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October, 1946

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We were recently afforded the opportunity of visiting the Lincoln works of Ruston & Hornsby Limited to inspect a number of their diesel-engined mines locomotives in course of manufacture. This firm has long had a reputation for oil-engined shunting locomotives, and claims to be the pioneer in this country of oil-engined locomotives for use in mines. The first Ruston mines locomotive was supplied in 1932, and since that date over 250 locomotives have been supplied to naked-light and safety-lamp mines; at the time of our visit over 60 such locomotives were on order. In 1934 the standard mines locomotive was flameproofed to suit Continental conditions and a certificate was subsequently issued by the Belgian Bureau of Mines. In England Ruston flameproof equipment for mines locomotives was tested at Buxton in 1938 and was approved without modification.

The present range of Ruston mines locomotives is, therefore, in no way experimental but embodies features that have been tested in service on shunting and mines locomotives for a number of years. In the light of this experience Ruston & Hornsby Limited have been able to follow a policy of standardisation that has reflected favourably on the initial cost of a locomotive and in the facility with which spares can be made available. It is even possible to supply a locomotive to one track gauge but arranged for subsequent conversion to a wider gauge by a mere interchange of wheels and axles. As manufacturers of oil engines for many years, Ruston & Hornsby Limited build their own engines for their locomotives, so that the entire locomotive is covered by the one guarantee.

Ruston mines locomotives are available in sizes from 13 to 48 h.p. for naked-light mines and from 20 to 48 h.p. for gassy mines, and for gauges between 1 ft. 6 in. and 3 ft. In view of the trend towards the use of large mine cars a 100 h.p. locomotive is in the design stage. One of the latest 48 h.p. flameproof locomotives is depicted in Fig. 1, and a flameproof locomotive that has been in use for man riding in a Manchester colliery since 1940 is seen in Fig. 2.

The main frame is a box-like structure built of rolled-steel sections electrically welded together. Engine and gearbox are disposed respectively over front and rear wheels, giving approximately equal loading on all wheels with resulting stability. A flexible coupling between engine and gearbox protects both units from damage due to racking strains on the locomotive, and its inclusion is facilitated by the absence of a clutch between the units. This arises from the design of the gearbox, which is a type that has been in use since 1931, and is a three-speed constant-mesh gearbox having a separate plate clutch for each gear. A gear lever working in a gate selects the gear required and engages the appropriate clutch, there being no separate clutch pedal, or, indeed, any foot control whatever on the locomotive. Gear changes are foolproof, and as the gears and their clutches revolve constantly with the engine, changes can be made without pause and with the engine moving at full power and speed. As the clutches are subjected to a constant flow of oil the pick-up is smooth and the heat is conducted away from the plates, conducing to long life of the friction linings. A further feature of the gearbox is its accessibility. On removing the gearbox cover, which is inside the driver's cab, the entire mechanism. can be lifted away in one piece.

Final transmission is by roller chain. This type of transmission has gained rather a bad name on the Continent, but Ruston & Hornsby Limited maintain that this has been due to fundamental errors in design which they claim to have overcome by the introduction of certain features that proved successful over a number of years. The unreliability of chain drives is stated to be due to uneven tension and "snatch". In the first place, therefore, connecting rods are eschewed and each pair of wheels is driven direct by a separate chain; secondly, each pair of wheels is guided on each side by a radius rod extending between axlebox and frame in line with the drive centres, with the result that the chain tension is not altered by the locomotive riding on its springs. Due to these two factors, it is claimed, the chain tension is evenly maintained and reliability assured. Owing to the use of radius rods the axleboxes do not ride in hornblocks, and the springs are not drilled for bolts but bear on renewable hard-steel pads. The axleboxes are fitted with bronze half-bushes and are pad-lubricated from an oil sump. Dust and moisture are excluded by means of a cork seal. Side thrust is taken by the end of the shaft bearing against an end face on the bronze bush, the axlebox being supported in turn by an extension plate on the main frame.

The brake is of the compensated type and is operated by a hand lever with pawl and ratchet quadrant, this type of control being preferred to a screwdown brake as being quicker to operate and not subject to the possibility of jumping a thread. On the latest 48 h.p. locomotives a compressed-air brake can be fitted, as is the case in Fig. 1 — a feature that enables a continuous brake to be fitted to a paddy mail.

The Ruston inlet and exhaust conditioner were described by Mr. Brian Reed in our July 1946 issue, page 173, and we cannot do better than refer our readers to his article for details of this equipment. The exhaust conditioner and flame trap unit is located at the back of the locomotive where it is immediately accessible — a position that has the further advantage of interposing a long run of exhaust pipe between engine and conditioner and assisting the cooling of the gas. A water-cooled exhaust manifold also contributes to this end. On the inlet side of the engine an oil-type air filter protects the inlet flame trap from becoming clogged with dust.

The radiator is thermostatically controlled and is blanked off from the engine compartment so that dust is not blown over the engine.

Drawings and Photographs accompanying the article