The servicing and repair of internal combustion engines oftentimes includes the surface finishing of various bearing journals employed in the engine, such as the main bearing journals and the rod journals of the crankshaft thereof. Machining of such journals, to bring them into acceptable tolerances, must be preceded by a gauging operation to determine the surface conditions thereof. One approach is to engage each cylindrical journal surface with a gauge to measure the irregularities of such surface. A pickup of the gauge normally traverses the journal surface and reciprocates to either provide a read-out on a suitably calibrated dial or to provide an electrical signal directly proportional to vertical displacement of the pickup.
Gauges of this type are normally not available at a servicing and repair center and thus other gauging procedures must be utilized. Furthermore, the use of such gauges oftentimes requires removal of the tested part, such as a crankshaft, from the engine resulting in substantial down-time of the engine and increased costs.
Another conventional procedure for determining surface irregularities on a particular journal is to provide the worker with a plurality of specimens which are replicas of various surface textures. The worker can compare such specimens to the journal surface under consideration by sight and feel and thus determine whether or not the journal surface requires machining to bring it within the desired tolerance. In particular, the worker may run his fingernail or a coin over the specimen displaying the desired surface finish thereon, as well as the journal surface, to compare the surface textures thereof. Although this surface texture comparison procedure has proven effective, it is obvious that it is prone to error on the part of the worker.
USPTO Backgrounds
USPTO Backgrounds