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2 Products availableWe offer the best product range of Motor and Pump Bearing EMQ, Tapered Roller Bearings, Spherical Roller Bearings, Cylindrical Roller Bearings and Needle Roller Bearings.
OMT is produce high quality EMQ Bearings under Japanese technology.Bearings are specially designed for applications where significantly required low noise and vibration.
We are proud of our breakthrough designs, which have been chosen and trusted across industries and perfect Choice and perfectly made forYour Application.
The following are features of OMT-EMQ ball bearing series,
Tapered roller bearings have the rolling elements under the form of frustra of cones. They roll on tapered surfaces which, if extended, converge towards a single point on the bearing axis.
The rollers are guided tangentially by the cage and axially by the big rib of the outer ring, on which they have point contact. As between rollers and raceways there is linear contact, tapered roller bearings can take heavy radial loads. They can also take heavy axial or combined loads, depending on the contact angle caused by the tapered rolling elements. The contact angle is the angle of the outer raceway generatrix.
Tapered roller bearings can be manufactured in the versions : single, double and four row rollers.
Single row tapered roller bearings are of separable design, i.e. the outer ring and the inner ring with rollers and cage assembly can be separately mounted. These two assemblies are interchangeable.
Tapered roller bearings can be manufactured both in standardized constructive versions with dimensions series 320, 302, 322, 303, 323, 313 and with non-stand-ardized dimensions, mm or inch.
Tapered roller bearings can carry only single direction axial loads. Under pure radial loads, an axial force occurs which is supposed to distance the bearing rings in axial direction. Therefore, tapered roller bearings are generally pair mounted on both ends of the shaft, in X or O arrangements, so that the shaft will be axially located in both directions (table 4). Thus, the optimum clearance in these two bearings can be adjusted.
Single row tapered roller bearings can also be manufac-tured with rib on the outer ring. This design is to be used when the housing cannot be manufactured with shoulder, but only with a passed through bore. In this case, axial location can be provided by the bearing ring.
Paired single row tapered roller bearings
If tapered roller bearings are pair mounted in X or O arrangements, the load carrying capacity increases and loads can be taken in both directions in the same bearing.
These bearing sets have guaranteed clearance after mounting since the distance rings are mounted between the bearing rings.
certain applications, paired bearings can be delivered with small clearance or lightly preloaded.
Double row tapered roller bearings
Double row tapered roller bearings are used where load carrying capacity should be greater, loads should be taken in both directions and axial space is smaller than in case of a set of two single row tapered roller bearings.
Double row tapered roller bearings can have the rollers in face- to-face arrangement, double inner ring and two outer rings respectively or the rollers in back-to-back arrangement, i.e. double outer ring and two inner rings.
The first design provides greater stiffness, can take tilting moments and shaft expansions can be compen-sated.
The bearings of the second design can be manufac-tured with tapered bore so that they can be frequently mounted dismounted.
Double row tapered roller bearings can have or not distance rings with lubrication holes, mounted between the simple rings.
In case of bearings with distance rings, the bearing clearance or preload are pre-adjusted; in case of those without distance rings, bearing clearance and preload can and should be adjusted while mounting.
Double row tapered roller bearings with rollers in back-to-back arrangement can also be manufactured in the following two versions:
-with rib on the outer ring; the housing has no shoulder and the bearing is axially-with two seals; this design is used in motor vehicles construction. The bearings are delivered filled with grease and relubrication is not needed.
Dimensions
Tapered roller bearings are manufactured with the fol-lowing dimensions:
-metric dimensions (mm), according to ISO 355;
-inchdimensions;
Misalignment
As between rollers and raceway there is a linear contact, tapered roller bearings have low capacity to compensate for errors of alignment between shaft and housing.
Permissible values of misalignment between shaft and housing are given in table 1, depending on bearing size and load magnitude.
Tapered roller bearings are generally manufactured to
For certain applications (e.g. bearings for machine-tools), they can be also manufactured to tolerance clas-ses P5 and P6X or 3 AFBMA.
At request, they can be manufactured to tolerance class P4.
Single row tapered roller bearings have the outer rings interchangeable with the inner ring rollers cage as-sembly (if they have the same mark) and also with bear-ings produced by other companies, according to ISO and AFBMA respectively.
The parts of the two and four row tapered roller bearings are non-interchangeable.
