Patent ID: 8056448
Filing Date: 2011-11-15
Classification: B25B

Abstract:
1. In a multi-size wrench comprising at least one head with an engaging hole for engaging with fasteners and a handle portion, an inner surface of the engaging hole of the head being formed by six arc-shaped engaging concaves and six arc-shaped connecting convexes which are alternatively connected to each other in such a manner that between each two neighboring engaging concaves is connected a connecting convexes such that the engaging hole of the wrench is applicable to both a Metric hexagonal fastener and a correspondingly sized English hexagonal fastener, the improvement comprising: each of the engaging concaves includes a first engaging end, a second engaging end and a middle engaging point, and each of the connecting convexes also includes a first connecting end, a second connecting end and a middle connecting point, an angle between the first and second engaging ends of the engaging concaves with respect to a center of the engaging hole is 49˜51 degrees, an angle between the first connecting end and the middle connecting point of the engaging convexes with respect to the center of the engaging hole is 4˜6 degrees, so that the engaging hole of the wrench is also applicable to a correspondingly sized torx fastener.