Worm gears and pinions should be ordered separately. Metric Worm Gears ; Pinion Gears - Steel ; Bronze. Worm gears and pinion gears designed to produce large speed reduction ratios, especially in low loading applications. Available in modules 0.8 and 1.0. Both the pinion gear and worm gear module number / number of starts must match to ensure correct assembly. Features and Benefits. Worm gear manufactured from steel (pinion gears from phosphor bronze each sold separately). Worm gears are secured onto a shaft using a M4 grub screw (supplied). H7 pilot bore tolerance. Right-hand gear direction