The tolerances for bearings overall dimensions are given in tables on page 24 for tapered roller bearings, both with metric and inch dimensions. Tolerances for mounting chamfer are given in tables on page 41.
Radial and axial clearance
In case of tapered roller bearings, clearance should be in radial direction, but it is measured and adjusted in axial direction. As tapered roller bearings are dismountable, their clearance is not guaranteed by design and it is adjusted while mounting. Thus, optimum clearance can be obtained for that application.
In case of double and four row tapered roller bearings with distance rings between bearing rings, the clearance is guaranteed and its values are given in table 2. The bearing parts are numbered for each bearing so that the prescribed clearance on each row should be observed while mounting.
??In case of bearings without distance rings, clearance is adjusted as for single row tapered roller bearings: for DB design by the inner rings and for DF design by the outer rings. The above specifications are also available for bearings matched in sets.
??The values of the axial clearance can be calculated using the equation:
axial clearance = radial clearance/2tg
where is the contact angle.
??In case of certain applications where clearance be-tween shaft and housing should be avoided, tapered roller bearings can also be pre-tightened. This can be adjusted while mounting or is pre- adjusted by distance rings, in case of two or four row tapered roller bearings.
Contact angle
Contact angle of tapered roller bearings is the angle of the outer ring raceway generatrix. In case of standardized single row tapered roller bearings, this angle can be found in the standard of dimensions (ISO 355 and nation-al standard STAS 3920 respectively). Bearings series 329, 302, 322, 303 and 323 have acontact angle between 10? and 17? and those of series 313 have a contact angle of 28? 48 39, so that they can take heavier axial loads. Non-standardized single row tapered roller bearings and also all double and four-row tapered roller bearings have the contact angle between 9? and 30?.
Cages
Small and medium sized tapered roller bearings are generally fitted with pressed sheet cages. Large sized bearings are generally fitted with machined steel or brass cages, with welded pins. In some cases, median or large sized bearings can also be fitted with machined steel or brass cages. In all cases, the cage is guided on rollers.
For small and medium sized bearings, glass fibre rein-forced polyamide
??Equivalent dynamic radial load can be calculated using the following equations:
-for single row tapered roller bearings:
Pr = Fr, kN, ??? when Fa/Fr e
-for paired bearings and double or four-row tapered roller bearings:
Pr = Fr + Y1 Fa, kN, when Fa/Fr e
??For single row tapered roller bearings, the Fa values can be calculated using the equations in table 4. These equa-tions are available when bearings are mounted so that axial clearance is in fact zero without preloading. FrA and FrB should always be considered as being positive, even if they act in the opposite direction to that in the figure.
??In case of paired bearings and of double or four row tapered roller bearings, Fa and Fr are the loads acting upon the paired bearings or single bearings.
??The values of e, Y, Y1 and Y2 are given in bearing tables
Abutment dimensions
The mounting dimensions of tapered roller bearings are given in the bearings tables, for single row tapered roller bearings. These dimensions are also available for bear-ings with ribs and for standardized paired bearings. For the other types of tapered roller bearings, the mounting dimensions should be adapted depending on the cross section size and mounting chamfer.
Spherical roller bearings operate in arduous condi-tions. The spherical rollers can be symmetrical or unsym-metrical and are self-aligning in the outer ring sphered raceway. Thus, the possible coaxiality deviations of the supporting bearings as well as shaft bending can be compensated.
Spherical roller bearings are manufactured in the following constructive versions, depending on the bearing size and series:
Spherical Roller Bearings, tables
Spherical Roller Bearings adapter sleeves tables
Spherical Roller Bearings withdrawel sleeves tables
MB design
These bearings have a central fixed rib, an one-piece cage guided on the inner ring
Cylindrical roller bearings are manufactured in a various range of constructive types and sizes, particularly single row cylindrical roller bearings but also two or more row cylindrical roller bearings, with cages or roller by roller, as shown in the designs below.
In case of cylindrical roller bearings, the rollers are laterally guided by the fixed ribs of one ring.
In case of bearings with cages, the ring with ribs and the rollers retained in the cage can be drawn out from the other ring, which means that these bearings are dis-mountable Therefore, bearings from joints can be much easier mounted and dismounted, especially were interference fits are needed for both rings due to the loading condi-tions. Bearings are provided with unloaded rollers at both generatrix ends. Therefore, the linear contact between rollers and rings alters advantageously, i.e.peripheral stresses are avoided.
