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   In 1959, General American Transportation Corporation introduced the Dry-Flo covered hopper.  With a capacity of 3,500 cubic feet, it was one of the largest covered hoppers of its day and could be equipped for either gravity or pneumatic unloading.  Dry-Flow hoppers were not built in large numbers, as they were soon overshadowed by ACF’s Center Flow and Pullman Standard’s PS-2.


   BLMA Models produced an N-scale model of the Dry-Flo hopper, which is now offered by Atlas.  Tangent Scale Models produced the Dry-Flo in HO scale, and their website contains detailed information on them.  The chart below is a comprehensive listing of Dry-Flo hoppers for those who’d like to decal their own or lobby Atlas for their next run.

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   In 1964, the New York Central received a lot of 25 cylindrical pressure differential covered hoppers for hauling cement from American Car & Foundry.  The cars were successful and two more lots were delivered in 1965 and 1966 for a total fleet of 220 cars.  The initial lot featured fourteen vertical ribs along the bottom of the car, but this was replaced by two large square horizontal ribs on the subsequent lots.  New York Central marketed this service as “Flexi-Flo”, and the cars remained in service with Conrail until the early nineties, when they were sold to Merchant’s Despatch as well as other private owners.  A few cars ended up in non-revenue service as scale test cars as early as 1969, lasting well into the 2010’s.  The Conrail Historical Society now owns the sole surviving car, former scale test car number 80019.


   Roco produced a model of this car for AHM in the early seventies.  While it has the vertical ribs of early New York Central cars, it has two elongated roof hatches instead of three round hatches.  Being a model from the early days of N-scale, it also lacks the discharge pipes of the prototype.  In addition, all of the paint schemes offered by AHM were stand-ins for 3,500 cylindrical of 5,250 Center Flow covered hoppers.  Fortunately, Eastern Seaboard Models re-issued the model in a variety of New York Central, Penn Central and Conrail schemes.   Though the model more closely resembles the early cars, most of the paint schemes are numbered for late series cars.  This is indicated by an asterisk next to the catalog number.


   Rapido Trains is accepting pre-orders for accurate N-scale models of these interesting cars until November, 15th 2022.  Both early (vertical ribs) and late (horizontal ribs) versions will be available in a number of road names.  This state-of-the-art model will include etched brass roof walks and full piping detail, and should be an eye-catching model.


   The chart below lists early versions, late versions and stand-ins separately.  The quantities for Penn Central and Conrail are calculated estimates as the series had been combined in the 1980’s Equipment Registers.  Exceptions for other railroads are as follows:


CHIGAGO, BURLINGTON & QUINCY- AHM 4441C is numbered for a series of forty-foot boxcars, but could stand in for a small series of cylindrical hoppers.


GREAT NORTHERN- AHM 4441E has no road number and is probably spurious, as it carries the goat logo that was adopted with the big sky blue paint scheme in 1967.


UNION PACIFIC- AHM 4441D is numbered for a series of thirty-three foot open hoppers, but could stand in for a series of cylindrical hoppers.


SHIPPERS’ CAR LINE (SHPX)- These seven cars were the only ones not sold to New York Central, and were initially leased to FMC Chemicals.  AHM 4441K is lettered for FMC, but represents a 3,500 cylindrical hopper with a similar scheme.  A 1977 photo of SHPX 76000 shows a plain car with reporting marks and dimensional data only.  By 1987, all of the cars carried ACFX reporting marks.

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   North American developed a pressure-differential hopper in the 1969 for hauling cement or other dense, powdered commodities.  The cars used a difference in pressure (usually 5psi) to fluidize the load to facilitate unloading through a hose connected to the car.  The vast majority of these specialized “3000pd” cars remained in North American Car’s “NAHX” lease fleet, though Penn Central bought 110 cars to supplement the fleet of Flexi-Flow cars it inherited from the New York Central.


   Trainworx produced a nicely detailed model of the North American Car 3000pd covered hopper.  In addition to the detail, some of the road names offer variations; the Conrail model, for instance, was produced in three different Penn Central “patch” schemes.  These variations are not listed in the chart below, unless they represent different time periods.


   Accurately dating many of these paint schemes was difficult, as the reporting marks are not listed in any of my Equipment Registers and many of the road names are repaints or “patch” schemes.  Many of the paint schemes offered by Trainworx are later paint schemes with only two lines of data (LD LMT, LT WT) under the road number, which dates them to 1985 or later.  Though outside the scope of this website, they are included in the chart below.

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