FAG housings and the associated bearings form bearing units that have proven successful in machinery, plant and equipment. It is only possible, however, to show here a small selection of the numerous sizes and designs (for an overview of the FAG series housings, see publication TI WL 90-30). For other housings or housing designs, please consult Schaeffler Group Industrial.

The bearing housings are predominantly made from flake graphite cast iron. We can supply housings made from cast steel or spheroidal graphite cast iron by agreement. Since the bearings are generally lubricated with grease and the initial grease filling lasts for a long period, most housings do not have relubrication holes. However, there are cast-on bosses or marks present so that lubrication holes can be made if necessary. If relubrication is carried out, it must be ensured that excess grease is allowed to escape.

All outer surfaces of the housings and housing parts not machined by chip-forming methods have a universal paint coating (colour RAL 7031, bluish grey). The coating can be finished using all synthetic resin, polyurethane, acrylic, epoxy resin, chlorinated rubber, nitrocellulose and acid-hardening hammer tone finishes. The anti-corrosion protection on the inner and outer surfaces machined by chip-forming methods can be easily removed.

The bearing seats in the housing are generally machined such that the bearings are movable and can thus function as non-locating bearings. Locating bearing arrangements can be achieved by the insertion of locating rings if these are listed in the tables. Locating rings must be ordered separately. Housings without locating rings are supplied in a non-locating or locating bearing design.

Bearing housings can be sealed, depending on the operating conditions, by the use of contact seals, non-contact seals or combinations thereof, Figure 1 to Figure 3.

Split and unsplit plummer block housings are generally intended for bearing arrangements with self-aligning ball bearings, barrel roller bearings and spherical roller bearings.

In split plummer block housings, the removable upper section of the housing is centred on the lower section by dowel pins, allowing easier fitting and maintenance. The upper sections must not be interchanged with each other.

In the case of split housings, the tolerance data for bearing seats are only valid for the delivered condition, i.e. before the screws connecting the upper and lower sections are loosened.

Housings SNV are designed in accordance with a modular concept. This allows the fitting of rolling bearings of various diameter and width series.

The housing SNV160 can accommodate three different self-aligning bearing types from 20 bearing series, namely self-aligning ball bearings, barrel roller bearings and spherical roller bearings if the named bearings have an outside diameter of 160 mm. Housings SNV can also accommodate deep groove ball bearings and split spherical roller bearings.

Bearings from different diameter series with the same outside diameter have different bore diameters.

The method of locating the bearing on the shaft is also significant:

• direct seating or location using an adapter sleeve results in different shaft diameters.

In housings SNV, this gives different sizes of gap between the shaft and housing bore, depending on the bearing fitted. This gap is taken up by the seal.

The dimension tables indicate the suitable seals and covers for the bearings listed. If the housing bore allows a different bearing to be used, the seals must be selected as appropriate.

In size SNV215 and larger, the housings have an eye bolt that must not be subjected to a load greater than the mass of the housing including the bearing.

The essential advantages of housings SNV are as follows:

• Simplified stockholding due to the modular concept, with one housing size suitable for various shaft diameters
• High load carrying capacity, see table
• Depending on the operating conditions, double lip seals, V ring seals, labyrinth seals, felt seals or combined seals may be used. Special seals are available by agreement
• Locating bearings are located centrally by means of two locating rings of identical width
• Flat end faces on the housing base allow abutment against stops if high forces do not act on the mounting face in a purely vertical direction
• Holes can be made at marked points on the housing for: lubrication and monitoring systems, fixing screws, parallel or tapered pins.

The dimensions of housings SNV correspond to ISO 113/II and, with the exception of the width, also to DIN 736 to DIN 739. The housings are interchangeable with the existing housings SN(E).

The housings SNV listed in the tables are made from flake graphite cast iron (suffix L). Housings made from spheroidal graphite cast iron (suffix D) are available by agreement.

