Bearing tolerances symbols

The dimensional and running accuracy of rolling bearings has been standardized internationally (Bearing tolerance). The tolerance symbols and their definitions are provided in table as blow:

Tolerance
symbol
Definition
  Radial bearings inner ring - cylindrical and tapered bore
 
d
  1. Cylindrical bore: Nominal bore diameter
  2. Tapered bore: Nominal bore diameter at the theoretical small end
Δdmp
  1. Cylindrical bore: Deviation of a mid-range size (out of two-point sizes) of bore diameter in any cross section from its nominal size
  2. Tapered bore: Deviation of a mid-range size (out of two-point sizes) of bore diameter at the theoretical small end from its nominal size
Δds Deviation of a two-point size of bore diameter of a cylindrical bore from its nominal size
Vdsp Range of two-point sizes of bore diameter in any cross section of a cylindrical or tapered bore
Vdmp Range of mid-range sizes (out of two-point sizes) of bore diameter obtained from any cross section of a cylindrical bore
B Nominal inner ring width
ΔBs
Normal, 
Modified1)
  1. Symmetrical rings: Deviation of a two-point size of inner ring width from its nominal size
  2. Asymmetrical rings, upper limit: Deviation of a minimum circumscribed size of inner ring width, between two opposite lines, in any longitudinal section which includes the inner ring bore axis, from its nominal size
  3. Asymmetrical rings, lower limit: Deviation of a two-point size of inner ring width from its nominal size
VBs
  1. Symmetrical rings: Range of two-point sizes of inner ring width
  2. Asymmetrical rings: Range of minimum circumscribed sizes of inner ring width, between two opposite lines, obtained from any longitudinal section which includes the inner ring bore axis
Kia Circular radial run-out of inner ring bore surface of assembled bearing with respect to datum, i.e. axis, established from the outer ring outside surface
Sd Circular axial run-out of inner ring face with respect to datum, i.e. axis, established from the inner ring bore surface
Sia Circular axial run-out of inner ring face of assembled bearing with respect to datum, i.e. axis, established from the outer ring outside surface
 
   
  Radial bearings inner ring - tapered bore only
 
d1 Nominal bore diameter at the theoretical large end of a tapered bore
Δd1mp Deviation of a mid-range size (out of two-point sizes) of bore diameter at the theoretical large end from its nominal size
SL Taper slope, the difference between nominal diameters at the theoretical large end and small end of a tapered bore (d1 - d)
ΔSL Deviation of taper slope of a tapered inner ring bore from its nominal size
 
 
  Radial bearings outer ring
 
D Nominal outside diameter
ΔDmp Deviation of a mid-range size (out of two-point sizes) of outside diameter in any cross section from its nominal size
ΔDs Deviation of a two-point size of outside diameter from its nominal size
VDsp Range of two-point sizes of outside diameter in any cross section
VDmp Range of mid-range sizes (out of two-point sizes) of outside diameter obtained from any cross section
C Nominal outer ring width
ΔCs
Normal, 
Modified1)
  1. Symmetrical rings: Deviation of a two-point size of outer ring width from its nominal size
  2. Asymmetrical rings, upper limit: Deviation of a minimum circumscribed size of outer ring width, between two opposite lines, in any longitudinal section which includes the outer ring outside surface axis, from its nominal size
  3. Asymmetrical rings, lower limit: Deviation of a two-point size of outer ring width from its nominal size
VCs
  1. Symmetrical rings: Range of two-point sizes of outer ring width
  2. Asymmetrical rings: Range of minimum circumscribed sizes of outer ring width, between two opposite lines, obtained from any longitudinal section which includes the outer ring outside surface axis
Kea Circular radial run-out of outer ring outside surface of assembled bearing with respect to datum, i.e. axis, established from the inner ring bore surface
SD Perpendicularity of outer ring outside surface axis with respect to datum established from the outer ring face
Sea Circular axial run-out of outer ring face of assembled bearing with respect to datum, i.e. axis, established from the inner ring bore surface
 
