Protection device for slot of parking meter or vending machine - prevents insertion of anything other than magnetisable coin or token by using magnetically actuated shutter mechanism

摘要

This slot meter protection device allows the insertion of fully magnetisable coins or tokens, but will prevent the insertion of keys, ice-lolly sticks, beer-car rings, in appropriate coins, etc. When the edge of a suitable coin is pressed into the opening of the slot, a permanent magnet (8) is attracted to the coin, and moves downwards against the pressure of a spring (11). A recess (12) in the magnet then allows a ball (4) to move out of a depression in the sealing shutter (2) at the back of the slot. The coin then pushes up the shutter via a pair of ball-bearings (14), rods (15), a yoke (17) and a lever (18). A non-magnetisable coin cannot get past the ball-bearings (14) as the shutter is locked in position by the small ball (4), thus preventing the lever, yoke and rods from moving, while the shutter itself prevents any narrow instrument from reaching the inside of the meter.