The bearing seat in the housing SNV is machined to H7. The bearings can be displaced and thus function as non-locating bearings. Locating bearing arrangements are achieved by inserting one locating ring (FRM) on each side of the bearing; the bearing is thus seated in the centre of the housing.

Housings SNV can accommodate rolling bearings that are seated directly on a stepped shaft or on an adapter sleeve.

Seals and covers can be accommodated in the rectangular-section annular slots on both sides of housings SNV. The seals must be ordered separately. They are principally suitable for grease lubrication.

The standard seal for housings SNV is the double lip seal DH. Other types available upon request are V ring seals DHV, labyrinth seals TSV, felt seals FSV, combined seals TCV and special seals.

The double lip seal DH made from nitrile butadiene rubber (NBR) is suitable for circumferential speeds up to 13 m/s. For continuous operation, a maximum circumferential speed of 6 m/s is recommended. The two-part seal can be easily inserted in the annular slots in the housing (pay attention to the position of the joint). The seal lips slide on the rotating shaft. The outer seal lip prevents ingress of contamination into the bearing arrangement. This effect is supported by the grease fed into the space between the seal lips at assembly. The inner lip prevents the egress of lubricant from the housing. The double lip seal allows shaft misalignment of up to 0,5° in both directions. It is suitable for temperatures from –40 °C to +100 °C. The contact area on the shaft for the seal lips should have a roughness to class N8 (DIN ISO 1302).

In V ring seals DHV made from NBR, the seal lip is in axial contact with the sliding surface. The seal allows misalignment of up to 0,5° in both directions and is suitable, if grease lubrication is used, for a circumferential speed up to 12 m/s (at ＞ 8 m/s, axial location is necessary).

Labyrinth rings of series TSV are suitable for higher circumferential speeds since they are of a non-contact type. The O ring pressed between the labyrinth ring and the shaft ensures that the labyrinth ring does not slip despite the loose fit. The O ring made from fluoro rubber (Viton^®) is suitable for temperatures up to +200 °C. The labyrinth seal allows shaft misalignment of up to 0,5° in both directions. If necessary, the labyrinth can be relubricated.

FAG felt seals FSV are suitable for grease lubrication and temperatures up to +100 °C (by agreement, aramid packing is available for high temperatures). The adapter holding the inserted, oil-impregnated felt strip is secured against rotation by an O ring in the housing slot. Felt seals are suitable for circumferential speeds up to 5 m/s and, after running-in, up to 15 m/s. The permissible shaft misalignment is 0,5° in both directions.

If housings SNV are to be closed off on one side, the covers DKV must be ordered specially. The plastic covers are suitable for long term operating temperatures up to +120 °C. Covers DKVT for higher temperatures are available by agreement.

In many applications, bearings can be operated with lifetime lubrication, i.e. the grease quantity introduced at assembly is sufficient for the entire bearing rating life when contact seals are used (for example DH, FSV). The bearings are filled completely with grease while the housing cavities are filled to 60%. Grease quantity for initial filling, see table.

For bearing operating temperatures ＜ +100 °C, bearing loads P/C ＜ 0,3 and a bearing-specific speed parameter k_a · n · d_M ＜ 700 000 min^–1 · mm, the most suitable rolling bearing grease is Arcanol MULTITOP, a lithium soap grease to NLGI class 2 with particularly effective EP additives, see also TPI 168, Arcanol rolling bearing greases.

For a speed parameter n · d_M ＜ 50 000 min^–1 · mm and a non-contact seal (e.g. TSV), where the grease should also perform a sealing function, the housing and seal cavities should be filled to approx. 100%.

If the achievable fatigue limit life of the bearing is significantly longer than the grease operating life, the existing grease must be removed and replaced by fresh grease.

If the grease change intervals for particular applications are too short, relubrication is recommended. The lubricant can be introduced into the housing from the side or, in the case of bearings with a lubrication slot and lubrication holes, through the centre.

