Engine type information - Newbury Diesel Company

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Engine type information

Engine data

This list of diesel types produced courtesy Tim Watkins, compliments the full database listing.

SID and SBD engines

I have kept clear of information on these types as they were outside my personal experience from memory of 60 yrs ago, The SID was in fact short for  ‘Sirron Induction Diesel’, not as is often stated ‘Solid Injection Diesel’. This information came from Mr Bill Self who worked on them when they were a new type. If you take this with SBD short for ‘Sirron Blown Diesel’ it does seem to make sense.  Both types were designed by Mr Henry Kent Norris, hence the Sirron title. SID were built from 1932 -1935 1 to 5 cylinder versions. With about 8 built. SBD from 1933 – 1937 in 3 to 6 cylinder versions and about 17 were built.


Built in 4,5 and 6 cylinder versions.
Dates uncertain, I suspect some of the smaller engines were moved from ship to ship as engine numbers and installation dates do not always tie up. However, that said, it would seem that the first of this type No 698 was built around 1938. 10 were built

“G” Type
Built in 4 and 6 cylinder versions. Date information as above. 9 were built

“GA” Type
Built in 6 cylinder version only. Once again, problems as to dates, but the last, number 866 was built about 1962. 6 were built

“L” Type
Built in 4,5,6,7 and 8 cylinder versions. Built between 1937 and 1940. 13 were built.

“O” Type
Built in 4,5,6 and 8 cylinder versions between 1941 and 1959. 37 were built.

Technical engineering differences between the various later Sirron diesels. Detail by Tim Watkinson.

“L” type engine.
It is assumed that the L type was derived from the SBD (Sirron Blown Diesel) engine.

“O” type engine
Alterations from the L Type

Each L type had a cast steel inner head with integral combustion space providing ’indirect combustion’. The O type cylinder head on the other hand was made of cast  iron with no combustion space, thus the O type became ‘direct combustion’ with the space between the head and the piston crown being the combustion space.

The L type piston crown was of cast steel and the crown profile was of a turned ‘hump’ to provide the scavenge air with a good flow. The cast hollow was intended to maintain an even wall thickness. A steel plate was fitted to provide a barrier  between the combustion space and the crankcase in the event of a ‘burn through’ of the piston crown and thereby preventing a crankcase explosion.
The O type crown was machined from a solid steel forging with a chamfer and semi hemispherical dish in the centre top to provide a combustion space within the underside of the inner cylinder head, also to provide a path for a ‘loop scavenge’ flow of clan air in through the sloping inlet ports and out through the exhaust ports. The O type cylinder crown was oil cooled, this oil provided from the normal lubricating oil system via the swinging arm ‘oil legs’ and pipes fitted  in the piston trunk. The oil space in the piston crown was made by machining from the solid during the turning operation.

The piston trunks were similar on both engines and made of cast iron, the exception being in the case of the L type, access to the fixing nuts for the crown was from the inside of the piston whereas on the O type trunks, pockets were provided to tighten  these fixing nuts.

O and L type liners were broadly similar in general design with water cooled bars between the exhaust ports. In general, the running gear and control gear was the same as was the scavenge pump system.

“O”Mkll engine.
This engine differed from its predecessor in that it was an exhaust gas driven turbo-charged engine. The scavenge pump however was retained to overcome problems with starting and manoeuvring. An improvement  was made to the scavenge pump with  the use of Streamline valves to replace the previous Circloflex valves of NDC manufacture, Improvements were also made to the oil pump, replacing the bushes with ball and roller bearings.
Mkll cylinder liners were different with no belt on the outside in the inlet and exhaust port area and no cooling of the exhaust port bars.
Turbo charging produced a 50% increase in power. Several engines of this type were built with provision for bridge control or were converted later.

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