Bearing units

Ložisková jednotka NSK
The bearing unit is a combination of a radial ball bearing, seal and housing. The outer surface of the bearing and the internal surface of the housing are spherical,  meaning the unit is self-aligning.
 
The inside of the ball bearing for the unit is constructed such that the steel balls and retainers used are of the same type as in series 62 and 63 of the deep groove ball bearing.
 
The housing is made of cast iron, pressed steel, stainless steel or plastic. They come in three types: Plummer block, flanged or special.
 
The shaft locking arrangement is very simple; most often by eccentric collar lock or set screw lock. Bearing units are a popular choice in many industries thanks to this easy installation.

Bearing units are distinguished according to the shape of the housing and type of shaft locking arrangement:

Ložiskové jednotky NSK
  • Plummer block units
  • Oval flanged units
  • Square flanged units
  • Round flanged units
  • Take-up units
  • Divided plummer block units with pressed steel housing
  • Divided oval flanged units with pressed steel housing
  • Bearing units with plain bearings and pressed steel housing

The two lines of bearing units:

  • Asian version (according to JIS) – producers SNR, NTN, NSK (for example UCP)
  • European version (according to ISO) –producers SNR, RHP, INA, SKF – different designation

Shaft locking arrangements:

  • Set screw type (UC, US, AS, 1000G, 1200G) – for standard applications without vibrations
  • Eccentric locking collar type (EX, ES, UEL, AEL, 1000DECG, 1200ECG) – applications with vibrations and without changing the direction of shaft rotation (eccentrically tightened in the direction of shaft rotation)
  • Adapter sleeve type (UK, 1000KG) – applications with high vibrations and shock loads. Better centring.
  • Press fit (tight fits and loose fits) – (6200 SEE, CS200LLU, 1726200-2RS)

Bearing materials:

  • Steel (100Cr6)
  • Stainless steel (AISI 440C, SUS440 C)
Ložiskové jednotky SNR

Housing materials:

  • Grey cast iron (FC200, FG20, FG25) with anticorrosive passivation and protective coating
  • Nodular graphite cast iron (FCD450) with anticorrosive passivation and protective coating. About 30% more durable and about 40% lighter than grey cast iron
  • Steel (SS400), for heavy loads, vibrations, shocks
  • Stainless steel (AISI 304 - X5CrNi 1810, SCS13)
  • Zinc-plated, cold-rolled steel sheet
  • Thermoplastic resin PBT

Basic requirements solved by bearing units

  • Easy mounting
  • Off-setting of the initial misalignment
  • Seals to prevent contamination

Ability to balance misalignment during assembly is high:

  • Bearings lubricated during operation          approx. +/- 2°
  • Bearings without additional lubrication      approx. +/- 5°–6°
  • With through covers          approx. +/- 1°
However, the bearing units are NOT designed to compensate for dynamic misalignment.

Bearing unit seals:

  • One-piece seal – flexible plastic lip on metal cover, for normal operating conditions and medium and high speeds.
  • Two-piece seal – one-piece seal plus a strong metal cover with lip for improved sealing capability without lowering the maximum speed. For medium to high speeds.
  • Seals with more lips (designation L3, L4 for SNR, LL for NTN, T... for SNR) – for heavily contaminated environments, providing excellent sealing capability for low to medium speeds.
  • High temperature silicone seals – up to 180°C.
  • Non-contact labyrinth seal for high temperatures – up to 200°C.
For additional protection against contamination, select metal, stainless steel, plastic or cast-iron covers. These covers may be either through or closed.

Lubrication of bearing units

Bearings are lubricated during production. Re-lubrication may be required under difficult operating conditions. The bearing units are provided with the grease fitting on the housing. It is necessary to choose the same lubricant or a type miscible with the original (the most common standard = lithium base, NLGI2) for relubrication.
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Special bearing unit designs for demanding applications:

Thermoplastic housing with stainless steel bearing – corrosion-resistant bearing units, Silver-Lube®

  • All the components of the insert bearing are made of 100% stainless steel
  • PBT thermoplastic housing
  • Operating temperature: -20°C to +90°C
  • Resistant to solvents and a variety of chemicals
  • Relubrication is possible
  • Polypropylene end covers are available
  • Food grade grease

Molded-Oil™ Insert bearing with stainless steel housing

  • Stainless steel bearing with solid grease – not necessary to re-lubricate
  • Operating temperature: -15°C to +80°C (permanently - max . 60°C)
  • Corrosion-resistant
  • Maintenance-free
  • Clean operating,  environment friendly

Thermoplastic housing with Molded-Oil™ insert bearing – corrosion-resistant bearing units, Life-Lube®

  • Stainless steel bearing with solid grease – not necessary to re-lubricate
  • PBT thermoplastic housing
  • Resistant to solvents and a variety of chemicals
  • Operating temperature: -15°C to +80°C (permanently - max. 60°C)
  • Corrosion-resistant
  • Maintenance-free
  • Clean operating, environment friendly

More details in the catalogues:

Ložiskové jednotky / Lož jednotky - Bearing units
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