Cruise control, lawnmower style

"Cé hé sin" (michael-m-mouse) 04/22/2020 at 18:00 • Filed to: Lawnmower

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Here we have our unserviceable lawnmower with its engine exposed.

That finned device on top is the flywheel. But not only. This is multifunctional. Those fins do what you might guess and act as a cooling fan for the aircooled engine immediately below. But they do more than that. They are part of the push mower equivalent of cruise control. As the engine spins the fins blow air onto that plastic vane you can see almost touching the left hand side of the flywheel. The faster the engine turns the more air pressure is applied to the vane and it gets pushed away from the flywheel. It pivots and so the other end is pulled towards the engine. It’s attached to the throttle and tends to close the throttle as revs increase so it acts as a governor, keeping speed constant. Start cutting heavy grass and the load on the engine increases. It slows down, less air is produced and the vane moves back in, thus opening the throttle and compensating for the extra load.

So there you have it. The lawnmower equivalent of cruise control.

ranwhenparked > Cé hé sin 04/22/2020 at 18:26

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My version of lawnmower cruise control is to just duct tape the stop lever to the handle. 

SilentButNotReallyDeadly...killed by G/O Media > Cé hé sin 04/22/2020 at 18:32

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Gotta start it before it’ll cruise...

https://www.nulon.com.au/amp/products/aerosols/start-ya-bastard-instant-engine-starter

Certainly puts some oomph into the ‘ starter motor’ even if only a blast into the air filter is sufficient.

Cé hé sin > SilentButNotReallyDeadly...killed by G/O Media 04/22/2020 at 18:34

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I’ve changed the plug, coil an d carb and it still doesn’t go!

RamblinRover Luxury-Yacht > Cé hé sin 04/22/2020 at 18:38

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*takes off hat* “Guv’nor”

RamblinRover Luxury-Yacht > Cé hé sin 04/22/2020 at 18:42

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Don’t suppose you’ve got a compression tester? Sometimes these sorts of bastard suffer valve seat recession until they relatively abruptly quit running. That is, of course, assuming you’ve confirmed that the magneto is chooching with the new plug.

For starting fuel substitute, on those occasions I haven’t had an eyedrops bottle of gasoline, I’ve typically used xylene-base carburetor cleaner, as it evaporates easily, but starts at a fairly wide lambda range without going “bang” as harshly as ether-base starter fluid.

SpecsGTP > Cé hé sin 04/22/2020 at 20:53

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Technically it's a pneumatic governor to maintain engine speed regardless of load. You can raise and lower the governed engine speed by bending the tab that the govern spring attaches to. Just don't bend it too much, top speed should be no more than 3500 rpm

MoparTech > Cé hé sin 04/22/2020 at 21:16

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I would argue that the engine governor is more of the cruise control than the flywheel.

MiniGTI - now with XJ6 > Cé hé sin 04/22/2020 at 22:53

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I always wondered how that works

Cé hé sin > RamblinRover Luxury-Yacht 04/23/2020 at 05:31

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I’ve got a spark but it’s not actually igniting anything except to kick back occasionally when trying to start. I’ve given up on it for now.

RamblinRover Luxury-Yacht > Cé hé sin 04/23/2020 at 09:14

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Kicking back does sound like classic partially sheared key out-of-time. Which, as I recall, was a suspect but hadn’t been verified due to being stuck on.

Cé hé sin > RamblinRover Luxury-Yacht 04/23/2020 at 11:51

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I eventually extracted the key with the aid of a reasona bly large hammer. Sadly it was like new.

RamblinRover Luxury-Yacht > Cé hé sin 04/23/2020 at 12:32

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May well be valve seat recession, then.