In 1961, American Car and Foundry (ACF) introduced a new type of covered hopper.  Up until this time, covered hoppers, like most freight cars had a heavy center sill to support the car and transmit the pulling force.  This required hopper cars to have two outlets for each bay; one on either side of the center sill.  ACF’s new design eliminated the center sill, allowing a single outlet that dumped between the rails.  The new design also centered the loading hatches atop the car and was cylindrical in shape.  ACF named their new design “Center Flow”.   The design was refined a few years later, becoming the Center Flow familiar to modelers.  By the mid-70’s, other car builders began producing similar designs.

   Though ACF adopted the name “Center Flow” for their earlier design, they will be referred to as “cylindrical” hoppers in this site to avoid confusion.  Many of the private owner schemes listed here were leased from Shipper’s Car Line or other lessors.  Information on how many cars were leased or how long the lease lasted is difficult to obtain.  Generally, only the built date of the cars is the most that I have been able to determine.  I will include quantities in the columns where car series are listed individually by the lessor, but this is no guarantee that the cars are still under the same lease.

CF Minitrix early.jpg




   The first Center Flow prototype never went into production; numbered SHPX 60000, it toured briefly as a demonstrator before being sold to the New York Central.  Numbered 885980 by the Central, it remained in NYC paint until at least 1987.  Minitrix offered a model of this pioneering car in the early days of N-scale, which was also sold under the “Postage Stamp Trains” label by Aurora.  Sadly, it was offered in the four schemes listed below, but not for New York Central.

DOW CHEMICAL- Minitrix 3121 is painted in a tank car paint scheme.  However, Dow Chemical owned a series of cylindrical hoppers numbered 73501-73533.  The paint scheme was undoubtedly different, but I’ve listed it in the chart below as this road name hasn’t been offered yet by Bowser.

SHELL- Minitrix 3124 is also painted in a tank car scheme.  However, shell owned a series of cylindrical covered hoppers numbered, SCPX 3501-3533.  Both Delaware Valley and Bowser offered more accurate models of this series.

UNION PACIFIC-Minitrix 3123 represents a series of 200 cylindrical hoppers delivered to the UP, which Both Delaware Valley and Bowser offered more accurate models of this series.

UNITED CARBON COMPANY-  Minitrix 3122 is numbered for a series of later 4600 cubic foot center flow hoppers, however, the chart below lists a series of cylindrical hoppers with a nearly identical paint scheme.

Trix Cylindrical chart.png