A detecting device is disclosed for detecting undesired movement of a shaft such as a wrist pin relative to a bearing such as a wrist pin bearing. The detecting device includes a housing a rod pivotally mounted to the housing, and at least one detecting switch mounted on the housing adjacent the rod. A pointed end portion of the rod engages the shaft. The rod pivots when a point on the longitudinal axis of the shaft moves from a central axis of the bearing. As a consequence, a portion of the rod located adjacent to the detecting switch is pivoted from its normally centered position to an off-center position and actuates the detecting switch.