机械密封是靠一对或数对垂直于轴作相对滑动的端面在流体压力和补偿机构的弹力(或磁力)作用下保持贴合并配以辅助密封而达到阻漏的轴封装置。常用机械密封结构由静止环(静环)1、旋转环(动环)2、弹性元件3、弹簧座4、紧定螺钉5、旋转环辅助密封圈6、和静止环辅助密封圈8等元件组成，防转销7固定在压盖9上以防止静止环转动。
Mechanical seal is a kind of shaft seal device which relies on a pair of or several pairs of end faces which slide relatively perpendicular to the shaft under the action of fluid pressure and the elastic force (or magnetic force) of compensation mechanism to keep close and match with auxiliary seal to prevent leakage. The common mechanical seal structure is composed of static ring (static ring) 1, rotating ring (dynamic ring) 2, elastic element 3, spring seat 4, set screw 5, auxiliary seal ring 6 of rotating ring, auxiliary seal ring 8 of static ring, etc. the anti rotation pin 7 is fixed on the gland 9 to prevent the rotation of static ring.