Selection guidelines for different capping devices under various operating conditions . However, these guidelines cannot substitute for testing a shield or seal in its application. For additional information, refer to Integral sealing.

The seals, which are fitted in a recess on the outer ring, make good, positive contact with the recess, without deforming the outer ring. The capping devices are available as:

Shields

• are identified by the designation suffix Z
• are primarily intended for applications where the inner ring rotates
• are fitted in the outer ring and form a narrow gap with the inner ring
• are made of sheet steel
• are available as standard with an extension in the shield bore , expect some sizes without extension
• protect from dirt and debris without friction losses

Non-contact seals

• are identified by the designation suffix RZ
• provide better sealing effectiveness than shields
• can be operated at the same speeds as shields
• form an extremely narrow gap with the inner ring shoulder
• are made of sheet steel reinforced NBR (oil- and wear-resistant)

Low-friction seals

• are identified by the designation suffixes RSL or RST
• provide better sealing effectiveness than non-contact seals
• are made of sheet steel reinforced NBR (oil and wear-resistant)

RSL design :

• can be operated at the same speeds as shields
• make virtually no contact with a recess in the inner ring shoulder
• are available for 60, 62, 63 series bearings in two designs, depending on the size

RST design :

• make positive contact with a recess in the inner ring shoulder for good sealing effectiveness
• are available on request for 60, 62 and 63 series bearings in three RST designs, depending on the size

Contact seals

• are identified by the designation suffixes RSH, RSH2, RS1 or RS2
• are made of sheet steel reinforced
  • NBR
  • FKM (designation suffix RS2 or RSH2, available on request)

  Bearings with designation suffix VA947 are equipped with seals made of blue food-compatible NBR.
  The material is FDA and EC approved. FDA approval is based on compliance with CFR 21 section 177.2600 ‘Rubber articles intended for repeated use’ for use in contact with aqueous and fatty foods. EC approval is based on compliance with the overall migration requirements of the German BfR recommendation XXI for category 3 materials.

• are available in different designs depending on the bearing they are used with:
  • for 60, 62 and 63 series bearings in two RSH designs, depending on the size
  • for RS1 designs, with sealing either against the inner ring shoulder or against a recess in the inner ring side face  the relevant design is determined by dimension d₁ or d₂ in the

ICOS oil sealed bearing units

• are typically used for applications with sealing requirements exceeding the capabilities of standard sealing solutions, i.e. oil retention
• have the following features compared to bearings with external sealing solutions:
  • need less axial space
  • simplify mounting
  • avoid expensive machining of the shaft because the inner ring shoulder is the seal counterface
• consist of a 62 series deep groove ball bearing and an SKF WAVE seal:
  • single lip, spring loaded radial shaft seal
  • made of NBR
• have limiting speeds quoted in the product table that are based on the permissible circumferential speed for the seal (14 m/s)

Bearings capped on both sides are lubricated for the life of the bearing and are virtually maintenance-free. They are filled with one of the following greases:

• standard deep groove ball bearings
• deep groove ball bearings with designation suffix VA947
  → GFM food-grade grease, registered by NSF as category H1
  The NSF registration confirms the grease fulfils the requirements listed in the US Food and Drug Administration’s guidelines under 21 CFR section 178.3570 (lubricant acceptable with incidental food contact for use in and around food processing areas).
• inch deep groove ball bearings
  • D < 63.5 mm → MT47
  • D ≥ 63.5 mm → MT33

On request, bearings can be supplied with the following special greases:

• high temperature grease GJN
• wide temperature range grease HT or WT
• wide temperature range and low-noise grease LHT23
• low temperature grease LT

The standard grease is not identified in the bearing designation (no designation suffix). Special greases are indicated by the corresponding grease suffix. Check availability of bearings with special grease prior to ordering.

Grease life for capped bearings

• is presented as L₁₀, i.e. the time period at the end of which 90% of the bearings are still reliably lubricated
  • for GFM grease
  • for other greases
• depends on:
  • the operating temperature
  • the nd_m value
  • grease performance factor (GPF)

The indicated grease life is valid under this combination of operating conditions:

• horizontal shaft
• inner ring rotation
• light load (P ≤ 0,05 C)
• operating temperature within the green temperature zone of the grease
• stationary machine
• low vibration levels

Where the operating conditions differ as described below, the grease life obtained from the diagrams should be adjusted:

• vertical shafts → 50% of the obtained value
• heavier loads (P > 0,05 C) → apply reduction factor

When capped bearings must operate under certain extreme conditions, such as very high speeds or high temperatures, grease may appear on the capping diameter. For bearing arrangements where this would be detrimental, appropriate actions could be taken. For additional information, contact the SKF application engineering service.

• can simplify the design of an arrangement
  • by locating the bearing axially in the housing by a snap ring
  • by saving space
  • by significantly reducing mounting time.

Appropriate snap rings

• open bearings with a snap ring groove only (designation suffix N)
• open bearings with a snap ring (designation suffix NR)
• bearings with a snap ring and a shield on the opposite side (designation suffix ZNR)
• bearings with a snap ring and a shield on the same side (designation suffix ZNBR)
• bearings with a snap ring and a shield on both sides (designation suffix 2ZNR)

• SKF Explorer rolling bearings accommodate higher load levels and provide extended service life. Optimized internal geometry reduces friction, wear and heat generation, allowing heavier loads to be accommodated. Advanced surface finish reduces friction and enhances lubricating conditions.

  Benefits of using SKF Explorer bearings include:

  • significantly extended service life
  • increased uptime and productivity
  • extended lubricant life
  • reduced sensitivity to misalignment
  • reduced noise and vibration
  • enabling downsized applications

  SKF Explorer bearings are clearly indicated in the product tables and product detail pages.

   

  For bearing solutions where you want to downsize, reduce vibrations, reduce friction or increase power density in your applications, select SKF Explorer.

• are designed to comply with stringent noise requirements
• are typically used in wind turbine generators
• provide consistent performance over a variety of operating conditions
• are identified by the designation suffix VQ658

• • are used where the load carrying capacity of a single bearing is inadequate
  • are used where the shaft has to be located axially in both directions with a specific axial clearance
  • where mounted immediately adjacent to each other, distribute the load between the bearings without having to use shims or similar devices

  A ‘V-shaped’ marking on the outside surface of the outer rings of matched bearings  indicates how the pair should be mounted. The bearing pairs are supplied as a packaged unit.

  Matched pairs can be supplied in three different arrangements

  Tandem arrangement

  • is identified by the designation suffix DT
  • is used where the load carrying capacity of a single bearing is inadequate
  • has parallel load lines and therefore shares the radial and axial loads equally
  • can accommodate axial loads in both directions

  Back-to-back arrangement

  • is identified by the designation suffix DB
  • has load lines that diverge towards the bearing axis
  • provides a relatively stiff bearing arrangement
  • can accommodate tilting moments
  • can accommodate axial loads in both directions, but only by one bearing in each direction

  Face-to-face arrangement

  • is identified by the designation suffix DF
  • has load lines that converge towards the bearing axis
  • is less sensitive to misalignment but not as stiff as a back-to-back arrangement
  • can accommodate axial loads in both directions, but only by one bearing in each direction