other four rebuilt after a short time as Atlantics (2'B1 '). A similar fate befell the only 2'B2 'in France, which was soon converted into a 2'C.

In Canada, two successful series of 2'B2 'for the Canadian Pacific Railway were built in the 1930s, the Series F-1a (20) and F-2a (5 locomotives). The latter were comparable to the giant Atlantics (Class A) of Milwaukee, St. Paul & Pacific Railroad. These locomotives were called "Jubilee Class".

Much of the information published above on Wikipedia.de appears to be drawn from the following site;

http://www.sulka.de/sites/eb/we/we008/we008.html

In my extremely limited knowledge of this pioneering era, I cannot attest to the accuracy of it but am fascinated that the problems discussed did not include the difficulty faced by most cab forward designs - that being the efficient transfer of fuel from the tender to the firebox as experienced with 05 003.

Does anyone have information on earlier designs and/or why they could not overcome the difficulties faced by the cab forward design? I would be most interested to find out if this was the earliest attempt at such a design or are there earlier examples?

Regards,

Michael.



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Offline steventrain  
#2 Posted : 18 February 2015 12:10:30(UTC)
steventrain

United Kingdom   
Joined: 21/10/2004(UTC)
Posts: 31,601
Location: United Kingdom
I never see the image before! Thanks for the Information.
Large Marklinist 3- Rails Layout with CS2/MS2/Boosters/C-track/favorites Electric class E03/BR103, E18/E118, E94, Crocodiles/Steam BR01, BR03, BR05, BR23, BR44, BR50, Big Boy.
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Offline SteamNut  
#3 Posted : 18 February 2015 13:35:41(UTC)
SteamNut

United States   
Joined: 11/05/2013(UTC)
Posts: 488
I believe the Germans preferred to use everyday coal as powdered coal was expensive to make and had to be kept dry making it harder to store/maintain. Oil was expensive and not as plentiful as coal, much of it imported. As far as I can tell the only reason cab forward for steam was developed is because of long tunnels. Visibility was great for the crews but many would rather had the boiler in front to act as a buffer in accidents. In other words economics played a role. In America it was also rare and used only for long tunnels.
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Offline H0  
#4 Posted : 18 February 2015 15:29:20(UTC)
H0


Joined: 16/02/2004(UTC)
Posts: 15,254
Location: DE-NW
Hi, Michael!
Thanks for the information.
Another link to German Wikipedia:
http://de.wikipedia.org/...i/Cab-Forward-Lokomotive

There they write that the main advantage was better view on the track ahead and also write that transportation of fuel is the biggest problem.

Originally Posted by: Token Go to Quoted Post
In my extremely limited knowledge of this pioneering era, I cannot attest to the accuracy of it but am fascinated that the problems discussed did not include the difficulty faced by most cab forward designs - that being the efficient transfer of fuel from the tender to the firebox as experienced with 05 003.
The two S 9 locos shown here were built in 1904 and they were built for high speed (but failed in that aspect).
They had two cabs, one ahead for the train driver, one at the rear for the fireman.

It seems the first DRG loco that was fired with coal dust was built in 1931 (http://commons.wikimedia.org/wiki/File:Bundesarchiv_Bild_102-11602,_Dampflokomotive_58_1894,_BR_58.jpg). So this probably was not an option back in 1904.

I don't know when the first oil-fired locos were built. Main reason for cab forward in the US were long tunnels and oil-fired locomotives made this possible. In Germany the main reason was security with high-speed locomotives (better view onto the track).
Regards
Tom
---
"In all of the gauges, we particularly emphasize a high level of quality, the best possible fidelity to the prototype, and absolute precision. You will see that in all of our products." (from Märklin New Items Brochure 2015, page 1) ROFLBTCUTS
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