Single or more rows cylindrical roller bearings
Single row cylindrical roller bearings are manufactured by MTK+ in various constructive versions, depending on the position of the ribs on rings. The four basic designs (NU, NJ, N and NUP) are given in the bearing tables Bearings of NU design have two fixed ribs on the outer ring and one smooth inner ring. Bearings of N design have twofixed ribs on the inner ring and one smooth outer ring. These designs allow an axial displacement in certain limits, of the shaft in relation to the housing. Therefore, these rolling bearings are used in non-locating bearing units. Bearings of NJ design have two fixed ribs on the outer ring and a fixed rib on the inner ring which can guide the shaft in a single direction (axially).Bearings of NUP design have also two fixed ribs on the outer ring and, on the inner ring, a fixed rib and a support washer. This way they can be used as locating bearings, guiding the shaft axially in both directions.For a shaft guiding in a single direction, it also can be used a bearing of NLJ design which is combined with a support washer. Thus, the constructive version NUJ is obtained Support washers on both sides of a bearing of NU design are not allowed as they lead to an axial blocking of the rollers.
Cylindrical roller bearings can carry heavy radial loads and can operate at high speeds.
Double or more rows cylindrical roller bearings have small sections, high load carrying capacity and stiffness.
These bearings provide high stiffness and maximum load carrying capacity and are particularly used for tool holders of the machine-tools and rolling mills.
Double row cylindrical roller bearings series NNU49 and NN30 are generally manufactured to tolerance classes P5 and SP, used for machine tools.
Large-sized bearings series NNU49 are also manufac-tured to the normal tolerance class.
Cylindrical roller bearings with snap ring groove
Single row cylindrical roller bearings are also manufac-tured with snap ring grooves on the outer rings. This design simplifies the bearing joint as the bearings are located into the housing by means of the snap rings. The snap ring groove and snap rings are in accordance with ISO 464, and tables 7 and 8 on page 84 and 87.
Cylindrical roller bearings without cage (full complement)
These bearings incorporate the maximum number of rollers and have a small section in relation to their width.
This provides a high load carrying capacity and allows space-saving designs to be achieved.
Cylindrical roller bearings without cage cannot be used at speeds as high as those with cages. These bearings are manufactured with single or more row rollers and suffix V is added to the bearing designation. The most utilized bearings are those of series NCF29 V, NCF30 V and NJ23VH and they are given in this catalogue on page 194.M
Dimensions
The main dimensions of standardized bearings given in tables are in accordance with ISO 15.
Misalignment
The modified contact between rollers and raceway al-lows not only peripheral stresses to be avoided but also, in case of single row roller bearings, permits an angular misalignment of the outer ring with respect to the inner ring, depending on the bearing series and load according to the table 1.
Tolerances and radial clearance
Single row cylindrical roller bearings are usually manufactured to normal tolerance class with normal radial clearance
They can also be manufactured to more accurate tolerance classes and with larger (C3NA and C4NA) or smaller (C1NA and C2NA) radial clearances.
Tolerances of cylindrical roller bearings are given on pages 24.
Radial clearances according to international standard ISO 5753 are given in tables 2 and 3 for cylindrical bore bearings both with interchangeable rings and with non-interchangeable rings (NA).
Cages
Small and medium-sized single row cylindrical roller bearings are generally fitted with pressed sheet cages. Large-sized bearings are fitted with machined brass cages of normal design, i.e. cages of separable design guided on rolling elements M, on the outside surface MA or inner surface MB.
In case of heavy loads and high speeds, cages are made in one piece.
Glass fibre reinforced polyamide 6.6 cages, are suc-cessfully used for small and medium-sized bearings, if the operating temperature doesnt exceed + 120?C. These cages have low weight, low coefficient of friction and are noiseless while running.
Cage design and some technical data are given in table 4.
Minimum load
Cylindrical roller bearings must be subjected to a given minimum load, so that a proper operation of these bear-ings can be guaranteed.
This is necessary especially as the bearings are operated at high speeds and the centrifugal forces produce additional friction in bearing due to the sliding between rollers and raceway.
