| 摘要 |
Each half of the switch cover includes a number of hollow pillars (3) which fit into each other (2b,3b). The outer ends of both pillars incorporate recesses (2e,3c), the lower having a slotted opening with a bearing surface (2d) on each side. Retention is achieved by locking tongues (1) of double-T shape (1a,1b) which incorporate a longitudinal slot (1d). Each tongue is inserted in a pillar so that its wider arm (1a) engages the bottom of the top recess (3c), with the narrower arm (1b) free in the bottom slotted opening. Clockwise movement of the upper arm (1a) causes the lower arm (1b) to engage the bearing surfaces (2d), after which the tongue twists so drawing the pillars together and engaging the lower arm in recesses (2f) in the surfaces (2d). The units are now locked in place until the tongue is untwisted.
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