Amphibious bulldozers; attachments for bulldozers; bulldozers; swamp bulldozers; attachments for excavators; bucket excavators; double shell grippers for excavators; excavators; excavators (earth working machines); excavators for hydraulic expansion machines; loader buckets for excavators; mini excavators; power trains for mechanical excavators; power transmission apparatus for mechanical excavators; power transmission belting for mechanical excavators; power transmission belts for mechanical excavators; trenchers (excavators)