I hope an expert can tell me the names and functions of various points on the compressor piston

In one diagram, the piston has large grooves at both ends, within which guide rings are fitted. The purpose is to fix the distance between the piston body and the cylinder wall ； The narrow groove houses a sealing ring, whose primary function is to provide sealing between the piston body (guide ring) and the cylinder wall. It should be noted here that the manufacturing process for the sealing rings includes seams, and it is required that the seams of each sealing ring not be in a straight line during installation, in order to prevent air leakage from one seam to another. In the second diagram, the piston rod serves to transmit power; the notch acts as the fixing point for installing and removing the piston from the piston rod (the location where the wrench is used). Figure 3 shows what appears to be a threaded protection sleeve, or guide protection sleeve, for installation and removal. Figure 4 shows the locking anti-loosening nut connected to the crosshead, or what is also known as the connection mechanism. (Parody language explanation, for reference only: lol)

The answer on the second floor was great; I’ve learned something from it. Thank you