Adjustable pre-tightening device and RV speed reducer

The utility model provides an adjustable pre-tightening device and an RV speed reducer, relates to the technical field of speed reducers, and aims to ensure the pre-tightening force of a bearing system to a certain extent, prolong the service life of the RV speed reducer and improve the transmission precision of the RV speed reducer. The utility model provides an adjustable pre-tightening device which is used for an RV speed reducer and comprises a flange shaft and a pre-tightening piece. The pre-tightening piece is annular, a matching part is formed on the inner wall of the pre-tightening piece, the flange shaft comprises a matching section, the matching section extends in the axial direction of the flange shaft, the matching part is matched with the matching section, and the matching part can move on the matching section in the direction close to the end of a main bearing assembly in the RV speed reducer and abuts against the end of the main bearing assembly. 本实用新型提供的一种可调预紧装置及RV减速机，涉及减速机技术领域，以在一定程度上保证轴承系统的预