A Real Dirty Job

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Carrdo
Posts: 1010
Joined: Thu Mar 06, 2003 2:20 pm
Location: Toronto, Canada

Re: A Real Dirty Job

Post by Carrdo » Thu Nov 08, 2018 6:19 pm

No new incidents to report.

The first leaf spring bundle assemblies. They are not finished yet but I am getting there.

I don't know if I like the leaf springs with the spacers or not. Will at least try it out and see how it works.

I do know that without the very fine control on the bench rollers, this would not have been possible as each leaf except the shortest two (top) spring leaves are curved slightly more than an adjacent leaf. I tried to make the curvature on each leaf such that when two leaves were set together without a spacer, if one pinched the two leaves at one end, the gap at the other end was equal to a leaf thickness (0.015").

You really can't see this feature with the spacers in place.

I also noticed another issue coming up with the Langworthy design regarding the above but I will deal with it shortly.
Attachments
201 The Leaf Springs First Assembly into a Leaf Spring Bundle.jpg

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NP317
Posts: 1446
Joined: Tue Jun 24, 2014 2:57 pm
Location: Northern Oregon

Re: A Real Dirty Job

Post by NP317 » Thu Nov 08, 2018 8:14 pm

I do not understad how that spaced leaf spring would work.
Normally, the spring functions by adding each leaf force as the spring is compressed.
Those spacers prevent leaf interaction, leaving the longest leaf to do all the work.
~RN

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Carrdo
Posts: 1010
Joined: Thu Mar 06, 2003 2:20 pm
Location: Toronto, Canada

Re: A Real Dirty Job

Post by Carrdo » Thu Nov 08, 2018 9:27 pm

NP317,

Yes, you are correct.

As I mentioned, this was the first setup.

There was a reason for doing it this way. I needed to know if I hit or missed another required dimension which was shown on the Langworthy drawings and this was the setup which would tell me. Yes, I did hit it or am very close.

The final result (most likely) will be the metal spacers will be replaced with a lot of dummy plastic leaves (to keep the dimension which I was trying to hit) or I am going to have to make a lot of additional curved spring leaves. The spring leaves were made curved, one slightly more curved than the one above, to try and make them "progressive". If I put in all those additional metal leaf springs, over what Langworthy specified, there will be no spring at all.

I simply don't know at this point as I really need to find a practical way of determining the actual weight which is on the locomotive lead truck, the drivers and on the trailing truck (and I don't have such a method). I suspect that virtually 100% of the locomotive dead weight (in 3/4" scale) is on the drivers and that the lead truck and trailing trucks are just going along for the ride but I can't prove it. The Langworthy lead truck dead weight is only 5 lbs.(and add another 15% for vertical impact loads - my guess) and if that is all the weight the lead truck springs will see then yes, the first two leaves are all that one needs to be working.

Otherwise, it is all just so much trial and error (so one needs to find a very flexible spring design/arrangement).

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NP317
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Joined: Tue Jun 24, 2014 2:57 pm
Location: Northern Oregon

Re: A Real Dirty Job

Post by NP317 » Fri Nov 09, 2018 12:31 am

Now I understand what you were doing.
Thanks.
~RN

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Carrdo
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Location: Toronto, Canada

Re: A Real Dirty Job

Post by Carrdo » Thu Nov 15, 2018 11:42 pm

Back to the Josslin lead truck for the moment to eliminate the problem I noticed with the outer equalizers fouling the inner curved surfaces on the frame brake lugs which prevented full vertical travel of the axleboxes in the truck frame. On the Josslin lead truck, the axleboxes should be able to move more than 1/4" vertically and they weren't moving anywhere near that amount.

That is when Murphy threw everything at me including the kitchen sink.

I had first to take the entire truck apart to be able to mill out much more clearance on the central upper equalizer surface of the outer equalizer than was shown on the Josslin drawings. See the first photo. Actually, in the end, much more relief was needed than what is shown in the photo.

Then I found that some of the leaf springs had jammed on the end hanger pins and would not lay flat on in the bottom of the hanger. OK, shave down some of the sticking leaf springs (on width) about 0.003" to give a little more clearance on the hanger pin.

Then, now that the ends of the leaf springs weren't jammed, they wouldn't stay on the pin in the end hanger. Now I had to cross drill a 3/32"" dia. pin with a #60 drill 4 times with the pin in place in the hanger. Bad move. Two I managed to do and with the other two the drill ran off the pin even though I had carefully aligned the drill and started the cross hole with a miniature center drill.

Pull the bad pins out and they refused to move. Get out the propane torch, heat everything up to a sub red heat, let it cool and try again as they may have been Loctited in - I don't remember (this time with a miniature made up tapered knockout punch - and with one bad blow I would be making a new hanger as well).

Make up a miniature steel drill bushing and cross drill a piece of 3/32" dia. rod by itself in the mill vise twice. Press fit or Loctite in the new pins and soft wire lock the pins so the leaf spring ends are free to slide on the pins but are captive. See the second photo.

Put everything back together (which is a big fiddly job) and the axleboxes hardly moved any more than before!

Now I noticed that the inner equalizers were jammed up against the two central cross beams of the frame which carry the 4 swing links and the truck bolster. The Josslin drawings showed the ends of the cross beams relieved but not to the degree needed to solve this new problem.

Take the lead truck completely apart again and set it up on the table of the mill to mill away the interfering frame material. Not an easy setup so in the end it was partially milled/filed with hours of work involved. See the third photo.

Put the truck pieces all back together again and see that the outer equalizers still need to have more metal removed so...

Finally, the latest (last photo). It just looks like the any of the photos of the truck taken previously but it isn't.
Attachments
678 A Relieved Outer Equalizer Needed to Clear the Truck Frame Brake Hanger Lugs.jpg
679 The Wire Locked Leaf Spring Ends on the Leaf Spring Hanger Pins.jpg
680 The Highly Relieved Bolster Cross Beam Ends To Clear the Inner Truck Equalizer.jpg
681 The Josslin Hudson Lead Truck with All of the Latest Changes.jpg

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Carrdo
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Location: Toronto, Canada

Re: A Real Dirty Job

Post by Carrdo » Fri Nov 16, 2018 3:57 pm

Back to the Langworthy lead truck.

Fully disassemble it to clean it thoroughly as it was absolutely filthy.

Install the leaf spring bundles between the side equalizers and set the ends of the bottom leaf springs (the longest ones) in the bottom "vee" of the spring hangers. The Langworthy has exactly the same problem as found on the Josslin lead truck. The spring bundles will just flip out of the spring hangers as there is no cross drilled locating pin in the end of the spring hangers to locate and hold captive the ends of the leaf springs. Maybe that is why I found the lead truck with the crude coil spring arrangement it came with.

And guess what. Despite everyone saying that the leaf spring bundle shown previously can't/doesn't work that way, this spring arrangement flexes beautifully in a truly progressive manner (despite the spacer washers being there) when I press down on the spring bundle. So I am going to leave it this way for the moment and see, when the truck is fully reassembled, if I still have the same effect.
Attachments
202 The Langworthy Lead Truck Fully Disassembled.jpg

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