An instrument including an actuation gear mechanism that provides two functions of a tool. The actuation gear mechanism comprises a cam mechanism and a gear segment mechanism. The circumference of the cam disk of the cam mechanism—in a first section (α1)—is a spiral curve for generating a stroke for closing the forceps tool, while the circumference of the cam disk—in a second, adjoining, angular range (α2)—is circular. When the cam disk with the circular curved line biases the spring means, no further movement takes place on the output of the cam mechanism. Preferably, two congruent cam disks are provided, whereby these—together with the driving gear and the segment gear, as well as the shaft—form a one-piece plastic injection-molded part. The installation space between the cam disks can be utilized for a slide with a gear rack for shifting the knife.
