Ball bearing unit data

Boundary dimensions in accordance with:
  • ISO 3228
    • SY .. M series
    • SY .. U series, except for some dimensions related to attachment bolts
    • SYK series
    • P series, except for the centre height H1, which deviates slightly
  • JIS B 1559
    • SYJ series
  •  no standard (neither national nor international), but common in the marketplace
    • SYF series
    • SYFJ series
    • P2BC series
    • P2BSS series
    • P2BTC series
    • P2BTSS series
Bearing data

Cast iron, composite and stainless steel housings

Shaft centre height H1 (fig. 1):

  • d ≤ 40 mm
    → ±0,25 mm
  • d > 40 mm
    → ±0,30 mm

The outside diameter of the bearing is matched to its seat in the housing so that the outer ring is prevented from turning, but is still able to compensate for misalignment.

Bearing data
Radial internal clearanceBearing data

Cast iron

  • SY(J) and SYF(J) series
    • grey cast iron EN-GJL-HB235 in accordance with EN 1561


  • SYK series
    • glass fibre reinforced PA6
    • "moulded in" steel coil reinforcement

Pressed steel

  • P series
    • cold-rolled sheet steel, chromium6+ free zinc-coated

Composite for the SKF Food Line

  • P2BC and P2BTC series
    • glass fibre reinforced PP

Stainless steel

  • P2BSS and P2BTSS series
    • cast austenitic stainless steel (AISI 300 series)
Components and materials
MisalignmentBearing data

For units with a back seal (designation suffix DFH), the permissible static initial misalignment of the bearing is 1°.

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