To provide a human engineering handwheel assembly used for a man ual brake device mounted on a rolling stock, so as to give a mechanical enlarge ment ratio for lessening the labor required for turning a handwheel.

A planetary gear device includes a sum gear 26 fixed and jointed to a handwheel 12, and a hub member 44 rotatably fixed to the handwheel 12. In this case, the hub member 44 is formed to be freely rotatable independent of the handwheel 12. Furthermore, the hub member 44 has a socket 46 at an axial center AX, so as to be mounted on the freely rotatable drive member of a manual brake device on a rolling stock, and includes a plurality of planetary gears 50 rotatably fitted thereto for gearing and engaging with the sun gear 26. A fixed ring gear 64 mounted on a structural element without any dependency on the handwheel 12 and the hub member 44 surrounds a plurality of the planetary gears 50 for gearing and engaging therewith.