Jonathan,

Just curious of how many reservations were received (2 and 3 rail) on the SD40-2 project

if you don't want to disclose, I totally understand

 

I've had a long standing reservation with Sunset for a pair of Bluebonnet SD40-2's. I remain hopeful they one day come to fruition, but with each passing year that seems more and more less likely.

OMI imported SD40-2's about 30 years ago, which I really like and think are pretty decent. They are sort of difficult to come by anymore but can occasionally be found for about what a new Sunset/Lionel/MTH sells for. Here's one I just upgraded DCC and lighting in, sorry the video is pretty crappy.

IMG_0265

John

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Last edited by jgtrh62

If there are enough orders for it to put the entire run over top Scott would do it!  Just send him an email requesting it.  Maybe Denzel and Chris Pine will order one.

Although an SD40-2 is certainly out of my modeling locale/time frame, as a long time 2R 0 scaler I was surprised that this project has not reached critical mass, and so I asked a friend, whose primary modelling is firmly [ well,....mostly ] in the -2 era, three questions, and his condensed replies follow:

A.  Is it feasible to kitbash a -2 from an Atlas SD40 ?

   He answered this question in a very lengthy, mod by mod manner, as he is not a 'good enough' modeller [ or has a definition of 'good enough' that is far higher than mine ].    The biggest single problem are the HTC trucks, which have a different wheelbase than the Atlas truck;  not only do you need different side frames, but a hence new power truck as well, even if one accepted the 'China drive', which he wouldn't.  For everything else, while the Atlas parts department would supply some items and PSC parts would require a lot of work if they were usable at all, there would still be a LOT of doors to rearrange, parts to make etc etc.

B.  What is the general availability of SD40-2 models by CLW, Overland, etc at the March Meet and other major 0 shows ?

   He didn't quite answer this one directly, but more as an extension of the first question.  Very condensed, ideally he would prefer the CLW model, or at least just the trucks if they were available, and he felt the OMI models of that era weren't very good.

C.  Would you buy one with a tank drive:

   No.   He does not like the visual aspect of tank drives.  So no 40-2 orders for Sunset from him.

********************

  One outcome of my first question was my realization that a major question any prospective 40-2 builder faces is " Which version(s) ?"  This loco model was produced over a 10 year time span -- 12+ if one includes the last group of SOO units -- during which there were many changes to the appearance in such areas as grills, nose length, fan styles,  etc, and that's BEFORE one gets to the road specific details.   And while HO sales might provide a guide, I doubt one can translate that directly to the 0 scale market.

Best regards,

SZ

Edited to add three 40-2 photos:  A  C&S from the initial run, an ATSF from the last [ not counting the final SOO's ] , and an MKT just because.

SD40-2 001-2SD40-2 002_edited-1-2SD40-2 003-2

 

 

 

 

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Last edited by Steinzeit
jgtrh62 posted:

I've had a long standing reservation with Sunset for a pair of Bluebonnet SD40-2's. I remain hopeful they one day come to fruition, but with each passing year that seems more and more less likely.

OMI imported SD40-2's about 30 years ago, which I really like and think are pretty decent. They are sort of difficult to come by anymore but can occasionally be found for about what a new Sunset/Lionel/MTH sells for. Here's one I just upgraded DCC and lighting in, sorry the video is pretty crappy.

IMG_0265

John

Really enjoyed the video. Great model.

Regarding the SD40-2, Why not offer the 5 or 6 railroads that had to most such as UP, BN, Milw (my favorite), etc.

Dick

CBQer posted:

Regarding the SD40-2, ............, Milw (my favorite),

Ref my post earlier today:  My friend specifically pointed out that the MILW units are especially handicapped visually were a tank drive used because of their smaller [ = shorter ] fuel tanks.

SZ

CBQer posted:

Regarding the SD40-2, Why not offer the 5 or 6 railroads that had to most such as UP, BN, Milw (my favorite), etc.

Dick

If only 5 or 6 RR’s were offered then this project would stand an even lesser chance of getting done. Lots of RR’s had or still have SD40-2’s, so why not offer them all?

I still stand firm on my 2 Wheeling & Lake Erie SD40-2’s that I reserved in 2016. I would add a 3rd if there was a real chance of these making the cut.

catnap posted:
CBQer posted:

Regarding the SD40-2, Why not offer the 5 or 6 railroads that had to most such as UP, BN, Milw (my favorite), etc.

Dick

If only 5 or 6 RR’s were offered then this project would stand an even lesser chance of getting done. Lots of RR’s had or still have SD40-2’s, so why not offer them all?

I still stand firm on my 2 Wheeling & Lake Erie SD40-2’s that I reserved in 2016. I would add a 3rd if there was a real chance of these making the cut.