If relubrication is carried out from the side, the housing cavities on the side with the lubrication nipple should be filled to approx. 100% with grease so that the relubrication grease can act immediately on the bearing. Depending on the seal selected and the application, the housing can be fitted at marked locations with devices for the inlet and outlet of lubricant.

Housings ordered using the suffix G944A* have a lubrication nipple and grease outlet hole. Position and dimensions of the holes and the lubrication nipple, Figure 6.

In housings with a grease outlet hole or non-contact seal, the bearing cannot be overlubricated. If the temperature reaches a higher level during relubrication due to the churning energy of the grease, it will return to its initial value after several hours of running once the excess grease has escaped. In the interests of the environment, controlled metering of lubricant is recommended.

Due to their favourable flow behaviour, greases of consistency class 2, e.g. Arcanol MULTITOP and MULTI2, are more suitable for relubrication than greases of higher consistency classes.

The quantities stated are valid for the initial filling of SNV housings. The bearings are thus filled completely with grease while the housing cavities are filled to 60%.

Housings SNV for grease relubrication (suffix G944A*, available by agreement) have a lubrication nipple and an outlet hole of the dimensions given in the table, see table. Example: design G944AA with tapered lubrication nipple to DIN 71412-A M10×1.

For operation at high speeds, for example in fan bearing arrangements, we can by agreement supply grease valves RSV, Figure 7 and Figure 8.

The grease valves for housings SNV of design G944A* must be ordered separately. For bearings located by means of adapter sleeves, grease valves RSV5 or RSV6 should be used, for bearings with a cylindrical bore, RSV2 or RSV3 should be used.

Housings SNV are designed such that they are suitable for both oil bath and recirculating oil lubrication. The housings have a large internal cavity with oil collector pockets in the lower section as well as connector facilities for oil inlet, oil outlet, oil level sensors and temperature sensors. When using oil bath lubrication, a minimum oil level must be ensured. If the FAG double lip seal is used, a certain amount of oil leakage must be expected, which is unavoidable with seals that are split and not spring-loaded. In order to limit oil leakage to a small quantity, the shaft in the double lip contact areas should be as follows: hardness min. 55 HRC, ground free from spiral marks with R_a = 0,2 μm up to max. 0,5 μm.

The parting line between the upper and lower sections of the housing must be sealed with a thin layer of a commercial sealant (with permanent elasticity).

Please note that the housing must be ventilated if oil bath lubrication is used (for example, the inlet hole can be closed off using a ventilation plug).

Split plummer block housings for spherical roller bearings 230..-K with tapered bore and adapter sleeve, Figure 9 to Figure 12.

The smaller housings including S3040 are non-locating bearing housings; locating bearing arrangements can be achieved by inserting a locating ring. Locating rings must be ordered separately. Housings closed on one side up to size S3040 have a polyamide cover inserted in the slot instead of the felt strip. This cover must be ordered separately.

The larger housings from S3044 are produced as non-locating bearing housings or as locating bearing housings. When ordering housings closed on one side, design A must be indicated in the order. The cover is made from steel. Housings of design B are intended for continuous shafts.

The housings are sealed using felt strips. Felt seals allow shaft misalignment of up to 0,5° in both directions.

Housings of series S30 can be relubricated via a lubrication connector in the centre of the housing. In size S3034 and larger, the housings have an eye bolt that must not be subjected to a load greater than the mass of the housing including the bearing.

The housing material is flake graphite cast iron (suffix L). Housings made from spheroidal graphite cast iron (suffix D) are available by agreement.

Load carrying capacity: see also Load carrying capacity of split plummer block housings, link.

The maximum axial load carrying capacity is 35% of F_180°.

The quantities stated are valid for the initial filling of S30 housings . The bearings are thus filled completely with grease while the housing cavities are filled to 60%.

Split plummer block housings for spherical roller bearings 231..-K with tapered bore and adapter sleeve, Figure 13 to Figure 16.

