Sherman M4A2 diesel engine designation

Originally posted by Richard Farrant
Fodens produced a straight 6 two stroke on the same lines as a 6-71, they were in production during the 50's and 60's, easily recognised by their wonderful exhaust note. Detroit Diesels were fitted in production trucks in the UK, they were options in Bedford TM and Scammell Crusaders, probably others I cannot think of at present. I seem to think they were all based on a German design, was it Junkers?

Richard F.

Yes the Fodens indeed had a two-stroke, but wasn't this the Foden Uniscavenge which relied on the Kadency Effect? There was the flat 3 opposed piston device in the Commers during the same time using rockers on the pistons to connect to a common, underslung crank, these had a reciprocating scavenge pump though unlike the DDA Rootes blower arrangement.

The DDA option on TMs and Crusaders must have had little take-up, I cannot ever remember the two-stroke howl from one of these.

I'm not sure about the Junkers connection with DDA though, Junkers aero diesels were always vertical opposed piston, twin crank and piston ported, even the early 1913 - 1916 engines are recognisable as nearly identical to the L60 which you know.

The early engines were injected and spark ignited but by '26 they were all compression ignition, in '31 the Junkers FO4 became the Jumo 4 and was both built under licence by Napier and developed by them into the Culverin.

All these Junkers diesels had very good hp/lb figures and of course excellent fuel economy, the Jumo 205 and 207 powered the JU86.

It is surprising how the L60 could be such an unreliable dog when its aero heritage was entirely different with lighter engines of greater power and very good reliability.

Take a look at http://www.enginehistory.org/Diesels/CH1.pdf as its a fascinating piece on aero diesel history and with many surprises too.

R.