Chris's Marion Valve Winding Engine

[crueby]

Hi all,
Time to start the build thread for the winding engine that I designed based on the valve system that the Marion Steam Shovel Company used on their slew/crowd/steering engines back in the early 1900s. This system uses a special porting and valve sliding scheme which eliminates the need for external reversing linkages, and also combines the function of the throttle into the central control valve. For details, see my build log in the Vehicles section on the Marion 91 steam shovel. I'll include several of the drawings here as well. As mentioned elsewhere, I am also working on a RC excavator model, but that is waiting for some more bar stock to arrive, so am switching to this model for a few days.

Here is a line drawing of what the engine will look like:

It has a 1.5" bore, 2" stroke, with a center valve for the throttle/fwd/reverse functions. The Marion valving works by having a center valve with tapered ports to admit steam into one or the other passages coming out, and directing exhaust steam back from the other passage. The steam chest on each cylinder has a sliding valve, which looks at first glance like a typical D-valve, but which has three chambers rather than one, the end two connected above the center one. There are four ports in the valve face rather than the usual three, so that the input steam and output exhaust can be swapped between two of them. The steam in the steam chest for each cylinder is just there to press the double-decker D-valve to the valve face, it never goes around the valve slider into a port. Very clever setup that Marion came up with - I learned how it worked from their patent filing. The one downside to this design is that there is nothing like a Stephenson linkage on the valve rod, so there is no way to control the steam cutoff. In their usage, with the shovel stopping/starting very frequently, there was no need for the economy of steam use that the early cutoff would give, so they took the tradeoff. Also, this design made it possible for them to make a very compact engine, which would fit in the cab between all the other machinery in the steam shovels. For this model, I am setting it up like a winding engine used at a mine, where having speed control and forward and reverse is needed rather than a mill engine that ran all day in one direction and one speed. By separating the two cylinders from the center valve body, it makes it look more like a typical commercial engine, while making it possible for me to build it larger on the smaller Sherline equipment that I have. Being a large bore and long stroke engine, it should be able to run at a nice slow speed, more like the MEM Corliss engine I built a while back.


Today, I got the official start of the build going, with the very exciting job of cutting out the bar stock. Yup, real exciting, but its a start:

The bars in the foreground are 1144 Stressproof Steel (left over from the steam shovel), cut to length for the cylinders and endcaps (including extra length for mounting to the faceplate on the lathe). The longer bars in the background are for the crosshead guides and mounting rings.


Next steps will be to true up the faces (the bandsaw gives a pretty square face, so just light cuts needed) and then drill/tap all of the parts in the cylinder section for the mounting holes around the rims, which will be used to bolt them to the lathe faceplate, which will get matching holes. I want to be able to drill all those holes in all the pieces in one setup on the mill, so they all match up.

The cylinders are large enough outer diameter (2.5") that I'll have to put the riser blocks in on the lathe to turn the center section between the end flanges down.

[Craig DeShong]

Woohoo!  Another Chris build 

This is going to be a BIG engine Chris.  I'll be following along as usual.

[crueby]

Woohoo!  Another Chris build 

This is going to be a BIG engine Chris.  I'll be following along as usual.

Nice to have you along again for this one - the finished engine will probably have about a 1' square footprint, will be nice to work on bigger parts again after all the teeny ones recently. Boring out the cylinders and such will take a while and make a big swarf pile, gotta get the apprentice shop elf a new broom!

[Ye-Ole Steam Dude]

Hello Chris,

I'm on board 

Have a great day,
Thomas

[Steamer5]

VIPPIE!

Normal service is resumed! I can have morning coffee again....... well ok I didn’t give up coffee but hay it much more fun reading this forum than what is supposed to pass for news!

Cheers Kerrin

[Kim]

I'll be following along too, Chris!
It's always fun
Kim

[mike mott]

Count me as one of the audience as well.

Mike

[Jo]

Chris what scale is this engine relative to the original?

38mm bore  be careful you don't loose any of your elves down there 

Jo

[Roger B]

Another good build to follow along      I was actually awaiting the steam powered cider press 

[Steam Haulage]

Following along as well. Missed your daily? updates on the Marion.
Jerry

[gbritnell]

HI Chris,
Glad to see you're back at the machines! Certainly no grass growing under your feet. I'm looking forward to seeing the valve system emerge.
gbritnell

[b.lindsey]

Excellent choice Chris!  It will certainly test the sherlines but will be fun to watch.

Bill

[crueby]

Wow - theater is filling up, I better get the elves out at the concession stand to whip up a lot more popcorn!   

Jo - there is no actual prototype for this engine, it is a combination of mill/winding engines I have seen and the Marion valve technology. I picked the size based on what my lathe would spin, and what spare bar stock i had on the rack.

Roger - love the idea for the steam cider press, just picked up another gallon of cider at the local apple mill (electric powered, sadly).

This morning I got a start on truing up the blanks that were bandsawn out yesterday, so far have the cylinder base and end caps done:

Need to do the end caps on the crosshead guide still, then will start on trueing up the ends of the cylinders and guides. They are long and heavy enough that it will require using the tailstock so the very centers will not be trued, but those will be bored off anyway, and the nubs will fit in the center hole of the faceplate. I'd use the steady rest, but it wont hold pieces this large.


For those that want to follow along with the plans, I've attached a copy of the pdf of them. They are subject to change during the build, will post a revised copy at the end if that happens (it is very likely to, always some tweaks to them as the build goes along, and I find missing dimensions).

[crueby]

And on to facing the ends of the cylinder blanks... 

[fumopuc]

And on to facing the ends of the cylinder blanks... 

Hi Chris, this is the picture of the situation I was bit worried about.
In my imagination I have seen the elves already holding the bar and the sherline lathe is spinning around.