Underground Locomotives.

A large number of narrow gauge Rustons worked underground in mining or tunneling, both at home and abroad and had to be adapted for this work. The main feature that allows an oil engined loco to work below ground is the exhaust conditioner, this device cleans the irritant constituents of the exhaust gases from the engine so they do not pass into the atmosphere where they would build up and make working conditions unbearable.
 In some mines the clearances were limited and the driver had to sit lower down, this meant that bodywork alterations had to be made so he could still see where he was going. In many early locos this was done by fitting a flatter engine cover vent and flat topped fuel tank.
The first loco built by Rustons for underground use was a 10hp type W/n 166027 and was delivered for use by Messrs Cafferata in their Hawton gypsum mine in Nottinghamshire.

The first RH loco for underground use, w/n 166027 - note exhaust filter on LH side of frame.

 Locomotives used in gassy coal mines must have the extra feature of flameproofing to ensure that any firedamp in the atmosphere is not ignited by the hot exhaust gases and were subject to approval of the Board of Trade. The first B.O.T. ‘Buxton Certificate’ as it was known was awarded to Ruston & Hornsby in 1939 for approval to use 33/40 and 44/48hp machines in British mines. The photo below shows W/n 195854 the first B.O.T. approved Ruston to enter service in a British coal mine in the yard at Boultham works prior to delivery to the Fife Coal Co LTD’s Comrie colliery. This however was not the first flameproof loco built by Rustons as a machine was put to work in a Belgian coal mine in 1934.

44/48hp loco w/n 195854 on test at RH works

 Later underground locos were given suffix letters to differentiate whether they were flameproofed or not, these were U, e.g. 48DLU for ordinary underground use and G for flameproofed.

There was another suffix; Z applied only to man-riding 48DLs. The above drawing shows a 48DLZ, the largest 4-wheel chain drive NG model made by Rustons and is basically a smooth bodied style loco but on a 12’ 10” frame. This type was intended for man-riding trains in coalmines and was fitted with airbrakes for this purpose.

Below is a cross-sectional diagram of a 40DLU exhaust conditioner showing the water bath through which the gases are bubbled to remove the irritants such as aldehydes and sulphur dioxide as well as some of the carbon particles. This unit is not intended for use in gassy mines and so is not equipped with flametraps.

Below is an exhaust conditioner as fitted to a flameproof locomotive for use in gassy mines.