Formation of sealing effect

Dynamic seal is divided into non-contact seals and contact seals. Non-contact seal mainly a variety of mechanical seals, such as: graphite packing ring, floating ring seals; rubber composite seals and rubber seals belong portfolio contact seals, relying on filling in a sealed chamber in the pre-compression force, leakage channel blocking sealing effect is obtained. Seals used in hydraulic systems are mostly static seal (seal), reciprocating seals (piston, piston rod seal) and rotating seal.

Sealing material and hydraulic oil (fluid) will affect the compatibility of the sealing effect of the formation:
The hydraulic fluid source of particulate contamination of the seal material is incompatible with the hydraulic oil and the resulting "chips" or "debris." Seals for "swelling" is damaged resulting "debris" or "extraction" is not out of a combination of inorganic and filling reinforcing material to id cable ties damage and failure, while the formation of pollution of hydraulic oil oil deterioration resulting failure.
Hydraulic vane pump system widely used in the state of working pressure greater than 6.9MPa, the wear problem becomes prominent, and therefore the hydraulic fluid used antiwear agent; in order to meet the high temperature heat and flame near the hydraulic system, use of anti- burning phosphate, water - glycol hydraulic fluid, oil, and oil-water emulsions and so on. And should "use" born of the antioxidant, rust and other types of composite additives configured for different uses hydraulic oil (liquid) variety. Such as: Anti-wear hydraulic oil compound type zinc-type (ash-free) anti-wear hydraulic oil compound, is a hydrocarbon sulfides, phosphates, phosphites, etc., as well as while sulfur, phosphorus and nitrogen SPN three elements extreme pressure anti-wear agents. In extreme pressure industrial gear oils, also PS-type extreme pressure agents based.
Seals have a "swelling" or "extraction" because the hydraulic oil additives of various chemical elements contained in its concentration, based on "like dissolves like" principle, for different sealing materials have different impact, but also both sealing material medium resistance. For example: Shell Omala 320 gear oils and gear oils Shell Omala 460 shows polar phosphorus (P) element concentrations in 300ppm or so, so for containing acrylonitrile butadiene rubber which has a polar group, with excellent oil resistance, but not suitable for this type of oil medium conditions.
With the hydraulic oil (oil) species continue research in order to improve oil (liquid) the performance of a variety of anti-wear, extreme pressure additives, metal deactivators, demulsifiers and anti-foam additives, the material of the rail car seals need to experiment to validate.