The values of the minimum load can be enough ac-curately calculated using the equation:
Frm = 0, 02 Cr, kN;
Minimum load
For cylindrical roller bearings purely radially loaded which dont locate shafts axially, equivalent dynamic load is:
Pr = Fr, kN;
If cylindrical roller bearings have ribs on the outer and inner rings and locate shafts axially in one or both direc-tions, equivalent dynamic load can be calculated using the equations:
The viscosity ratio k is the ratio of the actual viscosity at the operating temperature to the requisite viscosity for a proper lubrication at that temperature. Further details can be found in subchapter Adjusted rating life, life adjust-ment factor a3 on page 20.
In case of grease lubrication, the base oil viscosity of the grease should be used. These effects can be reduced at low speeds by using oils with EP additives.
The values of permissible axial load Fa max obtained from the equation above mentioned are valid for a con-tinuously acting constant axial load. If axial loads act only for short periods, the values may be multiplied by 2 or for shock loads by 3.
The constantly acting axial load Fa max (N) should never exceed the numerical value of 1, 2 D2( D= bearing outside diameter, mm) and occasional shock loads should never be greater than the numerical value of 3 D2.
In case of heavy axial loads (Fa > D2 ), the ribs of the outer and inner ring respectively are recommended to be supported by the bearing adjoint parts. Bearings of NUP and NJ+HJ designs which take axial loads in both direc-tions are to be placed so that main axial loads should be taken by the fixed ribs, if bearing design allows.
Heat treatment
Cylindrical roller bearings with outside diameter D > 240 mm of all series given in the catalogue are to be subjected to a heat treatment of stress relieving which allows bearings to be operated up to a temperature of +150?C.
The hardness of rings should not be less 59 HRC.
Small-sized bearings operate normally up to +120?C.
Abutment dimensions
For a proper location of bearing rings on the shaft and housing shoulder respectively, shaft (housing) maximum radius ru max should be less than bearing minimum mounting chamfer rs min.
Shoulder height should also be properly sized in case of bearing maximum mounting chamfer.
The values of the connection radii and support shoulder height are given in table 6.
Abutment dimensions for single row cylindrical roller bearings are given in table 7. The values for double row cylindrical roller bearings are given in table 8.
Needle roller bearings can be considered a version of cylindrical roller bearings. As these small-sized bearings can take over heavy dynamic loads, they provide high stiffness in bearing units.
Needle roller bearings are manufactured in the follow-ing constructive versions:
Needle roller bearings with inner ring
In case of limited space needle roller bearings without inner rings (RNA type) can be used instead of needle roller bearings with inner rings. The shaft must be har-dened and ground.
The shaft raceway must have a hardness of 5865 HRC and a minimum roughness Ra = 0, 2 ?m for normal bearings. In case of less pretentious bearings, Ra = 0, 3 ?m is allowed.
Minimum thickness of the case-hardened layer can be determined as a function of the rolling element diameter, using the equation:
tmin = (0, 070, 12)Dw, mm
where:
Dw = rolling element diameter, mm
Greater values are valid in case of materials with core low strength and heavy loads.
In case of heat treatment steels (e.g. 41 MoCM 1) which have been surface hardened and tempered, layer thick-ness can be calculated using the equation:
tmin = (0, 10, 15)Dw, mm
where:
Dw = rolling element diameter, mm
Layer thickness after grinding must be of minimum 0, 3 mm.
If the hardness of the surface layer is less than 58 HRC, bearing cannot accommodate the initial basic dynamic load Cr and basic static load Cor, respectively. In this case, basic dynamic load will be decreased by factor fH and basic static load by factor foH, according to the equations:
Cr ef = fH Cr, kN
C0r ef = f0H C0r, kN
Factors fH and f0H are given in table 1.
The dimensions of needle roller bearings are stand-ardized only for dimension series NA48, NA49, NA69, in accordance with ISO 1206.
Tolerances
Needle roller bearings with one-piece rings are general-ly manufactured to the normal tolerance class (P0). At request, they can be manufactured to other tolerance classes (P6 and P5).
The values of tolerances are given in chapter 3 on page 24.
Radial clearance
Needle roller bearings with one-piece rings are general-ly manufactured with normal radial clearances and the values of clearance are the same with those of the cylindrical roller bearings, according to ISO 5753 and are given on page 159, table 2. At request, these bearingsare manufactured with other clearances (C2, C3 or C4).
