John wrote:
"Graham." wrote in message
...

--
Graham.

%Profound_observation%
wrote in message
...
On 24 Mar, 20:49, "mark" wrote:
The warning says something like: Will come to a Sudden Stop at the Red
Line.

How does that work?

mark
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?


A cover sort of flips around the wheel. It requires a tool to reset it.

Trolleys - I think those that can travel up and down moving escalator
type ramps are clever.

Those usually have a fixed inner part of the wheel and rotating discs on
the outside edges. The edges of the discs only clear the fixed bit by a
few mm and are fairly slim. Hence on the travellator the wheel edges
drop into the grooves on the surface leaving the fixed bit of wheel
grounded on the raised bits of the surface.

--
Cheers,

John.

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