Toothed wheels go along with chain ends DIN 764 and CICSA chains LH.
They can be manufactures in one piece or two halves (assembled with transversal screws) for an easier disassembling.
Toothed wheels for scrapers and conveyors are made of GS-800 spheroidal graphite cast iron or special case hardened alloy steel, while toothed wheels for traction conveyors and other applications are made of quenched alloy.