Dave Liquorice wrote:
On Wed, 28 Nov 2012 16:35:40 +0000, usenet2012 wrote:

Our Tesco locks the wheels as you go up/down their travelators. Damned
annoying when in a hurry though the alternative is probably too amusing
a prospect to be allowed.

Normally defeatable by lifting the rear wheels but trollies are damn
heavy empty and as you say it could be ammusing.

I'd like to know how the "trollies won't go past this point" thing works.
I know some have bits of "travelator grid" the the wheels bind in but the
Hexham Tesco between it and Aldi is just an ordinary mix of paving slabs,
concrete or tarmac. Bit of steel buried and magnet in the hub?

Reading the specs in one patent, it is a radio frequency transmitter
loop and a receiver in the lump round the trolley wheel, which engages a
locking device of some sort. The patent description I've seen is a bit
vague about the actual design.

--
Tciao for Now!

John.