BRECO同步带同步带轮各种规格主要部位理论尺寸表（挡边尺寸仅供参考）XXH型（节距=31.75mm）规格齿数节径d外径do档边直径df档边内径db档边厚度h18XXH18181.91178.871991575.519XXH19192.02188.972091675.520XXH20202.13199.082191775.521XXH21212.23209.192291875.522XXH22222.34219.292391975.524XXH24242.55239.5025XXH25252.66249.6126XXH26262.76259.7227XXH27272.87269.8230XXH30303.19300.1440XXH40404.25401.2148XXH48485.10482.0660XXH60606.38603.3372XXH72727.66724.61)