If you need the content of Roloff/Matek—i.e., practical machine element design calculations in line with European standards—here is a curated list of legitimate replacements, some of which are freely available as PDFs or via university libraries.
If you cannot locate an English PDF of Roloff/Matek, or if you need immediate access to machine element data, consider these alternatives: roloff matek maschinenelemente pdf english
The diagrams in Roloff/Matek are legendary. They clearly illustrate complex assembly situations, fits and tolerances, and stress distributions. If you need the content of Roloff/Matek—i