机械制图中标明 6.125″-4STUB ACME-2G RH 右旋螺纹 大径￠156.08-￠156.82 中径￠153.67-￠154.41

求问各位巨巨，此螺纹标准，急求，多谢！

你所提的这个螺纹，应该是“美制矮牙爱克母螺纹，公称直径6.125英寸，4牙，公差带代号2G，右旋”，具体标准是ASME B1.8-1988，但是标准中貌似只有公称直径到5英寸的，没有6右1/8的，是我感到奇怪的地方。

ACME螺纹基本尺寸（in）公称尺寸牙数大径中径D2，d2小径D（内螺纹）D(外螺纹)D1(内螺纹)D1(外螺纹)1/4160.260.250.21880.18750.17755/16140.32250.31250.27680.24110.23113/8120.3850.3750.33330.29170.28177/16120.44750.43750.39580.35420.34421/2100.520.500.450.400.385/880.6450.6250.56250.500.483/460.770.750.66670.58330.56337/860.8950.8750.79170.70830.6883151.021.000.900.800.7811/851.1451.1251.0250.9250.90511/451.271.251.151.051.03013/841.3951.3751.251.1251.10511/241.521.501.3751.2501.2313/441.771.751.6251.501.48242.022.001.8751.751.7321/432.272.252.08331.91671.896721/232.522.502.33332.16672.146723/432.772.752.58332.41672.3967323.023.002.752.502.4831/223.523.503.253.02.98424.024.003.753.53.4841/224.524.504.254.03.98525.025.004.754.54.48一般用途爱克母螺纹的顶径和底径公差(in)牙数内螺纹外螺纹大径D4小径D1大径d160.010.0050.005140.010.0050.005120.010.0050.005100.020.0050.00580.020.00620.006260.020.00830.008350.020.0100.01040.020.01250.012530.020.01670.016720.020.0250.025注：1.外螺纹的大径公差为0.05P，最小值为0.005in2.内螺纹的大径公差为0.05P，最小值为0.005in3.外螺纹的小径公差为中径公差的1.5倍爱克母螺纹外螺纹的中径基本偏差值（in）公称直径2G，2C3G，3C4G，4C＞≤03/160.00240.00180.00123/165/160.00400.00300.00205/167/160.00490.00370.00247/169/160.00570.00420.00289/1611/160.00630.00470.003211/1613/160.00690.00520.003513/1615/160.00750.00560.003715/1611/160.00800.00600.004011/1613/160.00850.00640.004213/1615/160.00890.00670.004515/1617/160.00940.00700.004717/1619/160.00980.00730.004919/1617/80.01050.00790.005217/821/80.01130.00850.005721/823/80.0120.00900.006023/825/80.01260.00950.006325/827/80.01330.00990.006627/831/40.01400.01050.007031/433/40.01500.01120.007533/441/40.01600.01200.008041/443/40.01700.01270.008543/451/20.01810.01360.0091