Author Topic: ball or roller bearings at midpoints on a crankshaft  (Read 1518 times)

Offline tghs

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ball or roller bearings at midpoints on a crankshaft
« on: May 15, 2022, 10:45:32 PM »
working on making some 1/16th scale "fake" Napier sealion engines.. on reading the history of the lion engine W12 (3 four cylinder engine on a common crank) a method of bearing shells so that larger ID bearings could be moved along the crankshaft and then the entire assembly could be mounted in the block.. these were high perforance engines and state of the art in the twentys and thrities...
https://www.enginehistory.org/Piston/Napier/NapierLionHx/NapierLionHx.shtml
what the @#&% over

Offline Noitoen

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Re: ball or roller bearings at midpoints on a crankshaft
« Reply #1 on: May 16, 2022, 03:07:45 PM »
Last year we dismantled what the call here self propelled railway cars, a kind of short distance trains without a visible locomotive that had very compact Rolls Royce engines mounted sideways. They had roller bearings on the crankshaft main journals and connecting rods. They looked more than 50 years old but inside they looked new.

Offline lohring

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Re: ball or roller bearings at midpoints on a crankshaft
« Reply #2 on: May 17, 2022, 04:09:36 PM »
A model boat twin uses a split needle bearing as the center bearing. I believe they are for a 12 mm shaft, but check to be sure.
https://www.gizmomotors.com/online-store/twin-needle-bearing

Lohring Miller

Offline Vixen

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Re: ball or roller bearings at midpoints on a crankshaft
« Reply #3 on: May 17, 2022, 04:45:11 PM »
Hello Lohring

I could not find any dimensions or technical details for those split bearings other than your suggestion of a 12 mm shaft. Do you know where more information could be found? I have sent Gizmo motors an e-mail, it may get a reply.

They could be the perfect answer for my Mercedes W165 engines.

Do you know of any other split needle roller bearings?

Mike
« Last Edit: May 17, 2022, 04:54:52 PM by Vixen »
It is the journey that matters, not the destination

Oh! sod the journey, lets hit the bar and pool instead.

Offline Admiral_dk

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Re: ball or roller bearings at midpoints on a crankshaft
« Reply #4 on: May 17, 2022, 08:58:53 PM »
Never saw one like it before either .... looking at the website I see the outer shell too + the 'middle bearing' that is 12mm inside, 28mm outside and 8mm wide (6001C3) ....
Also looking at the 'Stroker Crank' - it appears that some of the bearings are the same size (but one might be smaller).

Googling "half bearing" gives quite a number of results - food for thought   :D

https://www.alibaba.com/product-detail/Original-high-precision-bearing-A11V095-bearing_62173510020.html?spm=a2700.7724857.normal_offer.d_image.1be56f582bN8yJ
Gives a company that make them from 12-320mm outside diameter.

Per
« Last Edit: May 17, 2022, 09:03:12 PM by Admiral_dk »

Offline dieselpilot

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Re: ball or roller bearings at midpoints on a crankshaft
« Reply #5 on: May 18, 2022, 02:29:05 PM »
That is one rare bird. It's very likely that these are special production in small sizes. I would guess it runs directly on the crank, so no inner race. RCMK decided this was the best design for their engine and special ordered these bearings and the price reflects that, 44USD for the split cage roller set. and 49USD for the split outer race.

Looking through bearing catalogs I did see some, but mostly in much larger sizes. I saw some that had split shells too. None of this appears to be stock items. One could make a cage to separate the rollers, but the races are much more work if they are to meet the hardness and finish requirements.

Offline Vixen

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Re: ball or roller bearings at midpoints on a crankshaft
« Reply #6 on: May 18, 2022, 09:53:06 PM »
Gizmomotors got back to me. The 'Needle Bearing Kit (pair)' SKU: RCMK S26372 dimensions are: width= 0.420" ID=0.670" OD=0.901". Unfortunately, the 44USD price tag for the split cage roller set and 49USD for the split outer race is a wee bit too pricey: I would need five for each of the two engines.   :toilet_claw:

Mike
It is the journey that matters, not the destination

Oh! sod the journey, lets hit the bar and pool instead.

Offline Overbuilt and Overkill

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Re: ball or roller bearings at midpoints on a crankshaft
« Reply #7 on: June 06, 2022, 04:00:13 AM »
Napier and a few others may have had some specialized reasons behind using those split needle or roller bearings that might not be quite as obvious as it seems. The exact details are now lost to me because of the 50 + years since I first read about it. One of the more famous racers or engine builders in the U.S. apparently went to a great deal of effort and expense trying to use roller bearings on the crank shaft and cam in there racing engines in an effort to free up more horse power. This was probably in the 1950's - 60's. Mickey Thompson maybe?????? Anyway the effort was a failure simply because it didn't gain any significant amount of HP. They explained it to the writer of the article that they had neglected to factor in just how much friction or drag was being produced once the parts were fully supported and spinning on the oil wedge. And that roughly the same amount was being produced with the roller type bearings. I'm not saying for sure this was the reason, but Napier and others may have had oiling issues for the more standard split sleeve bearings and this was just an easier and to me a bit illogical method around that. With the ever increasing and government mandated fuel mileage increases, if the split needle /roller bearings gave enough of an increase, the automotive engine designs would have been changed to use them for sure. Replicating in scale as closely as possible what original full sized engines used is of course something different. But this might save someone going down what could be a fairly expensive dead end path. For extremely high rpm such as for model and full sized turbine engines, then just enough flow restricted oil injection and to ensure barely adequate lubrication with ceramic ball bearings is helpful to prevent those bearings from over heating or causing too much drag. With those and afaik there always a total loss system once the oil passes through the bearings.
« Last Edit: June 06, 2022, 04:03:55 AM by Overbuilt and Overkill »