In the construction of machinery, and more particularly in the design of aircraft engines, frequently spanner nuts are utilized to secure gears or wheels on threaded shafts. A spanner nut is generally a circular piece of metal, having a central threaded aperture adapted to engage the threaded end of a shaft. The spanner nut includes a plurality of locking recesses spaced around the circumference thereof to facilitate the tightening of the nut. More specifically, in one type of spanner nut, generally rectangular recesses are formed in the perimeter thereof. In another type of spanner nut, rectangular recesses are formed in one of the planar faces of the nut. Spanner nuts, rather than the more common hexagonal nuts are utilized in applications, such as aircraft engines, where the total weight of the device must be minimized. More specifically, when dealing with large diameter shafts, the associated hexagonal nuts are relatively massive. In contrast, spanner nuts, which can be substituted for hexagonal nuts in many applications, are relatively lightweight. Thus, in a typical aircraft engine, the gear boxes and shafts are provided with spanner nuts of various diameters to reduce the overall weight of the engine.
Heretofore, wrenches designed to accommodate spanner nuts have been designed with fixed diameters. More specifically, prior art wrenches are designed to be used with a spanner nut having a particular diameter. Each prior art wrench is provided with a plurality of axially projecting tangs which correspond to the radial location of the locking recesses in a particular nut. Thus, in order to work on an aircraft engine, which is often provided with fifteen or more spanner nuts of different diameters, it is necessary for the mechanic to have at least fifteen different sized wrenches, corresponding to the nuts to be tightened. Clearly, the relatively large number of wrenches necessary to work on an engine is both inconvenient and expensive. In addition, when a manufacturer produces an engine, a spanner nut will often be used which conforms to the particular design requirements of the shaft, but which will not be of a standard size. In the latter situation, it is necessary to have a special wrench fabricated to accommodate the non-standard spanner nut. The need to order or fabricate an atypical wrench often results in substantial production delays. Accordingly, it would be desirable to provide an adjustable wrench which can accommodate a plurality of spanner nuts having various diameters. By this arrangement, the necessity of providing a large number of different sized spanner wrenches is eliminated.
Therefore, it is an object of the subject invention to provide a new and improved wrench head which is adapted to accommodate spanner nuts of various diameters.
It is another object of the subject invention to provide a new and improved wrench head having inserts which are radially adjustable to accommodate various spanner nuts.
It is a further object of the subject invention to provide a new and improved adjustable wrench head which is provided with sufficient structural rigidity to withstand conventional torque loads.