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Mar 31 2025
How to Replace Hydraulic Ram Oil Seals
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In a hydraulic transmission system, seals can be divided into static seals and dynamic seals based on whether there is relative motion between the sealing surfaces. If reciprocating motion occurs between the sealing surfaces, the seals are referred to as reciprocating hydraulic sealing components. If rotational motion occurs, they are referred to as rotational seals.
Common hydraulic sealing components in a hydraulic transmission system can be classified by their structural form into six types: gasket seals, packing seals, extrusion seals, lip seals, combination seals, and dust seals.
The commonly used gaskets in hydraulic transmission systems include cotton-rubber gaskets, rubber gaskets, and metal gaskets. Among these, non-metal gaskets have a lower sealing pressure, while metal gaskets have the highest pressure.
Packing seals achieve sealing under compressive force. They exhibit high frictional resistance and wear quickly, making them suitable for making sliding seals and low-speed, low-pressure rotational seals for low-pressure and low-speed hydraulic cylinders.
Common extrusion seals in hydraulic transmission systems mainly include O-rings, X-rings, and rectangular rings. They offer the advantages of simple structure, easy design, and convenient installation, making them widely used as static and dynamic sealing elements.
Common lip seals include U-shaped fabric-reinforced rubber seals, Y-shaped rubber seals, and YX-shaped rubber seals. They feature simple design and good sealing performance. However, because lip seals have a small contact area and wear easily, higher working pressure is required.
Common combination seals are mainly composed of bell-shaped seals, drum-shaped seals, coaxial seals, and slip-ring combination seals. These seals have low frictional resistance, excellent sealing performance, and long service life. As a result, nearly all high-pressure and medium-high speed hydraulic cylinders in hydraulic transmission systems widely use combination seals.
Dust seals prevent dust particles, rainwater, acid mist, and other harmful gases from invading the hydraulic transmission system. Dust seals used for the components of hydraulic cylinder pistons and piston rods are called "dust rings," while those used for rotary shaft components of hydraulic motors are called "oil seals." Dust rings and oil seals are generally made from rubber materials with good elasticity.
