A hemostasis mechanism includes a deformable seal, and a plunger guided for translation within a housing to displace a fluid to a clearance extending between the deformable seal and the housing. The displaced fluid increases fluid pressure in the clearance to deform the deformable seal into sealing contact with a medical device. An actuator for the plunger includes a linkage having arms rotatable about first and second axes, and configured such that their rotation is converted into translation of the plunger. The linkage is adjustable from a retracted configuration to an advanced, cammed-over configuration.
