ScaleTrains.com is excited to be the first manufacturer to offer HO scale plastic models of contemporary Thrall 5750 cubic foot and Thrall 4727 cubic foot carbon black covered hoppers. Two different versions of the 5750 represent the 1970s to present and 1980s to present while the 4727 is appropriate for the 1990s to today.
Found throughout North America, these unique freight cars are commonly found in large groups near major carbon black producers or users. They can also be seen singularly or in small blocks of cars in mixed freight trains. All three models were painstakingly researched from field documentation, photographs, reference books, and builder drawings.
During the 1970s, Thrall Manufacturing Co. introduced a new railcar designed for handling carbon black. These 3-bay, 70-ton capacity covered hopper cars boasted a volume of 5750 cubic feet, and measured 51’ over their ends. Unlike traditional covered hopper designs, where the end slope sheets are plainly visible, these cars featured an enclosed, boxy design, which was a necessity due to a special design feature to aid in the unloading of carbon black.
At the inside ends of the car are special inflatable bags, called “granuflators”. When the car is loaded, they lay flat inside the car. When inflated with pressurized air, the granuflators expand, and push the carbon black towards the outlets. And as typical with cars designed to haul carbon black, they featured tight-sealing 16” round roof hatches (22 hatches on most, but some customers specified 28), sampling spigots on the car sides, and “butterfly” type outlet gates.
The first version, the “1970s” 5750, represents Thrall 5750 production from approximately 1977 until 1979, which featured ten column-style posts per side, and a unique roofline. While the ends are peaked, and the end roof panels feature a single slope, the remaining roof panels feature a dual slope and a steep shoulder where it meets the side plate.
The second version, the “1980s” 5750, represents Thrall 5750 production from 1979 to 1989, which featured twelve column-style posts per side, and a revised roofline that saw the dual-slope and shoulder roofline continue from end to end.
Road Number Specific ScaleTrains
- From series SRCX 900-919, built November 1977
- As-delivered scheme with billboard “Sid Richardson Carbon Co.” lettering, and ACI labels
- 28 roof hatches
- All-new model
- Four (4) different road numbers
- 1970s carbody features 10 column-style posts per side
- Separate granuflator plumbing
- Separately-applied sampling spigot details
- Separate end and roof vent piping
- Per prototype: 22 or 28 roof hatches
- Photoetched metal outlet valve handles
- Separately-applied end “I” beam posts
- Photoetched stainless steel running boards and end platforms
- Separately-applied ladders
- Finely-detailed underbody brake detail
- Durable die-cast metal semi-scale Type E knuckle couplers
- All-new ASF Gould-cast 70-ton Ride Control Trucks with finely rendered raised foundry data, rotating bearing caps, separate brake beams, and side bearing detail
- 33” machined metal wheels
- Minimum radius: 18”
- Recommended radius: 22”
All Rivet Counter Freight Cars Feature
- Fully assembled
- Color matched to Tru-Color Paint colors whenever possible
- Printing and lettering legible even under magnification
- Accurately profiled .110" wide wheel tread
- Separately-applied metal grab irons
- Coupler cut levers
- Trainline hoses
- Intricate brake plumbing
- Weighted to Industry standards
- Operates on Code 70, 83 and 100 rail
- Packaging safely stores model
A byproduct of the petrochemical refining industry, carbon black is a fine, powdery substance with a consistency sometimes described as being akin to soot. Deep black in color, one of its major consumers is the automotive industry, where it’s used as filler in tires, belts, and other rubber products. It also sees usage as a pigment in inks, paints, and plastic products, all of which make it a popular commodity with a variety of industries. Hauling it, however, can be a challenge thanks to its physical properties. Covered hoppers are typically used to handle carbon black, with designs dating back to the 1920s specifically for hauling it.
Reference: Carbon Black Cars: Freight Cars Journal Monograph #15 by Eric A. Neubauer, ISSN 0884-027X, 1990