| 摘要 |
<p>This invention relates to a key operable security switch which can be used to prevent the operation or use by unauthorised persons of various items of equipment or apparatus. A security switch in accordance with the invention comprises a housing (10) in which is provided fixed contact means, the housing having a slider (12) provided with contact means (13, 14) movable with the slider which is capable of slidable non-rotary movement in the housing. There are also provided a plurality of locking pins (16, 17, 18, 19, 20) which are also slidably mounted in recesses formed in the housing and which are each urged by resilient means into positions in which they extend partly into the housing and partly into said slider so as to prevent slidable movement of the slider relative to the housing. …<??>In addition there are provided a plurality of plungers (22, 23, 24, 25) which at one end are engaged with the adjacent ends of said locking pins. The other ends of said plungers are engageable by the stepped edge (30) of a key (29) which can be inserted into the slot (28) of a barrel (27) which is rotatably mounted in the housing (10). Said stepped edge (30) of the key project through said slot (28) of the barrel (27) but does not engage the aforesaid ends of the plungers (22, 23, 24, 25) whilst the key is inserted into the barrel or withdrawn therefrom. Rotation of the barrel by the key after the latter is inserted into the barrel brings however said stepped edge (30) of the key into engagement with at least some of the adjacent ends of said plungers in order to depress them and effect corresponding movement of the associated locking pins (16, 17, 18, 19, 20) so that none of said locking pins will project into the slider thereby permitting sliding movement of the slider, such turning movement of said barrel (27) also having the effect of engaging said barrel with the slider whereby axial movement of the barrel and the key will effect similar sliding movement of said slider.</p> |
