PURPOSE: To provide a reduction and differential gear device for a vehicle, having a falling restraining means, capable of effectively preventing a breakage or abnormal abrasion of teeth of a reduction pinion and reduction gear and free from maintenance and adjustment for a long time.
CONSTITUTION: A falling restraining device 54 which abuts against the back surface 46 of a meshing portion of a reduction gear 38 so as to prevent falling due to meshing reaction force of the reduction gear 38 comprises a piston 64 slidably fitted into an oil chamber 56 and abutting at the tip thereof against the back surface 46 of the meshing portion of the reduction gear 38, a spring 66 for energizing the piston 64 toward the reduction gear 38, and an oil reservoir 60 communicated with the oil chamber 56 via a one-way valve 72.