Click here to download the price list for the 0-8-2T Large Shunting Engine.
|
LNWR 0-8-2T Shunting Tank Locomotives
The Prototype
The LNWR recognised in the early 1900’s that the quantity of goods traffic in their major marshalling yards required a larger engine for shunting purposes than they had produced so far. The large tank locomotives were designed by C J Bowen-Cooke in 1910 as a development of the ‘G’ class 0-8-0 tender engines. In essence they were the same chassis but with an extended frame to take the trailing radial axle. The cylinders were still the slide valve version and the strengthened frame incorporating the centre bearing on the crankshaft behind the cylinders was retained. It is clear from the works drawings that these locomotives were given strengthened axles compared to the original ‘D’ class and the journal sizes were increased to take the increased duty. It will be seen from the photograph that the coupling rods were fitted as separate entities; the centre portion being added outside the other two.
|
There were small differences to the boiler firebox tube space and the valve gear to make starting easier but for this application a pole reverser was fitted. It will be clear from the pictorial records that these locomotives were only fitted with round top boilers which gave a very clean appearance to the side tank plate work. Three batches of ten locomotives were built overall; one before the 1st World War and two more during the conflict. The latter two batches were painted just plain black but with LNWR on their sides. In service it was found necessary to fit the larger buffer heads as the locomotives had a greater sideways movement over the yard point work and ‘buffer locking’ was a problem.
Examples of these large locomotives with some variations in paintwork and buffer style.
|
Hauling a train out of the Sentinel Works in Shrewsbury with steam wagons loaded for distribution.
|
The Model
New frames and frame extensions have been designed for the locomotive as there are distinctive features that are obvious from the drawings. The addition of a trailing radial axle has meant the model is designed to be similar to the Coal Tank and the frames are set at 4¼” internal spacing compared to the ‘Wessie’ 0-8-0 design where the frames are only 4 1/8” apart. A slightly revised cylinder block has therefore been produced to fit this change in frame spacing and it allows the full 1 5/8” diameter cylinder bore to be used or even increased to be 1 11/16” if preferred. The front and rear steel plate beams have also been fitted with the correct strengthening gussets behind the buffers. The radial axle assembly itself is the same one used for the Coal Tank and all the wheel castings are the same. Also at the rear of the locomotive is a new drag beam and for use as a passenger hauler, a modified draw hook connection is provided in front of the radial axle to minimise the degree of ‘throw over’ between the engine and the driving trolley.
The driving and coupled axles themselves are now ¾” diameter and the wheel centres have been enlarged to 11/16” to represent the prototype. The crankpins have also been enlarged so the locomotive looks properly representative. The advantage of the wider frame spacing is that a more generous crank design can be adopted; the same crank web parts are used but as they are cut from 10mm material they are not machined down to the 3/8” width originally specified for the ‘Wessie’. In addition, instead of using simple brass angle for the horn cheeks, a bronze casting is available to which can be added brass blocks to give the necessary depth for the twin clamping bolts through the spacers under the bearings. It is proposed that all axles will be sprung with leaf springs consisting of a mixture of spring steel and ‘Tufnol’ or another low spring rate material such as nickel silver. |
The designer's model.
|
|
|
These two pictures show the development of the ‘D’ Class Tank chassis prior to the 2018 Bristol Model Engineers Exhibition. The valve gear parts have been completed and assembled with the slide shaft set so that the valves open as the pistons leave each dead centre in both forward and reverse gear. A simple strip and pin have been attached to the slide shaft reversing lever to demonstrate the operation and this is held with a small clamp. Later, the correct pole reverser will be attached to the inside face of the left hand side tank in the cab. The next phase requires the construction of the smokebox and the cover for the steam chest which has been left as a Perspex top for viewing purposes.
phone |
+44 1600 713913
|
|
address
|
1 Highmeadow, Wyesham, Monmouth, Monmoutshire NP25 3TB
|
Last updated 26th December 2020