The invention is a surgical instrument comprising a first toothed rack which can be pushed, in a linear manner, via a gear pair. The pushing causes an oppositely running linear movement of a slide, thereby opening and closing the surgical instrument. The first toothed rack is capable of being moved in a linear manner into a handle piece, or pulled out from the handle piece, via the corresponding movement of a lever. The lever is pivoted in the handle piece, and opened by a spring pair. A first gear and a second gear form the gear pair, and a size ratio of the gears determines the step-up, or the step-down, ratio of the surgical instrument. A cover guides the first toothed rack and the gear pair laterally and holds them in engagement. A screen protects the second toothed rack and the slide against damage.