Sprung drivers

Easier to list those that are not sprung.  Saginaw, Hines, Scale Craft (except for the fully sprung and equalized Northern), Alexander, Mini-Scale/Mi-Loco, International, and maybe Blum.  There are others, but never produced in any real quantity.

All MG/USH is either sprung or easily converted with a screwdriver.  All Lobaugh - sprung.  All subsequent brass imports sprung. CLW sprung.  Some All Nation sprung.

I have 5 MG locos and none were sprung, they had rubber pads about the bearing boxes in the slots for the drivers.   I have converted 1 to sprung, a PRR 0-8-0.

I have a bunch of US Hobbies locos and they are all sprung.    

I have a 2 weavers and they are sprung.    

I have a hines Mike, not sprung.   

I have some sunset and all are sprung.   

I make all but my 0-6-0s and two axle steam slotted for springs, with proper holes for the springs to seat in.  But I pad them with expensive cork gasket material, making them rigid for my use.  Whoever gets them when I croak will have an easy time springing them.

Thanks, Bob and Jim. It's good to know that the MG/USH locos are easily upgraded.

-Charlie

I do not know why this question has been asked but I will add this comment.  I have 10 Ken Henry scratchbuilt steam locos in my collection.  None have sprung drivers and they are all very smooth running models and can pull a good sized train.  Sprung drivers are nice but I don't think they add that much to the ability of the model to perform as long as the original workmanship on the mechanism is good.

Many sprung drivers are sprung so stiffly that they really never move up and down much.

Joe

You and I know that, but he specifically stated that he did not care what we thought.  That is why I did not say why I stick cork in there.

Since the cork has been popped and for the others who might be reading. Properly sprung drivers are smoother operating over trackwork which might be a little on the rough side. I notice the difference on my layout. Your mileage may vary, your layout may vary. The other stuff about pulling power I don't know and am not concerned about.

My trackwork is the worst.  It is practically outdoors.  Mostly handlaid with spikes at most every sixth tie.  And superelevated about twice the angle I will do next time.

A better question would be what company used proper spring rates. Most of my HO brass engines have sprung drivers but you have to put a 5 lb weight on them to see any vertical movement. Most are way oversprung.

Pete

Sprung drivers are an advantage in places where level track transitions to an upward or downward grade. At such a transition, a locomotive with three rigid drive axles (say a 2-6-0) cannot maintain wheel/rail contact on one set of drivers, whereas a model with sprung drivers can.

MELGAR

True.  Also true on almost perfect, almost level track.  The weight is then transferred to the driver actually in contact.  Pulling is not the issue - the issue is Chainsaw wants springs.  It is a little like my hangup on wood and metal, except it is clear that you get better detail in polystyrene (and it is way cheaper).

MELGAR posted:

Sprung drivers are an advantage in places where level track transitions to an upward or downward grade. At such a transition, a locomotive with three rigid drive axles (say a 2-6-0) cannot maintain wheel/rail contact on one set of drivers, whereas a model with sprung drivers can.

MELGAR

bob2 posted:

True.  Also true on almost perfect, almost level track.  The weight is then transferred to the driver actually in contact. 

The lack of sprung drivers on all the 3-rail (scale) diecast locomotives that I run is the reason that I do not have any changes of track elevation on my model railroads. At the beginning of a downgrade, the front drivers (of a 2-6-0) will lose contact with the rails. Looks unrealistic.

MELGAR

I'm not sure that sprung drivers make any real difference, in the absence of true equalization. If a 3-axle locomotive without springs encounters a vertical curve, then its weight on drivers will be transferred briefly to the first and third drivers when the center drivers rise above the rail head, presumably increasing the traction of the remaining four drivers that are in contact with the rail. I would like to see the quantitative results of tests to determine whether or not the tractive effort of the engine is actually reduced in this circumstance.

Question for Bob2.  Where and how are you using the cork on the drivers. and is there something special about the cork. I would be most interested to learn about this. Thanks

Franky-Ogee

The probem is not on regular mainline trackage at all. Everything is smooth as silk there on my layout. And again, my issue has nothing to do with traction or pulling.

The trackwork I am describing is where there are 5 or six turnouts in a row almost lapped on top of one another going into the yard. There are many little connecting pieces of track with electrical gaps, points and frogs and guardrails, and getting those little pieces of track and frogs to align, and stay aligned smoothly, up and down and otherwise is a challenge.  It isn't like the trains are bouncing off the tracks or anything but there are some subtle bumps that can develop.