These housings are intended for bearing arrangements subjected to heavy loads. The bearings are located on the shaft by means of adapter sleeves.

From SD3144, the housings are supplied as a locating bearing design or non-locating bearing design. Smaller housings initially give non-locating bearing arrangements. Locating bearing arrangements can be achieved by the insertion of locating rings on both sides of the bearing. Locating rings must be ordered separately.

The housings are intended for grease lubrication and can be relubricated via a lubrication nipple.

For the holes required for oil lubrication, the upper and lower section of the housings have cast-on bosses.

The seal is a three-section labyrinth. Labyrinth seals allow shaft misalignment of up to 0,25° in both directions. Housings closed on one side (design A) are supplied with a steel cover.

The eye bolts in the upper section of the housing must not be subjected to a load greater than the mass of the housing including the bearing.

The housing material is flake graphite cast iron (suffix L). Housings made from spheroidal graphite cast iron (suffix D) are available by agreement.

See also Load carrying capacity of split plummer block housings and table.

The maximum axial load carrying capacity is 2/3 of F_180°.

The quantities stated are valid for the initial filling of SD31 housings.  The bearings are thus filled completely with grease while the housing cavities are filled to 60%.

Split plummer block housings LOE are designed for oil lubrication.

Plummer block housings LOE2 and LOE3 are fitted with spherical roller bearings with a cylindrical bore of series 222 and 223, Figure 17 and Figure 18.

The bearings are located on the shaft using an interference fit and axially secured by means of a locknut.

LOE plummer block housings LOE5 and LOE6 are intended for spherical roller bearings with tapered bore and adapter sleeve location, Figure 19 and Figure 20.

The housing is split, the labyrinth covers are unsplit. The seal comprises two labyrinth rings. Labyrinth seals allow shaft misalignment of up to 0,25° in both directions. The grease chamber in the cover labyrinth can be relubricated. The housing base has four extended slots.

Plummer block housings of series LOE are suitable for high-speed bearing arrangements and are designed for oil lubrication. The oil is supplied to the rolling bearing from the oil sump in the lower section of the housing by a ring oiler. An angled oil level indicator is screwed to one cover.

Housings of series LOU for recirculating oil lubrication are available by agreement.

The eye bolt in the upper section of the housing must not be subjected to a load greater than the mass of the housing including the bearing.

The housing material is flake graphite cast iron (suffix L).

Plummer block housings VR3 are fitted with rolling bearings with a cylindrical bore, Figure 21 to Figure 26. The variants of these housings are available completely assembled and greased as bearing units VRE3.

In size VR(E)310 and larger, the housings have two eye bolts that must not be subjected to a load greater than the mass of the housing including the bearing and shaft. After mounting, the eye bolts can be replaced by the hexagon head bolts with seals included in the packaging.

These unsplit housings, developed for fan applications, contain two bearing positions. They are used where a precise and easy-to-fit bearing arrangement is required, for example in:

• conveying equipment
• test rigs
• materials processing machinery
• belt drives
• laboratory equipment
• textile machinery
• feeder mechanisms.

All variants of housings VR3 are available completely assembled and greased as bearing units VRE3. They can be integrated directly in existing machinery without substantial preparation. The shaft diameter range extends from 25 mm to 120 mm.

Advantages of bearing units VRE3:

• Easy to fit
• Low maintenance requirements
• Effective, low-friction sealing against dust and moisture (max. permissible operating temperature +100 °C)
• Bearing arrangement contained in single-piece housing, therefore requiring no time-consuming alignment work
• High tilting moments supported by two bearings with optimum spacing
• Six designs allow matching to different load conditions.

In addition to complete bearing units VRE3, the following are also available:

• housings VR3 with covers, grease valves, lubrication nipples, seals, locating elements and, if necessary, a spring washer
• shafts VRW with fasteners
• rolling bearings.

Design A is suitable for predominantly radial load and high speed. It can support axial loads in both directions (not alternating).

