Lubricating moving mechanical parts in UHV is a big challenge because lubricants usually have a high vapour pressure and cannot be used. There are, however, some solutions. One is to use a dry lubricant with a low vapour pressure such as graphite or boron nitride. But there are also UHV compatible hydrocarbon-based lubricants with a sufficiently low vapour pressure. A critical issue when using these is always that their presence reduces the maximum possible bakeout temperature for the system.