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Slewing bearing

Slewing bearings are considered to have high load-bearing capacity and can be used in a variety of ways. Due to their structural design, they absorb both radial and axial loads as well as tilting moment loads with just one bearing. There are essentially two types of slewing bearings. These are essentially:

    Thin section four-point contact bearing (slewing bearing mounted with balls)

    • no preload
    • low requirements for evenness and squareness of the connecting structure
    • suitable for applications with low requirements for bearing accuracy and rigidity (construction machinery, metalworking machines, wind turbines)

     

    Crossed roller bearing (Slewing bearing mounted with cylindrical rollers)

    • preloaded
    • higher load capacity than four-point bearings
    • suitable for applications with high axial forces as well as medium axial and tipping moment loads
    • suitable for applications with smooth, jerk-free running and low rotational resistance
    • suitable for applications with high requirements for axial and concentricity as well as high rigidity (machine tools, robots or handling systems)
  • Slewing bearings - Types

    Four-point contact bearing VA

    Four-point contact bearing VA

    Four-point contact bearing, Type VA, externally toothed, bearing clerance selectable, sealed, grease nipple on the circumference of the toothless ring

    Four-point contact bearing VI

    Four-point contact bearing VI

    Four-point contact bearing, Type VI, innenverzahnt, bearing clerance selectable, sealed, grease nipple on the circumference of the toothless ring

    Four-point contact bearing VU

    Four-point contact bearing VU

    Four-point contact bearing, Type VU, not toothed, bearing clerance selectable, sealed, grease nipple on the circumference of the outer ring

    Four-point contact bearing VLA20

    Four-point contact bearing VLA20

    Four-point contact bearing, Type VLA20, Leichte Reihe 20, externally toothed, bearing clerance selectable, sealed, grease nipple on the circumference of the toothless ring

    Four-point contact bearing VLI20

    Four-point contact bearing VLI20

    Four-point contact bearing, Type VLI20, leichte Reihe 20, innenverzahnt, bearing clerance selectable, sealed, grease nipple on the circumference of the toothless ring

    Four-point contact bearing VLU20

    Four-point contact bearing VLU20

    Four-point contact bearing, Type VLU20, leichte Reihe 20, not toothed, bearing clerance selectable, sealed, grease nipple on the circumference of the outer ring

    Four-point contact bearing VSA20 / Four-point contact bearing VSA25

    Four-point contact bearing VSA20 / VSA25

    Four-point contact bearing, Type VSA20/VSA25, Schwere Reihe, externally toothed, bearing clerance selectable, sealed, grease nipple on the circumference of the toothless ring. VSA25 rolling body diamter 25 mm, bearing clearance tailored to the series

    Four-point contact bearing VSI20 / Four-point contact bearing VSI25

    Four-point contact bearing VSI20 / VSI25

    Four-point contact bearing, Type VSI20/VSI25, Schwere Reihe, innenverzahnt, bearing clerance selectable, sealed, grease nipple on the circumference of the toothless ring. VSI25 rolling body diamter 25 mm, bearing clearance tailored to the series

    Four-point contact bearing VSU20 / Four-point contact bearing VSU25

    Four-point contact bearing VSU20 / VSU25

    Four-point contact bearing, Type VSU20/VSU25, Schwere Reihe, not toothed, bearing clerance selectable, sealed, grease nipple on the circumference of the outer ring. VSU25 rolling body diamter 25 mm, bearing clearance tailored to the series

    Crossed roller bearing XA

    Crossed roller bearing XA

    Crossed roller bearing similar to INA, externally toothed, preloaded, sealed, grease nipple on the circumference of the toothless ring

    Crossed roller bearing XI

    Crossed roller bearing XI

    Crossed roller bearing similar to INA, innenverzahnt, preloaded, sealed, grease nipple on the circumference of the toothless ring

    Crossed roller bearing XU

    Crossed roller bearing XU

    Crossed roller bearing similar to INA, not toothed, preloaded, sealed, grease nipple on the circumference of the outer ring

    Crossed roller bearing XSA

    Crossed roller bearing XSA

    Crossed roller bearing similar to INA, heavy serie, externally toothed, preloaded, sealed, grease nipple on the circumference of the toothless ring

    Crossed roller bearing XSI

    Crossed roller bearing XSI

    Crossed roller bearing similar to INA, heavy serie, innenverzahnt, preloaded, sealed, grease nipple on the circumference of the toothless ring

