Author Topic: Chris' Build of a Lombard Hauler Engine  (Read 297469 times)

Offline steam guy willy

  • Full Member
  • ****
  • Posts: 2250
Re: Chris' Build of a Lombard Hauler Engine
« Reply #990 on: March 22, 2017, 12:26:35 PM »
It's called an isometric projection.  Three axes at 120 degrees.  All measurements show as true length parallel to one of the axes.  Easy to handle on the drawing board for a scale representation in 3-D.

Parallel lines stay parallel rather than converging at a horizon, but an always be measured.  Not like a perspective drawing.  Distant parts appear to be over size as we normally see with a perspective view where parallel lines converge at the horizon.  As Pete says, it tends to look a little strange until you are used to it, but it is useful when it is desirable to show at scale rather than just an artistic presentation.  Obviously both have their places.

I always enjoy looking in on the inspiring work on this model, thank you Chris for your trouble in writing it up so well for us all to follow and enjoy.

MJM460

Thanks for the info I did wonder if it was isometric ,perspective ,trompe d'lol or just good old  "should have gone to specksavers"   and i have now cancelled my appointment to Specksavers  !!! Its a good job that cad doesn't work to Pespective although it might introduce some extra realism to our models !!


Offline ShopShoe

  • Full Member
  • ****
  • Posts: 326
  • Central Iowa, Central USA
Re: Chris' Build of a Lombard Hauler Engine
« Reply #991 on: March 22, 2017, 12:38:12 PM »
Getting OT, but one more observation.

Us engineering types tend to have our own way of understanding, perhaps because we can visualize the perspective or whatever else the general viewer may not see.

A few years ago my wife and I were at a museum of Navy and Military artifacts from WWII, and she was looking at a display of field radios: Marveling at what was "portable" in those days. She kept wanting me to come look at the display, but I was being entertained by the schematics of some of the radios that were displayed nearby.

--ShopShoe

Offline Brian Rupnow

  • Full Member
  • *****
  • Posts: 5263
  • Barrie, Ontario Canada
Re: Chris' Build of a Lombard Hauler Engine
« Reply #992 on: March 22, 2017, 12:38:58 PM »
Chris--I have always been faintly interested in Stephenson reversing links. Not enough to really pay close attention to them.--Just enough to think, "Gee, that's rather neat." After seeing the ones in your 3d model, I went on an "in depth search" about them and even downloaded a 3d model from "Grabcad" to follow the workings a little more closely. Very interesting mechanism.---Brian

Online crueby

  • Full Member
  • *****
  • Posts: 9213
  • Rochester NY
Re: Chris' Build of a Lombard Hauler Engine
« Reply #993 on: March 22, 2017, 12:58:41 PM »
Chris--I have always been faintly interested in Stephenson reversing links. Not enough to really pay close attention to them.--Just enough to think, "Gee, that's rather neat." After seeing the ones in your 3d model, I went on an "in depth search" about them and even downloaded a 3d model from "Grabcad" to follow the workings a little more closely. Very interesting mechanism.---Brian
One of the interesting things about that linkage is that they did not just run them at one end or the other. By coming in slightly from full travel, it reduces the travel on the valve, which changes the amount of steam inlet on each stroke. The farther you move in, the more that effect, until towards the middle of the travel you are not moving the valve at all. This gave some control of power vs steam used, sort of an early version of what the Corliss valve cutoff controls allow in much better form. Neat stuff.

Online Dan Rowe

  • Full Member
  • ****
  • Posts: 750
  • Dripping Springs TX USA
Re: Chris' Build of a Lombard Hauler Engine
« Reply #994 on: March 22, 2017, 02:26:59 PM »
Chris-

An ironic  thread about machining the bevel gears for a Lombard restoration over at PM:

http://www.practicalmachinist.com/vb/general/machining-bevel-gears-332469/?s=982f369009d6d1f6aa251517a2b5c5fd

-Bob
Sounds like as much confusion on making model ones as full size ones! They got all wrapped around the pole confusing straight form and gleason form teeth.
 :cheers:

Chris,
You have the simpler task as you are simply making a whole set of parallel depth gears. The problem with gears made before the AGMA was formed in 1916 is there were a bunch of gear standards and the ratio of the addendum and the dedendum was not standard. This fact makes it hard to match a gear set with no easy way I know of to determine the correct specifications of the existing gear the guy is trying to match.

Dan
ShaylocoDan

Offline kvom

  • Full Member
  • ****
  • Posts: 2056
Re: Chris' Build of a Lombard Hauler Engine
« Reply #995 on: March 22, 2017, 05:05:43 PM »
In looking at your model, I am wondering how motion of the eccentric straps get transmitted to the levers with the valve rod.  Certainly an interesting setup.

