A mobile robot having a removable wheel-drive assembly, comprising a mobile base having a chassis and a first wheel well member with a flange. There is a removable wheel drive assembly with a mounting bracket. There is a motor drive unit disposed on the mounting bracket and a wheel/tire connected to the motor drive unit via an axle. There is a second wheel well member on the mounting bracket and positioned between the motor drive unit and the wheel. The second wheel well member includes a central section having an aperture through which the axle passes and a top surface. The top surface of the central section of the second wheel well member engages with the flange of the first wheel well member of the mobile base.