Sealing
Functions
The sealing arrangement has a considerable influence on the operating life of a bearing arrangement. It is intended to retain the lubricant in the bearing and prevent the ingress of contaminants into the bearing.
In the selection of seals, attention must be paid to:
- the operating and environmental conditions
- the degree of radial mobility of the bearing
- the tilt angle of the bearing
- the design envelope
- the costs and work required.
ACHTUNG
For expanded temperature ranges, sealing must be agreed in consultation with Schaeffler.
Overview of seal types
For the sealing of bearings various seals and seal types are available, which are described in detail, see tables and link.
Seal types
Seal | Guidelines | ||||
|---|---|---|---|---|---|
Design | Internal | External | for | ||
|
| Page | |||
2RS  | █ | ‒ | █ | ‒ | |
2TS  | █ | ‒ | █ | ‒ | |
2RS2  | █ | ‒ | █ | ‒ | |
Seal types
Seal | Guidelines | ||||
|---|---|---|---|---|---|
Design | Internal | External | for | ||
|
| Page | |||
2RS4  | █ | ‒ | █ | ‒ | |
Seal RS or 2RS for plain bushes  | █ | ‒ | ‒ | █ | |
Grease collar  | ‒ | █ | █ | ‒ | |
External seal  | ‒ | █ | █ | ‒ | |
V-ring, single lip design  | ‒ | █ | █ | ‒ | |
Seal types
Seal | Guidelines | ||||
|---|---|---|---|---|---|
Design | Internal | External | for | ||
|
| Page | |||
V-shaped sealing ring, double lip design  | ‒ | █ | █ |
| |
Two component seal  | ‒ | █ | █ |
| |
Rotary shaft seal, preloaded  | ‒ | █ | █ | █ | |
Rotary shaft seal with lip seal  | ‒ | █ | ‒ | █ | |
Modified adjacent construction, gap seal  | ‒ | █ | ‒ | █ | |
Seals in the bearing
Various possibilities are available for the sealing of bearings. These should be selected as a function of the application.
Seal 2RS
Where higher requirements for sealing action are present, lip seals made from thermoplastic polyurethane TPU are used. The seal lips are radially preloaded against the bearing, ➤ Figure.
Seals 2RS for maintenance-free spherical plain bearings and spherical plain bearings requiring maintenance are designed for indoor applications and are suitable for operating temperatures from –30 °C to +130 °C.
Seal 2RS
Seal 2TS
Where very high requirements for sealing action are present, triple lip seals made from NBR with steel supporting elements are used, ➤ Figure. They give excellent protection of the bearing against water, dust and contamination and are suitable for indoor and outdoor applications.
Seals 2TS for maintenance-free spherical plain bearings and spherical plain bearings requiring maintenance are suitable for operating temperatures from –30 °C to +100 °C. For short periods, temperatures up to a maximum of +130 °C are permissible. Seals for expanded temperature ranges are available by agreement.
Seal 2TS
Seal 2RS2
Lip seals on both sides with increased sealing action for very high requirements and long maintenance intervals, ➤ Figure. They give protection against coarse and very fine contaminants.
Seals 2RS2 are suitable for maintenance-free large radial spherical plain bearings and operating temperatures from –40 °C to +120 °C.
Seal 2RS2
Seal 2RS4
Lip seals on both sides with increased sealing action for very high requirements and long maintenance intervals, ➤ Figure. They give protection against coarse and very fine contaminants.
Seals 2RS4 are suitable for large radial spherical plain bearings requiring maintenance and operating temperatures from –40 °C to +120 °C.
Seal2RS4
Seal RS or 2RS for plain bushes with ELGOGLIDE or ELGOTEX
ELGOGLIDE plain bushes and ELGOTEX filament wound bushes are available by agreement on one side with lip seals RS or on both sides with lip seals 2RS, ➤ Figure. The sealing rings used are made from NBR and are designed for temperature ranges of –30 °C to +100 °C. For short periods, temperatures up to a maximum of +130 °C are permissible.
Seal for plain bushes with ELGOGLIDE or ELGOTEX
Seals in the adjacent construction
Open and sealed plain bearings can be additionally sealed by means of external seals.
Grease collar
The grease collar is a simple and effective type of seal, ➤ Figure. By means of frequent relubrication, a grease collar is formed on the end faces of the spherical plain bearing that protects the bearing against contaminants.
The grease collar is suitable for spherical plain bearings requiring lubrication and has proved particularly effective, in conjunction with daily maintenance, in aggressive operating conditions.
The temperature range is dependent on the grease selection.
Sealing by means of grease collar
External seal
Simple but highly effective sealing can be achieved by means of sealing rings made from thermoplastic polyurethane TPU. This is specially developed for radial spherical plain bearings in accordance with DIN ISO 12240-1, dimension series E and can be integrated in the adjacent construction as an external seal, ➤ Figure.
Particularly low seal friction is achieved if the sealing rings for spherical plain bearings are worked in oil or flowable grease before fitting. In the case of maintenance-free spherical plain bearings, please consult Schaeffler.
External seals are suitable for operating temperatures from –30 °C to +130 °C.
External seal
V-ring,
single lip design
The V-ring, ➤ Figure is a lip seal with axial sealing action. During fitting, this single piece rubber ring is pushed under tension along the shaft until its lip is in axial contact with the housing wall. The seal lip acts simultaneously as a flinger shield.
The single lip V-ring is suitable for relatively large tilt motions and for operating temperatures from –40 °C to +100 °C.
It is particularly easy to fit and is resistant to grease, oil and ageing.
V-ring, single lip design
V-shaped sealing ring,
double lip design
The V-shaped sealing ring is a simple seal with lip seals on both sides. The inside diameter of the sealing ring is in contact with the spherical surface of the inner ring, ➤ Figure.
V-shaped sealing rings are suitable for operating temperatures from –40 °C to +100 °C.
V-shaped sealing ring
Two component seal
The two component seal is a seal lip made from a nitrile mixture modified with PTFE and is preloaded by means of a high-grade steel coil spring. The seal shoulder is made from a nitrile mixture reinforced with cotton, ➤ Figure.
The bearing is sealed on the protruding part of the inner ring spherical surface.
The two component seal is easy to use and is suitable for operating temperatures from –40 °C to +120 °C, with operation for short periods at up to +150 °C.
Two component seal
Rotary shaft seal
The rotary shaft seal is a steel-reinforced plastic ring with a seal lip. The seal collar with one lip is pressed against the shaft running surface by a coil spring, ➤ Figure.
Rotary shaft seals are suitable for small tilt angles with grease and oil lubrication. They prevent the egress of lubricant. A sealing ring with an additional protective lip also prevents the ingress of contamination.
The temperature range is dependent on the seal material.
If grease lubrication is used:
- the seal lip should be positioned facing outwards.
If oil bath lubrication is used:
- the seal lip should be positioned facing inwards
- an additional dust lip facing outwards should be used.
Rotary shaft seal
Seals for plain bushes
Possibilities for sealing the bearing position in the adjacent construction are as follows, ➤ Figure:
- a modified adjacent construction
- gap seals
- rotary shaft seals.
The suitability of the sealing arrangement must be agreed in consultation with the seal manufacturer.
ACHTUNG
If the seal is designed with additional outer seals, it must be borne in mind that the bearing clearance will increase due to the wear of the sliding layer. Plain bushes with ELGOGLIDE, ELGOTEX or E40 are not lubricated. Grease must be prevented from leaving a seal and coming into contact with these sliding layers.
Seals for protection of the bearing position
