Full definition
The large-diameter cylindrical pulley at the discharge (head) end of a belt conveyor that transmits tractive force from the drive motor/gearbox to the conveyor belt via friction. Typical diameters: 300-1,500 mm, selected based on belt tension, belt type (minimum bending radius), and power requirements. Construction: welded steel cylinder with integral or bolted stub shafts, machined and balanced. Lagging (rubber coating) on the drum surface is critical for traction: smooth rubber (6-12 mm, for dry conditions), diamond-grooved rubber (standard for most applications, channels water, increases COF to 0.35-0.40 vs 0.25 bare steel), ceramic lagging (highest COF 0.40-0.45, for wet/abrasive conditions, Rema Tip Top, Flexco). Face width: belt width + 50-100 mm. Per CEMA 7th Edition and DIN 22101. Crowned drum face centers the belt. Shaft designed for combined bending (belt tension) and torsion (transmitted torque). Bearing selection per ISO 281 with L10 life >50,000 hours.