267 GB/T 1567-1979 薄型平键 型式尺寸 Thin flat keys--Types and dimensions
268 GB/T 1840-1989 圆弧圆柱齿轮模数 Modules of cylindrical gear with circular arc profiles
269 GB/T 1974-1980 切向键及其键槽 Tangential keys and keyways
270 GB/T 2362-1990 小模数渐开线圆柱齿轮基本齿廓 Basic rack tooth profile of fine-pitch involute cylindrical gears 271 GB/T 2363-1990 小模数渐开线圆柱齿轮精度 Accuracy of fine-pitch involute cylindrical gears
272 GB/T 2509-1981 滑动轴承铜合金整体轴套形式、尺寸与公差 Copper alloy integrated shaft sleeves for plain bearings--Types, dimensions and tolerances
273 GB/T 2510-1981 滑动轴承铜合金带挡边整体轴套形式、尺寸与公差 Copper alloy integrated shaft sleeves for plain bearings with gears--Types, dimensions and tolerances
274 GB/T 2511-1981 滑动轴承铜合金整体轴套技术条件 Copper alloy integrated shaft sleeves--Technical requirements
275 GB/T 2555-1981 一般用途管法兰连接尺寸 Pipe flange connectors for ordinary use--Mounting dimensions
276 GB/T 2556-1981 一般用途管法兰密封面形状和尺寸 Pipe flanges for ordinary use--Sealing surfaces--Forms and dimensions
277 GB/T 2672-1986 内六角花形盘头螺钉 Hexagon lobular socket pan head screws
278 GB/T 2673-1986 内六角花形沉头螺钉 Hexagon lobular socket countersunk head screws
279 GB/T 2674-1986 内六角花形半沉头螺钉 Hexagon lobular socket raised countersunk head screws
280 GB/T 2685-1981 滑动轴承 粉末冶金筒形轴承型式、尺寸与公差 Powder metallurgy plain bearing--Cylindrical type--Types, dimensions and tolerances
281 GB/T 2686-1981 滑动轴承 粉末冶金带挡边筒形轴承型式、尺寸与公差 Powder metallurgy plain bearing--Rimed cylindrical type--Types, dimensions and tolerances 282 GB/T 2687-1981 滑动轴承 粉末冶金球形轴承型式、尺寸与公差 Powder metallurgy plain bearing--Spherical type--Types, dimensions and tolerances
283 GB/T 2688-1981 滑动轴承 粉末冶金轴承技术条件 Powder metallurgy plain bearing--Technical requirements