tor 29 jun, 2017 23:06
Christoph Heuer skrev:Hello,TKO skrev:Vilken var världens första ledvagn? Byggdes den i USA?(...)
Yes. According to an article by Jury Koffman the first articulated tramcar in the world was built in Boston in 1912. They were rebuilt from two four-wheel cars to what is know in English and "two-rooms-and-a-bath cars". The Gotha G4 probably is the best know example of that.
The first articulated tramcars with a central bogie were built in Milwaukee in about 1920/21. These were also rebuilds, in this case from two bogie cars. There was a new-built three-section car in Detroit, built in 1924: http://www.detroittransithistory.info/DSR/ArticStreetcar.html. As far as I could work out the first all-new two-section car in the USA was built for Cleveland in 1928. However, it appears that all of these used a different type of central bogie to the Harkortwagen.
What do we learn from this? The Harkortwagen is the first type of tramcar in the world using the Jakobs bogie which was later used under all Düwag articulated tramcars which were built in thousands (including those built under licence) from 1956 onwards. It is also the oldest surviving articulated tramcar in the world.
With this background I trust you will understand why most people doubt that the best possible solution for this tramcar is to be owned by a company in Norway and to be away from public view. Also, a spokesman from DVG said in a TV interview today that for them the car was not more than scrap, suggesting a very low purchasing price.
I also wonder, if DVG and even more so Daimex are doing themselves a favour. I am not entirely sure if Daimex know what they really get. Either way, I doubt that it is a commercially wise decision for them. Those people in the rail industry with both knowledge and some sense or morale might see them as either utterly stupid or as the greedy idiots that took away an important historic item from its native country and from public view. Herr Kühn might be regarded as a eccentric and egoistic wealthy collector who wants a treasure for himself and himself only.
Regards
Christoph
fre 30 jun, 2017 8:25
ferrovialist skrev:Harald skrev:Jakobs patent comprised bogies both with one common pivot for the two bodies and with separate pivots. However, an essential part was that the two bodies could move indepently including skewing movement. If I'm not mistaken, that is not possible with the Düwag articulation. Thus it's not a jakobs bogie. It should be noted that there is a common misunderstanding, especially in english speaking countries, that any bogie placed between two bodies is a jakobs bogie, but strictly speaking that is not correct.
My apologies for bringing this up late, I just came to read Harald's comment:
The Duewag articulated tram is often referred to as an example of use of the Jakobs (Jacobs) bogie principle, like in this Wikipedia article:
https://de.wikipedia.org/wiki/Jakobs-Drehgestell
What Wiki says must not always be true, but in this case I think it is. The important part of Wilhelm Jakobs’ patent of 1901 is that one single bogie supports two different carbodies. How the bodies are supported should be of less significance. Over the years we have seen two separated pivots (and rollers), pivots on top of each other at the bogie centre, slewing rings, or just mounted on beams which are able to slide, or supported by air suspension.
You seem to define the Jakobs bogie by the ability for each body to move independently. And yes I agree to that point. But then you say that this is not the case with the Duewag articulated tram. But it is, and it would be impossible for the tram to move from a straight track into a curve if each carbody could not move independently from the bogie. I know the SL79 Duewag car of Oslo by detail, and can describe it like this: In the central bogie there two separate slewing rings (a slewing ring is like giant ball bearing), one slightly smaller than the other, and both placed in the centre of the bogie. The top of one slewing ring supports one of the carbodies, the top of the other supports the other body. Thus they can move as if they had pivots on top of each other at the bogie centre.
According to the Wiki article the first successful use of the Jakobs’ patent was on the “Fliegende Hamburger” high speed train in 1932. I don’t know the criteria for “successful”, but the 1926 Harkort tram of Duisburg did use the Jakobs’ principle, also some suburban trains in Germany by 1927. But they were not the first, the same principle was used on a tramcar in Milwaukee in 1921, and I would not be surprised to see even older experiments.
Roy B.
ons 05 jul, 2017 23:01
Harald skrev:ferrovialist skrev:Harald skrev:Jakobs patent comprised bogies both with one common pivot for the two bodies and with separate pivots. However, an essential part was that the two bodies could move indepently including skewing movement. If I'm not mistaken, that is not possible with the Düwag articulation. Thus it's not a jakobs bogie. It should be noted that there is a common misunderstanding, especially in english speaking countries, that any bogie placed between two bodies is a jakobs bogie, but strictly speaking that is not correct.
