Structure and FeaturesSpherical Bushings are self-aligning spherical

plain bushings that have inner and outer rings withspherical sliding surfaces, and can take a large radialload and a bi-directional axial load at the same time.There are many types of Spherical Bushings, but theyare basically divided into steel-on-steel types andmaintenance-free types according to the kind of slid-ing surfaces.Steel-on-steel Spherical Bushings have inner andouter rings of high carbon chromium bearing steel, ofwhich sliding surfaces are phosphate-treated andthen dry-coated with molybdenum disulfide (MoS2).They can, therefore, operate with low torque, andhave excellent wear resistance and large load capaci-ty. They are especially suitable for applications wherethere are alternate loads and shock loads. They havewide applications mainly in industrial and constructionmachinery.Maintenance-free Spherical Bushings consist of anouter ring which has a special PTFE liner reinforcedwith copper alloy meshes on the sliding surface, anda spherical inner ring of which sliding surface has ahard chromium plating. Creep deformation due tocompressive load is small, and wear resistance issuperior. Thus, they are maintenance-free and canbe used for extended periods of time without re-lubri-cation. They are especially suitable in cases wherefixed directional loads are applied and are used main-ly in food processing machines and constructionmachinery and in other applications in which the useof oil is undesirable or lubrication is not possible.

Structures of Spherical Bushings

Outer ring (MoS2 coating)

Inner ring(MoS2 coating)

Steel-on-steel type

Outer ring (MoS2 coating)

Inner ring (MoS2 coating)

Seal (Polyurethane)

Outer ring

Outer ring

Special PTFE liner (Reinforced with copper alloy meshes)

Inner ring(Chromium plating)

Inner ring(Chromium plating)

Seal(Synthetic resin)

Special PTFE liner(Reinforced with copper alloy meshes)

Steel-on-steel type

Maintenance-free type

Maintenance-free type

TypesSpherical Bushings are available in various typesshown in Table 1.

Table 1 Type of bearingType

Series

Metric

Inch

SBSBAGEEESGEGGSSBB

GEES-2RSGEGS-2RSSBB -2RS

GEEC

GEEC-2RS

Maintenance-free

Without seals With seals

Steel-on-steel

Without seals With seals

K2

Steel-on-steel Spherical BushingsMaintenance-free Spherical Bushings

K1

ClearanceThe radial internal clearances of Spherical Bushingsare the values before splitting the outer ring, and areshown in Tables 4, 5 and 6. The radial internal clear-ances of the inch series are shown in the dimensiontable.Clearances other than these can also be prepared onrequest. Please consult .

AccuracyThe tolerances of Steel-on-steel Spherical Bushingsof the metric series is shown in Table 2.The tolerances of the GE type are applicable to bush-ings before splitting the outer ring and after surfacetreatment.The tolerances of the SB and SBA types are applic-able to bushings before splitting the outer ring andbefore surface treatment.The tolerances of the GEEC type are applicable tobushings before splitting the outer ring.The tolerances of the Spherical Bushings of the inchseries are shown in Table 3. The tolerances of thebore diameter are applicable to bushings after surfacetreatment, while other tolerances are applicable tobushings before splitting the outer ring and beforesurface treatment.Although minor dimensional changes may occur dur-ing surface treatment, they have negligible influenceon the overall performance.

unit: mTable 2 Tolerances of inner and outer rings of metric series (JIS Class 0)d or D1

Nominal bore dia.or outside dia.

mm

Over Incl. High Low High Low High Low

2.56

18305080

120150180250315400

618305080

120150180250315400500

000000000000

8 810121520252530354045

8 9111315182530354045

120120120120150200250250300350400450

00000000000

000000000000

dmpSingle plane

mean bore dia.deviation

DmpSingle planemean outsidedia. deviation

Bs or CsDeviation of a singleinner ring width or

outer ring width

Note(1) d for dmp, Bs and Cs and D for Dmp, respectively.

unit: mTable 3 Tolerances of inner and outer rings of inch series SBB

d or D1Nominal bore dia. or

outside dia.mm

Over Incl. Low High Low High Low

50.80076.20080.962

120.650152.400177.800

50.80076.20080.962

120.650152.400177.800222.250

00000

1315202025

13151520252530

130130130130130130130

0000000

0000000

dmpSingle planemean bore

dia. deviation

DmpSingle plane

mean outsidedia. deviation

Bs or CsDeviation of a singleinner ring width or

outer ring width

Note(1) d for dmp, Bs and Cs and D for Dmp, respectively.

