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1. Main performance: The cross-section of the Y-shaped seal ring is Y-shaped, making it a typical lip seal. Based on the different ratios of height to width of their cross-section, they can be classified into various types such as standard type, narrow type, and Yx type. If we consider whether the heights of the two lips are equal or not, then they can be divided into Y-shaped seals with equal-height lips that are suitable for both shafts and holes, as well as Y-shaped seals designed specifically for use in holes, as shown in the figure below. Y-shaped seals are widely used in reciprocating seal systems, and their service life is longer than that of O-shaped seals. The applicable working pressure of the Y-shaped seal ring is not greater than 40 MPa, and the working temperature ranges from -30°C to +8030°C. Operating speed range: 0.01~0.6 m/s when made of nitrile rubber ； When made of fluororubber, it is 0.05~0.3 m/s; when made of polyurethane rubber, it is 0.01~1 m/s. For Y-shaped sealing rings, polyurethane rubber provides the best performance in terms of sealing ability, service life, and maximum operating pressure when no retaining ring is used. Performance characteristics of Y-shaped seals: 1) Reliable sealing performance ； 2) Low frictional resistance, smooth motion ； 3) Good pressure resistance, suitable for a wide range of pressures ； 4) Simple structure, low cost ； 5) Easy to install. 2. Sealing principle: The Y-shaped seal ring relies on its flanged edges to make contact with the mating surfaces of the sealing pair, resulting in linear contact. Under the pressure of the medium, a \"peak\" contact pressure is generated; the higher the pressure, the greater the stress. When the coupling components move relative to each other at operating speed, a layer of sealing fluid is formed between the sealing lip and the sliding coupling surface, thereby achieving a sealing effect. After the sealing lip edge is worn, it has a certain degree of automatic compensation capability due to the pressure of the medium. The figure below shows a shaft Y-ring with a secondary lip. After each back-and-forth movement, a small amount of liquid (working medium) remains between its main and secondary lips. As the number of reciprocating movements increases, the residual liquid will fill the space between the main and secondary lips, creating a special \"enclosed area\". When the main lip is in operation, since the liquid within the \"enclosed area\" is incompressible, the pressure there is much higher than the operating pressure inside the small chamber (as shown in the figure above). At this time, the contact stress between the secondary lip and the coupling surface is also much greater than the contact stress between the primary lip and the coupling surface. Therefore, when the shaft extends outward, it forces the liquid in the \"enclosed area\" to be pushed back into the small cavity, thereby creating a reliable sealing condition and improving the sealing performance of the Y-shaped seal. “The higher the pressure within the \"enclosed area,\" the greater the contact stress of the secondary lip on the coupling surface, and thus the better the sealing performance. 3. When installing a Y-shaped seal, its lip must face the side with higher pressure in order to provide sealing functionality. To prevent the root of the Y-shaped seal from being squeezed into the gaps in the sealing interface due to plastic deformation of the material under high pressure, it is necessary to control the fit clearance δ between the sliding coupling components so that it does not exceed the maximum value c specified in the figure below, as shown in figure a. For Y-shaped seals subjected to a working pressure greater than 16 MPa, in order to ensure their service life and prevent the root of the seal from being forced into the fit gap, a retaining ring should be installed at the root of the seal, as shown in figure b below. To prevent the Y-shaped seal from flipping or twisting during back-and-forth movement, and thus to maintain the stability of its motion, a support ring can be installed at the lip of the Y-shaped seal, as shown in the figure below. The support ring is equipped with evenly distributed guide holes, which allow the pressure medium to act on the lip of the seal through these holes, thereby keeping the two lips apart and ensuring that the Y-shaped seal maintains its proper shape and thus delivers good sealing performance. For wide Y-shaped seals, the width of their cross-section is twice or more than their height. This type of sealing ring does not flip or twist in the groove, so a support ring is not required.