Holless Wilbur Allen changed the face of archery forever when he decided that he could make a better bow by sawing off part of the limbs of a recurve bow and attaching pulleys to the new ends. In the early 1960s this mechanic decided to try improve the current design of bows by using the pulley’s mechanical advantage to pull more weight than normally possible.
As Holless was experimenting with different ways of using the pulleys, he discovered that by using one with an offset axle (eccentrics), he created one of the biggest advantages of compound bows, let-off. When coupled with a cam shape instead of a round pulley, the draw length, weight and force curve could be changed and improved.
On June 23, 1966 Holless applied for a patent “Archery bow with draw-force multiplying attachments”; in December of 1969 it was granted. Holles joined forces with a current bow manufacturer, Tom Jennings, and the first compound bows began to be manufactured.