Chris's Slew-Crowd Engines

[crueby]

With all the clock work complete, back to building steam engines!   

Something I've wanted to do for a couple years, since completing all the CAD models of the different steam shovels that I was able to find plans for and/or measure, is to build a set of the slew/crowd engines from each of the brands. Each do the same job, and use basically the same valve style, but there are differences in layout between them that make for an interesting contrast. Here is a CAD screen shot of the set, Clockwise from upper left are the Erie, Bucyrus, Marion, and Thew versions.

They all use the same valve system to achieve an interesting feature - one throttle lever gives the operator control of both direction of rotation and speed plus just one eccentric per cylinder. They use a variation of the normal D valve, this one has four ports instead of three, two ports to the end of the cylinder, and two to the central throttle valve. The steam in the chest holds the cylinder valves down, but does not get admitted around the end of the valves. Instead, the central throttle valve directs steam to one of the two remaining ports, and takes exhaust from the other one. So, to reverse direction, the steam/exhaust are sent to the opposite ports as when going forward. More like a spool valve switching between inside admission and outside admission. Very clever setup. It was invented in the mid 1800s, and almost all the steam shovel manufacturers used that setup, though as you can see in the drawing the positions of the steam chests and levers/slides operating the valves varied quite a bit. These engines needed to be compact and light, since one would have been mounted up on the main boom to drive the dipper stick and the bucket in and out (crowd action), while the other would be back in the cab to rotate either the boom turntable or the entire cab and boom (slew action).

For my Marion 91 steam shovel build years ago I made four altogether - one spare/test unit, one for slew and crowd, and one that was 1/3rd smaller for use to steer the rear tracks. Now, I want to build this whole set at about twice that size, bringing the bore/stroke up to 1" for two of them, close to that on the others. These engines came in a variety of sizes from each manufacturer, same design scaled up or down to suit the size of the shovel. So, it works out to about 1:6 scale for this collection, depending on the size of the original. One of the plans I have, for the Thew shovel, includes a chart for 11 different sizes of their engine, from 4"x5" bore/stroke up to 6"x7". They just scaled the parts, and mixed/matched them to the castings as needed.

Now, I could build each one in turn, till the set was done. But, I decided to try something different. I am going to build the whole set at once, making each part for each alternately, all the cylinders first, caps, steam chests, crosshead guides, etc in turn. The setups needed for each subassembly will be pretty much the same, just dimensions different in a lot of cases. Should be able to share jigs and such. There will be a lot of silver soldering to make up the 'castings' for things like the cylinders/steam chests, main frames, etc. Should be interesting to do it this way. If for some reason it does not work out well, I can switch to one at a time partway through.

On to the build!      Once the shop elves had the workbenches all cleaned up and ready to go, we laid out two lengths of brass roundbar, one 1-5/8" OD and the other 2" OD, and marked off the rough cut lengths for all the cylinder blanks plus the end caps for the two engines that use individual caps. They were taken to the bandsaw and cut into sections and labelled:

One near disaster during that - when reaching for something else on the bench, the 2" round bar, about 30" long so quite heavy, rolled off the benchtop without my noticing, and landed vertically on the side of my left ankle, where it sticks out a bit from the leg.     Thoughts of broken ankle or bad swelling ran through my mind while in the shock of the moment till the pain subsided enough to take a look. Got REALLY lucky (well, considering the bad luck of the bar falling on me) and all it did was put a small cut on the top of the ankle. No swelling, bruising, anything. Not bad for such a heavy bar landing on it.     Anyway, then took the two bars up to the saw and got them sliced up.

And I can hear someone starting to type about the cost of so much brass - but, as mentioned on other builds, let me repeat that I buy large bars like this from commercial suppliers who normally sell 20 or 30 foot lengths, and sell the 2 or 3 foot long offcuts as 'drops' at a fraction of the normal price to get them out of their warehouse. Doing it this way I can get larger diameter bars, enough in each for half a dozen builds at least, for less than a quarter of what it would cost to buy in 2" lengths or whatever needed from the plans. Well worth checking suppliers near you!

While I was setting up the lathe to trim the ends of the blanks true, the shop elves got the workbench organized, including a list of dimensions for each of the cylinders:

Over on the lathe, I got the sawn ends trued up for all the blanks, and also turned a section on the end of each to hold in the chuck - 'round' bar usually is just round-ish from how they extrude it, plus often has nicks and scrapes in the sides from handling (and bouncing off of ankles) that keep it from chucking up repeatably straight. Each blank is a little under an inch extra-long to allow room to chuck it. This excess will be trimmed off later, leaving me with usable discs handy for end caps, gears, whatever.

Then turned one of the blanks around to center drill the end for the live center, and also took some light cuts down the length test the lathe to ensure it was in proper tram. It needed a very minor tweak to the headstock to get it all aligned and turning a parallel cylinder. Once that was set, I turned the diameter of the first blank (for the Marion) down to the diameter of the end flanges.

Then used the parting tool to mark the locations of the flanges at each end...

switched to center cutting tool to take out the bulk of the material between the flanges

and finished with the left and right turning tools to square up the inside corners, out to the marks from the parting tool

I'll do this step for each of the other 7 blanks before moving on...

