Chris's Holly Pumping Engine Build

[crueby]

Looks like a great show! Lots of interesting old goodies. I like the dump truck just as much as the steam shovel!

That shovel is an early backhoe type, before they had the pivot at the bucket worked out, so the whole boom had to tip to dump. All I could think was that it's a good thing that there was no sunroof in the truck!! Very cool to watch them work.

[crueby]

Great steam show pics! Thanks for posting them. TWO Corliss engines at one show! Never seen an oil burner on a boat's VFT boiler before - but a nifty idea. Cleaner than coal and safer than propane - and smells like the inside of a Kenworth engine's injector pump. The low slung Eclipse / Frick engine was nice to see. I used to see a few here in Ontario, but not in the last couple of years. You know I've looked and looked at them and never saw any "e" clips at all, not sure why they are called Eclipse.... 

Terrific progress on the Holly frame details and brackets!   

I didn't realize it was an oil burner, we were thinking it was a blower for starting the coal, but you are right! Very pretty launch.

[Kim]

Thanks for the pics of the steam show.  That looks pretty cool.

So, they just turned the shovels loose in a field and let them dig holes all over?  That's pretty amazing.  Did they have to put the dirt back when they were done?

Kim

[crueby]

Thanks for the pics of the steam show.  That looks pretty cool.

So, they just turned the shovels loose in a field and let them dig holes all over?  That's pretty amazing.  Did they have to put the dirt back when they were done?

Kim

It looked like they had piles of dirt trucked in at some point, no holes down below grade. The steam club there owns the land, so I think they just leave the piles year to year.

[propforward]

It's always good to see those old engines working and doing what they are supposed to. The annual steam threshers reunion at Rollag is coming up soon - might get along to that.

Your build continues to impress as always Chris!

[crueby]

It's always good to see those old engines working and doing what they are supposed to. The annual steam threshers reunion at Rollag is coming up soon - might get along to that.

Your build continues to impress as always Chris!

That Rollag show is one I wish I could get to, on my bucket list, but am taking a number of other trips this summer and it is about 20 hours of drive time (excluding stops) from home, just too much given the other trips. If you go, take pictures and videos for us!

[crueby]

This morning I got started on the little bits that form the fillets on the inside corners of the horizontal/vertical rail joints, like shown in this picture:

On the lower pump rails, I did this with some JB Weld and sanded in the radius. Worked, but I want to see if I can do this in metal instead. After some playing around in Fusion, I figured out the order of cuts that will make these pieces. Started with some 1" round bar, and bored in a hole to match the radius needed (a little under 1/4" radius). Then moved it to the rotary table on the mill, and started milling in flats that just touch the bore. First one at zero degrees

Then rotated the part 80.5 degrees, which matches the angle of the frame rails to each other, and milled another

Then one at another 99.5, last one another 80.5 degrees. This forms two pairs of corners, one pair that will work on the larger angle, one pair that will work on the smaller angle

Then raised the cutter .100, and milled another set of flats parallel to the first set - this forms the tenon that will fit in slots to be cut in the rails.

Before continuing on, milled slots at the center to seperate the tenons - doing this later would be tough, easier when still on the end of the bar. The cutter was lowered back down the .100 to the original height.


Then moved over and cut matching flats at the original height to shape in the flats on the other side of the tenon

The parts were then sawn off the bar, leaving them a little wide. They will get trimmed to final width when the side rails are trimmed too. Here is one showing how it fits into the corner, until the mortise slots are cut I can't center it on the rails. Does it show that I'm a long-time woodworker in naming the joints?!

This shows the two angles needed for the pairs of corners, the side rails are 80.5 degrees from each other, not 90, so two angles needed.

Four corners down, lots more to make!

[Jo]

Nice use of the rotary table to give you the 99.5/80.5 degree angles Chris 

Jo

[Kim]

Very cool technique, Chris!
It will be interesting to see how it comes out.  Looks like it should be pretty nice.
Love the fabrication technique
Kim

[crueby]

Thanks Jo/Kim,  so far so good, after the first set the next one took about 20 minutes. After six sets, will need just the wider angle ones for the top rail corners, can get three of those per set.

[crueby]

Working on more of the little corner pieces today, but a side question for you folks....

As I've mentioned previously, I got a copy of the blueprints for the Allis pumping engine in the Waterworks Museum in Boston back in June, and have been converting them to a 3D CAD model for them. The lower pump level is now done, and I'm looking to start on the engine beds and crankshaft next. While studying the crankshaft sheet, I spotted something that I have never seen before on the joint where the journal pin goes through the crank webs. Well, two things - the pins on the HP/LP cranks are smaller diameter than the IP pin, but thats just an interesting note.
The real interesting thing is how the pin gets held to the webs. It looks to be a press fit in one side, but the other has a bearing/box arrangement. At first I thought that it was just a way of connecting the two halves of the crankshaft for manufacture/transport, but on closer look it has a brass bearing and gaps for movement in it too. Here is a snippet of the IP crank web drawing:


