Importance

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Abstract

A lawn mower engine having a lightweight top rotor of low polar inertia drives a rotary blade through a clutch-flywheel rotor having sufficient inertia to provide the major flywheel effect for the engine. Clutch faces at the rotor periphery engage a surrounding blade-carrier drum and have a maximum torque arm for positively driving the blade. The faces are preferably on centrifugal shoes which slip at load-reduced speed so as to maintain engine operation, and release at idling speed to allow engine starting with the blade stopped. A brake band or ring about the drum is spring-pressed ON to stop the blade when a deadman control is released. The preferred clutch-flywheel rotor is made of two heavy circular plates (e.g., 1/4'.times.6') riveted together against spacer slugs and a shouldered hub. Wide clutch shoes are mounted on such rotor by end tangs and springs between the plates. The top rotor plate substantially closes the top of the drum. Access and hub openings in the two plates provide rotor spacer slugs. The drum is slightly smaller than the mower deck opening to permit preassembly to the engine, and permit mounting the brake band on the engine-mounting bolts. The throttle lever in the path of the deadman lever is driven to idle position when the deadman lever is released. The rotor carries a clicker which makes an audible noise if the engine is stopped while the brake is OFF and the blade runs free under its own momentum.

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First Claim