EMD Electro Motive Diesel

[smokinwrench]

Worked on my first emd today, same engine as what is in older trains. It is on a skid with a 2.7 megawatt generator as a black start unit at one of a power plants. It is a V20, 645 cubic inches per cylinder. Sent me up to find out why it was building crankcase psi when it should run it a vacuum. Found the problem scored liners.

The cool thing was this engine has rotating pistons, every time the piston goes down as it starts back up it rotates a tiny bit, to keep from getting deep scoring on the pistons and liners. I was just amazed by it, 3 of us that work here have big engine experience on all different brands and no one had ever heard of a rotating piston. Probably boring to most of ya but being a gear head I was amazed by it.

[charger]

wow that is awsome!

[KASEY]

this is what it looks like bare

[smokinwrench]

Yep thats it. Do you have those for sale Kasey? I sure like those easy off side covers, much better then the ones that are bolted on. Have you looked at the odd shape of the heads? I also noticed they are just held on with 4 clamps.

[brapp]

hoiw do they rotate similar to a heim joint or what??

[smokinwrench]

Pistons on several big engines are not attached with a typical rod through a wrist pin hole. They have carriers that attach the rod to the piston. The manual didn't show it very clearly but from what I could tell it has a floating device in it and when it comes down it pushes back up and it causes it to rotate a little bit each stroke.

That thing runs at 1800 rpm which is also amazing for a engine that big with that old of a design.

[250rAL]

That thing runs at 1800 rpm which is also amazing for a engine that big with that old of a design.

And they make sweet music when they do.