In message , Bruce
writes
"Graham." wrote:

Inductance loop buried in the ground at red line.Puts the brakes on.
Assuming you`re talking about shopping trolleys but just forgot to
mention it?

Assuming the trolley side is passive, it can't have too much
range can it?
Couldn't one just lift the trolley over the sub-surface coil, or
are trolley thieves not that bright?


Plenty of trolleys escape from out local supermarket, which is equipped
with that system. The brakes only work on one or two wheels, and since
those wheels are at the back, it is a trivial task to lift the rear of
the trolley while pushing it over the loop.


Having tried it once (when I'd parked in a bit of car park in a
shopping place outside the actual sainburys car park.

It wasn't easy at to push a trolley full of shopping keeping the braked
wheel off the ground (the brake stayed on in this system)

--
Chris French