Wheel Quartering and Crank Placement?

A good basic guide for positioning the eccentric crank is:

1) Rotate the drivers until the main crank-pin is at bottom dead center, on the side you desire to set the eccentric crank.

2) With the main crank-pin at bottom dead center, the eccentric crank shout be "tipped", or angled forward approximately 12 degrees. Another way to visually set it is to angle the eccentric forward until the tip, or small end, of the crank is visually in line with the center of that main axle.

Thanks Jack.

If I read you right it looks like the eccentric crank (first photo, fireman's side) should be rotated approx. 90 degrees forward (counter-clockwise)?

All this linkage doesn't really "move" out models but it sure will stop them if it's not adjusted correctly.

Sounds like a plan, thanks!

Suspect what happened on this model, and a number of others I have seen, is that the builder produced a batch of blank drivers, with the crankpin angled in one direction. When installed on the locomotive, one side was correct, one was incorrect - lagging, not leading. The remedy is twisting the crank pin so that the eccentric crank is in a leading position. Perhaps easier said then done!   (I had to do this on the Overland Models' Northern Pacific 2-8-2's of some 15 years ago)

Not all eccentrics go in the forward position.  It depends on whether the locomotives steam valves are inside admission or outside admission.  One the USRA 0-6-0 I believe the forward position is correct.

Joe

I tried to put them in the position Jack mentioned but the linkage just bottoms out on the underside of the hanger on the fireman's side (I can hear a slight tapping when it hits the hanger) and hits hard on the other, stopping the engine.  Both had a lot of travel in the "L-shaped" arm (expansion link?) near the center driver just above the main rod.

In the photos shown (prior to re-positioning them) the L-shaped arm moves very little, maybe 1/8" forward and backward, but the engine performs well with this setup.

I can position the linkage on the fireman's side (so I barely get the tapping on the hanger) but the engineer's side has to stay about 90 degrees from where I think it ought to go.

Folks such as Jack would notice this right off, but most modelers most likely don't notice or care if it's a bit off.

It's kinda like when you see a good-looking woman on TV and your wife says "Yeah, but look at those huge feet" and plants that image in your head, ruining your illusion forever

Bob, Are you going for appearance or performance?  You state it runs perfectly and your best low speed performer.

There are tits on those cranks so you don't have infinite adjustment.  If it was made not prototypical, but functions I think your stuck, unless you remanufacture?  G

Are you saying this for all model train engines, or real engines?  In Bobs case it is tipped aft 12degrees.  But the long linkage on this model probably drives that.  The orientation in his pictures looks right, though it may not be prototypical.

Normal MTH tits will only allow 90 degree adjustments.   G

George,

I was going for performance, but found the 4 tits you mention are preventing that.  I can get one side correct, but the other side will be 180 degrees out in order for it to work.  I figured there was some "modelers license" on making the linkage, otherwise they'd have to be made at really close tolerances or made to exact specs for all that motion to work right.  I'm not even sure all the necessary linkage is there for it to work like the real deal but it does give the illusion of working.

It runs a bit better at slow speed than my 2 RK 2-8-0s, and they don't have all the linkage this one does.

What do ya'll use to lube the siderods and other places that rotate?  How about gearbox grease?  Mine are well lubed, I want to clean them all and apply new lube.

Bob,

Maybe I am not visualizing correctly what you say is going on, but, I see no reason for that to happen. If the eccentric was rotated counter-clockwise to where the arm is located at the same angle as it is now, the amount of travel should be the same. Note that moving the arm in either direction away from the center of the axle toward the wheel rim will result in longer rod movement. 

Jim,

I don't understand it either but if I put the crank a certain way, it hits the hanger hard enough to hear it tap.

I'll take another look, I may be moving it away from center as you mention!

If it aint broke....G

You said it George!

I got to looking at all my other steamers and I'm not too sure if any of them are correctly placed, then there's the couple (RailKing) that have nothing but the main rod and no linkage whatsoever.

I'm going to put them in a row and see, maybe even take a picture!

If you want to get this right, you need new eccentric cranks, and some other way of holding them in place than those four tits that lock them so far away from the correct angle.

So folks can understand what is hitting what, let's review the nomenclature:

The piece that is bothering you is the eccentric crank.  It is the part that bolts to the rear driver crankpin, and should be about 15 degrees ahead of the axle centerline when at bottom dead center.  An arc drawn from the crankpin should roughly go through the driver axle center and the bolt hole on the eccentric crank.  Yours looks too long from the photo.

The long rod that attaches to that is the eccentric rod.

The eccentric rod forward end is attached to the bottom of a reversing link, in this case called a Walschaerts link.

The rod sort of centered up in the reversing link and going forward is called the radius rod.  On a real locomotive with Walschaerts gear, it moves up and down with the reversing mechanism.  It rarely does that on a model.

The radius rod attaches to the top of a vertical combination lever.  Just below that attachment is the valve spindle, then on the bottom you have a very small crosshead link which connects, obviously, to the crosshead.

Sorry to be so pedantic, but you seem interested in getting it right, and this is the starting point.

Thanks Bob, it'll take me a while to digest all that.

