Hall effect devices tend to be more reliable than mechanical things for this
purpose. I replaced a dodgy read switch in an old cassette deck autostop
with one some years back it outlasted the tape deck.
Brian

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The Sofa of Brian Gaff...

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"Harry Bloomfield" wrote in message
...
Its that time of year again...

My tractor mower, sometimes suffers from the cutter blades coming to a
stop due to becoming completely choked with grass. When that happens, it
slips the drive clutch, but from the driving seat, there is no noticeable
change in the noise and I carry on driving with no cutting taking place
and damaging the clutch.

I don't use a grass collector on the rear and because it tends to be
another cause of it choking up, but I can look back and see grass cuttings
being blown out the back when all is well. The drive clutch and its pulley
output to the cutting deck, is under the engine.

Ideally, I could do with a better way to be sure at a glance, that the
clutch isn't slipping and the deck is being driven round. One idea I have
is a magnet fixed to the edge of a pulley, rotating past a coil powering
an LED mounted on the tractors dash. Has anyone any other suggestions?