A flatcar (US) (also flat car (US) or flat wagon (UIC)) is a piece of railroad (US) or railway (non-US) rolling stock that consists of an open, flat deck mounted on a pair of trucks (US) or bogies (UK). One at each end containing four or six wheels. Occasionally, flat cars designed to carry extra heavy or extra large loads are mounted on a pair (or rarely, more) of bogeys under each end . The deck of the car can be wood or steel. The sides of the deck can include pockets for stakes or tie-down points to secure loads. Flatcars designed for carrying machinery have sliding chain assemblies recessed in the deck.
Flatcars
are used for loads that are too large or cumbersome to load in enclosed cars such as boxcars. They are also often used to transport intermodal containers (shipping containers) or trailers as part of intermodal freight transport shipping.
Bulkhead flatcars are designed with sturdy end-walls (bulkheads) to prevent loads from shifting past the ends of the car. Loads typically carried are pipe, steel slabs, utility poles and lumber, though lumber and utility poles are increasingly being hauled by skeleton cars. Bulkheads are typically lightweight when empty. An empty bulkhead on a train puts it at a speed restriction to go no more than 50 MPH. Since bulkheads are lightweight when empty, hunting can occur when the car is above 50 MPH. Hunting is the wobbling movement of the trucks on a freight car or a locomotive. If the wheels hunt against the rails for a period of time, there is a high risk of a derailment.