What are the characteristics of Robot 0° spiral gear? A zero-degree helical gear, also known as a robot helical gear, is a special type of helical conical gear characterized by a helix angle at the center of zero degrees. It combines certain advantages of both straight conical gears and helical conical gears. Advantages Let me walk you through the key advantages of zero-angle helical conical gears—they’re really standing out in industrial applications, and here’s why: First