hammasrattad

Hammasrattad is Finnish for gear wheels, and in English this refers to toothed wheels that mesh with other gears to transmit torque and rotational motion between shafts. Gears are used in many mechanical systems to change speed, torque, direction of rotation, or a combination of these. They can be arranged in various configurations, with external (spur) meshes being the simplest and internal (ring gear) meshes used in compact gear trains.

Gears come in several major types. Spur gears have straight teeth and are efficient for parallel shafts, while helical gears have angled teeth for smoother operation and higher load capacity. Bevel gears are used when shafts intersect at an angle, and worm gears provide high reduction ratios in a compact form. Planetary gear sets combine multiple gears to achieve compact high torque transmission. Key design features include the number of teeth, pitch circle diameter, module (metric) or diametral pitch (imperial), pressure angle, and the addendum and dedendum that determine tooth height and clearance. The involute tooth profile is the most common because it maintains a constant velocity ratio during mesh.

Manufacturing and materials vary by application. Common materials include steel alloys, bronze or brass for bushings, cast iron, and engineered polymers for lightweight uses. Manufacturing methods include gear hobbing, shaping, milling, and grinding, often followed by heat treatment and surface finishing to improve hardness and wear resistance. Lubrication, proper alignment, and controlled backlash are important for efficiency, longevity, and smooth operation.

Applications of hammasrattad span automotive transmissions, clocks, industrial machinery, robotics, and consumer electronics, reflecting their essential role in controlling motion and mechanical power in a wide range of devices.