Novel multifunctional variable-speed assistor

The invention relates to the technical field of transmission systems for motor vehicles, electric four-wheelers, small forklifts and the like, in particular to a novel multifunctional variable-speed assistor. The novel multifunctional variable-speed assistor is provided with a main shaft. An advancing gear, a backward gear and an assisting gear are arranged at a power input end of the main shaft. The advancing gear is a duplicate gear, teeth at one end of the advancing gear are engaged with a driving gear for power inputting, and teeth at the other end of the advancing gear are engaged with a switchover gear. The switchover gear is assembled on a switchover shaft, an assisting input gear is assembled on the switchover shaft and engaged with the assisting gear, and a second carrier gear engaged with a first carrier gear is assembled on the switchover shaft. The second carrier gear is assembled on a backward shaft, and a backward input gear is assembled on the backward shaft and engaged with the backward gear. The main shaft is further provided with a first combination gear and a second combination gear through a key groove structure to select to be engaged with inner teeth of the advancing gear or the backward gear or the assisting gear. The novel multifunctional variable-speed assistor is based on a novel developed technology, and is small in size, wide in use, multifunctional and convenient to install and repair.