Thanks Jon.

     I took the pictures at Hayes Rotary Engineering who were charged with overhauling
     a  CW RC2-60. It is the first  CW engine or picture or drawing of a CW RC2-60
     I ever saw with a center main bearing. I was under the impression that the
     CW RC2-60 never had a center main bearing. All the drawings I have are of the 2
     main bearing version. Here is an example.

     The incentive for the center main bearing is the shaft is deflecting over
     10,000 RPM and the rotor tips are rubbing on the end housings. Some taper
     the rotors for this reason. Ken Welter among them. Road racers are again
     experimenting with center main bearings. I have recently seen at least
     one but I was sworn to secrecy.

     I would be interested in seeing a drawing on the engines that have failed
     the center main. One obvious fact is the torsional stiffness and strength
     of the shaft would be reduced if the center main diameter was significantly
     less than the current size of the material connecting the two eccentrics.
     Perhaps the diameter or length of the failed center main bearing was not large
     enough due to an underestimation of the loads it would see.

     Two or more row radial engines have similar problems with center main
     bearings and they typically have very large diameter roller bearings in
     this location.

     Paul Lamar

Hi Paul,
I have no drawings of the Deere engines, but the center bearing design was nearly identical to what you have shown for the RC-60 engine. The bearing failures were ultimately attributed to a subtle
design problem with the oil feed to the crankshaft. Regarding shaft deflections, you can see in the cross-section of the RC2-60 engine that there was a so-called "outrigger" bearing (a rolling
element bearing) on the shaft close to the crankshaft pulley. By constraining the shaft at that end, the entire shaft will run straighter. I have an RC-2-60 engine that I "rescued" from the scrap
heap (I literally took it out of a dumpster!) when Deere decided to discard a warehouse full of historical engines and parts (a real shame, but another story....) I chose the particular engine I
have because it was a two bearing engine, and I didn't want to deal with the problems of the center main if I ever overhauled the engine. Most of the RC-2-60 engines did have center main bearings.
Jon

I did not know that about the RC2-60. I thought they were all like the drawing.
That engine will be worth alot some day.

That is interesting. Scrapping historical stuff not only happens here in
the US and Canada with the Avro Arrow but in England too. Sanders Roe built 
the equivalent of the Spruce Goose in aluminum. It wound up on the scrap heap
as well.

Paul Lamar
 
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