Design B is suitable for high radial load on one side. It can only support axial forces in one direction.

Design C is suitable for high radial load on one side. It can support high axial forces in both directions.

Design D is suitable for axial loads in both directions.

Design E is suitable for high radial loads on both sides and axial loads in both directions.

Design F is suitable for predominantly radial load and high speed. It can support axial load in one direction (facing away from the spring).

A cast-on boss on the housing body indicates:

• in design B, the position of the cylindrical roller bearing
• in designs C, D and E, the position of the non-locating bearing
• in design F, the position of the ondular washer.

On the shaft VRW3..-F, the position of the ondular washer is also marked.

The housing is made from flake graphite cast iron, the shaft is made from steel.

Further information on lubrication and sealing, fitting and maintenance of VRE units is given in publication WL 90121, FAG Bearing Units for Fans, Series VRE3.

Unsplit FAG housings of series BND are combined with FAG spherical roller bearings, seals and grease filling to form bearing units for very high demands, Figure 27 to Figure 38.

Unsplit housings of series BND, originally developed for belt conveyors, can also be used advantageously in materials processing, for example in hard crushers, sugar cane mill drives and rotor shafts in wind turbines.

The dimensions of housings BND are matched to spherical roller bearings of series 222, 230, 231 and 232.

In housings BND of design A for the bearing arrangements of shaft ends, one side is closed by a cover. Design B is intended for continuous shafts.

The housing body, labyrinth rings and cover are unsplit. The labyrinth rings are located by means of split tapered rings made from laminated fabric material. The labyrinth gaps are dimensioned so that the shafts can undergo deflection of approx. 0,5° in both directions without the labyrinths touching the bore.

The standard material for the housing bodies is cast steel (suffix S). If required, housing bodies made from spheroidal graphite cast iron (suffix D) are available.

The bearing seat in the housing is machined to H7. The housings are supplied as a locating bearing design or non-locating bearing design. In the locating bearing, the bearing is clamped between the housing covers. In the non-locating bearing, the bearing can align itself axially, since the covers have shorter centring collars.

Housings BND can accommodate rolling bearings with a cylindrical bore that are seated directly on a stepped shaft. For these bearings, we recommend machining the shaft to m6. Shaft seats for bearings with a tapered bore seated on adapter sleeves should be machined to h8.

Plummer block housings BND are sealed on one side (design A) or on both sides (design B) by labyrinths (suffix Y). If required, Taconite seals (suffix T) are available with a V ring integrated in the labyrinth (these must be provided with a separate relubrication facility).

Guide values for the rupture load of housings BND: see table. When determining the permissible load, a safety factor 6 should be applied to the housing rupture load.

Housings BND should not be subjected to an axial load greater than 20% of the housing rupture load F_180°. For load directions between 55° and 120° and axial load, we recommend that the housings should be secured in the load direction by means of stops or dowels.

The eye bolts in the upper section of the housing must not be subjected to a load greater than the mass of the housing including the bearing.

Housings BND are designed for grease lubrication. Suitable lubricants are lithium soap greases of consistency 2 and 3, for example the rolling bearing grease MULTI3 for low loads and MULTITOP and LOAD400 for high and very high loads. The housings have button head lubrication nipples with a head diameter standardised to DIN 3 404 of 22 mm. The grease is fed uniformly to both rows of rollers via the circumferential slot and three lubrication holes in the outer ring of the spherical roller bearings.

In initial lubrication, the cavities in the bearing, the housing and the labyrinths are completely filled with grease. Recommended grease quantities, see table.

The relubrication intervals should be matched to the environmental conditions. The bearings should be relubricated after an interval of no more than four weeks.

For relubrication, we recommend approx. 10% of the grease used for initial filling. For machinery operating in highly contaminated environments, relubrication should be carried out daily with small quantities.

The quantities stated are valid for the initial filling of BND housings.  The bearings and housing cavities are thus filled completely.