OK, you wanna talk BIG diesels? - PeachParts Mercedes-Benz Forum

Chris W. · #1 07-08-2003, 01:54 PM

There was a thread a short while back about the world's biggest diesel. I work for the company that makes it. That particular engine is a 2 stroke, and as such it really doesn't even look much like an engine that we would recognize, as it has a crosshead and 2 part con rod, etc.

I thought y'all might enjoy a pic of a con rod from our largest 4 stroke. Bore is 25.2" and stroke is 35.4". In a V-18 version it produces 47,490 HP. This con rod weighs about as much as a car!

Enjoy!

Rgds,
Chris W.

#2 07-08-2003, 02:29 PM

You can't show us that without telling us what this is used for:
My guess is marine?

The old Marathon Rubber factory here in town was recently torn down and I had the opportunity to tour it beforehand.

Believe it or not, they used the transmission from a WWII sub in the factory: it was pretty wild seeing those HUGE gears countersunk into the ground.

slowmoe · #3 07-08-2003, 03:27 PM

Now that's a cool company to work for!!! Any openings in sales?

I'm serious.

sixto · #4 07-08-2003, 03:30 PM

Do you use a finger in place of Plastigage?

Sixto
95 S420
91 300SE
87 300SDL
83 300SD

TN-W124 Diesel · #5 07-08-2003, 03:56 PM

and what do they start it with??

Stevo · #6 07-08-2003, 05:04 PM

I have run tugboats with large engines but that thing is HEMUNGUS.

Whats the tonnage of the ship that it propels?

Chris W. · #7 07-08-2003, 08:13 PM

The engine can be used for a ship's propulsion, or for a generator set - there is nothing which says it can't be used for either application. Traditional high horsepower applications like this have had to resort to 2 stroke (so called "slow speed") engines because there weren't any 4 strokes this large. This engine operates at a constant 400 RPM for 50 Hz generation or 428 RPM for 60 Hz duty, and for marine use it would typically drive a variable pitch propeller through a gearbox and stay at about 400 RPM. Even though this is very slow by our automotive standards, it's still classed as "medium speed" in the large engine biz. The slow speed engines typically operate in the 70 - 120 RPM range

These large engines are started with 430 psig (30 bar) air acting directly on the pistons, we use an air distributor to route the air to the right cylinder at the right time to turn it over. They actually start up quite quickly and reach operating speed within 10 or 15 seconds.

Rgds,
Chris W.

psfred · #8 07-09-2003, 01:13 AM

Vartsila?

With that kind of reciprocating weight and power, speed is a relative thing, I think.

That's the reason most 50,000 hp applications these days are turbine -- it only goes round and round, not up and down.....! Not as efficient, but it doesn't shake the earth, either.

Bearing oil clearance is probably still on the order of 0.005", though.

Peter

sixto · #9 07-09-2003, 04:18 AM

I would think a roller bearing crank and roller bearing rods would be the order of the day on components that size.

Sixto
95 S420
91 300SE
87 300SDL
83 300SE

Chris W. · #10 07-09-2003, 10:44 AM

Yes, Wartsila is the company. It's not quite true about turbines. There are VERY few gas turbine ships built for commercial use. (just a couple recent cruise ships) The military uses them because a gas turbine (aka jet engine) is very small and light for a given amount of power. The problem is efficiency. The most efficient gas turbine on the market has a shaft efficiency at ISO conditions (59F) of about 40 - 41%. If you bring the temperature up to 90F and allow for gearbox efficiency and some wear and tear, you easily drop that efficiency down to 35% or so. Also if you run a turbine "off the curve" at part load, the efficiency drops like a rock.

The big diesels have a shaft efficiency of about 50%, which maintains at high temperature, and maintains very well at part load. That efficiency difference is a huge factor when the main operating cost of a ship or power plant is fuel.

Large electrical power plants use combined cycle gas turbines, which recover exhaust heat to make steam and drive an additional steam turbine generator. These plants are in fact very efficient, (+/- 55-57%) and the largest gas turbine is on the order of 350,000 HP by itself, but this is a stationary unit, not made for ships. The trouble with a combined cycle plant is that you can not start and stop it often, or quickly either, because of the thermal cycling and thermal inertia. And with a heat recovery boiler and steam turbine it is a huge setup.

Sixto - these engines have sleeve type bearings exclusively for the main and con rod bearings, as well as cam bearings. No roller bearings.

Rgds,
Chris W.

Stevo · #11 07-10-2003, 03:25 PM

As a young deckhand in san Francisco I remember 'oiling up' the direct reversible engines that were common in tugs then. there is a plank to walk along which puts you at the right height to oil the rocker arms, valve springs and push rods as the engine chatters along at 300 or so RPMs. there was also a "Manzel (sp?) lubricater " that had to be filled which carried oil it other parts of the system. This had to be done every 4 hours and was somewhat of a challenge to hit the little holes in the rocker arms while they were moving especially in rough weather. those old "Washington" and "Atlas" engines were kindly referred to as "stamp mills", much nicer to listen to than Jimmies or even Cats. All that oil eventually wound up in the bilge and being pumped overboard

so I guess its a good thing there are not so many "stamp mills" around anymore.

I think all those engines were 2 cycle.