I'm using ROW number 6 frogs and they look great and I love them but they have some tight tolerances to work with as well. I've seen some people file some of the number 6 frogs away, but I'd rather not do that.

It isn't like it is terrible to watch and most people visiting probably would not notice, but it is noticeable to me. Of 20 engines I regularly run, I'd say 2 have the proper springs, the Overland J and the PSC Z1b. The Sunset Y6 engines are okay. The rest have springs that are too stiff or none at all. I enjoy running them all.

Equalization due to over stiff springs or not I can hear the difference between sprung and un-sprung locomotives (steam and diesel) running through a network of crossovers on my railroad.  The un-sprung ones (especially china drive diesels and MTH 3-2 locomotives "thunk" as they pass over my R-O-W smoothly laid frogs.  The difference in sound is amazing - and distracting.  

As far as tractive effort I found that a heavy MTH N&W J could pull 20% fewer passenger cars than a lighter and longer wheelbase sprung Sunset T1 on my 2.2% super elevated Horseshoe Curve.  Pretty sad given the well know results when the N&W and PRR swapped locomotives for comparative tests in the 1940's..  

It was said that the O Scale locomotives that Sofue built featured equalization.  Sounds like a pretty tricky thing to pull off !!

B Smith posted:

I'm not sure that sprung drivers make any real difference, in the absence of true equalization. If a 3-axle locomotive without springs encounters a vertical curve, then its weight on drivers will be transferred briefly to the first and third drivers when the center drivers rise above the rail head, presumably increasing the traction of the remaining four drivers that are in contact with the rail. I would like to see the quantitative results of tests to determine whether or not the tractive effort of the engine is actually reduced in this circumstance.

With a non-sprung (rigid) 2-6-0 locomotive, a vertically curved transition into an upward grade will cause the middle drivers to lose contact with the rails. To me, this is not acceptable because it looks unrealistic. With a downward transition, the front drivers will lose contact first. As the locomotive pitches downward, the rear drivers will lose contact. Does not look good. As for tractive effort, assuming the total torque delivered to two driver axles is the same as with three driver axles, the tractive force on each driver would be larger (by a factor of 3/2) when two sets of drivers are in contact, and the drivers would be closer to slippage, especially in an upward transition.

MELGAR

I use slots for drivers, with 3/8" square brass bearings ("driving boxes", in the vernacular).  At the top of each slot there is a hole for the spring to seat in, or two holes, depending on how I feel at the moment on spring size.

But rather than inserting springs, I cut 3/8" square pads from cork gasket material (or rubber, but I think the cork will last longer), and insert it in the slot to hold the bearing against the keeper ("pedestal binder").

Fully equalized is not that difficult.  The Scale Craft Northern was equalized between drivers, and sprung with actual leaf springs!  Ditto "Little Engines" live steamers.

Sofue and KTM equalized lead and trailing trucks as well.  That is slightly more difficult.

I agree with Chainsaw.  It makes absolutely no difference whether springing is better or not.  What makes the difference is what you like.  I like the idea of sprung drivers, so I set up that way.  I like the performance of a fairly rigid frame, and only insert springs if I see a problem - like the lead driver on a 4-10-2 climbing a rail.  But most of my locomotives can be sprung with a screwdriver and some spare time.

All of my steam locomotives are sprung . The interesting thing since I'm 3 rail scale , the third rail sprung pick ups provide some driver equalization on some grade beginnings and ends. Crazy huh?

Really very interesting guys thanks for the great information 

bob2 posted:

 - like the lead driver on a 4-10-2 climbing a rail.  But most of my locomotives can be sprung with a screwdriver and some spare time.

I have a Texas type that keeps derailing. I tried laying some wider curves just for this engine. It didn't work. I believe it's not only the curve's radii but any humps in the track work on those curves. I was thinking of making one set of axles into blind drivers to help. You can see her bind against the rails trying to go around the curves. It is always the lead axle that jumps first. It's not sprung. I still didn't know if the lead or the middle drivers should be made blind to help the best. (I think it's the rear set that jumps in reverse?)

 I figure when I get the money, I would just send her to Joe F and let him tell me the best solution. It's funny to me that my big heavy Alleghenies (and Challengers) handle the trackwork. They do jump around while running. Ultimately, I know I have to redo my benchwork so that all these engines run smoother. It was built for my G scale where it did not matter. I got lazy and tried to make the existing layout work by shimming the track. 

