Ball bearing eccentric

[DetroiTug]

I made this part for a Science museum this week and thought it had potential for a low maintenance and quiet valve eccentric. It uses a large OD/ID Kaydon ball bearing.

-Ron

[barts]

I bought two of these very cheaply at a surplus place back in the 1980s, and used them w/ the engine I made from a refrigeration compressor in Otter for 20 years or so. I put them right next to each other to cut down on any wracking forces. They're still in fine shape, even though the compressor main bearings failed finally. The slide valve certainly worked them w/ 150+ psi of boiler pressure, but they worked just fine.

- Bart

[DetroiTug]

That's almost identical and it's good to know you had good service from them. Some day I'd like to build a taller twin with cast-back columns like a Navy K and will consider using eccentrics like this. The less I have to deal with when firing, the better. The one I made above, if the eccentric diameter and retainer diameter was increased, it could conceal the bearing entirely and look like a standard eccentric. The Tiny Power twin uses sealed roller bearings on the crank and wrist pin, I'm sold on them.

-Ron

[barts]

I'm using 2 Type E pillow blocks for mains, a 50mm x 90mm spherical roller bearing for the big end, and needle bearings for the forked connecting rod. The cross head will be roller w/ ball bearings, and the poppet valves will be opened using roller following on the cams.

I want the only external lubrication to be a bit of grease on the surface of those roller cross head bearings.

- Bart

[racerfrank]

That's almost identical and it's good to know you had good service from them. Some day I'd like to build a taller twin with cast-back columns like a Navy K and will consider using eccentrics like this. The less I have to deal with when firing, the better. The one I made above, if the eccentric diameter and retainer diameter was increased, it could conceal the bearing entirely and look like a standard eccentric. The Tiny Power twin uses sealed roller bearings on the crank and wrist pin, I'm sold on them.

-Ron

I may have considered something like this for my engine if I had seen it sooner . LOL--- maybe on the next one......


Frank

[Lopez Mike]

My Strath Steam Warrego came with ball bearing eccentrics and they have given flawless service. If I ever have any trouble with my big end bearing (now brass on steel) I will most likely go to some sort of anti friction bearing. Either like Bart's solution or just a Torrington needle bearing. I would use the matching inner race, of course.

I will watch closely Bart's future experiences with the roller crosshead. I hope it works well.

[DetroiTug]

On second thought..

The guy that brought that bearing to me let me know how much it cost today. 3" id X 3.5" od X.25" wide - it was $256 through McMaster Carr (Over a thousand for 4 of them). Maybe there is something similar a lot cheaper. If not I'll endure the occasional click or clack for that much. Carry on..

Mike, the Mason model C car engine uses ball bearing crossheads, they seem to hold up just fine.

-Ron

[barts]

On second thought..

The guy that brought that bearing to me let me know how much it cost today. 3" id X 3.5" od X.25" wide - it was $256 through McMaster Carr (Over a thousand for 4 of them). Maybe there is something similar a lot cheaper. If not I'll endure the occasional click or clack for that much. Carry on..

Mike, the Mason model C car engine uses ball bearing crossheads, they seem to hold up just fine.

-Ron

I think I bought mine for $10 each or so 25 years ago surplus. You can often buy surplus stuff on EBay for a good price; that's where I picked up my spherical roller bearing for the big end at about 1/4 list...

- art

[Dhutch]

I can see it being a really good solution for a museum display, which is presumably required to be near zero maintenance, and dry in its operation.

I can also see certain advantages to both sealed and non-sealed rolling element bearings in certain applications in a steam plant.

However I would also worry about the susceptibility to water ingress and hence corrosion? As well as considering the eccentrics to be one of the areas of the engine in our boat that gives really no trouble at all, no noise, no wear, no issues?


Daniel

[barts]

The eccentric straps on the engine now in Otter were pretty badly worn after 100+ years, even though they run a piston valve
. If you can keep them well oiled, you're fine, but absent a little dip pan underneath, they tend to run dry from time to time. I put some grease on the dual open bearings on Otter's old engine, and once a great while I might have given them some oil.

There are some places on steam engines where rolling contact bearings make a lot of sense - wrist pins, for example, are a perfect place to put needle bearings. They take a lot of load, and only turn through a partial arc, and they're hard to keep oiled properly. Purists can hide them, too.

On Sea Lion, I want to get rid of the pervasive smell of oil if the engine is going to be in the enclosed living space, and reducing the amount of lube dripping from bearings and crosshead is one way of doing that.

- Bart