Adjustable scissors-action exerciser

An adjustable scissors-action exerciser comprising:

• a first motion arm having a coupling end;
• a coupling block pivotally mounted to said coupling end of said first motion arm and having a protruding rod;
• a damper mounted between said first motion arm and said coupling block for generating damping resistance upon rotation of said coupling block relatively to said first motion arm;
• a second motion arm having a coupling end pivotally mounted to said coupling block, a plurality of chisel grooves formed at said coupling end and smoothly curvely arranged in parallel, a first protrusion, and a second protrusion, said chisel grooves each having a sloping face and a stop face asymmetric with said stop face, sad sloping faces of said chisel grooves being sloped in counterclockwise direction;
• a locking member pivotally mounted to said coupling block and having an engagement portion at an end thereof and a stop portion at an opposite end thereof;
• a first spring member connected between said locking member and said coupling block for generating force enabling clockwise rotation of said locking member;
• a limiter pivotally mounted to said coupling block and having a first end and a second end at two opposite ends;
• and
• a second spring member connected between said limiter and said coupling block for generating force enabling counterclockwise rotation of said limiter;
• wherein
• when said first and second motion arms are at a normal position, said engagement portion of said locking member is inserted into one of said chisel grooves of said second motion arm, said stop portion of said locking member is stopped at said protruding rod of said coupling block, and the first end of said limiter is stopped at an outside of said stop portion;
• when said second motion arm is turned counterclockwise relatively to said coupling block to expand a contained angle between said first and second motion arms, said engagement portion of said locking member is moved over said sloping face of said respective chisel groove and then forced by said first spring member into engagement with a next chisel groove;
• when said second motion arm is turned clockwise relatively to said coupling block to reduce the contained angle between said first and second motion arms, said engagement portion of said locking member is stopped against said stop face of said respective chisel groove, thereby causing said second motion arm to drive said coupling block to turn clockwise relatively to said first motion arm;
• when the contained angle between said first and second motion arms grows beyond a predetermined angle, said engagement portion is forced by said first protrusion to reverse said locking member, thereby causing said stop portion of said locking member to move over the first end of said limiter and then to press on the first end of said limiter against said projecting rod, the second end of said limiter is disposed in a position touchable by said second protrusion, and said engagement portion of said locking member is kept away from said chisel grooves;
• meanwhile, said second motion arm can be turned clockwise relatively to said first motion arm till that the second end of said limiter is stopped at said second protrusion to force the first end of said limiter to move over said stop portion of said locking member and then to press on said stop portion of said locking member against said protruding rod, causing said engagement portion to engage said chisel grooves.