Table of contents
Bearing housings
Principles
Housing concepts
Standard housings
FAG standard housings are subdivided, in accordance with their fundamental design, into:
- split plummer block housings
- unsplit plummer block housings
- take-up housings
- flanged housings
Split plummer block housings
In the case of split plummer block housings, the housing body is split into an upper section and a lower section. This gives significantly simpler mounting and maintenance. The two halves of a housing form a matched pair and must not be interchanged with parts from other housings.
Unsplit plummer block housings
In the case of unsplit plummer block housings, the housing body is a single piece, so the bearing seat is free from parting lines. The housings are used where the bearings are subjected to very high loads.
The unsplit plummer block housings also include plummer block housing units VRE3. These are made available as completely assembled and greased bearing arrangement units comprising a housing, seals, bearings and shaft.
Take-up housings
Take-up housings SPA were developed specifically for tensioner drum bearing arrangements in belt conveyor plant. The housings are unsplit. There is a yoke-shaped drawbar eye for attachment to the tensioning device.
Flanged housings
Flanged housings have a flange perpendicular to the shaft axis and thus offer the ideal adjacent construction for numerous machines and pieces of equipment where the use of plummer block housings would be too demanding.
Special housings
Special requirements
Special housings are used in particularly challenging applications where not all the requirements can be fulfilled by the use of standard housings. These are not only specific industrial applications but also applications from the railway sector.
Customer-specific development
Special housings are developed in close cooperation and consultation with the customer. Schaeffler uses its comprehensive know-how of rolling bearing technology in order to ensure that every housing is optimally matched to the specific application. Further information on special housings is given in the Catalogue GK 1 http://www.schaeffler.de/std/1B63.
Locating and non-locating bearing concepts
Different concepts depending on housing series
In order to achieve locating bearing arrangements as well as non-locating bearing arrangements, one of the following concepts is applied in each housing series:
- housings in locating bearing design and non-locating bearing design
- housings with locating rings
The unsplit plummer block housings VR3, where two bearing positions are integrated in one housing, constitute a special case here. Complete plummer block housing units VRE3 can be ordered that, depending on their design, contain a locating/non-locating bearing arrangement, an adjusted bearing arrangement or a floating bearing arrangement.
Housings in locating bearing design and non-locating bearing design
In this housing concept for the implementation of a locating or non-locating bearing arrangement, the housing must be ordered as necessary in a locating bearing design or a non-locating bearing design. This applies to the housings RLE, KPG, KPGZ, LOE, BND and SPA.
Variation of covers
In the case of the locating bearing design, the bearings are axially clamped between the covers on the housings ➤ Figure. In the case of the non-locating bearing design, the covers have shorter centring collars. As a result, the bearing can be axially displaced ➤ Figure.
The housing design is part of the designation
When ordering, the designation indicates whether the housing should be supplied in a locating or non-locating bearing design.
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Housing in locating bearing design
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Housing in non-locating bearing design
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Housing with locating rings
In this housing concept for the implementation of a locating or non-locating bearing arrangement, locating rings are available as accessories that can be used to set the locating bearing function ➤ Figure. This applies to the housings SNV, SNS, S30, SAF and F5.
Variation of the number of locating rings
In the case of these housings, the bearing seats are designed such that the bearing is capable of axial displacement and therefore acts as a non-locating bearing if locating rings are not inserted ➤ Figure. Once locating rings are inserted, the bearings are axially located. The locating rings are generally inserted in the housing on both sides of the bearing. Normally, an even number of locating rings is specified in order to achieve concentric seating of the bearing in the housing. In some cases, a single locating ring is sufficient.
Locating rings must be ordered separately
The number of locating rings required is given in the product tables. Locating rings must be ordered separately.
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Locating bearing arrangement, as a result of inserted locating rings
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Non-locating bearing arrangement, no locating rings inserted
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Materials
Standard materials
Depending on the housing series, the standard material used for FAG standard housings is flake graphite cast iron, spheroidal graphite cast iron or cast steel. The material is generally indicated by a suffix in the housing designation. This indication is omitted in the case of some housings where these are only available in one material variant.
Suffixes:
- L for flake graphite cast iron
- D for spheroidal graphite cast iron
- S for cast steel
Other dimensions available by agreement
By agreement, housings made from other materials are also available. The material should be selected on the basis of a careful analysis of the application and the associated requirements.
Flake graphite cast iron
Restricted tensile strength and ductility, good compressive strength
For standard housings made from flake graphite cast iron, cast iron in accordance with DIN EN 1561 is generally used. In these cast materials with an iron/carbon/silicon base, the graphite inclusions are present in lamellar form. Under tensile load, these act as internal notches. The tensile strength of flake graphite cast iron is therefore limited and its ductility is comparatively low. The compressive strength of this alloy is, however, higher than the tensile strength by a factor of 4. These alloys also have good inherent stability.
Economical material for simple requirements
Flake graphite cast iron is therefore used in the case of housings with simple requirements. Furthermore, flake graphite cast iron represents the most economical variant of the cast materials available for use in housings.
In the case of split plummer block housings SAF, flake graphite cast iron to ASTM A48 Class35 is used.
Spheroidal graphite cast iron
Higher tensile strength and ductility than flake graphite cast iron
For standard housings made from spheroidal graphite cast iron, cast iron in accordance with DIN EN 1563 is generally used. Due to an addition of magnesium or, more rarely cerium or calcium, the graphite inclusions adopt a spheroidal form during casting. As a result, the tensile strength and ductility are higher than those of the grades with a lamellar graphite form.
Material for increased requirements
Spheroidal graphite cast iron is therefore used in the case of housings with an increased profile of requirements. The costs of spheroidal graphite cast iron are between those for flake graphite cast iron and cast steel.
In the case of split plummer block housings SAF, spheroidal graphite cast iron to ASTM A536 Grade 65-45-12 is used.
Cast steel
Moderate to high strength with high elongation at fracture
For standard housings made from cast steel, steel in accordance with DIN EN 10293 is generally used. Both unalloyed and alloyed steels are suitable for casting. The unalloyed cast steel used for housings combines moderate to high strength values with high elongation at fracture.
Material for high requirements
Cast steel is therefore used in the case of housings with high requirements for mechanical properties as well as a requirement for high ductility. The costs of cast steel are higher than the costs for flake graphite cast iron or spheroidal graphite cast iron. It is therefore recommended that checks be carried out to establish whether the material is really necessary in relation to the requirements of the specific application.
Corrosion protection
Universal paint coating
All outer surfaces of standard housings not machined by chip-forming methods and the locating surfaces on the lower housing section have a universal paint coating. The coating can be finished using all synthetic resin, polyurethane, acrylic, epoxy resin, chlorinated rubber, nitrocellulose and acid-hardening hammer tone finishes.
Corrosion protection
Inner and outer surfaces machined by chip-forming methods are provided with corrosion protection that can be easily removed. It is recommended that only volatile solvents and lint-free cloths should be used.
Special solutions available by agreement
If there are particular requirements relating to paint coating and corrosion protection, special solutions are possible. If particular specifications are presented by the customer, we check their feasibility and these can be implemented if the result is positive.