Welcome to ModelEngineMaker !If you have problems registering or logging in, please use the contact menu option to request assistance.
OK, I think we agree that these block thingees, whatever Holly called them, started out their life as a square-ish lump of brass with a hole through the middle of it. I've been wracking my brain, at least the 2 or 3 remaining working brain cells, trying to figure out why they took the chunks out of the corners - there HAD to be a good reason. I have a theory, in your best Baldrick voice say it with me - "I have a cunning plan M'Lord!"It was casting type black magic voodoo stuff - I think. If you look at the plan, the wall thickness through the cut-out section of that block is pretty consistent. It might have been to keep from getting voids in those areas as the casting cooled and the liquid brass froze. I doubt that it was to use less brass in the casting, if you were making a gazillion of these engines then yeah you'd want to save the pennies and use less brass. But in the onesy-twosy quantities that they made these engines they'd just pass the extra expense along to the customer - somehow. Don
Ah more information...... I am assuming the same connecting rod is connecting the steam piston and the water piston so how does it connect to the pin?How can the big end conrod bearing be changed? I spotted a split crankshaft engine made to use roller bearings the split was to be able to get the bearings on. So could the sliding box be an access point for the conrod bearing?Cheers Dan
Chris, I was a Marine Engineer and worked on 900mm bore Sulzer engines which are the closest thing to a large steam engine built today. I have looked at lots of books on large engines and that is a feature that I have never seen. The main difference between this type of engine and a ships engine is the starting load and the fact that not much load or no load is used on the end of the shaft. All the main load is in the center of the shaft. My guess is the big pin you posted on the Alias engine is in the center of the crank so it has to share some of the load from the other two pistons.I am not buying the alignment theory as lots of large engines were built without this feature.Cheers Dan
the beds could be aligned to each other.
Quote from: crueby on August 14, 2021, 02:30:52 PM the beds could be aligned to each other. Chris, the beds have to be aligned!! I have taken crankshaft deflection readings on a Sulzer. There is a witness mark on the crank webs to locate a dial indicator. The crank is rotated so the marks just clear the conrod and the indicator is attached and the crank is rotated away from the rod until the indicator is almost touching the other side of the rod. The readings are compared to the readings taken when the engine was erected. This checks how much the crankshaft has bent in service.I think the box joint was to keep the crankshaft from twisting or bending. My guess is that if a solid crankshaft was used it would have to be even larger to accommodate the forces of the pump plungers.Cheers DanEdit: here is a Sulzer a bit larger than the ones I worked on:https://www.autoblog.com/photos/w-rtsil-sulzer-rta96-c/#slide-1755060