One of the best 3D repositories of Industrial specifications and 3D models in various formats.
Maybe the largest repository of industrial components online. Most of parts have at least proper drawing with dimensions if not a full 3D model and for many drawing suits.
A ever growing community of Inventor/Catia/Solidworks designers with various 3D models in various formats.
Not a proper industrial repository but still a good source of 3D models in various formats. No specifications or dimensions.
Sketchfab is not per say a 3D model repository but more a showcase. It still offers various interesting 3D models for download. Also some of 3D models have animations.