Radial engine main bearings 1

[mdxinv]

How was the lubrication feed done for aircraft radial engine main bearings? For a vee-engine the top main bearing shell has a 180 deg groove which flows oil into (usually) two holes drilled into the crankshaft main journal, and then feed up to the crankpins to lubricate the rod bearings. The bottom shell is left plain (no grooves) so as to have maximum load bearing capability since the mains in a vee engine are loaded higher in the downward direction. What oil groove strategy for main bearings was used for (2x)R-9 and (4X)R-9 radial engines such as the Pratt & Whitney R-2800 and 4360? Since there are combustion forces acting all around what solution was used? Any pictures on the internet would be nice.

 

[berkshire]

Here is a picture.

http://www.flickr.com/photos/skyhawkpc/5548383006/in/photostream/

The main bearings were roller bearings.

B.E.

 

[thruthefence]

In the picture provided, I believe the "yellow" component is the "Master" rod, which is the only one that actually runs on the crank throw. The "blue" component is a "slave" connecting rod. Those cylindrical, "roller-like" things are knuckle pins for the slave rods. The slave rods themselves have been removed for clarity in this cutaway.

Here's a link to a master/slave rod assy:

http://en.wikipedia.org/wiki/File:Haupt_und_Nebenpleuel_BMW_132.jpg

Here's an R-2800 crankshaft specific link:

http://www.enginehistory.org/NoShortDays/CrankHX.pdf

Plain silver/lead bearings on this one.

 

[mdxinv]

Thanks berkshire and thruthefence for your resopnses.

Yes, that's a master con-rod type R-9 with a multi-piece crankshaft to enable use of a single-piece master rod. I still can't see the main bearings and what oiling/bearing design was used.

 

[tbuelna]

mdxinv,

The Pratt 4360 used a one-piece crank with journal type rod and main bearings. If you get a copy of Graham White's excellent book on the R-4360, there is a detailed lube circuit diagram shown on p.100.

Or take a look here:

http://www.enginehistory.org/P&W/R-4360/4360Cross.jpg

Good luck.
Terry

 

[franzh]

I am still in total amazement at the complexity of these engines, especially the four row 4360 Major. The fact that it was designed without the use of computers with little more than sliderules and a very forward-looking vision.

And it actually worked. I saw a motorized cutaway in a museum several years ago and spent an embarrassing amount of time just following the motion.

Beautiful.

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[Lou Scannon]

One of several iconic aero reciprocating engines that were highly developed during the WWII and post-WWII period out of military and subsequently commercial necessity. Other designs from this era I admire very much are the Merlin, Napier Sabre, Junkers Jumo (two stroke diesel opposed piston), Wright Turbocompound. I understand the later Daimler Benz DB60x series of engines were pretty exotic also, though I'm not so familiar with their design details. Though it never reached production, the Napier Nomad diesel turbompound was truly a mechanical marvel.

move along, nothing to see here

 

[tbuelna]

franzh,

The 4360 does appear outwardly complex. But the basic engine configuration is "simple". It uses 2 valves per cylinder with pushrods, a one-piece crank, air-cooling, and gets its power with slow-revs and large displacement cylinders.

Pratt & Whitney had some excellent chief engineers like Luke Hobbs. While others chose to use more exotic approaches like liquid cooling, 4-valve heads, overhead cams, and high revs to make power, Hobbs wisely kept things simple. As a result, the big Pratt recip engines (R-4360 and R-2800) tended to be more reliable and had less development trouble than other engines in the late 30's and 40's.

terry

 

[evelrod]

Franz, something for thought. Perhaps the 'ultimate' airboat?

http://www.youtube.com/watch?v=2d4HQ8ZM_2k&feature=related

Rod

 

[franzh]

Rod, the prop is in the wrong pitch, it would pull the truck backwards. Wonder how fast it would push it if it were a reverse prop? 200+?

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[evelrod]

I noticed the prop pitch. I've never been on an airboat but seems like I could have some fun with one.
I watched "When Vacations Attack" last night and a T6 had a crankshaft failure and landed on a highway in front of a couple Hwy Patrol cars. Reminded me of this thread.

My only aircraft restoration project was my cousins Cessna T-50. He got two of them surplus for $600 and we made one flyable. That's the only radial I have ever taken apart and overhauled. I think it was a Jacobs. The plane had two and I only did one of them as the AE that was signing off my work moved and I was not allowed to do the second one. It was just an engine, what was the big deal? Mine worked fine for many years!

Rod

 

[thruthefence]

The "bamboo bomber". Sky king 'n' Penny flew one!

Here's a local, at DTN:

http://tinyurl.com/3fcldvj

After a lengthy restoration, a test flight was made, but the pilot forgot to put the gear down on landing. Scratch two new props & a pair of fresh "Shaky Jakes".

The pic was taken after the Re-Restoration.

 

[evelrod]

That's the one. When I first saw them they were in yellow training command colors. I think they were radar trainers. We took over 1100 lbs. of radio stuff out of the nose. When finished it was painted silver and blueish. The Hamilton props were polished...that much is certain, cause I polished them...Man what a job that was.
It was lost in Alaska in the early 60's. Crashed on takeoff with ten people on board. No one was hurt. Robert said he "just ran out of lift"....his words.

Rod

 

[evelrod]

TTF, That was one of my favorite shows in the early 50's...I can still hear the introduction!!! I never made the connection to the T-50 until now. Wow, how could I have not made the connection?

http://www.skyking.com/

Rod

 

[thruthefence]

Yeah, we're both old farts,fer sure! Sky King later moved up to a spiffy Cessna 310. Got much better gas mileage!!