Before revision: Banks 1978, , p.63 Le Rhône and Bentley BR1/BR2 rotary engines used cylinder liners and were sealed using conventional piston rings rather than obturator rings.The Rotary Aero Engine, Andrew Nahum 1987, , p.27 An 'L' section obturator ring is shown in Patent US 1378109A - "Obturator URL
After revision: Banks 1978, , p.63 Le Rhône and Bentley BR1/BR2 rotary engines used cylinder liners and were sealed using conventional piston rings rather than obturator rings.The Rotary Aero Engine, Andrew Nahum 1987, , p.27 An 'L' section obturator ring is shown in Patent US 1378109A - "Obturator ring".