Maximum performance, reliability and durability, backed by a century of bearing expertise

To boost reliability for applications that must endure heavy loads, shock loads and shaft misalignment - such as conveyor head, tail and take-up pulleys in bulk ports, quarries, mining and mineral processing, etc. - SKF engineers developed SNL bearing housings. Compared to conventional bearing housings, advanced SKF SNL housings offer several important advantages:

• Greater reliability of housing performance
• Longer bearing service life
• Lower maintenance costs
• Reduced vibration levels
• Reduced outer ring creep and housing wear
• Higher load carrying capacity

Application Versatility

SNL housings are an excellent choice for sealed and open spherical roller bearings and CARB toroidal roller bearings. The housings are designed on a building block principle that allows for a wider selection of bearings and seals as well as an assortment of mounting and lubrication systems. Standard SNL housings can accommodate all common shaft sizes used in bulk conveyors as the size ranges from 20 to 500 mm in diameter, as well as a variety of seals. The standard range includes a number of options, such as tapped holes to accommodate grease fittings, dimples for the correct location of condition monitoring sensors, thereby creating an almost infinite combination of variants. Fitting a central lubrication or point lubrication system to the tapped holes means reduced need for manual lubrication of housings in places that are difficult and dangerous to access for maintenance staff. All SNL bearing housings are produced under SKF's strict in-house machining standards using high quality grey cast iron to provide maximum tensile strength.

For applications in which additional strength may be required, housings made of spheroidal graphite cast iron also are available. Furthermore, SKF quality standards ensure that SNL housing bores are machined to high accuracy to enable full service life.

Proven Performance

Machining quality affects bearing service life. SNL bearing housings have tested well against housings produced by leading European and Asian manufacturers. Tests measured a range of parameters, including:

• Housing bore diameter - Too large a bearing seating will allow the outer ring to rotate which will cause fretting corrosion; too small a bearing seating will prevent the free bearing from moving axially in the housing and result in early bearing failure.
• Roundness and flatness base plane, which will ovalize the outer ring of the bearing, increase the temperature and reduce bearing service life.
• Surface roughness
• Centre height
• Housing strength

In each test, SNL housings demonstrated optimal or superior results compared to the competition.

Design Stiffness and Heat Conduction

For housings, the three most important considerations within a bulk handling environment involve: the stiffness of the design, excellent heat conduction and certainty that the housing provides optimal axial displacement. Two key features of the SKF collection of SNL housings are the stiffer design and improved heat disbursement. The housing base is reinforced with ribs and extra material around the attachment holes to give added strength and prevent deformation in the base. The design allows mounting bolts to be preloaded and increased for better location and to prevent deformation of the housing base and bore. Additional ribs on the underside of the base improve heat flow from the bearing outer ring to the support surface. As a result, bearings in an SNL housing run up to 10% cooler than the bearings in other housings.

Simple Mounting and Alignment

SNL housings are easily installed, allowing pre-assembled shafts to be directly mounted in them. To further simplify the mounting process, SKF marks individual housing caps and bases during manufacture with a unique serial number. This prevents potential problems resulting from the mixing of caps and bases and enables traceability.

In addition, centre lines are cast into the housing base to allow faster and easier mounting and to help eliminate alignment errors. Finally, dowel position dimples cast into the housing help facilitate the identification of optimal drilling locations; thus enabling quicker adaptation of a standard housing to new applications.

Lubrication and Condition Monitoring

SNL housings feature two drilled and tapped holes in the cap, protected by plastic plugs, to allow for grease fittings - a relubrication facility that is standard. SNL housings also feature optimised positioning points to enable the easy attachment of condition monitoring sensors. This helps technicians to monitor and identify potential problems before they deteriorate, as well as to effectively plan regular maintenance and repair schedules.

Sealing Options

An important advantage of SNL housings is their adaptability. They can be fitted quickly and easily with a variety of seals, including:

• Labyrinth seals
• Four-lip seals
• V-ring seals
• Radial shaft seals
• Taconite (heavy duty relubricable) seals

In addition, SNL bearing housings are dimensionally interchangeable with earlier SKF designs (SNH and SNA). The result is that SNL housings offer a wide range of sealing options that provide maximum bearing protection.

Three-barrier Solution

SNL bearing housings are a key component of an innovative system developed by SKF technicians. The SKF "three barrier solution" brings together sealed bearings, sealed housings and selected lubricants to provide optimal protection and increased life cycle, particularly in tough and harsh working environments.

The result is an environment-friendly, cost-effective bundle of products that can typically extend bearing service life without additional complex and expensive sealing arrangements.

Particularly for applications that involve the transfer of heavy, high volume materials, such as bulk conveyors in port and cargo facilities, SNL housings offer a very strong and steady solution.

(For further information contact: SKF India Ltd, MGM Building, Netaji Subhash Road, Charni Road, Mumbai 400 002. Tel: 022- 6633 7777, Email: ibu.marketing@skf.com)