Early engines used O-rings (also called packing rings or toric joints) as seals (first patented in 1896). These are just mechanical gaskets in the shape of a torus (a circular ring--like a lifesaver), seated in a groove and compressed during assembly between two or more parts. It creates a seal at the interface. However, O-rings require a fluid film to lubricate them. They have limited usefulness in vacuum application and at extremes of temperature. The modern oil seal represents a significant improvement over the simple O-ring because it effectively seals in lubrication and prevents contamination from outside under a wide range of pressures and temperatures.
- Sealing lip: guarantees dynamic and static sealing.
Description
Heavy Duty Wheel Seals and Agricultural Equipment Seals can be divided into AP type, CRS type and ST type. Mainly be used in heavy pollution of agricultural machinery, construction machinery, mining equipment and trucks, buses and other environments. Compared to TC type, with special internal lubrication design, making it closed to the rotary shaft seal and bearing assembly which prevent external dirt effectively; a specially designed multi-lip inside the seal, makes it to achieve the function. Multiple external sealing lip design effectively prevents outside dirt and grease leakage immersion; the internal high-quality grease (butter) prevents muddy and water immersion.
Conventional oil seals
Notes
1) ISO: International Organization for Standardization
2) 2) JIS: Japanese Industrial Standard
The quality of the rubber or rubber fabric used to make an outer case is the same as the quality of the rubber sealing lip. Fabric reinforced rubber is, as the name suggests, rubber reinforced with a fabric.
Leather is probably the oldest of the lip materials still in common use, but the move towards mass production methods has seen a massive increase in the development of synthetic rubbers which lend themselves to accurate and repeatable injection and compression moulding. Nitrile (NBR) is still by far the most common elastomer for “normal” use, whilst Viton® (FKM/FPM) is rapidly replacing Polyacrylate (ACM) and Silicone (VMQ) for high-temperature applications. Viton® also has high resistance to abrasion and chemical attack making it a preferred elastomer. Recent developments in the use of PTFE for Rotary shaft seals has caused widespread interest particularly for high-speed shaft rotation or poor lubrication applications.
Well-balanced in terms of resistance to abrasion and high and low temperatures
Heat resistance
H7 or H8
2. If the nominal bore diameter exceeds 400 mm:
H7