Main speed reducer assembly and main speed reducer transmission structure

The utility model discloses a main speed reducer assembly and a main speed reducer transmission structure. The main speed reducer assembly comprises a back main speed reducer shell body (1) and a difference velocity machine assembly arranged inside the back main speed reducer shell body. An adjoining plane (A) provided with an interface is formed at an output end of the back main speed reducer shell body. A difference velocity machine shell body (3) of the difference velocity machine assembly extends out from the inner portion of the interface of the adjoining plane (A). An out-extending part (31) of the difference velocity machine shell body forms a hollow pipe shape for a half shaft (2) to penetrate. A mounting structure is arranged on the adjoining plane so that an end cover (6) or a slide-limiting difference velocity machine (4) which is used for selectively locking the difference velocity machine shell body and the half shaft can be mounted. The adjoining plane with the interface is designed to be arrang