GB/T 726-1994往复式内燃机 旋转方向、气缸和气缸盖上气门的标志及直列式内燃机右机、左机和发动机方位的定义Reciprocating internal combustion engines-Designation of the direction of rotation and of cylinders and valves in cylinder heads and definition of right-hand and left-hand in line engines and loca