Pennsylvania A3 Switcher (Kozo)

[Minh Thanh]

Hi Kim !
Your profile picture, do you have a video of that car ?

[Kim]

Hi Minh,

I have a few videos of it running before it was completed in my build thread: https://www.modelenginemaker.com/index.php/topic,8560.0.html

And a set of pictures after it was completed in the showcase here: https://www.modelenginemaker.com/index.php/topic,5264.0.html

But interestingly, no videos of it running when completed.  I have never steamed it up - I was going to... someday... but someday hasn't gotten her yet    So here's the closest I've got to a running video - it's running on air here, and it isn't completely finished, of course.  But it does run!

<a href="https://www.youtube.com/watch?v=eGZvS51xT-c" target="_blank">http://www.youtube.com/watch?v=eGZvS51xT-c</a>

Kim

[Minh Thanh]

Hi Kim !
 Thank you for looking
Thanks a lot !

[Kim]

Chapter 17.13 – Pins

The next parts were more than a dozen little pins.  This wasn’t really hard, but it did have its challenges since they are all quite small.  The “large” pins were 1/8” in diameter, and the smaller ones (most of them) were 5/64” (0.078”).  Here’s the whole lot of them:


The ones in the middle on the top had to be a sliding fit for 5/65” along 2/3s of the length, and interference fit into 5/64” for the last 1/3 of the length.  That took me a little doing, but I think I’ve got it.  You really can't see the diameter change in the picture, but believe me, it's there!  Interestingly, I have those two sitting in opposite directions.  The chamfered end is the end with the sliding fit, and I intended to have them be facing the same way, but they clearly aren't!

Next will be assembling and fine-tuning the valve gear so I can verify the length required for the eccentric rods.

We’re closing in on the valve gear!
Kim

[cnr6400]

 

[Kim]

Thanks CNR!  Sorry I never responded!


Chapter 17.14 – Setting Return Cranks

To set the position of the return cranks, Kozo has you make a little jig. This Jig has a cut out at exactly a specific height such that the driver pin will fit in the cut out exactly at maximum travel.  Then, the top of the jig is the correct height so that the return crankpin will sit exactly on top of it when placed correctly.

The jig is just a little plate and is not hard to make, and it works very neatly:


With the return crank set I can remove the jig and use it for the other side.

[Kim]

Chapter 17.15 – Eccentric Rods

Now we move on to the eccentric rods.  But before we can make those, we have to measure the EXACT length of eccentric rod we will need.  And to do this, we need a little adjustable eccentric rod.

Kozo doesn’t give the plans for this but does show a picture of what he used.  Based on his pictures I made this one out of 3 pieces of 1/8” x 1/4" 1018 steel bar.

It wasn’t hard, but I had to figure out the dimensions so that the parts would fit together and, even more importantly, it would cover the range of potential lengths that I may need.

Here are the 3 pieces I made for the adjustable eccentric rod:


And here it is assembled.  You’ll notice the little brass bushing on one end?  That’s because I mistakenly made both holes 1/8”, but one end needed to actually be 5/64”.  So I Locktited a 1/8” plug in the hole and drilled out the 5/64”


Now to measure the length we need for the eccentric.

But wait!  To do that I had to put all those little pieces together that I’ve been making! So, I spent a significant amount of time assembling it all.  It was harder than it should have been since this is the first time everything has been brought together, but I did it and it actually came together quite well!

Now, there is quite a little routine you have to do here – adjusting the position of the valve with the nut on the valve rod –you can’t turn the nut because it's locked in place by the valve.  And you can't rotate the valve rod because it's pinned into the rest of the valve gear.  So you have to disassemble the steam chest lift the whole assembly up away from the valve and turn the nut a bit, then reassemble everything. So, it took a while to get everything positioned.

Anyway, after a bunch of faffing about (as our British friends would say), I was able to set the rod length.  The blue tape is just to keep the wheels from turning since you’re supposed to set this at full extension with the valve placed just so.


And while it’s not all done, I thought it was so cool to see all the valve gear moving and doing its job, that I took a video to share with you all.   There's nothing connecting to the radius rod to keep it from flopping around and you can hear that in the video. But it's still pretty cool!  (And sorry for the furnace turning on halfway through the video - that's the price of having your shop in an attached garage!)
<a href="https://www.youtube.com/watch?v=TaJqwxswk6c" target="_blank">http://www.youtube.com/watch?v=TaJqwxswk6c</a>

Thanks for stopping by and taking a look at what I’ve been doing!
Kim

[RReid]

Very slick, Kim! There's a ton of work represented in that little video. 

I'm always a bit in awe of Walshaerts and some of the other brilliant engineers back in the day who could work out linkages like that with little more than pencil, paper and a slide rule.

[Minh Thanh]

Looks Great !
 

[cnr6400]

You are not far away from a runner Kim! Top notch work.

[Admiral_dk]

Another great milestone reached - and with a result you really should be happy with 

Can you help yourself from Not trying it on air 

Per

[kvom]

I didn't use the setting jig as the same heights can be set with gauge blocks.  Your result looks excellent.

[crueby]

Very impressive set of linkages, look to be working great!

[propforward]

Great progress on this build - and I really admire your long haul staying power! It is a mighty project and fascinating to look back from time to time at prior work done.

[Kim]

Thanks for all the comments, everyone!  I really appreciate it! And yes, it does feel pretty good to see the mechanism working!   

I'm always a bit in awe of Walshaerts and some of the other brilliant engineers back in the day who could work out linkages like that with little more than pencil, paper and a slide rule.

Yes, it is amazing the engineering that was done on these beasts!  No computers, no spreadsheets, no CAD - they just did it by hand!

Can you help yourself from Not trying it on air 

Per

Unfortunately, I can't do that until I get eccentric rods on both sides.  But I'm working on that and should have it up soon! (That's soon in MY universe, not in Chris's universe where he has dozens of shop elves working and has those 30 hour days  )

I didn't use the setting jig as the same heights can be set with gauge blocks.  Your result looks excellent.

That's a good point!  I'm sure there are many ways to do this - I didn't think about using gauge blocks, but you're right, I essentially made a single-use gauge block!

Great progress on this build - and I really admire your long haul staying power! It is a mighty project and fascinating to look back from time to time at prior work done.

Thanks!  Sometimes I wonder if I will have the staying power to complete it.  But I just keep chugging along.  And as long as I am having fun, I'll keep plugging away, one part at a time!

Thanks, everyone!
Kim