The present invention is a mobile storage unit including an electric motor operably connected to wheels movably supporting the unit, and a motor brake operably connected to the electric motor. A shaft is rotatably mounted to the unit and supports the wheels on which the unit moves, and is engaged with an electric motor. The electric motor operates to rotate the shaft and the wheels to move the unit in the desired direction. Upon deactivation of the motor, the motor brake, which is also engaged with the shaft, operates to prevent any further rotation of the shaft to maintain the mobile storage unit in a specified location regardless of deflection of the surface on which the storage unit is positioned.