The encyclopedia · Engineering & Operations · Technical decision · 1953-1970s
The PS-2CD covered hopper let grain fall out the bottom and reload itself
Pullman-Standard's center-discharge covered hopper let a train of grain unload by gravity, cutting the labor of bagging and shoveling.
Pullman-Standard
the move
Grain and cement moved in sacks and boxcars, where one person loaded and another shoveled every unit, and an open car let cargo get dirty or wet.
Pullman-Standard introduced its welded PS-2 covered hopper in 1953 for denser cargoes, then the PS-2CD center-discharge version in 1962.
The covered, sloping body ends in bottom doors; opening them dumps the load by gravity, so a whole train unloads in minutes rather than by hand.
That turned a railcar into a self-unloading bin, and center discharge became the basis for grain and chemical fleets for decades.
why it works
- Gravity does the unloading, so no shoveling and far less labor at either end.
- A covered body keeps grain dry and clean and keeps it from blowing out.
- A centered discharge under each pocket lets cars be drained quickly and evenly.
- The same car carried grain, chemicals and minerals, broadening its usefulness.
what transfers
Design the container so it empties itself, and the cost of handling a bulk commodity collapses.
what came after
The PS-2CD and rivals such as ACF's Centerflow became the standard grain carriers, and the covered hopper helped industrialize bulk shipping; thousands remained in revenue service for decades.
references
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