Online crueby

  • Full Member
  • *****
  • Posts: 9213
  • Rochester NY
Re: Chris' Build of a Lombard Hauler Engine
« Reply #996 on: March 22, 2017, 06:17:51 PM »
In looking at your model, I am wondering how motion of the eccentric straps get transmitted to the levers with the valve rod.  Certainly an interesting setup.

Its a little hard to see in that view of the model. The rods from the eccentrics go forward to a lever below the line of the piston, making a lever up above move that moves the valve rod in and out. I think they had to put in this extra lever to get the moving parts of the Stephenson linkage down lower, so it would not hit the bottom of the boiler when in the full up position. This lever is called a rocker arm in the diagrams I have seen.

Here is another view, isolating out the valve components for one cylinder. With everything visible, it is tough to tell whats what, there is so much packed into a small space.

Okay, so the normal Stephenson linkage is there, with a set of eccentrics running up to the link bar, with a slot that lets is slide back and forth under control of the link from the control rod, which has a linkage up to the reversing lever in the cab.
The difference with this setup is that instead of the follower in the slot of the link bar being on the end of the valve rod directly, there is a pair of rocker arms in between. The two rocker arms are connected so they move together.

Hope that helps!

One thing I noticed on the original is that the joint from the upper rocker arm to the valve rod has no intermediate con-rod type link to it, so it does not allow for up/down movement as the rocker arm rocks. I am guessing that it was not needed since the movement is so short, so the up/down motion is very slight? Something I want to wiggle directly when I am there.

« Last Edit: June 05, 2018, 05:33:59 PM by crueby »

Online crueby

  • Full Member
  • *****
  • Posts: 9213
  • Rochester NY
Re: Chris' Build of a Lombard Hauler Engine
« Reply #997 on: March 22, 2017, 08:37:40 PM »
Finally back to cutting metal on the Hauler!   :cartwheel:

Started with a length of 1/2" stainless bar for the crankshaft, trued up the ends and drilled a center hole for the live center, and trimmed the ends down to 3/8" diameter, first one end

then the other - note that with the Sherline the smaller diameter on the first end lets it go much deeper into the chuck.

Then got out the compound slide, set it to 14 degrees, and cut the tapered portions where it goes back up to the full 1/2" diameter.

Then took a thin trueing cut down the center portion, taking off about 2 thou, to match the bore on the drive gear, which I had left slightly under 1/2" to allow for this knowing that the bar stock is not always quite a true round.

The gear was then put in place with some Loctite retaining compound. I used the edge of the lathe tool to get it centered, measuring both sides back and forth. Once I had a good position, slid the gear down, applied the loctite, and ran it back against the tool while turning it to spread the goop. Let it set a while till it grabbed then removed it from the lathe.

And here it is sitting in place on the top of the differential gear:

Took a measurement under the shaft to the engine bed rails, to doublecheck that the bearing block height that the 3D gave me was still right, and found that the 3D model showed it being higher. Even allowing for the gap for meshing of the gears, it is still a bit off. Not surprising given all the parts involved - gears, bearings, bearing blocks, mounting plates, bed rails, main rails... So, am adjusting the height of the bearing blocks that I will make from the plans to give a proper mesh of the teeth. Starting on the blocks next...
« Last Edit: June 05, 2018, 05:34:06 PM by crueby »

Offline Brian Rupnow

  • Full Member
  • *****
  • Posts: 5263
  • Barrie, Ontario Canada
Re: Chris' Build of a Lombard Hauler Engine
« Reply #998 on: March 22, 2017, 08:48:29 PM »
Your a man after my own heart!!---If the part doesn't match the plan, then change the plan to match the part. Only those people who design in 3d cad and then build the parts they designed know how often that happens!!!

Online crueby

  • Full Member
  • *****
  • Posts: 9213
  • Rochester NY
Re: Chris' Build of a Lombard Hauler Engine
« Reply #999 on: March 22, 2017, 09:23:57 PM »
Your a man after my own heart!!---If the part doesn't match the plan, then change the plan to match the part. Only those people who design in 3d cad and then build the parts they designed know how often that happens!!!

Isn't that why they invented shims and sandpaper?!

Offline zeeprogrammer

  • Full Member
  • *****
  • Posts: 6383
  • West Chester, PA, USA
Re: Chris' Build of a Lombard Hauler Engine
« Reply #1000 on: March 22, 2017, 09:48:31 PM »
Your a man after my own heart!!---If the part doesn't match the plan, then change the plan to match the part. Only those people who design in 3d cad and then build the parts they designed know how often that happens!!!

Isn't that why they invented shims and sandpaper?!

Yes. As well as alternative rulers.
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
"To work. To work."
Zee-Another Thread Trasher.

