Patent ID: 7713177

Claim:
A treadmill comprising: an external frame; an internal frame connected to the external frame; a belt in the form of a loop supported on the internal frame; and a buffering apparatus comprising: a crossbar rotationally provided on the external frame between various angular positions; a knob connected to the crossbar so that the crossbar can be rotated by turning the knob; a non-circular block formed on the knob; a ring secured to the external frame and made with a non-circular aperture defined therein, wherein the knob is movable between a first position where the non-circular block is disposed in the non-circular aperture non-rotationally to avoid the rotation of the crossbar and a second position where the non-circular block is out of the non-circular aperture to allow the rotation of the crossbar; and two buffer sets each comprising a plurality of buffering blocks made with different elastic coefficients so that a selected one of the buffering blocks is brought into contact with the internal frame when the crossbar is in a related one of the angular positions.