12B-1 finished bore sprockets

12B-1 finished bore sprockets are simplex hub sprockets for 12B-1 chain of 3/4" (19.05 mm) pitch to DIN 8187 / ISO 606. They have a bored shaft hole and a cut keyway.

12B-1 finished bore sprockets for agricultural machinery and conveyors

12B drives work in agricultural machinery, scraper conveyors, presses and construction machinery, where the sprockets are already quite heavy and machining them takes more time. A finished bore sprocket saves this work - you fit it on a keyed shaft and the drive is running again.

12B-1 sprockets in C45 steel with bore and key

12B-1 simplex sprockets in C45 steel with bores of various diameters - the D value is given in the product name. The largest bores are available on sprockets with more teeth, which have a more massive hub.

Why large bores only on larger 12B-1 sprockets - questions

Why are large bores only available on larger sprockets?

The bore and keyway must fit in the hub while keeping a safe wall thickness. A sprocket with fewer teeth has a smaller hub, so its maximum bore is also smaller.