Brian builds a Corliss

[brian Rupnow]

After a couple of weeks off, dealing with my achy knees, I finally found some time to make different valve levers and fiddle with the engine some more. That first video I posted two weeks ago was running at 60 psi. After much fiddling the engine will run quite happily now on 20 psi. I don't have the rear covers and gaskets mounted on the far side of the engine to seal off the rotary valves, and when they are added I think the engine will run on less than the 20 psi as shown in this video. If my arthritis leaves me alone, I will work on painting the engine and making a wooden base for it.
https://www.youtube.com/watch?v=R82WXkjWaCI

[Ringo]

Good job there Brian.
Glad to see you back at it.

[olf20]

Great job! I know after my hip replacement I sure could do lots more and feel
great at the end of the day!!
olf20 / Bob

[brian Rupnow]

Two grandchildren came and raked my yard today. I helped a little bit, and my wife helped the kids rake up 18 bags of oak and maple leaves. There is still a couple of hours raking left to do, but they will do that some evening this week. As for the engine--I can not get the levers to grip the rotary valve-shafts tight enough---they slip and throw the valves out of time. It seems that no matter how well I get things set, the engine will start and run slowly, but if you rev it up very much, the levers slip and the engine gets out of time and won't run. I think I will make up one more set of levers, get everything set correctly, and then silver solder the levers to the end of the rotary valves. This may sound rather extreme, but if I do that, I can guarantee that they aren't going to slip on the shafts.

[PStechPaul]

Have you tried extending the slit into the part of the lever on the other side of the bore, so that it can flex when the clamp screw is tightened and grip the entire surface of the shaft? I think that would work a treat, and would not require any further machining. You might also drill a hole at the end of the slit, where it would hinge.

[J Tiers]

........................................... As for the engine--I can not get the levers to grip the rotary valve-shafts tight enough---they slip and throw the valves out of time. It seems that no matter how well I get things set, the engine will start and run slowly, but if you rev it up very much, the levers slip and the engine gets out of time and won't run. I think I will make up one more set of levers, get everything set correctly, and then silver solder the levers to the end of the rotary valves. This may sound rather extreme, but if I do that, I can guarantee that they aren't going to slip on the shafts.

That's where the adjustable pushrods would come in super-handy.

You might consider pinning the levers to the shafts. Just as solid, but removable to change out parts if that is needed for any reason later as you do adjustments.

[aostling]

. . . and then silver solder the levers to the end of the rotary valves. This may sound rather extreme, but if I do that, I can guarantee that they aren't going to slip on the shafts.

If you do that could it still be disassembled? It won't be a Corliss until you implement load-responsive variable valve timing.

[BobH]

How about a wicking grade of Loctite after you get it adjusted? A little heat and you could get it apart if needed. Bob

[reggie_obe]

As for the engine--I can not get the levers to grip the rotary valve-shafts tight enough---they slip and throw the valves out of time.

Could you knurl the shafts? Even a straight knurl would increase the grip.

[brian Rupnow]

The rotary valve shafts are not too tight. They rotate freely by hand. I have made two sets of "clamp bolt style" levers. The first levers had very little thickness on the threaded side, and the threads stripped out before they could draw tight enough to clamp the 1/8" diameter valve shafts securely---they slipped. The second set of levers were thicker in the threaded area, and still slipped on the valve shafts. Today we have a third set of levers, and they are not "clamp on" style. They will be pinned in place with a 0.039" diameter steel rod which passes thru them and the end of the valve shafts. This is to give the correct angular position. Then things will get torn down and the new levers will be silver soldered to the valve rods. The intermediate lever which the valve actuator rods attach to will get a hub welded to one side to keep it from pulling sideways during it's operation.

[J Tiers]

I looked back at the lever design.

I think you got caught in the same trap I have been in. The clamps end up being so strong in bending that the screw's force gets "used up" in bending metal, and very little of it gets through to actually hold the shaft.

Two things I have found to work. The first is that when you slit them, you need to slit a significant amount "through" into the opposite side of the hole, not just on the side where the screw is. That "weakens" the clamp enough that the screw can bend it and apply clamp force to the shaft.

Those clamps are pretty darn strong against bending if they are not slit that extra amount. By "slitting through", instead of having to bend the short bit near the screw head, you actually bend from further back. That allows the two sides of the clamp to tighten onto the shaft more effectively.

The other thing you can do is to thin down the clamping portion. You have to make it a lot thinner, for more distance around the shaft than you might think. That solution really is not particularly applicable to your clamps, as you need the thickness for the screw.

[PStechPaul]

Yes, as I said in my post #320, and also IIRC some time further back. The idea can be tested by tightening the clamp screw without the shaft to see how well it closes up, although having the shaft in the bore will increase the torque necessary to obtain a solid clamp.

[J Tiers]

Yes, you did. I had not seen that, it is the last post on a previous page, as my display of forum posts works.

However, I did provide some background and a second option.....

[brian Rupnow]

This is a very nasty picture of the levers and valve shafts cross drilled and pinned. Guarantee no slippage now. The drills are 0.040" diameter-they will be replaced with 0.039" diameter shafts, cut to length and then silver soldered as a final operation.

[Cuttings]

Can someone tell me where I might be able to get a set of plans for a model Corliss steam engine? I have a copy of the JDWDS plans but it is too big. 15" flywheel and the whole thing is almost 3 feet long. I was thinking of trying one as a new project once I get my shop cleaned up and rearranged and a new lathe installed whenever that happens. It is on order.