Monday, November 27, 2023

Modeling an SP Class O-50-9 tank car, Part 3

In the previous post in this series (see: ), I described my completion of the dome hardware and addition of the circumferential tank sheets to the tank body. As with a number of my models of Southern Pacific 12,500-gallon tank cars, the starting point was the Athearn “42-foot tank car,” as Athearn calls it. That model is virtually exact in overall dimensions to the SP prototype. 

Much of the work being done follows that in my original article of some years ago, giving details of this conversion of the Athearn model to an SP prototype, and thus I will only briefly mention the aspects already shown. Here is a link to that article: .

It’s been awhile since I posted about this project, so let me show the degree of progress. The noteworthy addition here is the dual-safety valve “elbow” housing on the side of the dome, a brass part from Owl Mountain Models (possibly shown more clearly in the previous post, see link in top paragraph, above). 

Since one safety valve was required for each 6500 gallons in a tank car compartment, a 12,500-gallon tank car like these SP cars required two safety valves. The dome-side mounting was superseded (though not prohibited) in the mid-1920s, replaced by the more familiar dome-top location. SP’s Class O-50-9, built in 1924, would be the last SP tank car class with elbow safety valves.

Note also the removal of the rivet rows along the top of the tank, since this tank is assembled with circumferential, not longitudinal steel sheets; and the lack of safety valves on the dome top, since they are located on the dome side in this car class. If you look closely (you can enlarge the image by clicking on it), you can see the overlay sheets of transparent plastic, added to represent the circumferential sheets.

The next step was to add Archer rivets along the edges of the circumferential sheets, as I mentioned in the post cited in the first paragraph, above. These were from Archer Fine Transfers set AR88031, double rivet rows suitable for tank cars like this (the set is based on data I supplied to Archer, as noted at the bottom of the decal sheet). To see the Archer line, you can visit their website at:

(Unfortunately, Archer went out of business two years ago. But the business is being revived, with new people having acquired the line. The link in the previous paragraph shows the materials.)

I applied them as one would apply any decal, finishing up with Walthers Solvaset. They were then protected with an overcoat of gloss. In the photo below, you can see how nicely they are spaced. At left are the extraneous Athearn rivet rows that were removed, obviously more widely spaced than the new ones. At photo center is the scar of the removed Athearn handrail support. As I did with my diesel fuel tank car in a recent post (here’s a link: ), that support will be replaced later.

Next came completion of the grab irons on the car ends, postponed until now. The molded-on grab irons are carefully sliced off, preserving the rivets at each end, and the new wire grabs are curved to match what was originally there. As I usually do, I made these from 0.015-inch wire ( Tichy Trains product) and attached them with canopy glue. Here is one end of the car.

The next job is to fabricate the new handrail. I have shown the process of making such a handrail in several places, most recently with a diesel-fuel tank car (here’s a repeat of that link: ). The K&S 0.020-inch brass wire is a pleasure to work with, being fairly soft and easy to form to fit. As you can see, the 12-inch length doesn’t go all the way around the tank, so another piece will be added.

The single grab iron on the dome (barely visible above)  is on the side with the dome walkway; obviously the other side, with no walkway, needs no grab iron on the dome.

The project will continue with finishing the new handrail, and preparing the underframe, followed by painting and lettering. I will describe those steps in a future post.

Tony Thompson

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