Author Topic: Chris' Build of a Lombard Hauler Engine  (Read 136390 times)

Offline crueby

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Re: Chris' Build of a Lombard Hauler Engine
« Reply #2130 on: September 24, 2017, 02:56:11 AM »
Hi Chris,
 Looking like you are on top of the issues..... even if the elves are still having after effects!

How about putting your camera on a selfie stick & taping it to the radio control unit?

Cheers Kerrin

PS.....now waiting for future video's of you playing in the snow!
Trying not to think about snow, we are in weather with 80 to 90 degree days for a couple of weeks!!


Might be fun to clamp the camera to the cab roof! Be a bumpy ride, but a neat vantage point.

Online Kim

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Re: Chris' Build of a Lombard Hauler Engine
« Reply #2131 on: September 24, 2017, 03:09:36 AM »
Well, that is just too cool Chris!  Loved watching you tool around your driveway with the Lombard!  That is just fun to watch!

I have no good advice for you on the flywheel.  I would think that going from almost noting, to something would make a difference in the smoothness of operation, but I have limited experience with this, so will be watching others replies.

Maybe you'll just have to try it and see!

Great work there Chris! You should feel mighty good about how it came out!
Kim

Offline Steamer5

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Re: Chris' Build of a Lombard Hauler Engine
« Reply #2132 on: September 24, 2017, 04:11:34 AM »
Hi Chris,
 Looking like you are on top of the issues..... even if the elves are still having after effects!

How about putting your camera on a selfie stick & taping it to the radio control unit?

Cheers Kerrin

PS.....now waiting for future video's of you playing in the snow!
Trying not to think about snow, we are in weather with 80 to 90 degree days for a couple of weeks!!


Might be fun to clamp the camera to the cab roof! Be a bumpy ride, but a neat vantage point.

From inside the cab......ELVE CAM???

 :lolb: :lolb:
Get excited and make something!

Offline Ye-Ole Steam Dude

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Re: Chris' Build of a Lombard Hauler Engine
« Reply #2133 on: September 24, 2017, 08:43:51 AM »
Thanks guys!


Passing thought: this engine has little in the way of a flywheel, the two crank discs are fairly small, and thd spur gear is also. A typical mill engine would have a large flywheel to smooth out the motion  locos would have the large drive wheels to do the same thing. There is room on the crankshaft to put two small flywheels, one either side of the center spur gear, approximately 1.25" diameter by 3/4" wide. Not huge, but a decent amount of weight in brass. They could be made in halves and bolted on around the shaft without removing the eccentrics.
Question: do you guys think it would make much difference in the smoothness and slow speed running?

Hi Chris,

Any and all weight that will add to and aid in the momentum will defiantly help.

Thomas

Offline MJM460

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Re: Chris' Build of a Lombard Hauler Engine
« Reply #2134 on: September 24, 2017, 09:03:14 AM »
Hi Chris, a few thoughts on flywheels.  A typical single cylinder mill engine requires that big flywheel as the torque fluctuates to zero from nearly twice the average twice each revolution.  With two double acting cylinders and cranks at 90 degrees, the torque fluctuates much less than for a single cylinder engine, as the peak torque from each cylinder falls between the peaks of the other, so the torque does not get to near zero and much less inertia in the way of a flywheel is required.

However, tracked vehicles tend to have a little irregularity in motion and if this coincides with the engine fluctuations the whole lot could seem worse than a smoothe load such as a ships propellor.  Moving the engine 1/8 turn relative to the tracks using the gear might make things smoother.

A flywheel contributes angular moment of inertia which involves mass, but mass distribution is even more important.  Each bit of the flywheel contributes angular moment of inertia equal to mass times radius squared.  Radius is the distance of the mass from the axis, so mass in the rim is much more effective than the same mass in the hub. 

The mass of the whole model has linear momentum when it moves along, but in a geared drive, every time this is called upon to help spin the engine through a low torque point, it reverses the gear teeth loads and will add to noise and jerkiness.  So a flywheel or two for symetry may well be worth a try, but try as far as practical for mass in the rim rather than disk or hub.  If you clamp it on as suggested, it can equally easily be removed or modified.

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

Offline crueby

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Re: Chris' Build of a Lombard Hauler Engine
« Reply #2135 on: September 24, 2017, 01:31:30 PM »
Some good points MJM, thanks! If I get the chance, think I will try the flywheels to see what it does, will be a simple set to make and the appearance won't matter much, they will be hidden under the boiler by the eccentric followers. Given both the gear reduction and the chain drive reduction, its a complex system. I don't think changing the gear position relationship to the track will do much, that changes in every turn anyway due to the differential letting the half shafts move independently. As you mentioned, if the flywheels don't help, I'll just unbolt them.

