Double action latching electrical safety switch - has double contact circuit with one lever latching on safety catch and second restoring to delay switching-on

摘要

Double-action electrical safety switch only latches to switch on the circuit if all associated protective guards etc are in position for use in e.g. electrical lawn mowers. The hand grip (1) of the electrical apparatus contains the press button switch (9) which pushes against an intermediate lever (4), against spring pressure (17) to close the circuit contacts (S1). The intermediate lever (4) latches (4b) against a lip (5b) on an adjacent lever (5) held depressed by an elasticised collar (2) or membrane above it (5a). As long as the membrane remains intact the contacts (S1) will be held closed by the latched lever (4). The press button (9) restores under spring pressure (10) to make the second set of contacts (S2) in series with the first (S1) and the motor. Alternative designs are offered using latched levers and relay latching.