Vacuum cleaner

A vacuum cleaner comprising:

• a base including a suction opening;
• a main frame including a dust collecting apparatus configured to remove dust from air sucked through the suction opening;
• a bracket coupled with the base and the main frame, wherein the bracket comprises a rack gear portion configured to slide together with the main frame with respect to the base;
• and
• a wheel assembly including a wheel housing and a wheel installed in the wheel housing, and rotatably coupled with the base,
• wherein the wheel housing comprises a pinion gear portion engaged with the rack gear portion, and
• wherein, based on the main frame and the rack gear portion sliding with respect to the base, the wheel moves toward or away from a floor surface as the wheel assembly rotates.

A vacuum cleaner comprising:

• a base including a suction opening;
• a main frame including a dust collecting apparatus configured to remove dust from air sucked through the suction opening;
• a left wheel assembly and a right wheel assembly each including a forward driving wheel and a reverse driving wheel, and rotatably coupled with left and right portions of the base;
• and
• a bracket coupled with the base and the main frame, wherein the bracket is configured to slide together with the main frame with respect to the base and comprises a rack gear portion configured to rotate the left wheel assembly and the right wheel assembly,
• wherein when the main frame is pushed, the left wheel assembly and the right wheel assembly rotate in a first direction so that the forward driving wheel of the left wheel assembly and the forward driving wheel of the right wheel assembly contact a floor surface, and
• wherein when the main frame is pulled, the left wheel assembly and the right wheel assembly rotate in a second direction that is opposite to the first direction so that the reverse driving wheel of the left wheel assembly and the reverse driving wheel of the right wheel assembly contact the floor surface.