Fixture of constant clamping forces

Move pink lever forwards to bring slider-crank mechanism (orange conrod, violet slider) into toggle position for clamping yellow workpieces. Clamping forces come from red spring.
The clamping forces are kept nearly constant thanks to a mechanism consisting of yellow slotted lever and two sliders (green and blue, sliding inside the violet slider). Green pin is fixed to the green slider. Blue pin is fixed to the blue slider. Two said pins slide in the yellow lever slot. The mechanism ensures that a large displacement of green slider on violet slider corresponds with a small deformation of red spring.
So at toggle position the fixture can clamp workpieces of different sizes with nearly the same force.
Red screw stops the pink lever at the toggle position.

Mechanism,Spring,Fixture,Clamp,