Full explanation
Drum speed critically affects threshing: (1) high speed (1,000–1,400 rpm) — wheat, barley, rapeseed — aggressive thresh, can crack grain; (2) medium (700–1,000) — mixed conditions; (3) low (400–700) — corn, sunflower — minimal grain damage. Modern combines allow on-the-fly speed changes from the cab. Drum type: (1) peg-type (Class Dominator, Case 1400/1600) — classic, good on tough crops; (2) raspbar (JD W/T/S, Case AFS, Claas Lexion, NH CR/CX) — today's standard, more efficient; (3) Claas APS drum (APS + Lexion — two drums) — modern premium. Full-rotary combines (Case AFS 9240, JD X9, NH CR10) have no classic drum but one or two long rotors. Rotor advantage: lower grain damage (1–3% vs 3–7%) but higher fuel (+5–10%).