Are Lawnmower Blades Reverse Threaded?

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You probably already love your lawn mower, that makes your lawn mowing work a lot easier, being equipped with blades to cut the blades of grass. A conventional lawn mower usually comes with an internal combustion engine which apparently acts as the power source of the lawn mower along with the lever mechanisms, nuts and bolts and the operating mechanisms which are so incorporated on the lawn mower for facilitating the functionality of cutting the grass evenly. So basic anatomy of a lawn mower isn’t any rocket science.

The Thinking Thread – How do the lawnmower blades work?

Now the interesting aspect in lawn mowers are undoubtedly the blades which cut the grass. Also they are the ones which catch most of our attention as well when we look at a functioning lawn mower.

So it’s quite evident why the blades become an area which fascinates many to be coming up with various thesis about the blades, it’s orientation and their incorporation to the internal combustion engine became vital for differentiating the type of lawn mower a particular mower is.

Threading become crucial as it’s the aspect which helps in the movement of the blades.

Generally for all such rotating objects, the threading is so designed that the rotation tightens the nut so that the blade remains intact with the frame. By turning the blade center opposite to the normal cutting rotation of the blade. A securing nut is exclusively provided for this purpose. Loosening refers to a right hand thread in the clockwise direction and tightening refers to the left hand thread which is in counter clockwise direction.

Reverse Verse

Having said that the blades of a lawn mower would be reverse threaded. Yes you heard it right. The right side tightens the blade and the left side refers to loosening it.

However we may have to block the blade from turning in order to break the bolt loose. This phenomenon is often seen as the blades of a lawn mower which function on the pitch angles of the blades with respect to the axes of the frame and the reference plane which in most of the cases is considered to be the ground for a lawn mower.

Removing your blade for sharpening or replacement will require the use of a socket wrench to unbolt the lock nut, which is often reverse-threaded.

Threaded safety

So it is reverse threaded in the case of a lawn mower but more often than not it is often seen it the other way round due to the movement of the blade which foxes the observer due to its motion. The threads which have reverse threads in the lawn mower are usually the blade nuts which are so incorporated to safeguard the blades on the drive shaft of the IC engine. This is done to make sure that the nut doesn’t get loose due to the blade’s rotation.

But having said that it is not mandatory for all blades to use a reverse threaded nuts to ensure safety of the engines drive shaft. They may resort to other mechanisms for maintaining the safety of the drive shaft as per the required conditions and optimum operating conditions of that particular lawn mower.

3 Responses

  1. It would be nice if you were consistent with left and right counterclockwise clockwise etc.

    Anyone talking about this should always use clockwise & loosens together always. Or counterclockwise & Tightens.

    I’ve read several articles and came up with nothing but confusion about it when they were saying clockwise or counterclockwise or left or right whether they were talking about tightening or loosening. and saying left and right is a piss poor way of looking at it because it depends on whether you’re looking at the bottom or the top of the bolt or whether you’re holding your wrench at the bottom or the top of the bolt. Clockwise and counterclockwise are easy enough concepts for anybody to understand and they more accurately portray exactly the direction of loosening or tightening turning.

    Hope that’s clear enough to understand what I’m trying to say.


    PS I have a Toro 21-in lawn mower I need to take the blade off and it’s so damn tight I’ve tried pushing it both ways and it sounds like the threads are binding and I might ring off the bolt so I want to make sure which way is loosening it for sure. But I can’t find the easily available answer anywhere. My guess is from reading this is probably clockwise loosens, because there are too many irregularities in terms between reverse thread left right clockwise counterclockwise etc. Just keep it simple clockwise – tightens or clockwise – loosens.

    If you say counterclockwise tightens, It’s pretty much given that clockwise loosens, that same Nut or bolt.

  2. Agree with prior commenter: article was not useful.

    Same problem as prior poster, nut won’t turn either direction and concern over potential I’m tightening rather than loosening.

    End the end the threads were not reversed. If any suggestion from the article was of use, assuming that the nut would tighten in normal use made me think that loosening it would require turning it such that it would go faster than the blade if the blade was going in its normal direction. That is pulling the socket handle away from the sharp edge of the blade.

  3. I have yet to see a bastard thread on any lawnmower blade here in the United States. While you are holding the bolt head you hand, turn the bolt clockwise (right) to tighten. Counter clockwise (left) to loosen. ((safety)) unhook power source and block the blade while changing a lawnmower blade.

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