    Crossed roller bearing XSU

    Crossed roller bearing XSU

    Crossed roller bearing similar to INA, heavy serie, not toothed, preloaded, sealed, grease nipple on the circumference of the outer ring

    Crossed roller bearing SX

    Crossed roller bearing SX

    Crossed roller bearing similar to INA, corresponding to dimension series 18 according to DIN 616, not sealed, greased, bearing clearance, non preloaded or preloaded, Outer ring split in the circumferential direction and held together by three retaining rings

    Crossed roller bearing XV

    Crossed roller bearing XV

    Crossed roller bearing similar to INA, sealed on both sides, greased, bearing clearance, Can be preloaded using a locknut, inner ring divided in the circumferential direction, outer ring can be screwed directly to the adjacent structure

  • Suffix

    Suffix Four-point contact bearing
    Suffix description
    H Hardened teeth on the bearing ring
    N Gearing on the bearing ring normalized
    V Teeth on the bearing ring are tempered
    VSP Bearings with preload
    ZT Centering on the bearing outer and inner ring
    RL0, RL1, RL2, RL3 narrowed bearing clearance

  • Calculation of rotational resistance

    v = DM/2000 ×(µ × k × ( MK × 1000/DM +  Fr × fL/2 +  Fa/k ) +  DM × Wr/1000)

    The torque of resistance (Mw) can only be roughly calculated using the influences listed in the table below (factors of rotational resistance).

    Legend
    Sign Unit of measurement description
    MW kNm Torque resistance
    DM mm Rolling body center circle diameter
    µ - Frictional resistance coefficient (Table A)
    k - Load distribution factor (Table A)
    Mk kNm dynamic tipping moment load
    Fr kN dynamic radial load
    fL - Career factor (Table A)
    Fa kN dynamic axial bearing load
    Wr kN/m specific friction force from seals, cages, etc. (Table A)

    Factors for determining rotational resistance

    Factors for determining rotational resistance
    Form µ k fL WR
    VL*20, VS*20
    (normal clearance and preload (VSP))    		 0,01 4,37 1,731) 0,21
    VS*25, VA, VI, VU 0,005 4,37 1,731) 0,21
    XS*14, XA, XI, XU 0,004 4,08 1,00 1 - (0,44 × DM )/1000

    1) Validity of the values ​​for the predominant load from the tilting moment and axial force.
    fL = 1 with predominantly radial loads, if:

    Fr ≥ (450 × Mk/DM ) +0,1 × Fa

    The values determined according to the equation can deviate significantly from the actual ones due to the influence of the above-mentioned variables, e.g.:

    • for unloaded or lightly loaded bearings
    • due to flatness deviations in the adjacent construction
    • due to deviations in the perpendicularity of the connecting structure
    • the relation: Mk × 2000/DM × Fabecomes  < 1.

    If four-point bearings/crossed roller bearings of the VL*20 or VS*20 series are used for reel bearings, greater fluctuations in rotational resistance must be expected depending on the application.

    Dimensioning of rotary drives

    When dimensioning rotary drives, the following factors must be taken into account in addition to the rotary resistance:

    • Acceleration performance
    • possibly tilted position
    • attacking wind forces


    If no exact values are available, twice the value of MW should be included in the calculation.

  • Maintenance note

    Relubrication periods

    Essentially, relubrication intervals depend on the operating conditions, environmental influences such as water, dust and dirt, but also on the type and design of the slewing bearing used. It is therefore not possible to specify exact relubrication intervals, but must be determined through tests under application conditions. If there are no comparable results from such tests yet, you can use the following guideline values assuming operating temperatures <70°C, peripheral speeds <= 0.5m/s and low to medium loads.

    Nachschmierfristen
    Application (use) Relubrication period*
    Clean and dry environment (e.g.: robots, turntables, etc.) every 500 h
    Heavily polluted environment (e.g.: excavator, crane, etc.) every 100 - 200 h
    Very polluted environment (e.g. drilling rigs, smelting works, etc.) continuously central lubrication


    *Does not apply to gearing.

    Please also note that relubrication must be carried out immediately after the following events:

    • After cleaning, for example, with water jets, steam or similar
    • Before and after longer downtimes, for example for cranes or construction machinery that were shut down due to winter or other downtimes
    • At high humidity

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