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Replacing an electric clutch on a lawn mower

Updated July 19, 2017

Electric clutches are used in some riding lawnmowers as a compact means of switching the blade drive on and off. This was accomplished on older mowers by means of a mechanical belt clutch, which pressed an idler pulley against the belt to tighten it in the pulley grooves. This system worked, but belts needed frequent replacement and slipped badly when wet. When an electric clutch is used, the belt tension remains constant, isn't as badly affected by water and generally lasts much longer.

Why a Lawnmower Has an Electric Clutch

Electric clutches are used in some riding lawnmowers as a compact means of switching the blade drive on and off. This was accomplished on older mowers by means of a mechanical belt clutch, which pressed an idler pulley against the belt to tighten it in the pulley grooves. This system worked, but belts needed frequent replacement and slipped badly when wet. When an electric clutch is used, the belt tension remains constant, isn't as badly affected by water and generally lasts much longer.

How to Tell if a Mower's Electric Clutch Needs Replacing

Electric clutches used in lawnmowers attach directly to the engine crankshaft and are held in place with a bolt that screws into the centre of the crankshaft end. The clutch clamps the clutch disc firmly when the clutch coil is energised. A properly working clutch will take about 3 amps to energise. Drawing significantly more amperage, slipping or noises that sound like a failed bearing are all reasons to suspect the clutch needs replacement.

Replacing the Electric Clutch

Electric clutches can generally be removed without taking the motor off the mower, though sometimes it may be necessary to loosen the motor mounting bolts and raise the motor slightly. The process starts with removing the blade drive belt. The bolt holding the clutch to the crankshaft is then removed. This is easiest with an impact wrench, as there is no need to prevent the crankshaft from turning due to the impact wrench's speed. After the bolt is removed, the clutch can be pulled off the engine crankshaft by hand. Slide the new clutch onto the crankshaft, making sure the key in the clutch hub is aligned with the keyway. Replace the bolt and tighten it securely. Finish the job by reinstalling the belt and plugging the wiring connectors together.

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About the Author

K.K. Lowell is a freelance writer who has been writing professionally since June 2008, with articles appearing on various websites. A mechanic and truck driver for more than 40 years, Lowell is able to write knowledgeably on many automotive and mechanical subjects. He is currently pursuing a degree in English.