In the mean time, here's some photos (fireman's side) of the 5 steamers I have with nay type of linkage attached (the two 2-8-0 Railking engines have none):

 MTH RK Imperial 0-6-0:

Williams brass 2-8-2:

Weaver 4-6-0:

Williams 4-6-2:

Williams 4-8-4:

I'll turn them around (without moving the wheels) to show the engineer's side shortly.

I turned the engines around without moving the wheels:

Finally, here's the engines with the engineer's side rotated so the main rods are down:

(maybe it's the stray cat hairs that I need to be concerned about )

From my photos, NONE of the eccentric cranks appear to be in the right location

But, they all run really good, if not fine.  The 2-8-2 has some hesitation at slow speed (cogging action of the motor armature?), but not a show-stopper.

The only incorrect one is the very first, showing the crank aft of the axle with rods down. The rest are correct.

And I stand corrected - your 0-6-0 has simulated Baker gear, and a very poor simulation at that.  When you get serious, I can send you a real Baker gear hanger.  You are no doubt hitting the upper crosshead guide with the front of the reversing link.

Time to memorize the nomenclature - takes two minutes.  MRR Cyclopedia can help, or google "baker valve gear"

Here is a link to a picture thqt may correct some of my nomenclature:

http://www.bing.com/images/sea...IXUJJmQqRiv6QDKOHqMg

Note that when the valve spindle is above the radius rod, the eccentric crank is adjusted aft.

This is sometimes true on cab forwards, since running forward it is desirable to have the radius rod in the bottom of the Walschaerts link.  So you have a prototype for each side, just not on the same locomotive.

Thanks Bob, I have the Cyclopedia, that's what got me asking questions

Yeah, I think there's a lot of "fakery" going on, as far as the linkage goes, on the 0-6-0 but **** it runs nice.

Now I see what you and Jack are talking about, that link you provided helps.

In the 1st group of photos (where I show all 5 engines), all but the 0-6-0 have the "return crank" (or is that eccentric crank?) positioned forward, the 0-6-0 is pointed towards the rear.

Yes.  If you want to see a photo of a real one with the eccentric crank positioned to the rear, look up SP S-9.

very difficult to see, but here is one:

http://www.rrpicturearchives.n...ture.aspx?id=3758776

On most all (if not all) of my steamers, the eccentric crank has "pins" so that it can only go on in two ways, 180 degrees apart, one of which is completely unusable--i.e. far from the axle.  So what am I( missing?  If the linkage doesn't hang up or hit the end of its travel, why would it be causing uneven running?

I'm interested in this question because I have a 1950 Lionel 736 Berkshire, converted to PS2, that runs unevenly at very slow speeds, when wheels hit a certain position.  Neither one of the major train gurus nor I can find the cause.

I can tell you how to find out, but the first step is to disconnect the worm from the worm gear and rotate by hand.  Do that, and report back - we can find it right here on the forum, and this is the best thread for that.

Given the above information, and assuming the front drive block is set up correctly how would articulate engines eccentric assemblies match up for the rear drive block?  Does it matter?  Imagine with slipping they could be out of sink front to rear anyway.

G

bob2, with the motor removed, the wheels spin freely.  Axles, gears, & bushings have been replaced.  I've been fixing Lionels for over 60 years, and one of the most experienced Lionel repairmen in the US has spent hours pouring over it.  Neither of us could pinpoint a problem, although at the present time I'm suspecting that the flanges of the end rivers are rubbing on the backs of the adjoining flangeless drivers.  This would not have been as issue with the original Pulmor motor that couldn't run slow, but with PS2 and speed control slow speeds are easy to attain

Since this is a 3-rail loco and this is the 2-rail forum, I'm not going to pursue the issue on this forum.  But thanks for the offer.

If you let it roll down a slight incline and there is no jerkiness, then it is not your mechanism.  It could be your worm gear - if it is worn, or eccentric, it will have a little hitch as it goes through each revolution.  It is probably not your motor or flywheel which rotate maybe twelve times for every revolution of the drivers.

GGG - each engine of an articulated or Mallet is an independent steam engine.  Once in a while they are set up differently; it just depends on a lot of things.  Some say they synchronize themselves while running; I have seen no proof of that, either analytically or photographically.

On a model, typically they are locked together.  I have one that has different gear ratios - 24:1 on the front, 25:1 on the back.  They go in and out of synch, and you cannot tell it is periodic.  Dual motors is the other way . . .

bob2:  Frank Timko, who supplied the motor and frame for the PS2 conversion, rechecked the motor and worm and found them ok.  A runout gauge on the spur gear showed it is true.  One opinion I have received is that the Mabuchi motor lacks the torque to overcome the varying load of the rods turning.  The incline test is interesting, and I'll try it next time I open the loco to tinker.

Re single-motored articulated, if there are differing gear ratios for front and rear engines, doesn't that raise havoc with traction tires.

2- railers do not use traction tires.  The slip is so slight I doubt you would notice it, but if a slipping traction tired locomotive sheds th rubber, then there might be problems ultimately.  It really isn't worth it - I just did it for a magazine article.  I also did a two-motor articulated which was a success, with both drive shafts below the level of the driver tops.  Down side was the Delrin chain I used for drop-down.  It was noisy, and at the time I did not know about shaving the sprockets.  Also the through bearings on the rear gearbox were specials, and $30 each in 1995.