37 Assembly, maintenance, repair and rental of machines and machine parts for the treatment of materials in the mineral, cement, lime, gypsum, ceramics, refractory, metallurgical and chemical industries; assembly, maintenance, repair and rental of excavators, earth-moving machines, attachments and hydraulic motors for excavators, bulldozers, buckets and attachments for bulldozers, mining machines, crushing mills, primary and secondary crushers, crushers, rammers [machines], mills and rock crushers, wearing parts for crushing machines [machine parts], drainage machines, ore processing machines, finishing machines, conveyors and conveyor systems, assembly line conveyor machines and conveyor apparatus for pits, mobile belt conveyors and roller conveyors, conveyor belts, milling machines, knives and milling cutters for milling machines, track-laying machines, trench-digging machines, shovel excavators [machines], stone-working machines, road construction machines