swapping trucks around between atlas and kato chassis

[u18b]

They will, but he needs the outside axls driven and the RSD 4/5 China trucks aren't. I presume he is going to make a 2 axle truck in TT scale.

Hmmm.  OK.  I guess I missed it.

I guess a better question might have been...

I need an N scale truck such that when I'm finished it will be 2 axles xxxx TT scale feet apart which comes out to xxxx  N scale feet.

Is that what he's wanting?

[johnh35]

Hmmm.  OK.  I guess I missed it.

I guess a better question might have been...

I need an N scale truck such that when I'm finished it will be 2 axles xxxx TT scale feet apart which comes out to xxxx  N scale feet.

Is that what he's wanting?

I am basing it on this comment he made:

"converting to a B- truck by removing the centre axle, would, if this is true, mean only one axle per truck is powered, which doesn't sound great." 

[scaro]

After checking some of my engines, the 628 truck will not work in the RS1 or the SD40. However, the SD40 truck is only 6 scale inches bigger than the AAR B truck to start with (from data I have read), so that would be even less in TT. If you are taking out the center axle, will that much difference be worth the grief? If you need the AAR B truck, cutting down a C628 would see to be the solution.

Another thought is the Trainmaster. It is almost spot on for the outer axle spacing and maybe the mechanism is close to what you can work with? Just some ideas

well, that kind of sinks it, i think. 

i am not really grasping what you're saying about the AAR B truck.  in 1:1, it's 9'4" wb , SD40 truck is 13'7". 

i probably should attempt to explain my calculations.  the N scale alco trimount truck is a scale 12'6" in N and that is 23.75mm wheelbase, which is 9'4" in TT.  ie, exactly right for an AAR B truck.   An SD40 truck, 25.8mm, would be about 10'2" in TT.  I think that's a bit much.

in TT, as it is, the N atlas C628/C630 (assuming it has the correct wheelbase) equates to a 31' wheelbase between truck 'midpoints', ie, ignoring the centre axle, which isn't relevant since it's going to be removed anyway.  that would be useful for things like an RS1 or RS11 in TT.

i was interested though in whether the truck midpoints could be pulled in a fraction, by putting these trucks into an SD40 / SD45 chassis, which is a touch shorter than the C628. that would take it to 30' between truck midpoints, ie correct spacing for an RS3.   i was hunting round for a bit of serendipity; TT, is bereft of chassis (and most things), and N has some damn fine ones. 

given it's not really possible to put the C628/C630 trucks into the easily lengthened RS1 it sounds as if I'm limited to adjusting the C628/C630 chassis.  I'm not sure it is an easy one to adjust. one thing i wonder is whether the C628 chassis is low enough to be shoehorned under a TT scale RS1 shell.  how many mm high is the C628 chassis block itself?

thanks for the advice so far.  knew i'd come to the right place.

[johnh35]

well, that kind of sinks it, i think. 

i am not really grasping what you're saying about the AAR B truck.  in 1:1, it's 9'4" wb , SD40 truck is 13'7". 

i probably should attempt to explain my calculations.  the N scale alco trimount truck is a scale 12'6" in N and that is 23.75mm wheelbase, which is 9'4" in TT.  ie, exactly right for an AAR B truck.   An SD40 truck, 25.8mm, would be about 10'2" in TT.  I think that's a bit much.

in TT, as it is, the N atlas C628/C630 (assuming it has the correct wheelbase) equates to a 31' wheelbase between truck 'midpoints', ie, ignoring the centre axle, which isn't relevant since it's going to be removed anyway.  that would be useful for things like an RS1 or RS11 in TT.

i was interested though in whether the truck midpoints could be pulled in a fraction, by putting these trucks into an SD40 / SD45 chassis, which is a touch shorter than the C628. that would take it to 30' between truck midpoints, ie correct spacing for an RS3.   i was hunting round for a bit of serendipity; TT, is bereft of chassis (and most things), and N has some damn fine ones. 

given it's not really possible to put the C628/C630 trucks into the easily lengthened RS1 it sounds as if I'm limited to adjusting the C628/C630 chassis.  I'm not sure it is an easy one to adjust. one thing i wonder is whether the C628 chassis is low enough to be shoehorned under a TT scale RS1 shell.  how many mm high is the C628 chassis block itself?

thanks for the advice so far.  knew i'd come to the right place.

