Any EMD guys in the house?

Question

All my experience has been with four-stroke MLW's, so we just check the fluids, cut in the batteries and fire them up. I remember watching someone start a GP18, and there were hand-tightened test c***s that you had to open up for priming. My guess is they kept compression from building in the cylinders. Anyway, I recently checked out a GP35 manual and found no mention of them in the starting process. What's the story here?

Answer 1

There are two types of cylinder test c***s that I know of employed on the critters you have referenced.  One type required a tool to open the test c***s, the others were equipped with handles.  The ones with the handles were referred to as "steer horns."  Around here they were called "flash c***s," but that's probably local jargon.  Easier to say, also...

The primary reason for using them was, when a locomotive had been shut down for some extended period, or a period of unknown duration, these c***s were to be opened when cranking the engine, to purge any water that maay be in the cylinders, either from condensation or, more often, leaking water jackets..  Failing to do so could result in some serious damage to rods, pistons or crank.

Another handy-dandy use is, when encountering weak batteries, the test c***s could be opened to reduce compression in several cylinders, sometimes to the point where there was enough juice in the batteries to fire the thing up.

In these instances, you didn't want anyone on the catwalks, as the flash c***s sometimes spit out carbon deposits, and at relatively high speed.

When in the shop, these were opened on all cylinders when ever the mechanics needed to "bar" the engine over.  This was an air powered device that engaged the flywheel and turned the crank in one or two inch increments, for whatever reason needed.

Every once in a while you'll hear one that has been left open on a running engine.

Speaking of starting, have you ever seen (or heard) a new engine at first start up, or in extremely cold weather, after being "Hot Shot"ed?  This is when ether is introduced into the injectors for start up.  Hellacious sounds.  Darn near scary...

Good question, Highball.  "Skid 'er back....."