Single fairlie
A Single Fairlie , also called Mason Fairlie or Mason Bogie in the USA , is an articulated steam locomotive with only one powered bogie and one bogie . The motor bogie corresponds to that of a double fairlie ; However, the boiler has a normal design, and optically a Single Fairlie resembles a normal, but relatively long tank locomotive .
Advantages and disadvantages
The advantage over the stiff-framed design is that a (thermally advantageous) large standing boiler with a sufficiently dimensioned ash box can be placed behind the coupling wheels and the side overhang, especially at the rear end of the locomotive , is still within limits even on routes with tight curves . Compared to the Double Fairlie, the disadvantage of the complicated double boiler and the confined space in the driver's cab are eliminated . Storing larger fuel and water supplies does not pose any problems either.
The main disadvantage of the single fairlie compared to the double fairlie is that only part of the weight rests on the driving axles. In addition, a Single Fairlie has no more driving axles than a normal steam locomotive, but it still requires moving steam lines with the associated leakage problems.
distribution
Single fairlies were rare in the UK . One standard gauge locomotive was built for the Swindon Marlborough & Andover Railway in 1878 - the first British locomotive with Walschaerts controls - and three narrow gauge locomotives for the North Wales Narrow Gauge Railways , Moel Tryfan and Snowdon Ranger (both 1875) and Gowrie (1908). Another narrow-gauge locomotive called Taliesin (1876) was owned by the Ffestiniog Railway, known for its Double Fairlies .
The locomotive builder William Mason licensed the letters patent number 1210 from Robert Francis Fairlie for the USA . However, he only built a single double fairlie and then only single fairlies. One advantage of the Double Fairlie, that it can be used in both directions, was hardly of any consequence in the USA, as there was usually enough space for turntables or track triangles . Mason built almost 150 locomotives of this type; the axle sequences included almost every conceivable combination of two- and three-axle motor and trailer bogies with or without a leading axle . Three series had motor bogies with four driving axles (wheel arrangement (1'D) 3 ').
In order to simplify the problematic, leaky, movable steam connection, Mason changed the basic principle of Fairlie by running the steam line through the bogie bearing and not, as before, from the smoke chamber directly to the valve boxes below. However, this arrangement prevented the use of the Stephenson internal control system, which is common in the USA, so that Mason's locomotive became the first with Walschaerts control in North America. A characteristic detail that can only be found on Mason Fairlies was the control shaft with a correspondingly long hanging iron, which was attached above the boiler for reasons of space (see pictures).
Whereabouts
Of the three NWNGR machines, the Moel Tryfan survived the longest; it was taken out of service in 1937 for repairs and in this condition saw the (old) Ffestiniog Railway being closed. In 1954 the vehicle was classified as unsuitable for restoration and sold as scrap.
The first Taliesin was also in use for a very long time, from 1876 to 1931, and the 18 machines of the New Zealand class R that were introduced in 1878 and z. T. were in use until the 1940s. This Taliesin was reproduced in 1999 by the Ffestiniog Railway, the reversing lever being the only original part used. The basic dimensions of the motor bogie of the locomotive correspond to those of the Double Fairlies of the railway.
In addition to the Taliesin, there may be only two other single Fairlies in the world: The Torch Lake , a Mason Fairlie from 1873, has been preserved in working order, and in New Zealand there is a class R in a museum.
Web links
- Mason Bogie Resource Archive (English)