Producing a new US style loco in TT scale

Re: Producing a new US style loco in TT scale

Postby areibel » Mon Mar 28, 2011 11:59 am

The Lok N Roll trucks are their own design, and they're right on for a Bloomberg (9' wheelbase). I haven't contacted them to see if they'd sell them as a separate item, I don't know if he's geared up enough to do a run other than for what he needs.
It would be nice, there may be more models using the 9'4" AAR truck, but in sheer numbers of locomotives the EMDs win hands down. If you count all the locomotives that used the Bloomberg in it's different flavors there are something like 24 thousand different locomotives produced (GP's and F's), vs. about 8300 using the AAR (all manufacturers). Don't get me wrong, I'd love to have both. I think a clever individual would be able to produce one truck that could be easily modified to work for either wheelbase, imagine a removable bearing block on one axle that could be taken out and flipped. The axle slot in the block would be offset enough to give a 9' wheelbase one way, 9'4" the other. It would take a little engineering, I doubt you'd be able to use the same gear train in it but all it would take would be a movable pin in the case to change the location of the last gear. It would only mean two sets of aligned holes in the gear case to choose the location.

But there's the rub. None of the technology we're using right now will let us build anything like that. Shapeways or any RP can do so much, but their tolerances aren't close enough to do anything that precise (down to .001 accuracy or better), and to get a smooth running quiet drive that's what it'll take. They need to be injection molded or die cast, and that's not in the budget yet.

Bull Ants are a possibility, but they're custom made- expensive and slow. Mass production of any US specific trucks will have to wait until there's enough demand.

That's why for now we have to look at all the options. Take the Piko Herculese truck. The wheelbase is a scale 103.9", the wheels are huge but they're on a 2mm axle and I've replaced them with NWSL wheels- they look good. OK, We're still a scale 4 inches off, but Athearn sold THOUSANDS of HO scale models with a hood that was a scale foot too wide! And check some of your older HO models, you'll be real surprised if you check things like wheelbase, truck centers, etc.. The recent drive for 100% prototype accuracy has only been something of the last 10 years or so, and HO had a lot more time to get it right!

Few people have taken the bull by the horns and done something in TT, too many just sit back and say "We need...". It used to be there was one person that kept things creeping forward at a snail's pace- Jim O'Brien and Elmer McKay for example. They started in the late 80's (in Jim's case) and started building. Was it the same as HO? No, but it was better that what was out there. Trucks, resin kits, even the first NMRA style standards gauge for TT. I see hope for TT now because it's no longer a one man band. Alex has put a lot of time (and $$) into producing TT, there are several others on this board with their own projects cooking too. Some are moving faster than others, butno one is making a living off of TT, and I doubt anyone here will. And the guys at LokNRoll and Art and Detail (and others) in Europe are bringing out more US TT too. This is a growth process. The guys that started the Society were accused of trying to push HO or N out of their place. Nope. We'll never overtake either as a percentage of market, period. We wanted to get something out there that anyone considering TT would look at and think about. When we finally get the GP38-2 done (and it's close), I'm hoping Lok N Roll will do a chassis for it (and they're very interested!). That will be the closest to a RTR diesel locomotive TT has seen in 50 years. Need a U Boat? almost got that covered too, along with a better GP7/9, a GP35 and maybe even an Alco C series. There will soon be a resin FA/FB back, The brass Kemtrons are scarce enough now to be collector's items (PSC supposedly got all of the original Kemtron masters for all their TT parts, but several inquiries and offers to buy them over the last 20 years or so haven't gotten them to bother looking for them)
Brass is an idea, but at what price? Check out the prices on new N and HO brass diesels, I'd bet we'd be looking at $500 easily for a TT locomotive, and probably more if it was a limited run of some sort.
For that I might buy one, but how many could be sold? It might give us a source as a potential for new drives. Overland did a series of replacement chassis for different HO locomotives years ago. Maybe that would be an option too, sell a limited run of diesels and hope they would produce the chassis as a separate piece after the run sold out? I don't know enough about brass to say.
None of this is easy, there aren't any quick answers. For now we just have to keep promoting what we have available and hope we can find more interested modelers. S scale had a similar problem, but it wasn't exactly the same. There were enough Flyer guys still operating along with the scale guys, and that's what's not present in TT. When American Models or S Helper came out with something they offered the option to run on either style of layout, and that helped their numbers. TT is just TT, and like I've said before it's not for sissies!
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Re: Producing a new US style loco in TT scale

Postby ConducTTor » Mon Mar 28, 2011 12:54 pm

railtwister wrote:Is the driveshaft coming out of the worm's knuckle caused by running the loco on too sharp of a curve?