Out of curiosity, do you know if the Sunset offering would be an accurate representation of the W&LE prototype?

 

I see those units periodically in Medina.  If I were to place a reservation it would likely be for one of those.

"Is it feasible to kitbash a -2 from an Atlas SD40 ?"

Isn't the biggest problem the fact that the -2 is about 3ft longer than the SD40?

When I got an Atlas SD40 I was intent on numbering it in the Soo Line's 66xx-series of SD40-2, mainly so I could have a four-digit unit to contrast with my other locos which were mostly 3-digit numbers. Once I started doing some research on the differences between the SD40 & -2, I soon gave up on that idea!!! My model ended up as SOO 755.

 

SundayShunter posted:

"Is it feasible to kitbash a -2 from an Atlas SD40 ?"

Isn't the biggest problem the fact that the -2 is about 3ft longer than the SD40?

Yes, at least 3 feet longer, plus the trucks are different on the "Dash 2" series SD units.

When I got an Atlas SD40 I was intent on numbering it in the Soo Line's 66xx-series of SD40-2, mainly so I could have a four-digit unit to contrast with my other locos which were mostly 3-digit numbers. Once I started doing some research on the differences between the SD40 & -2, I soon gave up on that idea!!! My model ended up as SOO 755.

 

 

Daniel Raible posted:
catnap posted:
CBQer posted:

Regarding the SD40-2, Why not offer the 5 or 6 railroads that had to most such as UP, BN, Milw (my favorite), etc.

Dick

If only 5 or 6 RR’s were offered then this project would stand an even lesser chance of getting done. Lots of RR’s had or still have SD40-2’s, so why not offer them all?

I still stand firm on my 2 Wheeling & Lake Erie SD40-2’s that I reserved in 2016. I would add a 3rd if there was a real chance of these making the cut.

Out of curiosity, do you know if the Sunset offering would be an accurate representation of the W&LE prototype?

 

I see those units periodically in Medina.  If I were to place a reservation it would likely be for one of those.

I guess it bears repeating for the 100th time, ANY ROAD NAME which receives sufficient reservations will be done, IF the SD40-2 in general receive sufficient reservations.  I think 20 is the minimum for a specific road name but Scott would be the person to ask directly about that.  IF it does not show up on his reservation pages if it because no one has reserved any.

I don't know if it helps you 2R guys, but put in a reservation for 2 W&LE 3R SD40-2 in 3R.  I found this thread very helpful in learning about the other SD40-2 models out there.  I'm glad I didn't buy any of them.  One question though, what exactly is a tank drive?

Last edited by rplst8

Jonathan,

    I'm considering ordering a pair of these SD40-2's and wondering if any of them have operational ditch lights?  I'm leaning toward CP Rail and all the prototypes in this paint scheme I see have ditch lights.  

Rich

Hi Rich.  Operating ditch lights are actually one of the easier items to add.  As I recall they were done for the late era SD7/9 project.  At a minimum the Norfolk Southern units had them on that project.

Some of the other issues regarding the phasing of this locomotive will need a lot more scrutiny, but until the orders reach critical mass design won't start in earnest.  That is why these threads are helpful to keep a database of all information shared to date.  With the recent resurrection of this thread and renewed interest perhaps this project can stay alive!

rplst8 posted:

I don't know if it helps you 2R guys, but put in a reservation for 2 W&LE 3R SD40-2 in 3R.  I found this thread very helpful in learning about the other SD40-2 models out there.  I'm glad I didn't buy any of them.  One question though, what exactly is a tank drive?

A tank drive is a common name for a horizontally mounted motor with a worm gear that powers all axles.  The Sunset / 3rd Rail drive is a roughly center mounted can motor in the body with a geared belt similar to some timing belts in cars that connects to the worm gear inside the fuel tank.

From a performance standpoint the drive has more torque than the vertically mounted "China drive" as it is commonly referred to.  Atlas has used a tank drive in the AEM7 and the early SW units.  My AEM7 is an outstanding puller for its size.  Also slow speed performance without command is a little better and with command the tank drive can run right at 1 smph.  

From an aesthetic standpoint the worm being exposed visually in a few spots at the level of the fuel tank can be distracting on locomotive with smaller tanks.  The benefit it that it does allow for a complete cab interior with control stands and other interior features.  

Hope that helps.  I should take some photos.

Recent  SD9 offering from Sunset.   

Takes space and swing to do this, IMO.  Way different from a two vertical can design.  

There is a variation where the motor drives a dropdown over each truck, eliminating the U joint problem with the shaft coming out of the fuel tank. Old as the hills, and in all All Nation Diesel models.

