Chris's Holly Pumping Engine Build

[ddmckee54]

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

[crueby]

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

Good thinking Baldrick!!     Been a long time since I saw that show, but it sticks with you like Baldrick's smell...   


That does make sense, thanks!

[cnr6400]

 

[crueby]

And after a very nice lunch out with friends and some nap/read time on the porch, I got the last of the little inside-corner filler pieces milled out. Saved making a batch from what I thought since I could get four of the wider-angle ones plus a little waste rather than the three per batch than I was thinking ahead of time. Here are the two piles, 12 of the narrow-angle ones for on top of the middle cross rail, and 24 of the wider angle ones for below the middle and top cross bars:

Next up would appear to be to make the crosshead guide rails and their supports, which go between all four rails at the top opening, like in the picture I used to show the inside corners - just finished the bits at the red arrows, time to make the grid between them:


They will also have tabs sticking out to slot into the rails. Once they are done there will be a lot of assembly work, followed by thinning the rails and adding those mounting pads around the edges and all the mounting holes there and in the top rail. May have the engine frames all done by September. Or in September.

[Dan Rowe]

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

[crueby]

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

Hi Dan,
The water piston/plungers on the pumps at the bottom have four rods coming up from big plates on top of the plungers - those rods come up around the sides of the cranks and connect to arms coming off the crossheads, so the pump plunger itself does not need a crosshead, the motion is kept vertical by the rods on the upper crosshead.

The bottom end of the conrod is split, with a bolt-on lower end cap so the split bearing can be changed out that way (the plans show Babbit bearing liners).  The conrod/crank setup is pretty typical of any big steam engine, the only real change is that connection to the crosshead for the plungers, pretty clever. On both engines, they even have provision for a small water/air pump down at the bottom that connects to one of the pump plungers (my term plungers, I dont know what they call them, they are essentially the same as a hand-operated ram pump like we use for testing boilers, except a LOT bigger and they have 1200 to 1400 check valves!
That sliding box looks like it was just there for the crankshaft motion/alignment, though a lot of that is a guess. The other end of the crank pin is fixed into the other web, appears to be a one-time press fit, no keys or bolts over on that side is shown. On the Holly engine, the two end cylinders have one-sided cranks, on the Allis they are all two-sided, though the second side is a lot lighter and the end of the crankshaft there is thinner. It looks like they only did that since there is another offset crank off each end that drives the lay shaft up above for the valves. On the Holly the lay shaft has a pair of bevel gear sets to drive it.
I'm going to be back at the waterworks museum in Boston in a couple weeks to meet with the director again and tour the engines up close/on the catwalks, will be getting a lot more pictures then of the pump level and the upper machine levels. Great working with them, I get access to the plans and machines, they are learning a lot about steam engines and pumps in return plus I am making them diagrams and animations - a win/win for all.
For better view of how things connect up, here is a picture from the CAD version of the relevant parts of the Holly engine (have not gotten up to the crankshaft on the Allis drawings yet). Note that I do not have the conrods/pistons all linked up to the proper positions on the crankshaft yet, that will come later when I get a chance to animate the movements, all are at one level at the moment, but you can see the relationships better than my rambling words up above!

[Dan Rowe]

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

[crueby]

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

Hi Dan,


This feature really has be puzzled. On the Allis engine they have it on all three cranks. On the Holly the two end cranks are one side webs, so no box joint there.  I spent a lot of time last night doing patent searches, could not find anything related to it.
After more thought I am discounting alignment too, the cranks are in the middle of each engine bed, and the beds could be aligned to each other.
Hmmmm...

[Dan Rowe]

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 Dan

Edit: 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

[crueby]

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 Dan

Edit: 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

Thanks Dan!  That Sulzer is a beast!

[crueby]

This morning I worked out in the CAD app the dimensions for a silver-soldering jig for the crosshead guide parts. Need to make six of them, so well worth the time to make up a jig. The weather today is SO nice compared to the high heat this past week, so rest of the day is outdoors!

[crueby]

The last two days have been used to get the jig and bar stock ready for the crosshead guides that go in each of the engine frames. Here is the jig for silver soldering plus the rough cut bars for the guides:

The taller posts will hold the 1/2" wide bars on edge at top/bottom/sides, and the shorter posts along the sides will have the narrow bars laying flat on them, held in the middle of the 1/2" bars to form a T shape. The screws along the bottom and sides will hold things together for soldering - will show pictures of that once the bars are trimmed to length. Bunch of time in the jig, but the bars are too thin to use screws to hold them together for soldering, and this setup should give repeatable results. I cut the large holes in the back of the jig to let the torch flame pass through, keeping the jig from getting quite as hot - the bars are thin, so they should get up to temperature quickly.

[cnr6400]

 

[crueby]

Thanks CNR - don't overdose on the popcorn, throw in some peanuts too!   

Got the bars prepped for soldering, took them all to length, doing them all ganged up a size at a time. Clamped them in the vise, trimmed the ends square, then grabbed the ends with a small clamp to hold them together to flip them around and trim the other end to length. For the shorter pieces, that means using two clamps - one to get them out of the vise, attach the other clamp to the un-cut end, remove the first clamp, and put them in the vise using the second clamp.

and a few shots showing the first set all held in the soldering fixture - two long/wide bars for the crosshead guides, two long/narrow bars for the T shape next to them, a short bar at the top and a long bar for the bottom.

The narrow bars are held up in place so they land in the center of the wide bars, a view at the top

and from the bottom end

Tomorrow I'll set up the torch outside and get started silver soldering them all together....

[cnr6400]

Soldering jig looks great!   

I have just dispatched 2 of my peskiest shop gnomes in a very rusted 1961 Ford Falcon with iffy piston rings , 17 litres of oil, and 147 pounds of roasted peanuts. Rochester or bust, they said. Could mean they are looking for a strip club rather than Rochester, or will be by with your peanuts in a few days (or months, in that car) 

PS do keep the gnomes  if when they arrive........