A Y-type seal ring is a lip seal with a "Y"-shaped cross-section. It is mainly used on reciprocating parts (such as piston rods and pistons) in hydraulic and pneumatic systems, with the core function of preventing leakage of fluids like oil, gas, and water while maintaining system pressure.
Its key advantage lies in the "self-sealing effect": when there is no pressure, the lip only lightly adheres to the sealing surface; as the system pressure increases, the lip is pressed more tightly, and the sealing effect strengthens with higher pressure. It can adapt to medium and high-pressure scenarios (usually up to 32MPa) and offers higher sealing reliability than ordinary O-rings.
It is simply divided into three types based on application scenarios to meet different needs:
- Shaft-mounted type: Installed on moving shafts to prevent fluid leakage from the gap between the shaft and bore.
- Bore-mounted type: Mounted in the groove of fixed bore walls to seal the mating surface between the piston and bore.
- YX-type: Features a more regular cross-section, is less prone to flipping, and is suitable for high-pressure or high-speed reciprocating motion, requiring no additional support parts.
Choosing the right material is crucial for sealing performance. Three common materials are as follows:
- Nitrile Butadiene Rubber (NBR): Oil-resistant and cost-effective, suitable for ordinary hydraulic oil and water systems at -40°C to 120°C (e.g., hydraulic cylinders of small machine tools).
- Polyurethane (PU): Wear-resistant and high-pressure resistant (up to 40MPa), with a service life 2-3 times longer than NBR. It is commonly used in construction machinery (e.g., hydraulic cylinders of excavators) and automotive gearboxes.
- Fluororubber (FKM): High-temperature resistant (-20°C to 260°C) and resistant to strong acids and alkalis, suitable for sealing in chemical pipelines and high-temperature equipment.
- Hydraulic/pneumatic equipment: Used for piston sealing in hydraulic jacks and pneumatic cylinders to prevent pressure loss.
- Automotive field: For sealing piston rods in gearboxes and fluids in brake systems.
- Construction machinery: For sealing hydraulic cylinders in loaders and cranes, withstanding high pressure and frequent motion.
- Correct installation direction: The lip must face the pressure source (e.g., if there is pressure inside the cylinder, the lip should face the inner side of the cylinder); reversing the direction will cause direct leakage.
- Pre-lubrication: Before installation, apply lubricant compatible with the medium (e.g., hydraulic oil, special sealing grease) to the lip to avoid scratching during installation.
- Avoid collisions: Use special tools for auxiliary installation to prevent metal edges (e.g., cylinder ports) from damaging the seal ring.
- Regular inspection: If cracks, wear, or deformation are found on the lip, replace the seal ring promptly to prevent leakage.
- Advantages: Excellent sealing performance, wide pressure adaptation range, and low friction during motion.
- Disadvantages: Only supports unidirectional sealing (bidirectional sealing requires paired installation in opposite directions) and requires slightly higher installation precision.
In general, the Y-type seal ring is one of the most commonly used reciprocating seals in industry. As long as the right material is selected and installed correctly, it can stably perform its sealing function.
