Answer: A. Hydrostatic guide rail
The guide rail of the mechanical transmission structure of the CNC machine tool feed system is a hydrostatic guide rail.
Hydrostatic guide rail is a key component of the mechanical transmission structure of the feed system of CNC machine tools, which can effectively bear the load, reduce friction, and improve the motion accuracy and life.
The hydrostatic guide rail makes the sliding parts slide on the guide rail surface by generating an oil film with a certain pressure on the guide rail surface, so as to achieve high-precision and high-efficiency processing.
Rolling guide rails and plastic guide rails are usually used in the transmission structure of general mechanical equipment, while pneumatic guide rails are guide rail structures that use gas pressure to push the movement of sliding parts, and they are not suitable for the requirements of mechanical transmission structure of CNC machine tool feed system.
Therefore, the answer is A. Hydrostatic guides.