Hydraulic seals - oil seals can be used as dustproof seals, but when dust is serious or to protect other seals, special dustproof seals are often used.
The dust seal of the hydraulic seal is multi-rubber, the pneumatic machinery is multi-felt (square or trapezoid), the hydraulic cylinder of the aircraft and the cold zone work is metal in order to deal with the outside of the piston rod icing, and the chemical department is also metal to prevent the adhesion on the piston rod.
The square or trapezoidal dust ring belongs to the packing seal in the sealing mechanism, and the dustproof ability is related to the tightness of the contact, the tighter the contact, the better the dustproof ability, but the greater the friction resistance. The wedge dust ring is actually no different from the lip ring, which relies on the contact force of the lip tip to scrape away dust and dirt. Its friction resistance is small, but the Angle between the lip tip and the shaft surface has a great impact on the sealing and wear, and its dust prevention efficiency. When the lip tip is outward, the included Angle can be obtained as long as it is greater than 4°, and the dust proof effect is not good when the lip tip is inward.
The contact state between the lip and the shaft surface also directly affects the dustproof effect and the wear of the lip. Several common contact conditions, including normal contact state, thin oil film, good dust effect, less wear; The interference amount is too large, the contact is too tight, and the contact surface is wide, the contact Angle is changed, the lip tip is warped, not only the dustproof effect is poor, but the friction resistance is large, the lip tip contact is not sufficient, the friction is not large, but it can not be dustproof; The contact Angle of the lip tip is too large, the dust-proof effect is short, it is easy to wear, and it becomes the cause of serious oil leakage.
Pneumatic hydraulic seals - dust-proof seals are extremely important to protect critical hydraulic equipment components. Infiltration of dust will not only wear the seal, but also greatly wear the guide sleeve and piston rod, impurities into the hydraulic medium, will also affect the function of the operating valve and pump, in the worst case, may also damage these devices. The dust ring can remove any dust on the surface of the piston rod, but does not damage the oil film on the piston rod, which is also beneficial to the lubrication of the seal.