Sunset 3rd Rail Tank Drive System

not any more visible than any other tank drive out there... they are however very smooth and reliable

Hi Santiago,

Thank you kindly for your reply.

Are you able to take a close up photo of where the drive shaft is?

Do you know if the motor has flywheels fitted?

Do these locos have smooth low speed capability for switching?

My layout will only be a very small short line railroad with slow track speed and lots of switching so I need very smooth low end speed. As good as the Atlas SW8/9 or MP15DC if possible.

Thanks once again.

Daryl

emdalco01 posted:

Hi Santiago,

Thank you kindly for your reply.

Are you able to take a close up photo of where the drive shaft is?

Do you know if the motor has flywheels fitted?

Do these locos have smooth low speed capability for switching?

My layout will only be a very small short line railroad with slow track speed and lots of switching so I need very smooth low end speed. As good as the Atlas SW8/9 or MP15DC if possible.

Thanks once again.

Daryl

Yes to the flywheel

Yes to the switching capabilities. They sure are comparable to Atlas SWs. They just need some breaking in. 

Sunset SD7/9 model. 

I have some E7s and F units and they run real smooth and slow.   They are a little tight as delivered and need some breaking in.

this is a very nice drive system aimed at scale speeds and operations as compared to the "china block" 2 motor drives which in my experience run like slot cars and have jerky starts and stops.    the 2 motor truck mount drives have the advantage of being able to handle much tighter curves in most cases depending on the truck detail.    I think the speed disadvantage has two causes:    First they importers/builders use very cheap motors which have very weak low end torque so they have to run at higher speeds to get any power.    Second the gearing is set up for higher speeds because the importers/builders think that is what the 3 rail market wants.      A 3rd negative on them is that to accomodate the gearing on one side, the truck side frames tend to be set way too wide on the trucks.    Visually the truck sideframes should be tucked pretty far under frame, not parallel to it.

I never noticed them unless you are looking really hard to see them... yes mine were 3 rail but still... and as Santiago says, very smooth, reliable, and quiet. Excellent slow speed operation

My major complaint with the 3rd rail trucks are the pickup rollers, I've had more problems with those than either Lionel or MTH stuff.

Fortunately, that isn't a problem for a 2-rail model.

catnap posted:

Fortunately, that isn't a problem for a 2-rail model.

I refer to the pictures above, all are 3-rail.

2-rail has all it's own issues.

John, What issues with 2-rail?

Jay

I have no issues with the 2 rail versions.

gunrunnerjohn posted:

catnap posted:

Fortunately, that isn't a problem for a 2-rail model.

I refer to the pictures above, all are 3-rail.

2-rail has all it's own issues.

John,    You're one of the nicer and more knowledgeable folks on these forums so I'm not calling you out, just exposing a "trap". The original post is located in the 2 rail forum, so I'll presume the intent was to discuss the 2 rail version. People sometimes come into these posts from the "blurbs" on the "sidebar" which DON'T give the forum name, and we end up with a mix of 2 railers and 3 railers posting. Not necessarily anything wrong with that, but sometimes things clash because the 2 formats are just different . I always try and look at the top to see what subforum I'm in to assure I am not posting about the wrong subject.

Regards,

Simon

I have a few of these diesels, and I think if you were at eye level with the trucks,  you might see the shaft or universal.    But from any other angle you won't see them.

On China block drives, you most often see trucks that are too wide looking from the front and back.    

So most models have compromises.

prrjim posted:

  A 3rd negative on them is that to accomodate the gearing on one side, the truck side frames tend to be set way too wide on the trucks.    Visually the truck sideframes should be tucked pretty far under frame, not parallel to it.

 

That is a function of scale rather than motor arrangement. Simply put, 1/4 inch scale on a track gauge of 1 1/4 inches works out to a scale 5 feet. That is OK for countries such as Russia (4 ft 11 ²⁷⁄32 in) but in the US the track gauge is 4 ft 8 1/2 in. It is clear from all the photos posted of the 3rd rail SD9's that the trucks are still way too wide for the frame of the locomotive. If that is really a concern then I think there would be strong demand for the models to be built to 17/64 inch scale in which the model track gauge moves to prototypical correctness. 

I completely agree with that.  But don't forget - pizza cutter wheels are considerably wider, so sideframes are correspondingly further out.  They usually stay that way for the 2-rail versions.  Easy to fix, usually.

I say this as a dedicated wide wheel 17/64ther - the only perfect cure for sideframe appearance is Proto-48.  I won't go there; my track laying skills are not up to the task.

I have built a layout with 500 feet of handlaid track when I lived in Ohio.    I am not up to doing it again.    I also built all my cars from kits back then because in both cases that was all there was available.     Now we have a lot more rtr and can build model RRs like our smaller scale compatriots instead of test loops.

Another cause of the wide trucks are the gears on one side of the truck gearbox casting.    

I have found with the narrower 2 rail wheels on some such as the older MTH GP30s, you can move the side frames in closer to the truck frame and get a better look on the model.    

prrjim posted:

 

So most models have compromises.

This is probably the most correct statement yet. Don't let anyone kid you, all of our toys, regardless if we run on 2 rails, 3 rails or no rails, have compromises.

Now, the big problem is see on this and other forums, is that so many people (not all) have a problem when someone else has a different set of "compromises" from their own. This thread is a perfect example.

The OP's question of seeing the shaft on a 3rd Rail Tank drive has basically been answered, he will now have to make a decision as to what compromise he is willing to accept... or simply not to purchase anything.

Charlie

The truck sideframes on diesels offered in 2- and 3-rail versions protrude sideways too far because the 3-rail wheel width is so big.  It would be better if, as with their 2-rail freight car trucks, at least Atlas would have an alternative mounting arrangement for 2-rail diesel sideframes.

I have a couple of Lionel diesels (CN Dash-8 and U30C) on which I've mounted dummy 2-rail wheels.  At some time in the distant future I expect I'll be unable to resist drilling holes and trimming tabs to get the frames and brake-shoes to line up better with the thin wheel treads.  If I get used to the annoying 3-rail way of mounting long-hood handrails so that rough handling by 5(?)-year olds doesn't demand them, I'll see if I can get the gears back on my dummy axles or admit defeat and get the box of Central and Weaver gearbox odds and ends out.

Jason

The sideframes are set wide on China drives (and even on the vaunted Atlas SW) because these drives have inboard axle bearings.  The sideframes are purely decorative, and you wouldn't want them contacting the wheel face under any circumstances.  Especially on 2-rail models, I've observed that there's ample space to tuck them in.

For Weaver, 3rd Rail, CLW, and most tank drives, the side frames are a functional part of the truck, and their lateral spacing is a function of both the wheel gauge and the tread width.  For prototypical appearance, Proto 48 is king in both respects.  BUT... the Ow5 "mistake" was made decades ago.  It might not be convenient to convert everything.  Realism is based on total perception.  How realistic are the other aspects of the loco, and your layout as a whole?  Something always ruins the illusion, the question is what are you personally willing to live with?

That's well said: "Realism is based on total perception." Just think of all the things we don't obsess about, like electric motors in steam engines, horizons made of sheetrock, and the fact that everything happens indoors, to name only a very few such things. 

Yes, it's all caricature. The goal is GOOD caricature whereby our suspension of disbelief is triggered allowing our minds to enter right into the scene.

I have less difficulty accepting the incorrect truck-frame width than I do the incorrect truck wheelbase of the MTH Blomberg truck.