Aftermarket & Scratch Trucks

[Steve_GScale]

Research says that I need to model the following trucks:

• 4-TC-6
• 4-TC-7
• 4-TCA-3
• 6-TCA-1

Pointers/links to modeling any of the above appreciated!

I’ve discovered that Southern Pacific, Vol. 1: Daylight, Train 98-99 by Richard K. Wright has a full chapter on the Daylight trucks: Trucks, Chapter 14, pages 549-569.

• 4-TC-6: pages 556-557
• 4-TC-7: pages 558-559
• 4-TCA-3: pages 556-567
• 6-TCA-1: pages 568-569

The Official Pullman-Standard Library, Vol. 5 Southern Pacific Prewar Cars,
Truck Detail, pages 197 - 199
has a few pictures.

The Official Pullman-Standard Library, Vol. 6 Southern Pacific Postwar Cars,
Mechanical Details - Trucks, pages 186 - 198
has several dozen pictures with annotations.

[ctown2 (Craig Townsend)]

Got with #1. They look much better and will force you to have good trackwork.

[manimal (Dan Gilchrist)]

I model in 1:29 and originally planned to use Kadee #1’s but have now standardized on Kadee “G” scale and AML 1:29 couplers to be more reliable and compatible with club stock. However, If I were running 1:32 as you are, I’d go with #1 for sure.

[Steve_GScale]

On the #1 vs. G, I really WANT to go #1, but its a big investment to outfit all those cars… G would be so much safer.

Question of the day:
I’m trying to decide if those 2 rounded contact blocks on the bottom of the car bolster could be moved to the top of the truck bolster.

First for reference:

The current car bolster:

Those 2 blocks are aligned with the direction of the car body, when the body pitches on straight track the wheels rock on the same line:

But when in a sharp turn the wheel set pitches across its diagonal:

(the ruler is more or less parallel to the car body)

If the 2 contact points were on the truck bolster the pitch would align with the wheel set:

I believe this would be at least marginally better. I think I’ve convinced myself that its not a big issue either way. I have a design in mind that would be better it the 2 blocks were moved to the truck bolster. Does anyone see a valid reason this shouldn’t be done?

[David_Marconi_FOGCH (David Marconi CHHN)]

Personally Steve whether the contact point is on the truck or body bolster won’t abate your tilt issue, unless the contact points remain in contact equally with their respective opposing surfaces.
You don’t mention whether or not the body bolster and truck bolster have the same surface size or if one is bigger than the other.
If one of the two bolster surfaces is not large enough to remain in contact with the surface of it’s mate you’ll lose the needed support.
Above is working from the provided pics and not being able to compare the
That said I would look at a ring or circle support, i.e. extend the current supports into a full ring. Or add a plate to the truck bolster to maintain full contact with the contact points.
Above is working from the provided pics and not being able to compare the parts in question. YMMV JMHO

[Steve_GScale]

@David_Marconi_FOGCH

You don’t mention whether or not the body bolster and truck bolster have the same surface size or if one is bigger than the other.
If one of the two bolster surfaces is not large enough to remain in contact with the surface of it’s mate you’ll lose the needed support.

The truck bolster is wide enough to remain in contact at all times:

Note the wear marks above.

As I am designing and printing both the car and truck bolster I can make them however I want,
I’m just trying to decide exactly what that is

[Steve_GScale]

Here’s my current proposal for the car bolster:

The pad and the stud would be Teflon. As you can’t glue Teflon, there would be a counter-sunk head 1/8" bolt running thru the stud and providing an attachment point for the washer that holds the truck on the car. Then I would place a pair of contact blocks on the truck bolster, providing full circular contact.

[PeterT]

@Steve_GScale

Does anyone see a valid reason this shouldn’t be done?

No, but . .

First thought is that it looks as if you are setting them up for R1 curves. Those coaches won’t do R1, and probably look terrible on R3. I would suggest doing the research on how far the trucks turn on your normal curved track.

Second point is that the trucks should not be rigid and therefore even if on a turn/curve, the diagonal tilt will be offset by the wheels being able to lift/drop a fraction. Both axles should be able to pitch in opposite directions - usually the sideframes have a tiny bit of free play to allow this, or the springs actually work when bearing the weight of the coach. (Easy test - put a small screwdriver on one rail and push one truck wheel on to it. Check that all the other 3 wheels are still firmly on the track.)

If the trucks track properly, then I wouldn’t see the need for moving the contact blocks.

[Steve_GScale]

@PeterT

First thought is that it looks as if you are setting them up for R1 curves. Those coaches won’t do R1, and probably look terrible on R3.

Not sure where R1 came from … These are #1 scale on R5 track, probably with #1 couplers…
The only place R3 is used is freight yards/ spurs, etc. Then they will be running dead slow.

@PeterT

If the trucks track properly, then I wouldn’t see the need for moving the contact blocks.