[Kim]

Great start, Chris!    

(All except the decapitation of your ankle part! That was sub-optimal for sure.)

This is a gargantuan undertaking, as are all of your projects.  I'll be following along!
Kim

[vtsteam]

I love horizontal mill engines, and I love twins, and I love engines in vehicles, so, you can guess the admiration I have for a quartet of something that combines them all.

Oh also I remember seeing steamshovels when I was very little at construction sites in NYC. Yeah, so man, on with this show! 

[cnr6400]

  Sorry to hear about the bar drop accident - glad it didn't result in a much worse injury.  You know, many guys have been hurt bad when a whole bar fell on 'em - usually liquor, pool tables, neon signs and all, I admit, but nonetheless... 

Great to see the slew and crowd engine built start! I'll send a fresh 8 ton load of premium dry white popcorn kernels your way in the Screamin Jimmy dump truck. Still haven't fixed the exhaust stack so you'll probably hear it coming about16 miles out....

[crueby]

Thanks guys! Great to have you along for the ride! Maybe not a great idea to ride in CNR's popcorn truck...   

Steve, neat that you got to see the shovels in action as a kid, I've seen diesel ones going at shows, so far have not seen an actual steam on in action in person.    Really high on my list! I keep meaning to get down to one of the shows in Pennsylvania where they usually have some, but other stuff keeps getting in the way.

[Sanjay F]

I knew it wouldn't take long before we were all in for another treat - hope the ankle gets better soon and i'll be watching the build 

[crueby]

I knew it wouldn't take long before we were all in for another treat - hope the ankle gets better soon and i'll be watching the build 

The ankle is fine, thanks!

[vtsteam]

I just looked it up online and read that steamshovels were losing favor in the 30's. So that makes me doubt myself. But I have a very clear memory of my father pointing one out as we stood at a wooden barricade in Manhattan, and the steam and the cables and the crossed booms, so characteristic.

But it was 1952-1954, not 30's. It was far down below us digging a foundation. Maybe he said the words "steam shovel" generically to a child - I had the Mike Moran book. But my father was an engineer and designer of machinery with a large machine shop that he owned. I can't imagine him approximating what we were looking at. He seemed as excited by it as I was. I don't think it was diesel therefore. Maybe it was one of the last shovels doing work. I don't know. But I remember the sight of it, and the billowing smoke, and the details. So to me, I did see one at work, once upon a time! 

[crueby]

I just looked it up online and read that steamshovels were losing favor in the 30's. So that makes me doubt myself. But I have a very clear memory of my father pointing one out as we stood at a wooden barricade in Manhattan, and the steam and the cables and the crossed booms, so characteristic.

But it was 1952-1954, not 30's. It was far down below us digging a foundation. Maybe he said the words "steam shovel" generically to a child - I had the Mike Moran book. But my father was an engineer and designer of machinery with a large machine shop that he owned. I can't imagine him approximating what we were looking at. He seemed as excited by it as I was. I don't think it was diesel therefore. Maybe it was one of the last shovels doing work. I don't know. But I remember the sight of it, and the billowing smoke, and the details. So to me, I did see one at work, once upon a time! 

Lots of people still call brand new hydraulic  diesel excavators  a "steam shovel". Actual steam ones were still used long after they stopped making new ones. The one here at the quarry in LeRoy was used till the late 40s. They often got used till they wore out, if it aint broke dont replace it!

[vtsteam]

 

[crueby]

Got the first four cylinders shaped on the outside, these are the Marion on the left and the Erie on the right. Right now I have the first of the Bucyrus cylinders chucked up in the lathe...

So far the production line approach is working well, with the common setup and process, the second pair went pretty quick! 

[vtsteam]

I like the assembly line method you're using for all 4, Chris. And I like all of the engines a lot, but for my own odd reasons I particularly like the Thew. Surprisingly compact and simplified, almost like a model itself. True, it's smaller displacement than the others so naturally smaller package. But just seems like compact efficient design, too, so I like it.

Keep on turnin' 

[crueby]

I like the assembly line method you're using for all 4, Chris. And I like all of the engines a lot, but for my own odd reasons I particularly like the Thew. Surprisingly compact and simplified, almost like a model itself. True, it's smaller displacement than the others so naturally smaller package. But just seems like compact efficient design, too, so I like it.

Keep on turnin' 

Thanks!  Not sure I have a favorite of these (yet), but for the hoist engines I really like the Erie - it uses a lot of the same features as the slew/crowd engines. The Thew engine is very compact, which may make it wind up being a harder one to build. Being between the cylinders, they arranged the cylinder valves so they are on their sides, up against the sides of the cylinder, with the throttle valve being horizontal in the center, so three seperate valve faces, with a single steam chest spanning them all. Should be fun!

[cnr6400]

  The 4 cylinders look great Chris! Have the shop elves got their 72 wheelbarrows and the Mann truck ready for removal of the 58 cubic yards of brass swarf?   

[crueby]

The 4 cylinders look great Chris! Have the shop elves got their 72 wheelbarrows and the Mann truck ready for removal of the 58 cubic yards of brass swarf?   

I hope so! They will need the crane to lift the 5 gallon bucket under the dust separator connected to the shop vacuum, its about ready to haul away.