| 主权项 |
1. A winch comprising:
a rotatable sheave mounted for rotation and means for application of rotational forces thereto, said sheave having:
a base;two opposed faces with a plurality of generally radially extending alternating primary ridges and valleys circumscribing each of said two opposed faces of said sheave, each of said primary ridges extending outwardly from the base of said sheave in a curvilinear direction curving toward a rotational direction toward which a rope or cord reeved on said sheave is advanced by rotation of said sheave, said primary ridges being positioned at intervals around the circumference of said sheave, said primary ridges projecting a first height above the surface of said valleys,a generally radially extending secondary ridge projecting from the center of the surface of each of said valleys, each of said secondary ridges having a second height that is smaller than said first height, a housing within which said sheave is rotatably mounted, said housing being open for insertion and removal of the rope or cord around said sheave, and, a flattened spring having a lower side that forms a guiding cam surface adjacent to the outer perimeter of said sheave, said spring having a first end pivotally mounted to a slotted shaft affixed to said housing, said spring, when pivoted away from said sheave, allowing insertion and removal of the rope or cord from around said sheave, and when pivoted toward the base of the sheave, maintains the rope or cord in contact with the sheave, and wherein a second end of said spring opposite to said pivotal connection is supported on a block which limits movement thereof toward said sheave, and said block having an angled edge for removal of said rope or cord from said sheave. |