The China drives could be made in the same gear ratios, and then would have roughly the same speeds and pulling power.  The problem is that the motor bearings absorb radial force due to worm engagement, and those spur gears can get rocks in them.  Those two problems are not a real headache unless you run eight hours a day for years or have loose ballast.

As noted a tank drive makes the connection to the trucks in the fuel tank, hence tank drive.  In addition to Sunset Key uses the tank drive system for it's diesels.  Another horizontal drive system was used by Overland wherein the connection between the axle gears and the motor is done in a tower attached to each truck near the pivot point attachment between the truck and the chassis.  A third method, used by Midwestern, is to put the connection just above the floor of the chassis.  Erik at Midwestern has been doing these type of drive updates for many years and is how he got started.  This makes it possible to add detailed entire nteriors and maintain a functional drive system.    For the foreseeable future it's either the vertical drive, the tank drive or Midwestern's.  It depends on how big a deal it is to you and how much you are willing to pay, or not pay, for it to make a difference.

Last edited by rdunniii

If an accurate model of AWVR 1206 is offered with the odd headlights I am all for it. I'm actually having the AC4400s custom painted right now.

 IMG_6160.PNG

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rplst8 posted:

I don't know if it helps you 2R guys, but put in a reservation for 2 W&LE 3R SD40-2 in 3R.  I found this thread very helpful in learning about the other SD40-2 models out there.  I'm glad I didn't buy any of them.  One question though, what exactly is a tank drive?

Thanks for your reservations.  Every bit helps.

2-rail vs 3-rail irrelevent.  It used to be the majority were 3-rail,  they are now a decreasing minority.

It's the total reservations that matter.

A tank drive means that there are drive shafts emerging from the central fuel tank, usually with universal joints, conveying power to the trucks fore and aft.

It was probably the most common arrangement for 2-rail O scale diesels made during the 20th Century, including Weaver, P&D Hobbies, and Sunset/3rd Rail.  Some object to this setup.  Because depending on the length of the fuel tank and style of truck, the protruding drive shaft can be visible when viewed at or near eye level, which ruins the illlusion for some.

Most newer low-priced road diesels from Atlas and MTH use a small can motor mounted vertically on each truck, that swivels with the truck.  This is sometimes known as a "China drive" because these locos are made in China.  As mentioned the gear ratios are usually too tall for best performance, and the motors are much smaller, developing less torque.  Also since the worm gears in each truck are self-locking (i.e., wheels cannot turn the motor), the motors can sometimes buck each other at very slow speeds, which is not a desirable characteristic.

@GG1 4877 The Atlas AEM-7 and SW's don't have a tank drive.  They have what I like to call a cassette drive.  This is what most locos in S and HO scale use, maybe N scale too.  A central motor in the body has two shafts with a universal joint on each end.  This drives a worm at the top of a clam shell "gear cassette" which is mounted on, or part of the truck frame.  So in these cases you don't see a protruding shaft.  The truck sides are ornamental because the axle bearings are inboard.  This design lends itself to mass production,  but it's difficult to retrofit a cassette drive to existing models.  First, the clam shell gear cassette has to be specific to the truck wheelbase.  Also, the frame has to have a gantry or pivot point for the gear cassette.  If the pivot point is too high, the trucks will tend to "wheelie" under load.  This was a problem with the 1970s Atlas F9s (and Red Caboose GPs that used the same drive.)  It can be mitigated through the fabrication and installation of "Armstrong brackets."  If the pivot point is low enough, the model can usually have a detailed cab interior.

I love the Midwestern Model Works drive, it might be the best of all.  But are they actually being produced?  What's the wait time, and how much do they cost!?

Last edited by Ted S

Thanks for the expanded clarification Ted.  I had not heard the term cassette drive before.  Coming out of HO and N for so many years I'm quite familiar with the gear towers coming up from the truck to a drive shaft connected inside the body.  There were kits designed for Athearn and others that added gears to improve the gear ratios for very slow speed performance pre command.  I think it was Rail Power Products, but that goes back to the 80's and my teens which I kind of remember?

The vertical can motors in HO and N do predate the common term of "China drive" as Rivarossi, AHM, and early Atlas used a vertical motor powering a single truck going back to the late 60's.  Most were produced in Italy or Austria at the time.  They were know for their speed more than anything else  but I still have several as all the Rivarossi GG1s used this drive.

I found this picture of a W&LE SD40-2 (according to an online W&LE engine roster) in my photo archives that would be very tempting.  This picture was taken not far from my house back on 4/13/2018.  Doubtful the engine is this clean today.

 

W&LE 7005

 

 

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W&LE recently started renumbering their SD40-2's in the 7000 series, I would want mine with the 4K gallon fuel tank. The ex-MILW RD SD40-2's have 3,200 gallon tanks.

