The 5701 cubic foot covered hopper was introduced in the early Seventies for transporting bulk plastic pellets. Since 1972 ACF has built nearly 15,000 cars. Most of these were acquired by private companies including leasing companies, chemical companies, oil companies, and plastics companies.
The ACF 5701 grain hopper is similar to its 5701 plastics relative except it is equipped with continuous loading hatches and gravity outlets. The larger size was needed to transport lower density grain-related and similar agricultural products (e.g. feed, sunflower seeds etc) more efficiently than the then standard 4650, 4740, and 4750 cubic foot capacity grain hoppers. These were originally built as 263,000 GRL (Gross Rail Loading) cars but many have recently been rebuilt into the higher 286,000 GRL.
Features:

Eight full-width panel body with nine weld seams
Etched metal roof walks
Ten 20" hatches (plastics hopper only)
Longitudinal mounted air reservoir
Pneumatic outlets (plastics hopper only)
100-Ton Roller Bearing Trucks
Two continuous hatch designs (applied as appropriate on grain hoppers only)
Gravity outlets (grain hopper only)
AccuMate couplers

AccuMate couplers are made under license from AccuRail, Inc.