Definition of sun-and-planet gear in US English:

sun-and-planet gear


  • A system of gearwheels consisting of a central wheel (a sun gear or sun wheel) around which one or more outer wheels (planet gears or planet wheels) travel.

    • ‘In the compound-split mode, clutch two is opened and clutch one is closed, linking up the sun gear from planetary one to the ring gear of planetary two, creating a compound planetary system.’
    • ‘That gear meshes with three planet gears which in turn drive a second sun gear attached to the pinion shaft.’
    • ‘This last-named function means that MG1, which is connected to the sun gear in the power split planetary gear set, controls the output speed of the transaxle by regulating the amount of electrical power it generates, as that varies its rpm.’
    • ‘This invention overcomes this problem by providing a planetary gear system where the sun-and-planet gears are of one-piece, double-helical construction formed by welding together the two helical portions of the gear and thereby allowing substantial reduction of the apex gap between the helical portions.’
    • ‘Self-centering planet gears reduce material costs and machining tolerances and improve gearhead performance.’