1. The function of B-B is to express the shape of the sealing groove or oil groove and mark its width and depth dimensions.
2. The main dimensional reference in the length direction is the center of the 62H7 semicircle.
3. The function of the eight-shaped groove may be to install the sealing strip, which is the sealing strip. It may also be an oil tank. The specific function can only be determined by looking at the assembly drawing.