barley reel

A barley reel is a cylindrical drum, typically 36 to 48 inches in diameter and 24 to 36 inches wide, made of steel or aluminum with slots or perforations of specific widths cut into its surface. It rotates at 15 to 25 rpm and uses gravity and motion to separate seeds and foreign material by size and weight, allowing smaller seeds to drop through the slots while larger ones roll along the curved surface toward a discharge chute.

The machine addresses a practical problem in grain handling: wild oats, which are nearly identical in size to barley, cling to harvested barley and reduce its market value and milling quality. Similarly, pin oats (small, thin oat varieties) contaminate wheat crops. A barley reel achieves this separation by exploiting the difference in seed thickness. Wild oats are flatter than barley; they drop through slots sized to reject barley but accept the thinner wild seed. The same principle works for separating pin oats from full-width wheat kernels.

Slot width is the critical specification. A reel used for wild oat removal from barley might have 12/64-inch slots, while one designed for pin oat removal uses 14/64-inch or 15/64-inch slots. The reel is inclined at 15 to 25 degrees from horizontal and fitted with lifter blades inside the drum to carry material up and drop it repeatedly as the cylinder turns, ensuring thorough contact between seed and openings.

The barley reel sits in the grain cleaning train between initial screening and final grading. It typically follows a magnetized aspirator that removes ferrous metal and lightweight chaff, and precedes a shaker table or gravity separator that makes final cuts based on density and length. Operators must monitor for bridging, where seeds jam in the slots and stop dropping, usually caused by damp grain or inadequate cleaning of the drum surface. The reel works best on dry grain with moisture content below 12 percent.

Named for its primary historical use in barley preparation for malting and brewing, the barley reel design dates to the early 20th century and remains largely unchanged in principle. Modern variants use stainless steel drums for easier cleaning and higher throughput designs capable of processing 50 to 100 tons per hour, depending on crop type and slot size. The reel has declined in use in some countries due to competition from optical and density-based sorters, but remains common in cooperatives and smaller mills where capital budgets limit upgrades.