Screw gears transmit rotary motion between offset shafts. Also known as crossed helical gears, they have disc-shaped bodies and slanted teeth that curve to the right or left of their center axis. They pair with gears that have identical pitch, pressure angle, and helix angle. Combining two same-direction screw gears transfers motion between non-parallel skewed shafts, while matching two opposite-handed screw gears transmits motion between parallel skewed shafts. Their meshing motion creates friction, so they're typically paired in different materials to minimize heat and wear. Since their teeth engage at a specific, concentrated point, they're only suitable for low-speed and lighter load applications, such as conveyors, textile machines, and pumps.