WOW, I NEVER
dreamed the mention of two-stroke engines would create such a groundswell of emotion from you lot. Okay, so I made a tech blunder when I first mentioned two-stroke diesels (I assumed the crankcase was pressurised. It’s not.) and a couple of you picked me up on that, but more of you again have made contact to express a deep appreciation of what the two-stroke engine has to offer.
And geez, Laurie, four decades with the same lawn mower! Most marriages don’t last that long. Meantime, the Napier Deltic you’re talking about was/is indeed a monumental piece of work. You’ve got to hand it to the bloke who came up with the idea of using opposed pistons at either
end of the cylinder, trying to headbutt each other and, in the process, forming the combustion chamber, even if it meant having three crankshafts; one on each corner of the delta.
I think – and I’m happy to be corrected here – that the venerable Commer Knocker (another Pommy contraption) used similar technology, although it had a single crankshaft with the second piston operated by a con-rod and a rocker lever. From what I can gather (it was before my time) the Knocker performed well but the big problem was that the shaft, which ran all the way from the back of the engine to the front to drive the scavenging blower, could be a bit brittle. And without the supercharger to scavenge the cylinders, she no go.
Apparently, the move to the compact opposed-piston layout was aimed at keeping the engine physically low so it could be mounted under the cabin floor as one of the early `cab-over’ designs. Anybody out there with experience of a Commer Knocker? Let’s all share.
Actually, I’ve just had a better idea: Anybody out there actually own a running Commer Knocker or anything else with an opposed-piston diesel two-stroke? I’d love to come and have a look at it and maybe start a little video series on Weirdness We Love. I’d watch that. What do you lot reckon? Does a little UC video series on weird engineering grab you? And what subjects should it tackle?