Yes and no - the angle between knuckle and shaft is too sharp to begin with so even when going straight there is a noise where the shaft actually rubs against the knuckle. It's just worse on turns.

railtwister wrote:I'm not familiar with Tillig/LNR trucks.


I on the other hand am not familiar with Kato/Atlas trucks :smile:

The Tillig/LNR are two plastic halves sandwiching the gears with copper strips mounted on the outside for current collection.
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Re: Producing a new US style loco in TT scale

Postby ConducTTor » Mon Mar 28, 2011 1:03 pm

As far as trucks and chassis go, sourcing from existing models (European) is simply not an option. Period. If anything is going to be made in any substantial numbers (read: more than 1) the manufacturers are useless because they don't want their parts in others' models. Having to buy an already existing model just to use for parts is not a proposition I like - if someone wants to do a run of 20 locomotives, they have to first buy 20 locomotives?

The U boat will be a huge jump forward for me as far as being able to offer other models. Once the kinks are worked out, variations of trucks / chassis should be very easy to make for use in other models.
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Re: Producing a new US style loco in TT scale

Postby railtwister » Mon Mar 28, 2011 1:30 pm

ConducTTor wrote:
railtwister wrote:Is the driveshaft coming out of the worm's knuckle caused by running the loco on too sharp of a curve?


Yes and no - the angle between knuckle and shaft is too sharp to begin with so even when going straight there is a noise where the shaft actually rubs against the knuckle. It's just worse on turns.

railtwister wrote:I'm not familiar with Tillig/LNR trucks.


I on the other hand am not familiar with Kato/Atlas trucks :smile:

The Tillig/LNR are two plastic halves sandwiching the gears with copper strips mounted on the outside for current collection.


Hi Alex,
concerning the driveshaft angle problem, are you talking about the LNR F-unit chassis or their Geep chassis? From the photos they look to be quite different, the F-unit motor is mounted below the floor between the trucks, where the prototype fuel tank would be, while the Geep looks to be more like the typical N scale split-frame design, with the motor presumably mounted higher and within the two frame halves.

I have looked at the Bowser webpage for their HO trolley drives, and while the wheelbase/wheel diameter dimensions look to be within reasonable range, the snap cover that holds the worm shaft in place at the top of the gearbox looks like it is wide enough to prevent the truck from pivoting in a curve on any kind of hood unit (Geep) carbody. It may work for cab units like the F's or possibly even a BL2, but even then it may restrict the operation on curves to very wide radii. It is hard to tell for sure without actually having one in hand...

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Re: Producing a new US style loco in TT scale

Postby ConducTTor » Mon Mar 28, 2011 2:35 pm

railtwister wrote:are you talking about the LNR F-unit chassis or their Geep chassis? From the photos they look to be quite different, the F-unit motor is mounted below the floor between the trucks, where the prototype fuel tank would be, while the Geep looks to be more like the typical N scale split-frame design, with the motor presumably mounted higher and within the two frame halves.


It's the Geep chassis and your assumption is spot on - thew motor sits high in the chassis. If they moved it down just a few mm it would likely solve the problem.

railtwister wrote:the snap cover that holds the worm shaft in place at the top of the gearbox looks like it is wide enough to prevent the truck from pivoting in a curve on any kind of hood unit (Geep) carbody. It may work for cab units like the F's or possibly even a BL2, but even then it may restrict the operation on curves to very wide radii. It is hard to tell for sure without actually having one in hand...

Bill


The above problems with various off the shelf parts are why I'm doing everything from scratch. I'm designing everything to fit within a hood unit. It's super tight and the tolerances are within tenths of a millimeter in some places but so far things are working out.
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Re: Producing a new US style loco in TT scale

Postby ctxmf74 » Mon Mar 28, 2011 5:39 pm

ConducTTor wrote: The above problems with various off the shelf parts are why I'm doing everything from scratch. I'm designing everything to fit within a hood unit. It's super tight and the tolerances are within tenths of a millimeter in some places but so far things are working out.


That's why the old athearn GP7 had such a wide hood :>)
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Re: Producing a new US style loco in TT scale

Postby scaro » Mon Mar 28, 2011 7:38 pm

railtwister wrote:I have looked at the Bowser webpage for their HO trolley drives, and while the wheelbase/wheel diameter dimensions look to be within reasonable range, the snap cover that holds the worm shaft in place at the top of the gearbox looks like it is wide enough to prevent the truck from pivoting in a curve on any kind of hood unit (Geep) carbody. It may work for cab units like the F's or possibly even a BL2, but even then it may restrict the operation on curves to very wide radii. It is hard to tell for sure without actually having one in hand...