Offline crueby

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Re: Chris' Build of a Lombard Hauler Engine
« Reply #2136 on: September 24, 2017, 03:08:48 PM »
This morning I took the drive chains off the small sprockets (very easy to do, just lift the frame to let the track assembly rotate at least 45 degrees on the main axle, which loosens the chain) and ran it on low pressure air, with and without the con rods in place, turning it over by hand to see where the trip points on the valves are by watching when the pistons moved themselves and also when the pressure on the pistons stopped. I found that there were two issues (as usual!).

First one, causing the stuttering motion, was that the right cylinder's valve rod was one full turn too far in. This most likely happened a couple weeks ago when I pulled the cylinders to remake the cover gaskets, must have accidently let the rod rotate during handling despite trying to be careful not to. Quick fix, undo the link pin, turn it one, and put the pin back in. With that done, the engine is turning over smoothly once again, like it did when I first timed it. The timing looks to be spot on still, no need to adjust that.

Second issue is that the differential half shafts have a little too much play lengthwise now - was fine at first, but the bearing in one block slipped out on a touch on one of the bearing blocks. The bearings were not lipped (should have been) but instead just loctited in place, and one of them is loose now. Rather than depend on the loctite again, I think I will make a small bronze collar for the shaft with a set screw for adjustment, and let that keep the shaft from moving lengthwise and messing up the gear teeth mesh distance.
Quick fix there as well, fortunately. Will make that today, not sure if I will get another steam up in today since we have our first RC submarine run at the local Y pool later today and I need to get the Alfa prepped and packed up. No weed monsters in the pool, but the Y tends to use way too much chlorine without shocking it occasionally, so the salts build up and reduce the depth that the radio signal can penetrate. Always something...
If no steamup today, definitely will get one in tomorrow morning.
 :cheers:

Offline crueby

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Re: Chris' Build of a Lombard Hauler Engine
« Reply #2137 on: September 24, 2017, 06:33:51 PM »
The collar is made and installed on the differential half shaft, keeps things meshing nicely now. Need to update the plans for this part. I've decided not to do the flywheels for now, with the timing fix it should be fine.
With the diff and valves adjustment done, ready for a new steamup, but its too hot out on the driveway (about 90 today, black asphalt adds too much more), so will run again in the morning!

Offline 90LX_Notch

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Re: Chris' Build of a Lombard Hauler Engine
« Reply #2138 on: September 24, 2017, 06:52:37 PM »
I just watched the latest video Chris, outstanding!  I love this thing.  It is just too cool.

-Bob
Proud Member of MEM

My Engine Videos on YouTube-
http://www.youtube.com/user/Notch90usa/videos

Offline crueby

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Re: Chris' Build of a Lombard Hauler Engine
« Reply #2139 on: September 25, 2017, 04:11:20 PM »
The adjustment to the timing on the right cylinder worked out very well, as did the addition of a collar on the left differential halfshaft to keep the gear mesh in the proper range. Got outside with it this morning before it warmed up too much (going to be another really hot one out there today) and ran it for about 40 minutes, not bad for one load of water and fuel. Below is a compilation of clips from the run. It is very humid out there, so you can see the exhaust plumes very well. The steam at the bottom is from a vent I have in the exhaust elbow below the boiler to allow draining condensation - looks just like the condensate vents in the videos I have in the real one! The only times it was stopping was when one of the front wheels dropped into a hole or depression in the driveway - those little wheels can't handle the speed bumps!
Anyway, I'm calling this a very successful run, very happy with how it went. Next stop, the event at the Maine Forest & Logging Museum at the end of next week! Hmm, better start on the display base too...
 :whoohoo:


Offline Steamer5

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Re: Chris' Build of a Lombard Hauler Engine
« Reply #2140 on: September 25, 2017, 05:31:23 PM »
Hi Chris,
 AWSOME!! You've got her nailed!  :cartwheel: :cartwheel:

Cheers Kerrin
Get excited and make something!

Offline crueby

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Re: Chris' Build of a Lombard Hauler Engine
« Reply #2141 on: September 25, 2017, 06:08:37 PM »
 :pinkelephant:


 :cartwheel:


 :whoohoo: :whoohoo:

Offline Jo

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Re: Chris' Build of a Lombard Hauler Engine
« Reply #2142 on: September 25, 2017, 06:25:38 PM »
 :whoohoo:

Jo

 :pinkelephant:

Surus   ::)
Usus est optimum magister

Offline elciego

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Re: Chris' Build of a Lombard Hauler Engine
« Reply #2143 on: September 25, 2017, 09:00:29 PM »
Just beautifull

 :pinkelephant: :pinkelephant: :pinkelephant:
 :NotWorthy:
 :cheers:
Abraham

Offline tvoght

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Re: Chris' Build of a Lombard Hauler Engine
« Reply #2144 on: September 25, 2017, 10:46:15 PM »
Quite an achievement, Chris.

--Tim