My apologies for bringing this up late, I just came to read Harald's comment:
The Duewag articulated tram is often referred to as an example of use of the Jakobs (Jacobs) bogie principle, like in this Wikipedia article:
https://de.wikipedia.org/wiki/Jakobs-Drehgestell
What Wiki says must not always be true, but in this case I think it is. The important part of Wilhelm Jakobs’ patent of 1901 is that one single bogie supports two different carbodies. How the bodies are supported should be of less significance. Over the years we have seen two separated pivots (and rollers), pivots on top of each other at the bogie centre, slewing rings, or just mounted on beams which are able to slide, or supported by air suspension.
You seem to define the Jakobs bogie by the ability for each body to move independently. And yes I agree to that point. But then you say that this is not the case with the Duewag articulated tram. But it is, and it would be impossible for the tram to move from a straight track into a curve if each carbody could not move independently from the bogie. I know the SL79 Duewag car of Oslo by detail, and can describe it like this: In the central bogie there two separate slewing rings (a slewing ring is like giant ball bearing), one slightly smaller than the other, and both placed in the centre of the bogie. The top of one slewing ring supports one of the carbodies, the top of the other supports the other body. Thus they can move as if they had pivots on top of each other at the bogie centre.
According to the Wiki article the first successful use of the Jakobs’ patent was on the “Fliegende Hamburger” high speed train in 1932. I don’t know the criteria for “successful”, but the 1926 Harkort tram of Duisburg did use the Jakobs’ principle, also some suburban trains in Germany by 1927. But they were not the first, the same principle was used on a tramcar in Milwaukee in 1921, and I would not be surprised to see even older experiments.
Roy B.
There is a link to the patent in Wikipedia. If one reeds and understands the patent, it is obvious that the Duewag articulation is not an implementation of Jakobs patent. In the patent claim it is stated that independent movement is possible around the vertical axis as well as both the horisontal axes. As you describe the SL79 articulation independent movement is possible only around two axes, the vertical and one horisontal but not around the horisontal axis along the car. The two rectangles below picture the two carbodies seen from one end. A movement as in the figure is possible accordning to Jakobs patent, but is not possible with the SL79 (or M21) articulation.
tor 06 jul, 2017 17:38
Waggonfabrik Actiengesellschaft und Wilhelm Jakobs skrev:Der Gelenkwagen nach vorliegender Erfindung gehört zu der bekannten Gattung von Wagen, bei welcher der Wagen in mehrere Teile zerlegt ist, derart, daß die in der Mitte aneinanderstoßenden Enden auf einem gemeinschaftlichen Untergestell gestützt werden. Die Erfindung bezieht sich auf die Art der Stützung auf diesem Untergestell und hat wesentlich eine unabhängige bewegliche Lagerung jedes Wagenkastenendes mit Rücksicht auf das gegenüberliegende Ende zum Zweck.
sön 09 jul, 2017 10:54
Harald skrev:If you had taken the trouble to read the patent, you had seen that cars supported by a common bogie existed before Jakobs invented the Jakobs bogie and that the invention he claims to have done, is a suspension that permits indpendent movement. You don't even have to read the entire patent. It's enough to read the first two sentences:Waggonfabrik Actiengesellschaft und Wilhelm Jakobs skrev:Der Gelenkwagen nach vorliegender Erfindung gehört zu der bekannten Gattung von Wagen, bei welcher der Wagen in mehrere Teile zerlegt ist, derart, daß die in der Mitte aneinanderstoßenden Enden auf einem gemeinschaftlichen Untergestell gestützt werden. Die Erfindung bezieht sich auf die Art der Stützung auf diesem Untergestell und hat wesentlich eine unabhängige bewegliche Lagerung jedes Wagenkastenendes mit Rücksicht auf das gegenüberliegende Ende zum Zweck.
I.e. the patent says that cars with carbodies supported by a common undercarriage are an already known type of cars and that the invention described in the patent concerns the type of the support and that the purpose is to make the car ends independently moveable.
So just as the invention of the airplane didn't turn hot air balloons into airplanes, the invention of the Jakobs bogie didn't turn other types of bogies supporting two car bodies into Jakobs bogies.