You'd be surprised what you'll find in a hydraulic system. Bird bones, feathers, sandwiches and shop rags are just a few of the items routinely found. In fact, just about anything that's used on a typical shop floor can end up in a hydraulics system as contamination. Bird Bones and Sludge is a book published by Eaton Hydraulics Training Services that provides a comprehensive reference on contamination control of hydraulic systems. Written for individuals with a basic knowledge of hydraulics, the book's purpose is to help people find ways to identify and eliminate particles as small as a few microns in order to prolong hydraulic machine and component life.