Chris's Marion 91 Steam Shovel

[fumopuc]

Hi Chris, always a real pleasure to see your progress.

[Kim]

That's great Chris!  I can see how segmenting the wood really helped.  That was a pretty good insight ddmckee! 

I love those shots of the brake - just so much going on there.  It looks too cool!   

Kim

[crueby]

Thanks guys!  Lots of little tweaks, and it all came together and works well. Next is the hoist clutch mechanism, when ch is another new one for me. Its sort of an exploded single cylinder engine, with a piston actuator and a d valve separately mounted down on the floor. Should be an interesting setup.


 

[crueby]

Turned up the post that holds the fixed end of the hoist clutch band, disc at the end to retain the band, then steps down to go inside the end loop, and down again to go through the gear plate. There is a hole at the far end for a cotter to keep it in place.

And made up the little crank that actuates the band. Looks a lot like a crankshaft from a small wobbler engine, it is silver soldered together. There will be a crank arm bolted onto the other end that will be moved by the steam piston to actuate the clutch.

[crueby]

After lunch I milled out the actuating lever for the hoist clutch. Drilled the holes in some 303 stainless bar, then bolted it down to the rotary table on a sacrificial bit of aluminum to shape the outside down.

Here it is test fit on the model. It goes on the other end of the crank arm I made earlier today. The steam actuated piston will push on the outer hole in the arm, the spring loaded return rod that will be next to the piston attaches to the inner hole, to take the tension off the band when steam pressure is removed.

Testing the motion on the band with finger pressure shows this has plenty of grip - there is much more leverage on this linkage than on the brake band. Makes sense, since this band has to transmit the full lifting force from the engine to the hoist chain.

[ddmckee54]

Chris:

Is there an adjustment on the clutch band to take up any wear?  Or don't you think that the elves will be using this thing that much when they try and dig their way into the mint chocolate chip cookie storage vault?

Don

[crueby]

Chris:

Is there an adjustment on the clutch band to take up any wear?  Or don't you think that the elves will be using this thing that much when they try and dig their way into the mint chocolate chip cookie storage vault?

Don

    hmm, may need to reinforce the vault!!




According to the Marion catalog writeup, the piston on the hoist band has more travel than needed, so as the band wears the piston moves farther till it gets stopped by the pressure on the drum. Sort of like car brakes, the calipers move farther in as the pads wear.  They say this design eliminates need for constant adjustment for wear and temperature expansion like with a purely lever linkage. Clever.

[Craig DeShong]

Stunning progress Chris, always something new to see on this thread. 

[crueby]

Stunning progress Chris, always something new to see on this thread. 

Thanks Craig!

[J.L.]

Chris, you should show those teeth to your dentist!

 I doubt whether he has ever seen ones in such good shape.

John

[crueby]

Chris, you should show those teeth to your dentist!

 I doubt whether he has ever seen ones in such good shape.

John

Mine sure aren't!!


Maybe I can get him to install these as replacements...

[cnr6400]

I'm not sure even the famous Irish dentist, Dr. Perry O'Dontal , could install those in a human jaw! 

Just kidding. Looking forward to seeing the steam cylinder and spring system evolve for the hoist clutch. I will have to do a similar one for the hoist clutch on the Erie B shovel I plan to build. My main concern is condensation in the tiny plumbing and the steam cylinder when the hoist is not working, and how to get rid of the water at the appropriate time when steam in the cylinder is needed and not water. On one full size Erie shovel I have seen working several times, the hoist cylinder exhaust spewed a lot of condensate before it started getting steam. However the steam piston had some pretty bad ring leakage and spewed a lot of steam when operating too. Don't think it was intended to by the original designers, but they probably didn't anticipate their product built in 1921 would still be working in 2018! 

Have you given any thought to how to get rid of the condensation in your hoist steam cylinder Chris?

[scc]

When not fitted with rim brakes the standard system on a traction engine is a series of individual blocks on a contracting brake band. So you are spot on now.... As ever  wonderful work..                Terry

[crueby]

CNR, on the patent for the hoist clutch, they show a drain line running from the dead side of the cylinder back through the hub to keep exhaust and condensate from flinging around the machine room. They had no drain cock on the piston, but mentioned that bliwby past the puston would get out that way, maybe they kept the piston there a slightly loise fit on purpose, since it would not reciprocate like a normal engine? Also, they have a passage in the d valve block on the floor that lets condensate/exhaust drip back down from the piston when disengaged and go through the floor that way.


One thing I have wondered is how much it would matter if there was condensate in a actuator like this, that is more like a hydraulic ram than an engine piston? Pressure is pressure, right? Hmmm...  I will put up a diagram from the patent in a bit...

[crueby]

When not fitted with rim brakes the standard system on a traction engine is a series of individual blocks on a contracting brake band. So you are spot on now.... As ever  wonderful work..                Terry