Crankshaft mechanism having a variable stroke and a press employing said mechanism

A crankshaft mechanism comprising

• housing;
• an eccentric crankshaft including a first cylindrical portion having a first diameter and being rotatable within said housing about a longitudinal axis, said crankshaft further including a second portion having a second diameter greater than said first diameter and a first radial bore, the center of said second portion being displaced radially from said longitudinal axis;
• an eccentric sheave rotatably mounted on the outer circumference of the second portion of said eccentric crankshaft and having an outer circumference with a center displaced radially from the center of the second portion of said crankshaft, said eccentric sheave having a second radial bore therein;
• a connecting member rotatably mounted on the outer circumference of said eccentric sheave and having a third radial bore therein, said first, second and third radial bores being in alignment when said crankshaft is at a predetermined bottom dead center position;
• locking means located within said radial bores, said locking means being movable to a first position wherein it is within said first and second bores and locks said crankshaft to said sheave, said connecting member being movable with respect to said sheave when said locking means is in said first position, said locking means being further movable to a second position wherein it is within said second and third bores and locks said sheave to said connecting member, said sheave being movable with respect to said crankshaft when said locking means is in said second position;
• and
• actuating means for positioning said locking means at one of said first and second positions.