On the tank drive - it may well be the most common, but it probably doesn't work well on things like F7s, GP7s, or RS-3s.  The problem is geometry - the angle of the u-joints becomes extreme with smaller wheelbase models.  An F7 would simply lock up on a 36" radius curve.  U joints have a critical angle, beyond which they just don't work at all well.

Thanks for all the info on the tank drive!  I was aware of that style (central motor with universal joints) but never heard that term. 

It would seem to me, that with the way it's implemented in the 3rd Rail models, the drive shaft would need to be able to lengthen when going around turns since the pivot point is further forward.  Do they use a slip yoke of some sort?

The Athearn HO models I had in my youth used a similar design, but the driveshafts went to a worm gear with a universal joint above the pivot point.

Bob knows a lot more about O scale locos than I do.  But I have a 2nd generation Weaver GP38 that has U-joints.  Strictly speaking it's not a tank drive, because the high-low transfer tower is mounted on one of the trucks.  But it does have an underfloor drive shaft that runs the length of the body through the fuel tank, with two intermediate U-joints.  It's a 3-rail unit.  I've operated it through un-eased "O42" (21" radius) circular curves with no issues.  The driveline angles get pretty extreme, but it works without hesitation or binding.

The U-joints used by Weaver / P&D have a telescoping yoke.  I like this design better than the slotted hollow tubes originally used by All-Nation, etc.  Without some kind of telescoping shaft and a provision to retain the horned ball / swivel, I can definitely see the ball sliding out of the cup on a sharp curve.  [Now let the debate begin about whether the slots on opposite ends of the tube should be in the same plane, or offset 90 degrees!  ]

Sunset 3rd Rail has recently offered F3s and GP7s which are a central tank drive with U-joints.  The 3-rail versions are rated to negotiate un-eased O54 (27" radius) curves.  With a telescoping shaft or sliding yoke the geometry can be made to work.  But I would agree that a truck-mounted system is probably a better choice for very sharp curves.

Last edited by Ted S

The 3rd Rail drive system does operate on 054 minimum curves in 3 rail O scale and is more of a function of the swing of the coupler with a fixed pilot versus the tank drive.  There are a lot of universals that allow for this accommodation.  The 2 rail versions are 54" radius recommended but the F units have negotiated 48" radius without issues.  The FL9, FT, FP7, F7 models are all able to take the 054 curves barely.  The longer models don't do quite as well.

There is no doubt that these are never going to be O42 or O36 models.  That is where the vertical truck motors make the most sense.

My GGD F7s, FP7s with single motor drive will go around 48 inch radius with no problem.    Even my E7s will do this.    I just got a pair of Alco PAs and it looks like they will too.    I set them on the curve and there was still play in the trucks.   I don't have them programmed to run yet.

You guys have a different definition of tank drive.  The reason it is called "tank drive" is because the drive shafts come out of the fuel tank area, straight in to the closest gearbox.

The smaller wheelbase locomotives use a higher drive shaft connecting to a tower.  U joint angles are much, much lower.  Same with the shaft that goes all the way from one truck to the other  - much, much lower U joint angles.

With a good size motor, a tank drive on an F7 just won't work except on straight track.

The original Weaver RS3s had a sprocket tower in the tank with shafts out to both trucks.     The motor was in the hood.    It would go around 24 inch radius although the pilot over hang was so much it could not pull anything.      It could work with 40 ft cars on 36 inch radius.     

While the motor was on in the tank, the drive train was.

And by the way E7s are not particularly small locos.    

Yes- it will work on the E7.  I doubt seriously that it would work on the SD7.  The central drop-down gives you slightly more room, since the drive shafts can be longer.  The original CLW tank drives were only on the very long SD40 series, and even then they were not great.  The longer the wheelbase, the more the truck swivels.

Any of these systems require high quality U joints.  Don’t get me started on early Overland.

bob2 posted:

Yes- it will work on the E7.  I doubt seriously that it would work on the SD7.  The central drop-down gives you slightly more room, since the drive shafts can be longer.  The original CLW tank drives were only on the very long SD40 series, and even then they were not great.  The longer the wheelbase, the more the truck swivels.

Any of these systems require high quality U joints.  Don’t get me started on early Overland.

Works fine on Sunsets SD7s.  It is more visible in the single tank vs dual fuels tanks but was designed and tested for it's minimum rated radius.

I just ordered a couple 2-rail Chessie SD40-2 from Sunset.  These are my very first true 2-rail engines.  I hope they get enough orders.  I've got time though, I'm planning to tear down the Black Diamond Railway and rebuild a new 2-rail layout with one 3-rail upper level.   I'm working on the layout design now.  

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