Engagement of Metal Debris into a Gear Mesh
A series of bench top experiments was conducted to determine the effects of metallic debris being dragged through meshing gear teeth. A test rig that is typically used to conduct contact fatigue experiments was used for these tests. Several sizes of drill material, shim stock, and pieces of gear teeth were introduced and then driven through the meshing region. The level of torque required to drive the "chip" through the gear mesh was measured. From the data gathered, chip size sufficient to jam the mechanism can be determined. INTRODUCTION In some space mechanisms the loading can be so high that there is some possibility that a gear chip might be liberated while in operation of the mechanism [1-5]. Also, due to the closely packed nature of some space mechanisms and the fact that a space grease is used for lubrication, chips that are released can then be introduced to other gear meshes within this mechanism. In this instance, it is desirable to know the consequences of a gear chip entering in between meshing gear teeth. To help provide some understanding, a series of bench-top experiments was conducted to engage chips of simulated and gear material fragments into a meshing gear pair. One purpose of the experiments was to determine the relationship of chip size to the torque required to rotate the gear set through the mesh cycle. The second purpose was to determine the condition of the gear chip material after engagement by the meshing gears, primarily to determine if the chip would break into pieces and to observe the motion of the chip as the engagement was completed. This document also presents preliminary testing done with metal debris other than chips from gears, namely steel shim stock and drill bits of various sizes and diameters.