Adjustable speed control arrangement for motorized exercise treadmills

In an exercise treadmill including a generally planar slider bed having a head end, a tail end, and a top surfacing extending substantially between said ends thereof, an endless belt trained over said slider bed top surfacing and a lower run passing under said slider bed, and means for driving said belt for movement of said belt upper run from said head end to said tail end of said slider bed, said slider bed having a cross member extending transversely thereof adjacent and fowardly of said head end thereof, said belt driving means comprising:

• a head roller journalled in said slider bed adjacent the head end of same over which the belt is trained, said head roller being journalled for rotation about an axis paralleling said cross member, an electric drive motor assembly mounted on the cross member for pivotal movement about an axis substantially paralleling said cross member, said drive motor assembly including a drive motor driving a drive shaft about an axis substantially paralleling said motor assembly pivot axis and having keyed to same a first drive pulley for rotation about said drive shaft axis, with said head roller having keyed to same a second drive pulley for rotation about said head roller axis, a pulley belt in drive transmitting relation between said pulleys, said head roller axis and said drive shaft axis being in substantially coplanar relation in a plane substantially paralleling said slider bed, said motor assembly pivot axis being disposed below said plane and said motor and disposing said motor assembly in cranking relation to said head roller axis about said motor assembly pivot axis for shifting said drive shaft axis toward said head roller axis in one direction of movement about said motor assembly pivot axis, and for shifting said drive shaft axis away from said head roller axis in the opposite direction of movement about said motor assembly pivot axis,
• the improvement providing for setting the speed of said movement of said treadmill belt by the human user of said treadmill,
• said improvement comprising:
• an adjustable speed control arrangement that comprises:
• said first drive pulley being a variable speed pulley,
• said motor assembly having a depending lever arm extending through and below said motor assembly pivot axis,
• a manually actuated speed control mechanism mounted on the treadmill above the treadmill belt and intermediate said slider bed ends,
• said mechanism including a reciprocable member and hand crank means for moving said reciprocable member a predetermined distance in opposite directions,
• a cable connected between said lever arm, below said motor assembly pivot axis, and said mechanism reciprocable member,
• a flexible cable guide through which said cable extends having one end anchored to said bed adjacent said lever and the other end anchored to said mechanism,
• said first drive pulley including spring biasing means for biasing same to the high speed position whereby said pulley belt is tensioned to swing said drive motor assembly about its said pivot axis to maximize the spacing of said lever arm from said head roller axis and said treadmill belt is driven at maximum high speed,
• said connection of said cable to said mechanism reciprocable member including means for effecting a pulling action on said cable when said reciprocable member is moved by said hand crank means in one of said opposite directions for speed reduction of said treadmill belt, means for effecting a lost motion action on said cable when said reciprocable member is moved by said hand crank means in the other of said directions when said motor is deenergized, and for permitting said biasing action of said first drive pulley spring biasing means to bias said cable through said pulley belt and said lever to return said lever arm toward said maximum spacing from said head roller axis for speed increasing of said treadmill belt when said motor is running,
• said movement of said reciprocable member in said one direction said predetermined distance defining the minimum low speed position of said first drive pulley and minimizing the spacing of said lever arm from said head roller axis whereby said treadmill belt is driven at minimum speed,
• said hand crank means being operable by the treadmill user to set said reciprocating member along said distance as desired for providing infinitely variable speed adjustment of said treadmill belt between said minimum and maximum speeds thereof, when said motor is running.