US Patent 7537093 Brake device for pushcart

A brake device for a pushcart includes a rotary lever rotatable on a base between first and second positions and biased to the first position. A cam member is rotatable within the rotary lever, and has a convex portion and a concave portion. A braking pin is disposed movably on the base, and is biased to contact the cam member. When the rotary lever is rotated from the first position to the second position, the cam member rotates so as to move an end of the braking pin from one of the concave portion and the convex portion onto the other one of the concave portion and the convex portion, thereby switching the braking pin between a braking position and a release position.