High

unit: mTable 4 Radial internal clearance of SB and SBA types (Steel-on-steel)

SB type

Min. Max. Min. Max.

12152022253035404550556065707580859095

100110115120130150

70

75

85

90

95

100

110

120

125

140

150

160

170

185

200

215

3240

60

85

100

6882

50 100

120

72 142

165

192

dNominal bore dia.

mm

SBA type

K41N=0.102kgf=0.2248lbs.1mm=0.03937inch

Steel-on-steel Spherical Bushings SBThese bushings have an outer ring split into halves.The split outer ring and the inner ring are held togeth-er by a snap ring placed in the groove around theouter periphery of the outer ring.

Steel-on-steel Spherical Bushings SBAThese bushings have an outer ring split only at oneposition, and therefore, the outer and inner rings willnot separate. Handling before mounting and mount-ing to the housing are simple. The boundary dimen-sions are the same as those of the SB type.Therefore,SB and SBA types are dimensionally interchange-able, but the radial internal clearances of the SBAtype are smaller than those of the SB type.

Steel-on-steel Spherical Bushings GEEGEESThe dimension series of these types conform to ISOstandards and they can be used internationally. Theouter ring is split at one position. The GEE and GEES types are available. These are classified bybushing size.The GEES type can be provided with seals, whichare double-lip type polyurethane seals effective forprevention against grease leakage and dust penetra-tion. The sealed type is indicated by the suffix "-2RS"at the end of the identification number.

Steel-on-steel Spherical Bushings GEGGEGSAs compared with the GEE and GEES types,these bushings have larger load capacities and largerpermissible tilting angles. The dimension series alsoconform to ISO standards, and they can be usedinternationally. The outer ring is split at one position.The GEG and GEGS types are available. Theyare classified by bushing size.The GEGS type can be provided with seals, whichare double-lip type polyurethane seals effective forprevention against grease leakage and dust penetra-tion.

Steel-on-steel Spherical Bushings SBBThese are inch series bushings. The outer ring is splitat one position.These bushings can be provided with seals, which aredouble-lip type polyurethane seals effective for pre-vention against grease leakage and dust penetration.

Maintenance-free Spherical Bushings GEECThese bushings have the same boundary dimensionsas the GEES type and can be used internationally.A special PTFE liner reinforced with copper alloymeshes is used on the sliding surface. Therefore,creep deformation due to compressive loads is small,and wear resistance is superior. These bushings areused as maintenance-free bushings.These bushings can be provided with synthetic resinseals which are effective in preventing dust penetra-tion. They are indicated by the suffix "-2RS" at theend of the identification number.Spherical Bushings with superior rust preventionproperties, which can be used in a corrosive environ-ment or in an environment where water splashes, arealso available on request. Please consult .

Identification numberThe identification number of Spherical Bushings con-sists of a model code, a size and any supplementalcodes. Examples are shown below.

K3

2 Static load capacityThe static load capacity Cs is the maximum static loadthat can be applied on the spherical bushing withoutbreaking inner and outer rings or causing any perma-nent deformation severe enough to render the bush-ing unusable.It must be noted that if the magnitude of the appliedload becomes comparable to the static load capacityof bushing, the stresses in the shaft or housing mayalso reach to their limits. This possibility must betaken into consideration in the design.

Equivalent radial load

Spherical Bushings can take radial and axial loads atthe same time. When the magnitude and direction ofloads are constant, the equivalent radial load can beobtained from the following formula.

PFrYFa (2)where, PEquivalent radial load N

FrRadial load NFaAxial load NYAxial load factor (Refer to Table 11.)

Table 10 Temperature factor ft

Type of bushing

Steel-on-steel

Maintenance-free

Without seals

With seals

Without seals

With seals

1

1

1

1

1

1

1

0.9

1

0.75

1

0.55

0.7

Temperature

3080

8090

90100

100120

120150

150180

Before attempting to calculate the life, make sure thatthe operating conditions are within the permissiblerange by referring to the pV diagram in Fig.1. When the operating conditions are out of the permis-si