JCB Seal Kit 991-00095

Hydraulic cylinder repair seal kits JCB Seal Kit 991-00095

Description Of Hydraulic Cylinder Seals

Hydraulic cylinder seals are used to seal the opening between various components in the hydraulic cylinder. They are designed to retain hydraulic fluids, exclude solid or liquid contaminants, and maintain hydraulic pressure. These tasks require a variety of different seal designs and performance-enhancing features. Seal material must conform to irregularities in metal surfaces to block fluid passage. To adjust to clearance gap size changes, the seal must expand or compress rapidly to follow dimensional variations. Finally, to resist being extruded into gaps, the seal must have sufficient modulus and hardness to withstand shear stress produced by system pressure. Successful sealing involves containment of fluid within fluid power systems and components while excluding contaminants. The surfaces in contact with a seal determine what type to use. The surface can either be static or dynamic—in motion or without movement. Static seals are typically used when there is no relative motion between mating surfaces. Dynamic seals are the opposite. They are used when there is motion between surfaces. This can be either reciprocating or oscillating motions.

Types of Hydraulic Seals

Dust seal It is installed in the inner side of the end cover of the hydraulic cylinder, the main sealing lip is exposed to the air, and the sealing medium is the attached dirt such as dust, sand, rain and frost, so as to prevent the external dust and rain from entering into the sealing mechanism and affecting the sealing performance. The viscosity of the hydraulic oil and the function of scratching the sealing lip of the internal seal. Dustproof seal ring is divided into many types, numbers and sizes, including polyester and metal skeleton, so it is more widely used and targeted. Advantages: excellent wear resistance, extrusion resistance, impact resistance, small compression deformation, wide adaptability and easy installation. Piston rod seal It is installed in the dustproof seal inside the end cover of the hydraulic cylinder to prevent the leakage of hydraulic oil. It is one of the main pressure bearing components. It bears pressure in one direction and directly contacts with the hydraulic oil. It is required to have good pressure retaining performance in static state, high pressure bearing in motion, good sealing performance, small friction coefficient and strong anti extrusion ability. There are many cross-section forms and materials of piston rod seal, so different cross-section forms and materials are selected according to different working environment. Support ring It is installed in the inner side of the end cover of the hydraulic cylinder, and its main function is to support the piston rod; it can prevent the poor sealing effect and short service life caused by the uneven pressure on the rod seal caused by the non vertical force on the piston rod. Guide tape Installed on the piston, the main function is to guide the piston to make a linear motion, prevent the piston from internal leakage caused by uneven force and reduce the service life of the seal. The service life of guide belt and support ring directly affects the service effect and service life of piston seal and piston rod seal, so the requirements for guide belt and support ring are also higher, such as small friction coefficient, high hardness and long service life. There are many forms of guide belt and support ring, and some are used in combination with the main seal. Piston seal Installed on the piston, the main function is to seal the gap between the piston and the cylinder, to prevent hydraulic oil leakage. Piston seal is the main seal in the hydraulic cylinder, which is bidirectional pressure bearing and one of the most important seals that the hydraulic cylinder can bear. The main requirements for piston seal are good sealing effect, good pressure maintaining effect under static state, strong pressure bearing capacity during movement, anti extrusion, small friction coefficient, long service life, etc. There are many forms of piston seal, and the most suitable one is selected according to different use environment. Static seal The end cover static seal ring is installed at the contact position between the outer circle of the end cover and the inner wall of the hydraulic cylinder, and the piston static seal ring is installed between the piston and the piston rod. They are all static seal rings in the hydraulic cylinder. The static seal of the end cover is to prevent the hydraulic oil from leaking out from the gap between the end cover and the cylinder barrel. It is required to have strong anti extrusion ability and good sealing effect on one side. The static seal of the piston is to have two-way pressure bearing to prevent the hydraulic oil from leaking out between the piston and the piston rod. It is required to have strong anti extrusion ability and good sealing effect. The common static seal ring is O-ring with retaining ring. Rotary seal It is installed on the shaft of hydraulic pump and hydraulic motor to prevent the working medium from leaking to the outside of the shell along the shaft and the external dust echo from invading into the body. The pressure bearing capacity of general oil seal is poor, generally 0.2-0.3mpa, the pressure bearing capacity of fluororubber pressure seal is 0.25-0.7mpa, and the maximum pressure bearing capacity of high pressure oil seal is 40MPa.

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