Socket wrenches typically include a plurality of sockets that are interchangeably attached to a wrench arm, for example, a ratchet arm. The plurality of sockets cover a range of standard and metric sizes and includes socket point shapes such as square, hexagon, octagon and double hexagon or dodecagon. The sizing fit between the socket size and the fastener, e.g., bolt, to be tightened or loosened is important, as stripping or rounding of the bolt head can result from a sizing mismatch. In addition, conventional sockets apply pressure on the corners of the bolt head. For bolt heads manufactured from softer metals, this enhances the risk or stripping or rounding. For painted bolts, epoxy coated bolts and chromed bolts, pressure applied to the corners of the bolts results in chipping or removal of the paints or coatings. As these paints and coatings are important for corrosion prevention, the chipped portions must be fixed by touching up the chipped portions in-situ after the bolt has been installed and tightened. This is a labor intensive process that is exasperated for applications where large numbers of fasteners are used and the fasteners are located in remote locations, e.g., bridges and towers.
Attempts to provide improved contact between a socket and the head of a bolt include using a cam mechanism that attempts to grasp or contact the individual faces of the head of a bolt. These mechanisms translate the rotational motion of the socket and the torque applied by the wrench arm to radial forces impacting on the faces of the head of a bolt. In general, these cam mechanism sockets include custom arrangements of sockets with custom internal parts. This requires an entire new set of sockets. In addition, the arrangement and interaction of the internal parts can be complicated, increasing costs and he potential for mechanical wear and failure. These cam arrangement mechanisms still only contact a portion of each face of a bolt head and apply lateral forces to the each face, i.e., forces along the face of the bolt. Lateral forces and partial contact, which permits movement of each face relative to a point of contact, still present the risk of chipping or removing a coating or engaging the corners of the head of a bolt.
Other attempts use inserts placed in existing sockets. These attempts include inserting magnets to hold a bolt for positioning and installation. In addition, the inserts form a more rounded profile to the interior of the socket to compensate for a bolt head that is stripped or rounded. Inserts include elastomeric components that grip and hold or cushion the head of the bolt. However, these elastomers will also deform under applied forces and will loose elasticity over time. In addition, these inserts do not utilize cam mechanisms that translate the rotational forces to radially forces. Therefore, devices are desired that provide for improved contact between a socket and a bolt head and that eliminate the risk of damage to coatings applied to the bolt head.