Editing Hopper car (section)

== Types ==
Two main types of hopper car exist.  Covered hopper cars, which are equipped with a fixed roof, are used for cargo like [[cereal|grain]], [[sugar]], and [[fertilizer]], and [[Portland cement]]<ref>{{cite book |last=Walthers |first=W. K. |author-link=Wm. K. Walthers |title=Handbook for Model Railroaders |date=1937 |publisher=The Modelmaker Corporation |location=Wauwatosa, Wisconsin |page=114}}</ref> that must be protected from exposure to the weather.  [[Open wagon#Hopper wagons|Open hopper]] cars, which do not have a roof, are used for commodities such as [[coal]], which can suffer exposure with less detrimental effect.

Removable [[canvas]] covers are sometimes used to protect moisture sensitive commodities in open hopper cars.  Closed hopper cars have a metal top with waterproof loading hatches, which provides superior protection.<ref>{{cite book |last=Henry |first=Robert Self |title=This Fascinating Railroad Business |date=1942 |publisher=The Bobbs-Merrill Company |edition=First |location=New York |pages=248 & 249}}</ref> These loading hatches along the top of the covered hopper may be a single long opening along the centerline or a pattern of multiple round or square openings positioned to allow uniform weight distribution when loading the car.

Some covered hoppers have two to four separate bays, with chutes at the bottom to direct unloading contents.