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Fig. 2 | BioMedical Engineering OnLine

Fig. 2

From: Retraction mechanics of Finochietto-style self-retaining thoracic retractors

Fig. 2

Actuation kinematics of a Finochietto-style retractor (rule = 10 cm). a Assembled retractor. b Rack-and-pinion mechanism for actuating retractor. c Close-up of two-pin gear of rack-and-pinion. d1d5 Diagram showing sequence of rotation for the two-pin gear and how it generates motion. d1: Start position; d2: 45° rotation—the right-hand pin slips further into the teeth of the drive as the left-hand pin moves out of the teeth; d3 90° rotation—the gear has translated a distance equaling half the distance separating the two pins; d4: 135° rotation; d5: 180° rotation (half turn completed)—the blade has moved a distance equal to the spacing of the gear teeth (5–9 mm for most retractors). At 0° and at 180°, the retractor locks

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