Sunday, April 1, 2018

Pennsylvania Railroad FM Flat Car Modeling

Wilmington, Delaware, April 13, 1933, T. S. Martorano collection
PRR FM Flat Car Prototypes*
At the turn of the century, the Pennsylvania Railroad adopted five freight cars as "standard" for simplicity and efficiency of maintenance ("Standard Freight Cars on the Pennsylvania Railroad, The Railway and Engineering Review, June 17, 1905, pp. 446-448.) The designs included the GLa hopper, GSa gondola, Nc cabin car (caboose), XL box car, and FM flat car. All were produced in large numbers (with the obvious exception of the Nc, given its specialized use.)
Drawing of the PRR FM from Railway and Engineering Review
The FM was produced in large numbers, although I have not been able to arrive at an exact total. My best estimate is a number approaching 4,000 copies, based upon a tabulation of FM cars listed in the August, 1922 volume of the Official Railway Equipment Register. I arrived at a total of 3,579 in service at that time. I have read musings that there were up to 14,000 FM flat cars produced. I find those numbers to be questionable at best and fanciful at worst.
PRR FM 925273 was in idler service for a load of catenary supports when photographed ca. 1930
The design was durable. The basic construction consisted of pressed steel fishbelly side sills and center sills, with a pair of deep crossbearers and six large, wood stringers. Each side had a dozen cast steel stake pockets (and NO stake pockets "in" the deck, at the car ends). The cars were originally equipped with KD schedule air brakes, arch bar trucks and staff-type hand brakes at each end. Cars that remained in service were converted to hand brakes at only the B end, PRR 2D-F8 cast steel sideframe trucks, and AB schedule brakes. Uncoupling devices were two-piece Carmer style.

A sizable number of cars were converted to LCL (less-than-carload) container service, beginning in 1928. Many cars so converted remained in this service into the 1950s. As a PRR online service, this iteration would be of little use to modelers of other railroads. There were still just under 800 of the general service cars laboring on in October, 1951, a total larger than the entire flat car fleets of most railroads!
PRR FM 473467, photographed in LCL container service, with a load of five DD1-A containers. Altoona, Pennsylvania, May 1, 1937, T. S. Martorano collection
Modeling the FM in HO Scale
There are several options for replicating the FM in HO scale. Railworks imported nice brass models, including versions for the container variant, with DD1-A containers. Sunshine Models offered cast resin kits in both revenue and MOW lettering (kits 30.7 - 30.9). The Sunshine kits did have some benefits compared to the F&C kits, but are not as finely rendered or as well detailed (at a later date, I will be posting a separate build post about modeling a B&O P-11 using the Sunshine Models kit). The last options are the Funaro & Camerlengo offerings in HO scale, for both the general service and container versions. The general service versions are available in two-packs, kits no. 6500 with stamped steel stake pockets and no. 6501 with cast steel stake pockets. I selected kit 6501.

In essence, the kits are one-piece bodies with separate stake pockets, brake gear, a few other details, and not much else. These would be excellent candidates for first-time resin car builders, with one notable exception: the stake pockets are finicky and challenging to apply.

After adding several of the stake pockets, I came up with a technique that I believe is relatively easy and durable. The instructions suggest using ACC to glue the stake pockets to the sides. I found this to require that things be aligned very quickly and, more importantly, the ACC results in a joint that could be prone to stake pockets "popping off" through handling. My recommendation is to use sparing amounts of Walthers Goo (or similar) thinned 50% with MEK. This allows the stake pockets to be tacked in place and properly oriented. Then add ACC to secure and fill the joint. The result is a secure, but modestly flexible bond.

The rest of the construction is a breeze. I chose to replace/augment a few parts. I used A-Line sill steps in the interest of durability. The grab irons were fashioned from 0.010" brass wire. The Carmer cut levers (from Yarmouth Model Works) are the primary aftermarket detail addition. They were secured using wire and ACC. The towing loops on the car side were fashioned from brass wire. The pressure retaining valve on the car side is a Precision Scale part with 0.008" wire. The hand brake is a spare part from an "overstock" sale that I believe came from Overland Models production of PRR X23 box cars, decades ago.

For the brakes, I opted for a car upgraded with AB brakes. The cylinder and AB valve are resin parts from the kit. I used a spare part for the reservoirs. The "rear" of the cylinder is a Speedwitch part (no. P118) to replicate the pressure head cylinder with integral lever bracket. The dirt collector is from a Tichy AB brake set. Piping and rods are brass wire. The clevises were fashioned from Tichy turnbuckles with one end trimmed off.

The trucks are from Bowser with Reboxx semi-scale wheelsets. Of note is that there are several flavors of PRR 2D-F8 trucks on the market, representing different types of truck bolsters. I plan a future post highlighting these differences, as they can be useful for replicating a specific car's trucks. The couplers are Kadee proto with whisker centering devices. I secured the lids with 0-80 screws.

I will provide a follow-on post highlighting the finishing of the model. Stay tuned...

*If you are looking for a great reference about PRR flat cars, consult Pennsylvania Railroad Flat Cars, Revenue & Work Equipment, 1881 to 1968 (a bargain at $20 - scroll down the linked page), by Elden Gatwood & Al Buchan, published by the PRRT&HS.


  1. Guess I should pay closer attention to your blog - esp. since I'm trying to finish the B&O P-11 car that's based on this prototype. But in my defense, I was focused on that car more last fall and April of this year I was head-down at work.... But better later than never. And it's not late - I'm just getting back to (and hopefully finishing!) the B&O car. And this post will be a nice addition to my research! :^)

    1. Funny your timing as I am trying to finish a Sunshine version of the P-11 to complement the F&C FM. We can race to see who can finish first!

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Comments always welcome!