1)The material for U-joint cross is 20Cr or 20CrMnTi alloy steel(hardness after heat treatment is HRC 58 -63 degree) 2)Thematerial for bearing caps is 20Cr or 20CrMnTi alloy steel(hardness after heat treatment is HRC 58 -63 degree); 3)Thematerial for needle roller is GCr15(hardness after heat treatment is HRC 59 -63 degree); 4)The material for circlip is 65Mn; 5)Cementite deepness:0. 8-1.3mm