Patent ID: 7878095
Filing Date: 2011-02-01
Classification: B25B

Abstract:
1. A reciprocatable open end wrench comprises a handle and at least one driving head, the driving head being located at one end of the handle, wherein the driving head comprises: a first jaw includes a first clamping surface; a second jaw, the second jaw is disposed to correspond to the first jaw and includes a concave arcuate surface disposed on the inner side thereof; a swing member includes a second clamping surface and a convex arcuate surface, between the first clamping surface and the second clamping surface is formed a working area, the radius of the convex arcuate surface is equal to that of the concave arcuate surface, and the swing member allows to slide relative to the concave arcuate surface; a bottom surface, the bottom surface is located between the first jaw and the swing member, and the bottom surface includes a midpoint for dividing the width of the working area into two parts; a stop portion, the stop portion is fixed between the second jaw and the swing member, as the open end wrench rotates a fastening element in one direction, the stop portion resists against the torque of the swing member; and a returning device, one end of the returning device is biased against the swing member so that the swing member moves close to the stop portion at any time; wherein between the concave arcuate surface and the convex arcuate surface is provided with an engagement structure which includes a slot member and a peripheral protrusion, both are disposed around the arcuate surfaces, so as to engage the swing member with the second jaw; wherein the thicknesses of the swing member and the second jaw are equal; wherein on the curve line of the convex arcuate surface of the swing member forms a center, and the height difference between the center of the convex arcuate surface and the midpoint of the bottom surface is H, the width of the working area is S, wherein the relation between S and H is wherein a second slot of the engagement structure is mounted on the convex arcuate surface of the swing member, and a second peripheral protrusion of the engagement structure is fixed on the concave arcuate surface of the second jaw, the radius of the second peripheral protrusion is larger than that of the second slot.