Abstract: An improved mechanical donut and donut assembly in which donuts made of plastic materials are formed in segments that facilitate installation, removal and/or replacement for manufacture and maintenance. The donuts of the preferred embodiments are made of urethanes, especially polyurethane, while fastening members such as threaded bolts are made of nylon. The relative characteristics of the urethanes and nylon are such as to facilitate a self-tapping feature for the nylon bolt.

Abstract: An improved particulate handler that includes one or more elastic sheets that are particularly effective in facilitating the easy and complete removal of particulate from transporters or containers such as railroad cars, dump trucks, chutes and the like. The combination of the elastic sheets and supporting walls overcomes the problem with sticking of particulates to the interior surfaces and facilitates smooth and easy movement and/or removal under the influence of gravity and changes in tensile stresses and stretch that develop in the sheets during loading, unloading and conveying.