Slider 1 and 2 move along fixed guides p-p and are spring-loaded by springs 6 and 5. Wedge 4 slides along plane a-a of slider 1 and its tapered surface contacts ball or roller 3 which, in turn, is in contact with plane b-b of slider 2. When links 4 and 7 move in the directions shown, sliders 1 and 2 are spread apart and move vertically in guides p-p.
$2178$WL,6L$