Commer Knocker Opposed Piston Common Crank


One of the odder Diesels

The Commer Knocker Opposed Piston Common Crank is one of the loudest Diesels you would ever wish to work with. They didn’t seem to use any Mufflers in the trucks they are used in?

It is an interesting design for sure but, is it really a good use as opposed to the normal crankshaft and connecting rod arrangement that we are all so used to seeing?

Opposed engine
Opposed engine

I have not seen one used in Tractor Pulling yet. Just in videos over seas making a ton of racket for the most part. The drivers wear ear protection when they drive them from what I have read and seen too.

Now the real odd part is that this engine has no cylinder head to speak of? Instead both pistons share a cylinder and come at each other to make compression. It uses a Roots supercharger to force are into the cylinder like a GMC diesel does.Then the pistons come together to compress the air and the fuel is injected pushing both pistons back. Then as seen it the second video rocker arms are used to change the mpveent down to a crankshaft under the cylinders. It is a very odd layout and you may think it is ingenious to an extent. However seeing how it never caught on so to speak then it had to have inefficiencies or some other weaknesses?

So much for all these knew engine designs as they just are not working out.

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