I am continuing with the project to complete the very nice 3D-printed Southern Pacific piggyback cars made by AJ Chier. In my last post about the flat cars, I showed completion of the body details (grab irons, sill steps, brake wheels), shown at: https://modelingthesp.blogspot.com/2025/02/sp-piggyback-part-5-3d-printed-flat-cars.html . I should repeat that because I model 1953, the first year of this service on the SP, my models reflect the very earliest practices of SP piggyback.
First I needed to prepare the models for trucks and couplers. I used a bottoming tap to tap the bolster and coupler pocket holes 2-56.
For lettering, I used the Protocraft set for SP Class F-70-6 and -7 flat cars (Rick Leach artwork). Each set is intended for lettering a single car. I used the set, but was a little disappointed in the low opacity of the white lettering in the smaller sizes. Here is the model as I lettered it with the Protocraft set.
Below is the central part of a builder photo (AC&F) of the last car in Class F-70-7 (they were numbered 140500–142549). You can readily see, in comparison to the above model photo, what I mean about the appearance of the smaller lettering (you can click to enlarge). But in layout operation, no doubt this will go unnoticed. I did omit the AC&F builder emblem, as these are not visible on any of SP’s piggyback cars.
Next I turned to installation of trucks and couplers. This involved making a styrene sheet cover plate for the coupler pocket, what’s sometimes called a “one-minute job.” Then Kadee No. 158 couplers were added.
Trucks are an interesting problem. These 70-ton flat cars of course had 70-ton trucks, and most modelers aren’t sensitive to the differences between 50-ton and 70-ton trucks: 5' 8" wheelbase instead of 5' 6", and slightly beefier sideframes; both aspects essentially invisible in HO scale. But several HO scale truck makers do offer 70-ton trucks, and I chose to use those.
The SP prototype cars had Barber S-2 trucks, of the early A0 (A zero) variety. Most commercial Barber S-2 trucks are S-2-B (so marked by the rare truck maker who actually designates such details, such as Kadee). Can we tell? Actually, yes. Below is a view (AC&F photo) of an SP Barber S-2-A0 truck.
Here you can see the distinctive Barber bolster end, with its friction-wedge corners, and a pair of truck springs outermost (there were five such springs in the spring package). For more on this, for those interested, I would direct you to Bob Karig’s superb truck chapter (Chapter 6) in Coal Cars, University of Scranton Press, 2007.
(For background, on model trucks, I recommend Richard Hendrickson’s HO scale truck document, available on Google Docs at this link: https://docs.google.com/file/d/0Bz_ctrHrDz4wcjJWcENpaDJYbUU/edit?usp=sharing .)
Commercial HO scale trucks, such as the very nice Kadee 70-ton Barber S-2-B, are visibly different, having three outermost springs visible in the spring package, a very noticeable aspect of a truck. I show the Kadee S-2-B below.
I chose the Rapido 70-ton truck (no. 102059), which does have the Barber bolster end and a pair of outermost springs, thus looking like the SP Barber trucks. You could also use the ExactRail 50-ton Barber, which is close to the SP prototype.
The completed flat car is shown below, loaded with a pair of the Pacific Motor Trucking trailers, which I described in the previous post (available at this link: https://modelingthesp.blogspot.com/2025/05/sp-piggyback-part-6-trailers.html ).
I look forward to seeing this car in a mainline train during a layout operating session, a single car being appropriate in the earliest days of SP piggyback. And thanks, one more time, to AJ Chier for making these very nice 3D printed models.
Tony Thompson
I believe Moloco currently offers a Barber 70 Ton S 2-A friction bearing with Code 88 or 110 wheelsets. They also list the trucks without wheelsets.
ReplyDeleteThanks, Ken. I will check them out.
DeleteTony Thompson