My reasoning is that I can design the pad into the car bolster more effectively than the truck bolster.
To put the Teflon pad on the car I need to move the blocks to the truck.

[Steve_GScale]

@PeterT

Second point is that the trucks should not be rigid and therefore even if on a turn/curve, the diagonal tilt will be offset by the wheels being able to lift/drop a fraction. Both axles should be able to pitch in opposite directions - usually the side frames have a tiny bit of free play to allow this, or the springs actually work when bearing the weight of the coach. (Easy test - put a small screwdriver on one rail and push one truck wheel on to it. Check that all the other 3 wheels are still firmly on the track.)

I did this test, the stock MTH trucks do have sprung “bearing blocks”. Placing the screwdriver under the left front wheel lifted it (and compressed the 2 springs over the bearing block) without lifting the other 3 wheels:

I have to admit this surprised me as I thought those springs were way too “hard” to actually compress from the weight of the car.

@PeterT

If the trucks track properly, then I wouldn’t see the need for moving the contact blocks.

Perhaps I should restate the goal in other words:
I would move the blocks from car bolster to truck bolster, and create a slide pad on the car bolster instead of the truck bolster. In essence just flip the functions from one to the other. All hole clearances, post length, block spacing, etc. would remain the same.

[PeterT]

@Steve_GScale

Not sure where R1 came from …

Steve, my point is that you haven’t investigated exactly how much the trucks have to swivel on your curves. On the photos off the track you have them turned a lot - much more than they would turn on R5 curves.

[Steve_GScale]

@PeterT

Steve, my point is that you haven’t investigated exactly how much the trucks have to swivel on your curves. On the photos off the track you have them turned a lot - much more than they would turn on R5 curves.

Understood.

When exploring an idea, especially one I have zero knowledge of, I will often test the “extremes”. Then I back off as it becomes apparent what is possible and what isn’t.

It would seem to be something that becomes most stressed if both changing elevation and direction at the same time. Fortunately I have surveyed out the whole site, Cheyenne / Ogden / Sacramento / San Jose / SF & LA at 0% elevation. I might someday want to add a line to Seattle, which would have to have 1% - 2% elevation, so I want to at least think about that.

I think the next step is to actually print a sample, attach them to a flat 3.5" x 27" panel and then pull them thru both an R3 and R5 curve.

===
What do people use for springs? The ones in the MTH trucks are too stiff, even if I could identify and acquire them.

[PeterT]

@Steve_GScale

What do people use for springs?

Soft plastic, in Bachmann’s case.

If you visit a decent hardware store, you’ll probably find a box of springs in all sizes and stiffness in the nuts-and-bolts section. That’s where we found replacements for the Aristo truck springs.

[freddy (Fred Mills)]

There is a very simple solution for what I think I’m reading.
For example; on the Aristocraft “Body Bolster”, there is the centre pin, and on both sides of it are, what are called “Bolster bearings” On the prototype they are usually closer to the ends of the bolsters. On our models they are not sprung, and are useful for keeping our cars from rocking while in motion, as long as the screws holding the trucks to the body bolsters are not too loose.
If both of the bolsters have these bearings, and both screws are rather tight, then cars will not run on less than smooth track, without derailing.
The idea goes along with the three legged stool, which will always sit squarely on an un-even floor…so…
If you remove the “Bolster bearings” on one end of the car, and leave the mounting screw on that end slightly loose, your car will negotiate irregular trackage much better…greater flexibility.
The prototype bolster bearings usually have small rollers in them, which roll on plates on the outer ends of the truck bolsters.
In our models the truck springs are usually much too firm to give much flexibility/equalization, and if they did, it would usually disturb the very close coupler heights needed for trouble free operations. We also usually find that most of our freight trucks have short enough wheel spans that they don’t require equalization on anything close to being impassable in our track work…passenger trucks may be more fussy…and your track work is in desperate need of attention.
Others may disagree, and seek more complicated solutions…go to it, and have fun.

[Steve_GScale]

Just posing some thoughts…

@freddy

on the Aristocraft “Body Bolster”, there is the centre pin, and on both sides of it are, what are called “Bolster bearings” On the prototype they are usually closer to the ends of the bolsters. On our models they are not sprung, and are useful for keeping our cars from rocking while in motion, as long as the screws holding the trucks to the body bolsters are not too loose.

In post 24 I show a photo of the MTH body bolster, I believe this is what your are describing?

@freddy

In our models the truck springs are usually much too firm to give much flexibility/equalization, and if they did, it would usually disturb the very close coupler heights needed for trouble free operations.

If you look at post 30 of this thread you see one of the MTH passenger car trucks with a screwdriver under the left front wheel. Although the springs seem much too stiff to me, that wheel lifts without any of the other wheels lifting, so it would appear MTH did it more or less correctly.