Shaft seals

Shaft seals (also called oil seals) offer an economical solution for sealing rotating shafts. Shaft seals prevent lubricant leakage and prevent external contamination across a range of applications:

• Gearboxes
• Hydraulic pumps
• Axles
• Power steering columns
• Speed reducers
• Transmissions

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Profile seal types of rotary shaft seals

Profile	Type	Description
	Type A+AI.	Standard type acc. to DIN3760. A rubber covering on the outside secures a good sealing in the housing. Supplied in metric and inch sizes (AI)
	Type AT	Designed for increased pressure (0,5-10 bar). The lip is self-supported, but the seal must be secured in the bore by e.g. a circlip or flange. As the sealing lip is short and stiff, this type is less suitable for coping with eccentricity and whip. See graph page 2 for max. permissible pressure. Supplied on request
	Type AG	Like type A, but with complete rubber covering on both sides. For use with food and drinking water. Supplied on request. Requires special tooling. Type A can be supplied with hydrodynamic helix ribs on the lip for pumping back possible leak oil. Especially recommended for applications, which suffer from high eccentricity or vibrations. Can be designed bi-directional, or for a specific direction. Supplied on request
	Type ATS	Like type AT, but with a dust lip. This type can be supplied in application 110 standard sizes, or per request in other sizes
	Type AX+AXI	Like type A/AS, but the outside circumference is corrugated. This design eases the pressing in of the seal, and thereby allow a tighter fit. This can secure a better static sealing - especially where the housing are exposed to high rates of heat expansion. Supplied on request
	Type AUF	Seal without spring loading. Used in narrow construction, e.g. sealing of needle bearings, and mainly for dust or grease.
	Type AS+ASI	Like type A, but with an additional dust lip. The dust lip protects the shaft and main sealing lip under certain service conditions where the oil seal is exposed to dust, dirt or e.g. high pressure cleaning. But in some applications, it might accumulate dirt between the two lips, and score the shaft more rapidly than with a type A seal without the dust lip.
	Type B+BI	This type is without rubber covering on the outside. Used under conditions where maximum heat transfer to the housing is desired. Compared to type A, this seal demands a better finish of the housing bore in order to secure a proper secondary sealing, but on the other hand, a better fastening can be achieved, eventually by gluing.
	Type BS+BSI	Like type B, but with additional dust lip in both metric inch sizes (BSI).
	Type BP	Oil seal with housing in stainless steel (std DIN1.4301) and with sealing lip of PTFE. The characteristics of this seal are very low friction and very good resistance to high temperature and chemical attacks. Can be specified for speeds up to 30 m/sec., and for a certain degree of dry-running. Due to its low friction, the BP seal can be used at pressures up to 10 bar (20 bar in special design) considering the speed. Low breakaway force after long time of standing still. The only oil seal that can work in the temperature range between -60 to +220°C (-76 to 428°F). Stocked by M seals in standard sizes.
	Type BUF	Like AUF, but without rubber covering
	Type ADUO	Can be used where two fluids has to be separated. Supplied in certain sizes or per request.
	Type C+CI	Like type B, but with reinforced housing (double shell). Used where a higher grade of stiffness is desirable, e.g. by large dimensions where there is a risk of distorting the ring during the fitting. Thinner inner housing also protects the lip from mechanical impact e.g. in mill machinery, earth moving equipment and the like. Supplied in standard dimensions in metric and inch sizes (CI).
	Type AE	For external sealing. Used where the housing rotates in relation to a non-rotating shaft, or for relative movement between shaft and housing. If a standard type is used in such applications, the sealing lip will lose its radial force against the shaft due to the centrifugal force. Supplied per request.
	Type CS+CI	Like type C+CI, but with additional dust lip.

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Heavy duty shaft seals

M Seals Heavy duty seals are especially suited for large diameters and/or rough applications like rolling mills, wind turbines, pulp and paper industry, gearboxes and other demanding applications where you find high speed, great misalignment in severe environments.

	The DR10 range is constructed with a flexible textile reinforced rubber structure that allow an easy fitting, and with a garter spring. Also available in a split form for re-fitting in place, without removing the shaft. This type normally requires a retaining cover. Can be supplied also with additional dust lip and different types of lubricating grooves (where the seals are used back to back or in tandem).
	The DR20 is a rubber seal with finger spring. In split form, this seal type is very suited for difficult fitting conditions, and in endless form it is also suited as wiper ring in hydraulic applications.
	The A10 is a rubber seal with garter spring, with a stiffening steel reinforcement. Good flexibility for easy installation, which in some cases allow use without a retaining cover. A variation for use in very narrow cross sections is type A20. The steel reinforcement can then prevent the seal from tilting in the groove, and the spring is the finger type for secure installation and even radial force.
	The C10 range is built with a strong steel casing and with a finger leaf+garter spring, making this type of seal especially suited for large misalignments (shaft deflection, large bearing clearances etc.). This type is also capable of shaft speeds up to 35m/sec. widely used in rolling and paper mills.

All types are offered in a selection of rubber grades like NBR, FPM and HNBR with or without PTFE content for auto lubricating properties. Some types can even be offered with PTFE anti-friction band vulcanized to the sealing lip for very high circumferential speeds.
The choice of material is highly depending on the actual application, and we at M Seals will happily assist you in the selection.

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How do shaft seals work?

The sealing-lip run on an oil film, which forms under the lips contact area, through capillary action. The oil film varies in thickness; however it must be around 0,001 mm to avoid leakage.

The lip of the shaft sealing ring has a slight interference to the shaft, which is calculated to ensure an even radial preload. Shortly after a seal has been put in service, the seal lip, which is sharp-edged from the manufacturing, will become bedded in, and a smooth contact surface is formed. This will normally take place within a few hours, after that, the friction will be near to constant. The temperature during the bedding-in period is higher than the normal service temperature, therefore lubrication is important.

Eccentricity

It is naturally desirable for efficient sealing that the shaft should run dead true, but in practice, a certain amount of eccentricity must be accepted. Shaft seals are designed so they can follow the movement of the shaft within certain limits by its flexible resilient lip.

Eccentricity of the housing is not so serious as eccentricity of the shaft (shaft whip), since the latter involves alternating displacement of the sealing lip at a frequency determined by shaft speed.

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You can also buy shaft and oil seals in our webshop, but don’t hesitate to contact us if you don’t find your seals as we also can custom made seals for your specific needs.

At M Seals, we take our commitment to supply the best sealing solutions for every application very seriously. Therefore, we are more than happy to guide you and make sure you get the right sealing products.

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