The Trinity 3230 Pressure Differential (PD) covered hopper is essentially a smaller version of TrinityRail’s 5660 PD. The smaller version was developed from the base design introduced by Thrall Car in the late 1990s.
The smaller size enables the cars to be loaded with heavier ladings such as cement and various grades of fly ash. Most of the cars are operated by Railcar (Leasing) companies or Shippers