Nope you are really talking about two different devices. The gas/oil mix fueled 2-stroke provides lubrication and fuel for the engine. Whether the oil is injected into the air/fuel stream or pre-mixed makes no difference. Since chain saws, yamahas and model aircraft engines, including model diesel engines run this way proves that it will work.
But, we were discussing specifically Detroit Diesel 2-styroke diesel engines that do not premix the oil and fuel. Quite the opposite, they are vary carefully separated. Thus, a blower scavenged 2-stroke diesel will not run without it's blower.
Right - but how did that model engine lubricate the main and rod bearings, and the wrist pins and piston bores? If they were misting the fuel into the crankcase as a bearing lubricant before it got inducted and burned as the fuel, that isn't a true Diesel engine, it's a modified Glow-Plug engine.
And how did they get the crankcase pumping effect to work on a multi-cylinder engine where one piston is going down when the next is going up? The glow-plug engine would need solid dividers between the crankcase sections so each piston pumps for itself.
The Detroits have an open crankcase, so no pump effect. And they use conventional pressure oil lubrication, plus most diesels have an oil jet aimed at the underside of the piston for cooling and wrist pin lube - not sure, but Detroits have to do it like everyone else... If any of that motor oil in the crankcase was to accidentally get into the cylinder intake air, you have a runaway engine.
Same thing if an oil seal on the blower or the Turbocharger (if equipped) blows and starts dumping motor oil into the intake - a runaway engine that will soon "Go Splodey" when it exceeds redline by a sufficient amount.
This is why they have that Emergency Shutdown air damper on the air intake, that's the only way to kill a diesel engine if the oil it is running on isn't coming in through the fuel injectors.
Actually a lot of multi-cylinder engine makers did exactly that, to name a few US makers: Fabco-Tuxham, Fairbanks-Morse, Kahlenberg, Kromhout, Markey-Viking, Mianus, Wolverine etc
No, the statement was all diesels require a blower. There were lots of old fishing boats with 1 and 2 piston diesels, that did not require a blower to run. But they were designed like gas 2 stroke to use the crankcase as the compressor.
Fair 'nuff. Missed that. I thought we were referring to DDs. Should'a been all 2 stroke diesels require a mechanism to pump air into the cylinder. Blower or crankcase, depending on the design.
I had assumed that as the original post was concerning s 3-53 Detroit Diesel engine we were still talking about D.D. engines, however the subject seemed to have slipped a bit, Mia Culpa.
But I am interested in these 1 and 2 piston diesels, used in fishing boats that did not use a blower? can you tell me the approximate period they were in use and what the manufacturer was?
Early 1950's late 40's. Lot of Monterey's used them. Just use to hear them as they ran. About one explosion every 5-6 seconds. Montereys were built and designed in Monterey, Calif and used in the sardine fisherey.
That is interesting. If anyone has any additional information on these engines I would really like to find out what they were using.
On the New England coast engines of this type were long gone although some of the older fishermen used to talk about one cylinder gasoline inboards , possibly Fairbanks, that could be reversed by moving the manual spark lever to the point that ignition was so far before TDC that the engine kicked back and ran in reverse.
I don't know why I didn't think to post a link like this yesterday. It makes it much easier to see and understand the difference between the two designs (crankcase induced air vs blower induced air) and see why a DD design won't run without a blower.
Early on (1920) Fairbanks-Morse mad at least one 15 HP semi diesel that used the crankcase to pressurize air for the 2 stroke engine The engine lubrication was by a mechanical oil pressure pump pumping oil to the two main bearing shells and to the cylinder. However the later two piston Fairbanks-Morse 2-strokes used in locomotives and ships all had a mechanical blower for scavenging.
From looking at pictures and drawings the engine was constructed much like any other horizontal engine of the same era except that the "crank case" was closed on all sides. The main bearings were simple babbeted bearings with caps lubricated by an external lube pump connected through external "oil pipes". A third oil line ran to the cylinder and I assume that some of the oil that lubricated the piston dripped down on the horizontal connecting rod and flowed back to lubricate the connecting rod ends. The manual refers to a "oil tube" on the connecting rod connected to the big end.
The oil pump was a cam operated devise as the manual discusses "giving the oil pump several pumps prior to starting the engine".
So essentially the engine had a constant loss lubrication system which was not unusual in that era. I have seen other horizontal semi diesel engines of the same eras that had oil cups or drip oilers on both main and connecting rods.
I was looking at a couple of multi cylinder marine steam engines last week which dated from the late 1800s/early 1900s. They had oil cups on the main bearings. Couldn't figure out how the rod bearings were lubed if at all. Good thing they were slow turning.
On Mon, 27 Aug 2007 20:56:17 -0400, Wayne.B wrote:
I crewed as a fireman/watertender on a couple of Great Lake tankers with steam engines, both built in the teens I believe. The Rocket (Cleveland Tankers) and the Illinois (Standard Oil). Unfortunately I can't remember the lube systems, as I didn't pay much attention. My impression is the rod bearings were splash lubed, but I could be wrong. Occasionally I'd spend some time in the engineroom chatting with the oilers, and here's what I remember: The engines were beautiful machines, with the steam heads high in the space, the crank down below, and the men and auxiliaries mid-level. Safety rails surrounded the engine pit, and you could chat without yelling as the large rods pumped up and down nearly next to your ears. The steam head valves and exhausting steam made the bulk of the noise. The deck of a similar sized tanker powered by diesels was more bothered by noise than the engineroom of a steam reciprocator. The rods were articulated, the knee moving up and down on a slide, which was lubed by the oiler with a common squirt oilcan. Every moving part was clean, shiny, and slick. I was shown by one oiler I was friendly with a lube retention hole on one of the rod knee slides, and told a story, confirmed by others who were there. The slides were maybe 6" wide, and the lube holes maybe 1/2", spaced a couple feet apart. An oiler had lost a little finger in this particular lube hole, sliced clean off after the first knuckle. Everybody wondered at his bad luck, since it was almost impossible to get a finger cut off there even with lackadaisical attention to safety. He was paid $3,000 for the loss of the finger. Less than 2 years later the same finger of his other hand was cut off in the same hole. He was again paid $3,000, but was blackballed. There was no doubt he had done self-amputations for the cash. I don't know if this guy wanted the cash to buy an ETEC or a Parker, but every time I look at the driver of one, the thought enters my mind.
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