Offline Flyboy Jim

  • Full Member
  • ****
  • Posts: 1629
  • Independence, Oregon
Re: Chris' Build of a Lombard Hauler Engine
« Reply #1001 on: March 23, 2017, 01:51:30 AM »
I bet you were glad to get back to cutting metal. I like the clever use of the lathe tool to register where the gear needed to go on the shaft. Filed that one away.

Jim
Sherline 4400 Lathe
Sherline 5400 Mill
"You can do small things on big machines, but you can do small things on small machines".

Online crueby

  • Full Member
  • *****
  • Posts: 9213
  • Rochester NY
Re: Chris' Build of a Lombard Hauler Engine
« Reply #1002 on: March 23, 2017, 01:57:08 AM »
I bet you were glad to get back to cutting metal. I like the clever use of the lathe tool to register where the gear needed to go on the shaft. Filed that one away.

Jim
Not sure where that one came from. I had slid the gear on to check the fit, started to measure to find center, and it kept slipping as I brought the calipers up. The toolpost was right there, so moved it in to hold against, and Voila! Or, Guitar!  :Lol: (get it, Voila, Viola... oh, never mind...)  :ShakeHead:

Offline MJM460

  • Full Member
  • ****
  • Posts: 927
  • Melbourne, Australia
Re: Chris' Build of a Lombard Hauler Engine
« Reply #1003 on: March 23, 2017, 09:49:34 AM »
Hi Chris,

Referring back to your comment on the rocker arm connection to the valve rods, this is similar to the monitor engines on another thread.  It has a short vertical slot instead of a close fitting hole in the rod end connector to allow for the vertical part of the rocker arm motion.   It would be pretty difficult to see this in looking at the original.  While it does not seem ideal due to the vertical friction force which will still tend give a little side load to the packing, it would be much better than trying to bend the valve rod as it passes through the packing. In any case it will be a wearing part and I would suggest some care in making the rod end and the pin easily replaceable.  I would also suggest making a spare set of pins and rod ends as part of your two years spares kit.  (You did order two years spares with this machine, didn't you?). 

Some sort of rod guide and Conrod type connection would seem better, but not true to original, and clearly one of the necessary compromises in fitting everything in on the original.  It is also a machine that would probably flex enough on rough conditions to offset any advantage in the extra complexity.

MJM460
The more I learn, the more I find that I still have to learn!

Online crueby

  • Full Member
  • *****
  • Posts: 9213
  • Rochester NY
Re: Chris' Build of a Lombard Hauler Engine
« Reply #1004 on: March 23, 2017, 01:21:54 PM »
Hi Chris,

Referring back to your comment on the rocker arm connection to the valve rods, this is similar to the monitor engines on another thread.  It has a short vertical slot instead of a close fitting hole in the rod end connector to allow for the vertical part of the rocker arm motion.   It would be pretty difficult to see this in looking at the original.  While it does not seem ideal due to the vertical friction force which will still tend give a little side load to the packing, it would be much better than trying to bend the valve rod as it passes through the packing. In any case it will be a wearing part and I would suggest some care in making the rod end and the pin easily replaceable.  I would also suggest making a spare set of pins and rod ends as part of your two years spares kit.  (You did order two years spares with this machine, didn't you?). 

Some sort of rod guide and Conrod type connection would seem better, but not true to original, and clearly one of the necessary compromises in fitting everything in on the original.  It is also a machine that would probably flex enough on rough conditions to offset any advantage in the extra complexity.

MJM460
I think I have an idea of how they did it. First, here is the connection at the top of the rocker arm to the valve rod, does not look like there is any vertical play in it, unless there is a slot in the top of the rod. But, I found the drawing they did, and the hole in the rod is just a round close fit on the bolt.

What I did find that is interesting is that the valve slider itself has a slot in it rather than a hole:

and the valve rod has large washers and jam nuts on either side, so that there is no pressure on the slider from the nuts, but it can float. Since it is a balanced type valve, it presses against the cover plate as well as the valve seat, keeping it in place vertically.

What I am wondering, is if they let the rod be arced through the gland fitting, and the connection at the valve slider slips to take up that up/down part of the motion. At the size of the rocker arm, and the short travel of the valve (only about 1.28" total), this arcing was slight enough that this was enough to handle it without bending the valve rod. The drawings I found do not give dimensions for the valve rod or the gland holes, so I can't be sure that there is clearance for any rocking motion.
I am going to send a question up to the folks at the museum, see if they can confirm if this is truly how it works.
If so, worked for them, but for the model, with a much smaller radius on the valve rocker, it would make sense to put in a con-rod type linkage, wouldn't it? Its a much smaller radius on the rocker, and a 0.106" travel, gotta run the math on that...

« Last Edit: June 05, 2018, 05:34:30 PM by crueby »