My bad. I did not mean AAR B. It should have said tri-mount.

[johnh35]

Ok, here is another thought. The FM Trainmaster truck will fit the SD40. It will also fit the SD7/9 (Kato pr Atlas). It is right between the Flexicoil and the trimount for length.

[scaro]

hi

i can't find a plan for a trainmaster that shows the truck wheelbase.  i seem to recall it's 13'.  is that right?

cheers, ben

[johnh35]

From what I can find, yes.

[AVR Mark]

I have just been doing a little research for you and while you need to know this you probably won't want to hear it. I can only check on those locomotives that I own, but on all the 3 axle Atlas and Kato trucks that I looked at the inner (third) axle is driven off the center axle. The first and second axles are both driven off the same gear. What this means is that if you remove the center axle the third axle is not powered. I checked this on C-630, H24-66, SD40, SD7, SD35, SD40-2 (first production) C44-9, and PA-1 trucks. I suspect that all the other Atlas and Kato 3 axle trucks will be the same.

Mark

[nkalanaga]

How about removing the WHEELS from the center axle, but leaving the axle and gears in place?  The new sideframes should cover those.

[johnh35]

How about removing the WHEELS from the center axle, but leaving the axle and gears in place?  The new sideframes should cover those.

My thoughts too, but as the axle ends center the gear in an oversize hole, it will need some modification to keep the gear centered once you remove the wheels. It would be a simple task.

[scaro]

yes, i knew i had to do leave some of the wheel in situ so the centre gear/axle muff stays centred. 

it might even be possible to leave the bulk of the centre wheel in place, frankly, it would be hidden behind the spring on a new TT sized AAR-B truck spaced wider for 12mm gauge. 

the new wheels will be 8.4mm diameter so as long as the old N scale centre wheels don't interfere with the track, there's not necessarily any reason to remove them.  i suppose one might just mill off the flange to ensure they don't connect with anything they shouldn't.

[nkalanaga]

Or make metal washers that press fit to the axle.  As long as they were larger than the hole they'd work, and they could be made much thinner than a wheel if you wanted to model springs or something in that area.

[scaro]

the gauge of the new truck would be 12mm so i doubt the existing wheel would take up too much room.  i'm hoping to get the wheels made in the next couple of weeks.

[randgust]

Wow, Ron, that's great stuff.  Completely different approach for the frame splice.    I've done some but not that way, and considered that frame just too difficult to do.

Hey, I've got an original Kato RSC2 frame if anybody wants it, no trucks, no motor.   Motor ended up in the Heisler and trucks ended up under the rotary plow, but if somebody wants it PM me or contact me via the randgust.com web page.

I'll confirm that the Kato RSC2 has 12-wheel drive and the Altlas has 4-wheel with 2 idler.  The Kato has evenly spaced wheels and the Atlas has the odd-spaced ones.   I tinkered with the Atlas to see if I could make it into a RSD15 chassis and ended up giving up and selling it, another story.

[johnh35]

Wow, Ron, that's great stuff.  Completely different approach for the frame splice.    I've done some but not that way, and considered that frame just too difficult to do.

Hey, I've got an original Kato RSC2 frame if anybody wants it, no trucks, no motor.   Motor ended up in the Heisler and trucks ended up under the rotary plow, but if somebody wants it PM me or contact me via the randgust.com web page.

I'll confirm that the Kato RSC2 has 12-wheel drive and the Altlas has 4-wheel with 2 idler.  The Kato has evenly spaced wheels and the Atlas has the odd-spaced ones.   I tinkered with the Atlas to see if I could make it into a RSD15 chassis and ended up giving up and selling it, another story.

Randy, I could use that frame if not already taken