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Truck & coupler tool idea Locos and rolling stock
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Prolific poster 3,069 posts DKRickman Prolific poster 3,069 posts
DKRickman

I have another weird idea.  If anybody likes it, I'd love to hear how it works.  I might even try it myself one of these days.

The way I see it, there has to be a definite relationship between the height of a body bolster and a coupler mounting pad.  If we imagine that there is one standard bolster height, and one standard coupler pad height (for a given scale/gauge, of course), then you could make a go/no-go gauge which touches both and would show whether one or the other was off.

Two problems with that assumption:

  1. Different trucks have different height bolsters
  2. Some cars have built-in coupler boxes, others need separate boxes.  Also, there are different coupler box heights, depending on the coupler style.

So here's what I'm thinking.  Start with a pair of rails which would run parallel to the center of the car.  On those rails would be two crossmembers (at least one of which should slide, to adjust for car length) with suitable posts and holes to mount in place of a car's trucks.  There would then be a third crossmember with a micrometer style threaded post in the center.  The end of the post should be bored so that it fits over a mounting pin for a Kadee #5 (assuming HO scale here, adjust to suit the scale), and small enough to fit inside a #5 box.  This would allow accurate measurement of the difference in height between the coupler box and bolster, and a reference chart showing different trucks and couplers would quickly show exactly how much modification would be needed for a proper fit, or which truck/coupler combination to use.

Alternately, if you find that the majority of your cars need the same coupler/bolster relationship (I do), then the micrometer could be replaced with a brass block with the same dimensions as your preferred coupler box, and drilled for the screw holes.  Simply mount the tool on the car, slide the coupler box gauge into place, add or remove material as needed for a close fit, and drill the holes.  You're guaranteed to get them centered and you know the couplers will be at the correct height.

What do you think, folks?  Would something like this be of any use to you?  I think it would come in handy, since I like to kitbash and upgrade older, cheap cars, and of course to build my own as well.  I have a hard time measuring the bolster and coupler height accurately.  What I usually end up doing is mounting the trucks and using a Kadee coupler height gauge to see where the coupler mounting pad should be.

Ken Rickman

Danville & Western HO modeler and web historian

http://southern-railway.railfan.net/dw/
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akarmani Regular poster 298 posts
akarmani

Sounds like an interesting idea

I am having a hard time visualizing how it compensates for different size trucks, but I like the concept.  Any diagrams or drawings?

Art  
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DKRickman Prolific poster 3,069 posts
DKRickman

No drawings yet

Quote:

Any diagrams or drawings?

Give me a few days, and I'll see what I can come up with.  I'm on vacation with my family, so I might have other things going on, but if I have some down time at the computer I'll try to doodle something up. 

Ken Rickman

Danville & Western HO modeler and web historian

http://southern-railway.railfan.net/dw/
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ctxmf74 Super User 15,952 posts
ctxmf74

"difference in height between the coupler box and bolster"

p651255b.jpg   I get this measurement by sitting the car on the trucks in question then sliding a gauge under the end to see what the mis-match is. If the car is too low the gauge bumps the end and I can either add shims to the truck/bolster interface or can grind off some of the car floor, if the car is too high I measure the gap and decide if I want to file some off the bolsters or shim the coupler mounting pad. The decision to grind or shim is based on how the car ride height looks compared to photos if available or to other cars if not. For example here's a gondola I was working on last night , when I rolled it up to the gauge there was a bit of space so I could either add a shim between the car floor and the coupler box or I could file some off the body bolster.since the car looked like it was riding too high I decided to file off the bolster till the car matched the gauge. ......DaveB

1990.jpg 
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Larry of Z'ville Frequent poster 984 posts
Larry of Z'ville

Different manufacturers trucks do make a difference

I like the concept. I find that there are design variations unique to the various manufactures assemblies. Thus when you use an Atlas truck on a Walthers car, the coupler pocket may not be at the same height. Of course the same can be said using the same companies trucks from different design times. I always struggle with should it be a 145 (#5), a 147 or what. The tables really talk to the average and not to you current problem. This could indicate the shim thickness to always use a 145. That would be beneficial. Larry

So many trains, so little time,

Larry

check out my MRH blog: https://model-railroad-hobbyist.com/node/42408

 or my web site at http://www.llxlocomotives.com
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DKRickman Prolific poster 3,069 posts
DKRickman

Drawings

Here you go.  As I drew, I realized that there's no real reason to build a micrometer.  A simple plunger with a scale marked on it will work just as well and be much easier to build.  I drew two different tools - on one end is a tool to measure the difference between the coupler pad and bolster, and on the other end is a tool to determine if the pad is at the right height for a specific coupler/truck combination, and to drill the hole in the right place.

_gauge_1.jpg _gauge_2.jpg 

Ken Rickman

Danville & Western HO modeler and web historian

http://southern-railway.railfan.net/dw/
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jeffshultz MRH Staff 7,982 posts
jeffshultz

Wheel size

Okay, I just did a very quick read of this and one thing that I don't see being taken into account (possibly because it doesn't need to be) is wheel size - there is a pretty significant difference in end height of a car between 28", 33" and 36" wheels. 

orange70.jpg
Jeff Shultz - MRH Technical Assistant
DCC Features Matrix/My blog index
Modeling a fictional GWI shortline combining three separate areas into one freelance-ish railroad.
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DKRickman Prolific poster 3,069 posts
DKRickman

different size wheels

The way I see it, you will still have to figure out the bolster height of the chosen trucks.  A modified caliper with a pair of jaws spaced at track gauge, so that the wheels touch them and the bolster touches the single center opposite jaw.

To control for different wheel diameters in the same truck, you could use spacers.  Most of us, if we only use 33" and 36" wheels, could just use a .017" spacer when working with a 36" wheel.  If you use 28" wheels as well, then you'd want two, a .029" and a .046".  If you're just measuring and referring to a chart to determine what shims or modifications would be needed, then no spacer would be needed - the chart would be designed to account for the different wheel diameters.

The inspiration for me was when I realized that the vast majority of the cars I build use trucks of the same height, so if I could accurately compare the coupler and bolster heights I would know without a doubt that the couplers would come out at the right height.  While I have used Dave's technique of comparing the coupler height on a Kadee gauge, it doesn't fit underneath a car when there are details hanging down (such as when a coupler box is recessed into the end of a car), an dI would rather not have to temporarily mount a coupler just to see if it's right.

Ken Rickman

Danville & Western HO modeler and web historian

http://southern-railway.railfan.net/dw/
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CM Auditor Regular poster 349 posts
CM Auditor

Ken, In both of your more recent posting you don't appear to con

consider the relationship between the actual flange size and model flange size.  Since you are not using Proto 87 trucks this difference offers major differences between the axle of your scale trucks and the floor of the cars or axle spacing on your drivers.

CM Auditor

Tom VanWormer

Monument CO

Colorado City Yard Limits 1895
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