Vector-resultant type epicyclic-gear stepless speed-changer

The utility model relates to a vector-resultant type stepless speed-changer with a planetary gear. Power from a shaft 1 rotates a gear 3 which is engaged with gears 2, 4 which are engaged with a gear 5 on a shaft 6; another gear 7 on the shaft 6 is engaged with gears 9, 14 on a shaft 8; shafts 15, 16 are fixed on a casing 17 which can rotate on the shaft 1; a gear 18 which is arranged on the casing 17 is engaged with a gear 19 fixed on an oil pump 20 which is connected with an oil motor 21 via a control system 22; a gear 23 is engaged with a gear 10 on the oil motor; a gear 13 is engaged with the gears 9, 14; the gears 13, 10 are duplicate gears. The speed changer has the advantages of high efficiency, large ranged of speed change, small dimension of external shape and good operating performance.