Motor Speeds up and slows down, is this normal?

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  • Updated 4 years ago
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I just purchased the 21" mower, not the self propelled one.  I did my first cut yesterday and I noticed that the motor's speed alternates from faster to slower.  Is this normal?
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Dan Marakowski, Jr.

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Posted 4 years ago

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David Cline

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Official Response
Yes! The 21" mowers are able to sense when the blade encounters resistance and increase power to maintain rotation speed. Think of it as riding the throttle on a gas mower, starting on medium and increasing whenever you hear the motor struggle.

There is a brief delay in the power adjustment, so the blade may slow a bit when you first hit a thick patch, then rev up to get the blade back to full speed. I believe when you reach the end of the thick grass and have less resistance the extra power makes the blade speed up briefly before the power drops back down. You can definitely hear the motor get louder and softer as the power needs fluctuate while mowing.

This is INFINITELY better than the 20" which would sense the extra resistance and the blade would slow down, reducing cutting performance and flashing an overload warning light, possibly even shutting off if the grass was thick enough.