The 5660 Pressure Differential [PD] Covered Hopper was first introduced in 1999, by Trinity Industrie’s, as the latest advancement in the evolution of Pressure Differential Covered Hoppers. Production continues today under the TrinityRail brand, with nearly 4,000 cars already in service. These specialized PD covered hoppers are notably different from traditional "gravity discharge" covered hoppers in both form and function. Designed to transport powdery commodities such as flour and talc, the 5660 PD Covered Hopper features five non-opening bays connected by a master pipe. The cars are unloaded by pressurising the interior of the car with air, thus blowing the commodity out. An icon of today's railroading, the Trinity 5660 PD Covered Hopper is perfect for your modem layout! Coming in HO & N, collect all 24 numbers by ordering now!