A bevel gear is a type of gear used to transmit rotary motion and power between intersecting shafts. Its most typical application is changing the direction of rotation by 90 degrees—for example, converting horizontal power transmission into vertical power transmission.
It works like two rolling cones: when the driving gear (pinion) rotates, its teeth engage the driven gear’s teeth, transferring torque while changing the rotation axis. The gear ratio (difference in tooth counts) determines output: a smaller pinion driving a larger gear increases torque but reduces speed; the reverse increases speed. Equal‑tooth miter gears only redirect motion. During operation, tangential, radial, and axial forces act on the teeth; the axial force on one gear equals the radial force on the mating gear.
Common types include straight bevel (simple, low‑speed), spiral bevel (smooth, high‑load), and hypoid (offset shafts, high torque).
Applications range from automotive differentials and power tools to marine drives and industrial right‑angle gearboxes. In essence, bevel gears enable efficient, compact right‑angle power transmission with adjustable speed and torque, making them indispensable in many mechanical systems.