On the left side of the pin, it steps down from 14" to 13-7/8" to go through the web, I assume that is a press fit. All as I expected. On the right side though, it steps down more, and has a tapered sleeve and bolt/washer too. Again, at first I thought it might be a taper collet arrangement of some sort. But, elsewhere on the page is this diagram with a closeup view of it:
Here it shows the tapered piece is brass, which implies that it is more of a bearing? Also, that piece is not round on the outside, but square. Even more interesting is the gap shown by the red arrows - the box is 15" square, but the hole it goes in is 15" x 16", so there is a 1/2" gap either side in the one direction, no gap in the other direction. In the view on the right, the gap direction is along the length of the web, making me thing that it can slide in/out as needed, but is held close in the rotation direction. Is that to allow for any misalignment or flex in the main frame/bearings maybe?Also, the blue arrows show that there is a hex shapeto the internals of the box, I dont understand that part at all - is that another piece, or a cutout in the corners?I've never heard of the term 'drag box' before, searching for it gives results about joints on locomotive tender frames, but I have not found an explanation in that context that makes sense either.
So, anyone out there who can give a good explanation of what this feature is all about? Free shop gnomes to anyone who does.  Whats that? Oh, okay, free shop gnome capture and removal then!!

[cnr6400]

It looks to me that the drag box approach was intended to deal with tolerance stackup of the crankshaft and bearings/frame during assembly. It could take up any misalignment that may arise at final assembly. No matter how careful the crank pressing operation was, there could be slight errors of tolerance. In the frame, due to the massive size and the stationary pit installation, some settling and mass related flex is inevitable (and hard to predict at the design stage due to the many variables). The drag box could be intended to take up these errors at install time but also actively during running. Having a drag box providing some flex might be the difference between a workable assembly and a bound-up one, or the crank going over stress limits and cracking. That would be a costly disaster. Expansion and contraction as the engine heats and cools is another factor that could be addressed by the drag box approach. Yes, the cranks are a long way from the cylinders and heat has to travel across a couple of bearings, but eventually heat from the cylinders will reach the crank and later, the frames, as the engine runs and component temps rise. This will affect a fixed stroke crank as well as the bearing fits, however small the temp change and size change is. If the whole assembly doesn't have somewhere for the thermal growth or shrinkage to be taken up, breakages could result. Likely the designers of the Holly and other large engines were very aware of these issues and my hat is off to them for working through the issues - with no computers or calculators at all, just slide rules and a pencil - and solving them.

Small machines have their own stackup problems but generally are much easier to sort out than similar issues in massive assemblies.

Just my opinion about the purpose of the drag box approach - I do not know if this was the reason or if there were other reasons.

[cnr6400]

Forgot to mention a couple of thoughts about the angled cutouts in the big box bearing piece:

1. could have been intended to be reservoirs for grease or oil
2. could have been intended as a weight or a material cost reduction purpose (a heck of a lot of yellow metal in a 15 x 15" box!)
3. could have been intended to keep Holly shop elves/gnomes from sitting on the edges of the boxes while they were on the shop floor 

 

[Dan Rowe]

Chris, very interesting feature. The brass bearing for the crankpin has square flanges and is octagonal in the center section, this is how I read the dotted lines indicated by the blue arrows.

Is this a joint for two halves of the crank or does each crankpin have a drag box?

Cheers Dan

[crueby]

Chris, very interesting feature. The brass bearing for the crankpin has square flanges and is octagonal in the center section, this is how I read the dotted lines indicated by the blue arrows.

Is this a joint for two halves of the crank or does each crankpin have a drag box?

Cheers Dan

Hi Dan,
Each crank pin has a drag box on one of its connections to the pair of webs, the other web has the pin press fit in place. I didn't show the other two cranks, but they are the same setup but with a smaller diameter pin and smaller drag box. I don't know why the HP and LP would have smaller pins either, except that they dont join two halves like the center one does.

This is on the Allis engine design - on the Holly, which this build is about, has all three pins the same size, and pressed in both webs in the center one, though it does have one round end and one square end,

.....he says, as he goes and takes another look through the Holly plans to be sure.....
Now wait just an elf-scratchin minute! 

Just found a similar feature there, but just on the middle (IP) crank on the Holly since that is the only double-web crank on the Holly.  Just found these two pages (there are several hundred sheets on the Holly plan set)
This is the side of the crank web on the holly with the square hole - had seen that, but didnt see the one following it:


This one has the same type of box, they call it a Sliding Box - I hadn't realized what that was before:

On this one for the Holly, the gap on the non-rotation axis is smaller, just 1/4" total rather than the full 1" on the Allis, but its the same basic shapes! The Holly one does not call out brass, or show any shims, like the Allis uses. The Holly one has the same bolt in the end as the Allis to hold the cap for keeping the box from sliding off.


Now that is quite interesting! I am leaning towards agreeing with you guys, it would help out the alignment/flexing issues, though the cranks these are part of are in the center of one of the engine beds, so things can't be that far out other than twisting moments. Twisting could be a large issue on engines this big, so that would be a concern I guess - maybe this helps with metal fatigue problems - the forces on pistons/cranks this large must be immense.

And as for the hex relief cuts in the Allis engine, that would both cut down on material and allow for easier movement in the opening, the Holly one does show oil channels in the box. Gee, wonder if they would let me borrow that giant wrench leaning on the machine and pull off some bolts....!

Thanks guys - just talking this through got me to look closer at more plan sheets, plus more opinions help out too!  Anyone else with knowledge of this feature please speak up as well!
Chris