Power split transmission system and vehicle

A power split transmission system, comprising:

• a hydrostatic transmission mechanism;
• an input main shaft in transmission connection to an input terminal of the hydrostatic transmission mechanism;
• a first planetary gear train, a second planetary gear train, and a third planetary gear train, wherein an output terminal of the hydrostatic transmission mechanism is in driving connection to a sun gear of the first planetary gear train and a sun gear of the second planetary gear train, a planetary carrier of the first planetary gear train is coaxially fixed to a planetary carrier of the second planetary gear train, the planetary carrier of the first planetary gear train is coaxially fixed to a sun gear of the third planetary gear train, and a planetary carrier of the third planetary gear train is in transmission connection to a gear of the input main shaft;
• a reverse gear, a first clutch, a second clutch, and a brake, wherein the first clutch is configured to make the input main shaft in transmission connection to a gear ring of the second planetary gear train to drive the gear ring of the second planetary gear train to rotate forward, the second clutch is configured to make the input main shaft in transmission connection to the gear ring of the second planetary gear train through the reverse gear to drive the gear ring of the second planetary gear train to rotate reversely, and the brake is connected to a gear ring of the first planetary gear train to control locking of the gear ring of the first planetary gear train;
• and
• an output main shaft, a third clutch, and a fourth clutch, wherein a driving plate of the third clutch is in transmission connection to a gear ring of the third planetary gear train, a driving plate of the fourth clutch is in transmission connection to the sun gear of the third planetary gear train, and each of a driven plate of the third clutch and a driven plate of the fourth clutch is coaxially fixed to the output main shaft.