Bill



thanks bill. you saved me the cost of ordering one to find out ... if that is the case then it would require a lot of modifications. the length we are looking for is 22.86mm exactly.

alex mentioned the economics of buying 20 RTR locos to make 20 TT locos, and this not being the most favourable equation. quite so ... but the aussie N manufacturers buy quantities of N mechs from atlas for their projects ... so not all manufacturers are averse to the idea of their stuff being employed. i've occasionally been a fan of the idea of using N mechs with lengthened axles and larger dia wheels for TT, as the 'guts' of the thing, ie gears and what not, are 'sorted' and quite probably reliable. however you need something with a 12' wheelbase in N to give you a 9' wb in TT and the only thing i can think of are the N scale versions of the former east german units such as the 'ludmilas'. even then you do need to alter the trucks, and get longer wheelbase wheels milled. i can't think that a manufacturer would be happy on-selling to someone who was planning to make those kinds of adjustments.
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Re: Producing a new US style loco in TT scale

Postby railtwister » Mon Mar 28, 2011 8:34 pm

Bowser has a PDF drawing of the trolley truck on their website which I will try to attach to this message. The cutout for the truck to pivot is just under 1.5" long by just under 3/4" wide. My thoughts as to this truck not fitting into a TT scale hood unit are based on this drawing. Since a cab unit in TT would be about an inch wide (slightly over 10 scale feet), the thickness of the shell may determine the turning radius of a loco using this drive. I know that an HO trolley can be expected to go around a pretty sharp curve, so it probably would be OK for a TT loco, which should have slightly shorter truck centers. Another question that remains unanswered is the vertical clearance required to clear the gear tower, and whether or not it will fit into a TT gauge body shell sitting at the proper height from the rails.

Look at the file and draw your own conclusions, and please don't make your decision either way based solely on anything I have said, because I have never seen this item "in the flesh". I'm still debating whether or not to spend the $$ for an HO trolley to satisfy my curiosity about this drive's suitability for TT. At least then if it's not suitable it will be a complete unit that I could sell to recoup some of it's cost...

Regards,
Bill


Trolley Mechanism Drawing.jpg
Bowser's HO Trolley Power Unit
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Re: Producing a new US style loco in TT scale

Postby Carsten » Tue Mar 29, 2011 1:23 am

areibel wrote:The Lok N Roll trucks are their own design,


They aren't their design. These are H0m tram trucks. I believe they are from Halling.
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Re: Producing a new US style loco in TT scale

Postby scaro » Tue Mar 29, 2011 7:19 am

railtwister wrote:Bowser has a PDF drawing of the trolley truck on their website which I will try to attach to this message. The cutout for the truck to pivot is just under 1.5" long by just under 3/4" wide. My thoughts as to this truck not fitting into a TT scale hood unit are based on this drawing. Since a cab unit in TT would be about an inch wide (slightly over 10 scale feet), the thickness of the shell may determine the turning radius of a loco using this drive. I know that an HO trolley can be expected to go around a pretty sharp curve, so it probably would be OK for a TT loco, which should have slightly shorter truck centers. Another question that remains unanswered is the vertical clearance required to clear the gear tower, and whether or not it will fit into a TT gauge body shell sitting at the proper height from the rails.

Look at the file and draw your own conclusions, and please don't make your decision either way based solely on anything I have said, because I have never seen this item "in the flesh". I'm still debating whether or not to spend the $$ for an HO trolley to satisfy my curiosity about this drive's suitability for TT. At least then if it's not suitable it will be a complete unit that I could sell to recoup some of it's cost...

Regards,
Bill


Trolley Mechanism Drawing.jpg



Hi Bill , I was thinking of its use in hood units, and for that at least, it appears to be ruled out. I can’t see how one could easily reduce the width of the truck frame without similarly reducing the gear tower. I am sure it could be done, with difficulty though ... which may negate the point in going down that path in the first place. And it does not come cheap. If I ever see one secondhand I'll buy it and pull it to bits.

Reading what Al says above, I take the point that what is needed is a Blomberg truck that can be used in GPs and Fs, and the Bowser appears not to be that ‘drop in’ solution. I also thought that when they called it a ‘power truck’ that they meant that the motor was actually an integral part of the truck. That appears not to be so.

This and the truck or mech for an SW are the ‘bare bones’ things needed for a ‘bog standard’ EMD-using American railroad, for not only for lots of the biggies, but even small roads like GA/WPR, C&EI, FEC, B&M or BAR who had SWs and F units, then graduated to GP7s and or 9s, and then to GP38s or GP40s. Such a prototype only needs these two trucks. In some cases, ie, C&O, MEC, SAL/ACL/SCL and WP, the Blomberg even turned up under their U-boats.

http://www.rr-fallenflags.org/acl/acl0977pma.jpg

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