Engineer-Joe posted:

 

I have a Texas type that keeps derailing. I tried laying some wider curves just for this engine. It didn't work. I believe it's not only the curve's radii but any humps in the track work on those curves. I was thinking of making one set of axles into blind drivers to help. You can see her bind against the rails trying to go around the curves. It is always the lead axle that jumps first. It's not sprung. I still didn't know if the lead or the middle drivers should be made blind to help the best. (I think it's the rear set that jumps in reverse?)

Joe,

In a curve, the sideforce (due to the rails) on the front drivers steers the locomotive into the curve - like a lead-truck. Having the sideforce applied to the locomotive as far forward of the locomotive center-of-gravity as possible (like a lead-truck) produces the maximum steering moment. On the contrary, the sideforce on the rear drivers acts to prevent the locomotive from steering into the curve. Therefore, the tracking will be best with blind rear drivers. This will produce larger overhang (at the rear drivers) and will not look as good as with blind middle drivers. But it will track best...

This analysis pertains for the locomotive moving forward. In reverse, there will also be some benefit due to the shorter wheelbase with blind rear drivers.

MELGAR

Or do what the real railroads did and get some lateral motion in there.  For us, with wide gauge and wide tread, crankpin pin clearance is a problem, so the rear drivers are the candidate.  Pull the rear driver and figure out how to allow it more side to side motion.  Narrow the bushing on the driver bearing, or narrow where it slides in the frame.

A caveat: ten-coupled O Scale rarely works well on less than 72" radius.  And if you superelevate, you may need to spring at least the front and rear drivers.  Avoid unprototypical blinding - it reduces the value of your model considerably.

Google: "Lateral Motion Device".  Oh - and Alleghenies and Challengers have half the rigid wheelbase of your Texas type.  They are designed for tighter radii.

I agree with Melgar’s advice: make the LAST pair of drivers unflanged.  I had a Sunset decapod with this arrangement and it could negotiate O42 (21” radius) without difficulty.

Ted - a 2-rail Decapod on 21" radius?

3-rail (Sunset 3rd Rail circa 1990.)  This was the version with the ‘shorty’ tender.  Only the first and fourth pairs of drivers were flanged.  I believe the fourth and fifth pairs of drivers were identical except for the flange, and interchangeable to the user’s preference.  With the flanged axle in the 4th position, it worked fine on 3-rail 42” diameter flat profile track, including circular (non-eased) curves and “switches” (curved turnouts.)

Thanks.  2-rail is not quite like that.  Even blind drivers are only about 3/16" wide, and will drop inside the railhead causing what looks more like a snaproll than a derailment.

In fact, that is one of the only remaining significant advantages of 3-rail - your wheels and flanges are designed for extremely tight radii.  All the other advantages are illusory.  Opinion.

Engineer Joe,

I doubt that there is anything that I can do in my shop that will totally correct the problems you are encountering with this locomotive.  If your railroad is not set up to handle locos with 10 drivers, trying to make this one run on it will require things I would not want to do.  No thanks.

Joe

I got my answer. Thanks for all who responded to this thread and for creating it!

At first, I had thought it was because the drivers aren't sprung. I don't believe there's a lot of free movement on this engine either. I will look closer once again.

 I believe the answer for me is strictly to have smoother, wider curves. After shimming my RR tracks, this is the only steam engine that still has big troubles. Watching the big heavy Alleghenies up close, I see them hopping as they go over some poor track work. Their long solid boilers also point out where the hills are in my track. I have to believe I'm not fully there yet. Reading Joe's reply, I'm left with attacking this one more time.

 The best news for me, is I can just attack the problem areas first. Unfortunately, that is a big amount of the RR. So for anyone else starting a build, please do it right! I hate the idea of having to restrict running to lower speeds, and limiting which engines are allowed on my rails. I knew I should have ripped it all out and called Tom Tee. I was saving that for an eventual move to a new house.

I love ten-coupled steam.  I wound up enlarging the train room by two feet and re-laying to 74" radius on the outer loop, just so I could see my 2-10-2s and 4-10-2s run.  And run they did!  Now I need to finish the 4-12-2, which just barely makes it.

You should see the Nickel Silver Gresley levers, from Jay C.!  Thanks, Jay!

Bob,

Really happy you were able to make use of them.

Jay