: Where the hub must slide along the shaft under load.
Because the flanks are parallel, the forces are purely tangential. This eliminates the radial "bursting" force on the hub, allowing engineers to use low hub wall thicknesses . din 5464 standard pdf
Compared to the DIN ISO 14 standard, the DIN 5464 "heavy series" features more teeth to provide a higher load capacity. Standard Status & History Current Version: DIN 5464:2010-03 , published March 1, 2010. Previous Version: DIN 5464:1965-09 (withdrawn). Document Length: Approximately 9 pages. Accessing the PDF : Where the hub must slide along the shaft under load
The best way to obtain the current is through national standards bodies: published March 1