2 stroke locos

[wisandsouthernkid]

now i read the forum below i was wondering is the 2 stroke diesel the same principle as say my snowmobile with no oil in the crankcase and it uses roller bearings instead of friction bearings maybe i have seen it in the below forum but must have missed it if it was thanks

[silicon212]

What is your question?

Diesel two stroke engines use an external tank pressurized lube oil delivery system - also called a dry sump system - as used in piston aircraft engines and race cars.  Oil is contained in a separate tank and is otherwise supplied to the engine bearings under pressure (like your car engine).  The oil is retained within the engine, scavenging pumps pull the circulated oil from within the engine and send it back to the external tank.

They don't have roller bearings, they use sleeve bearings like a car engine - albeit much larger.

The diesel two stroke doesn't combust (very much of) its lube oil.

[GP40-2]

The diesel two stroke doesn't combust (very much of) its lube oil.

Apparently someone forgot to send EMD that memo. EMD's, especially after some wear and tear, burn plenty of their lube oil.

[edbenton]

We OTR boys had a joke on the old 2 stroke Detroits.  Check the fuel and fill the oil.  Seriously though I have seen reports from friends in the shops were EMD's shut down do to low oil pressure the reason low oil level and considering they hold 200 gallons OUCH.  Also they are not a dry sump they are a wet sump system like a normal car engine ust the pump is external think the old 3800 V6 by buick.

[silicon212]

Ed, sorry, it is a dry sump system.   "Dry sump" by designation means oil stored in external tank, not in the sump.  There is no 'sump' on the 'oil pan' on these engines!

[edbenton]

Hate to tell you this I worked for Relco and the ones we Rebuilt were WET SUMPS.  Yes they have an external tank to store some of the oil but a true dry sump oiling system has pumps that remove the oil as soon as it gets thru lubing the spot it was needed at.  What EMD uses is a combo system partly dry and wet and that is the worst way to do it.

[Railway Man]

I'm not an engine designer, but I think Ed's correct, the EMD is neither a "wet sump" or a "dry sump" by the conventional definitions as I understand them.  There is no external lube oil tank as required for what I understand to be a "dry sump" system though there's quite a bit of oil "in transit" in the lube oil strainer, filters, and cooler.  On the other hand the EMD does have a scavenging oil pump (as well as piston cooling and main lube oil pumps, and if turbocharged, a lube oil pump for that, too), which is characteristic of a "dry sump" engine.  When the engine shuts down, almost all of the oil drains into the oil pan except for some that's in the strainer and whatever is sticking to surfaces.  At the bottom of the pan is the sump, where the scavenging oil pump sucks from.

The oil level in the pan is well beneath the level of the main bearings.  I recall glumly looking into the crankcase of a 567BC one bitter January morning in Wyoming and observing that the oil was so gelled that I laid a 16" Crescent wrench on top of it, and it didn't sink.  It took us two days with a pair of salamanders running around the clock to warm that engine enough where we could start it.

RWM

[bobbo]

Hi Railway Man, could you please tell me what salamanders are? Thanks

[edbenton]

A salamder is a Kerosene power convection heater that will normally heat the heck put of anything.  We used them to keep the shop warm in the winter when the shop heater was not enough.  Great for thawing out water lines under a moblie home.  Here is a link to a site that will give you some details on them http://www.masterheaters.com/

[dldance]

I'm not an engine designer, but I think Ed's correct, the EMD is neither a "wet sump" or a "dry sump" by the conventional definitions as I understand them.  There is no external lube oil tank as required for what I understand to be a "dry sump" system though there's quite a bit of oil "in transit" in the lube oil strainer, filters, and cooler.  On the other hand the EMD does have a scavenging oil pump (as well as piston cooling and main lube oil pumps, and if turbocharged, a lube oil pump for that, too), which is characteristic of a "dry sump" engine.  When the engine shuts down, almost all of the oil drains into the oil pan except for some that's in the strainer and whatever is sticking to surfaces.  At the bottom of the pan is the sump, where the scavenging oil pump sucks from.

The oil level in the pan is well beneath the level of the main bearings.  I recall glumly looking into the crankcase of a 567BC one bitter January morning in Wyoming and observing that the oil was so gelled that I laid a 16" Crescent wrench on top of it, and it didn't sink.  It took us two days with a pair of salamanders running around the clock to warm that engine enough where we could start it.

RWM

and that's why UP keeps them idling

dd

[bigbird_1]

Your snowmobile engine and every other small 2 stroke engine uses a pressurized crankcase that sends the fuel/air mixture from the carbs (or throttle intake in the case of fuel injection) down into the crankcase. Because the fuel/air has lube oil injected into it, this fuel/air/oil mixture lubricates the motor's lower end. The fuel/air mixture then travels through transfer ports in the block on into the cylinder to be ignited. In a 2 stroke railroad or marine diesel, the air alone is blown straight through into the cylinder head by the super/turbo charger. Then the fuel is injected into the cylinder head to cause combustion. Since the crankcase is not needed to transfer air/fuel, typical dry or wet sump pressurized lubrication can be used.