 
  Chamfer limits
 
rs Single chamfer dimension
rs min Smallest single chamfer dimension of rs, r1, r2, r3, r4 …
r1, r3 Radial direction chamfer dimensions
r2, r4 Axial direction chamfer dimensions
 
 
  Tapered roller bearings
 
T Nominal assembled bearing width
ΔTs Deviation of minimum circumscribed size of assembled bearing width from its nominal size
T1 Nominal effective width of cone (inner ring, with roller and cage assembly) assembled with a master cup (outer ring)
T2 Nominal effective width of cup assembled with a master cone
ΔT1s Deviation of minimum circumscribed size of effective width (cone assembled with a master cup) from its nominal size
ΔT2s Deviation of minimum circumscribed size of effective width (cup assembled with a master cone) from its nominal size
 
 
  Thrust bearings shaft washer
 
d Nominal bore diameter of shaft washer, single direction bearing
Δds Deviation of a two-point size of shaft washer bore diameter from its nominal size
Δdmp Deviation of a mid-range size (out of two-point sizes) of shaft washer bore diameter in any cross section from its nominal size
Vdsp Range of two-point sizes of shaft washer bore diameter in any cross section
d2 Nominal bore diameter of central shaft washer, double direction bearing
Δd2mp Deviation of a mid-range size (out of two-point sizes) of central shaft washer bore diameter in any cross section from its nominal size
Vd2sp Range of two-point sizes of central shaft washer bore diameter in any cross section
Si
  1. Range of two-point sizes of thickness between shaft washer raceway and the back face, cylindrical roller thrust bearing
  2. Range of minimum spherical sizes between the raceway and the opposite back face of the shaft washer, obtained from any longitudinal section which includes the shaft washer bore axis, thrust ball bearing
 
 
  Thrust bearings housing washer
 
D Nominal outside diameter of housing washer
ΔDs Deviation of a two-point size of housing washer outside diameter from its nominal size
ΔDmp Deviation of a mid-range size (out of two-point sizes) of housing washer outside diameter in any cross section from its nominal size
VDsp Range of two-point sizes of housing washer outside diameter in any cross section
Se
  1. Range of two-point sizes of thickness between housing washer raceway and the back face, cylindrical roller thrust bearing
  2. Range of minimum spherical sizes between the raceway and the opposite back face of the housing washer, obtained from any longitudinal section which includes the housing washer outside surface axis, thrust ball bearing
 
 
  Thrust bearings assembled bearing height
 
T Nominal assembled bearing height, single direction thrust bearing (except spherical roller thrust bearing → T4)
ΔTs Deviation of minimum circumscribed size of assembled bearing height from its nominal size, single direction thrust bearing (except spherical roller thrust bearing → ΔT4s)
T1
  1. Nominal assembled bearing height, double direction thrust bearing
  2. Nominal assembled bearing height, single direction thrust bearing with a seat washer
ΔT1s
  1. Deviation of minimum circumscribed size of assembled bearing height from its nominal size, double direction thrust bearing
  2. Deviation of minimum circumscribed size of assembled bearing height from its nominal size, single direction thrust bearing with a seat washer
T32) Nominal assembled bearing height, double direction thrust bearing with seat washers
ΔT3s2) Deviation of minimum circumscribed size of assembled bearing height from its nominal size, double direction thrust bearing with seat washers
T43) Nominal assembled bearing height, spherical roller thrust bearing
ΔT4s3) Deviation of minimum circumscribed size of assembled bearing height from its nominal size, spherical roller thrust bearing
  1. 1) Modified applies to inner rings and outer rings of bearings of matched bearing sets consisting of two or more bearings. Does not apply to universally matchable angular contact ball bearings.
  2. 2) Not included in ISO 199:2014.
  3. 3) In ISO 199:2014, the symbol T is used.

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