Cylinder clearance measurement shall be accurate

When measuring the cylinder clearance, if the piston skirt is not measured in the direction perpendicular to the piston pin hole, the measurement result will be inaccurate. The structural characteristics of aluminum alloy piston are small at the top and large at the bottom, which is a cone, and the local section is elliptical, so the cylinder clearance along the circumference is not equal. When measuring, it is specified that the clearance in the direction of the ellipse major axis shall prevail, that is, the clearance of the piston skirt perpendicular to the direction of the piston pin hole shall be measured. This measurement is more convenient and accurate. In reciprocating motion, the direction of the piston skirt perpendicular to the piston pin hole is greatly worn due to the effect of lateral pressure. Therefore, when measuring the cylinder clearance, the measurement should be made in the direction of the piston skirt perpendicular to the piston pin hole.