If needle roller bearings are to be matched in pairs, radial clearance should be the same for both bearings so that loads should be uniformly distributed.
Cages
Needle roller bearings with one-piece rings are generally fitted with pressed sheet cages. At special request, when bearings are to be operated at high speeds and/or under heavy loads, machined steel cages are recommended to be used. Glass fibre reinforced polyamide 6.6 cages are also successfully used up to an operating temperature of+ 120?C.
??Cage design and some technical data are given intable2.
Fits
??Needle roller bearings are generally mounted with in-terference fits so that rings should not get deformed due to their low section. In case of large-sized bearings, heavy loads and shock loads, bearings are more tightly mounted. When determining the fit, the difference of temperature between the inner ring and the outer ring, respectively, should be considered. The manufacturing tolerance of the shaft should be in the tolerance class 6 (IT6) and of the housing in the tolerance class 7 (IT7). In case of bearings manufactured to more accurate tolerance classes, the manufacturing tolerance of the shaft should be in the tolerance class 5 (IT5 ) and of the housing in the tolerance class 6 (IT6). These classes are also compulsory for the raceway on shaft. Deviations of form and position should be in accordance with the stipulations on page 57.
??The shaft tolerances are given in table3. They depend on the radial clearance necessary for needle roller bearings without inner ringswhich are mounted into the housing, the housing bore being manufactured to the tolerance class K6.
Deep groove ball bearings are manufactured in a varied range, both of standard design and various constructive versions.
Deep groove ball bearings can take double direction radial and axial loads and also allow good operation at high speeds.
For these reasons, they can be widely used. Therefor, single row deep_groove_ball_bearings are manufactured in many constructive versions as shown below
manufactures two versions of sealed and shielded bearings, namely:
-bearings RS and Z type, with recess on the inner ring for sealing or shielding;
-bearings RSR and ZR type, when shielding and sealing respectively are done directly on the outside surface of the inner ring;
In case of bearings with non-rubbing shields, there is a small interstice between the shield and the rib of the inner ring; in case of bearings with seals, the gasoline and oil resistant elastic rubber lip rubs on the groove on the inner ring side or directly on the outside surface.
Bearings sealed and shielded on both sides manufactured in series are delivered filled with lithium base grease and are used at temperatures between -30?C and + 110?C, in accordance with the specifications in chapter 5. Bearings can also be greased with special greases, relubrication not being necessary. Washing or heating are not allowed before bearing mounting in the assembly.
Bearings with shields have been designed first of all for cases when the inner ring rotates.
When the outer ring rotates, the lubricant can flow out of the bearing at a certain speed. In such cases, we recommend you to consult our experts.
Deep groove ball bearings with snap ring groove
Deep groove ball bearings, with snap ring groove on the outer ring can be located in the housing with snap rings.
Because of their simple and space saving mounting, these bearings simplify the assembly design. The groove for the snap ring and the snap rings are in accordance with ISO 464 and tables 7 and 8 respectively.
Paired deep groove ball bearings
If the basic load of a single bearing is inadequate or the shaft has to be axially located in both directions with a certain clearance, paired deep groove ball bearings are recommended to be used.
These bearings can be delivered matched in pairs in three versions, as follows: DT (tandem arrangement), DB (back-to-back arrangement) or DF (face-to-face arrangement). They can be delivered with axial clearance or preloaded. The values of clearance or preload are given in table 2.
The producer marks V on the bearing outside surface as shown in the next figure, so that paired bearings to be correctly mounted.
Stainless steel deep groove ball bearings
Deep groove ball bearings can be made and constructive version of stainless steel.
Dimensions
The overall dimensions of deep groove ball bearings are in accordance with the stipulations of ISO 15.
Misalignments
Deep groove ball bearings have limited abilities to compensate for bearing errors of alignment. The permissible misalignment between the outer ring and the inner ring, which will not produce inadmissible high additional loads in the bearing, depends on the bearing size, operational radial clearance, inner bearing design and also on the magnitude of loads and moments acting upon the bearing.
Because of the complex relationship of these influence factors, definite and universally valid values of permissible misalignment cannot be determined.
Considering the above mentioned factors, under normal operation conditions the permissible misalignments are between 2 and 10 minutes of arc, depending on the bearing series and load.
It should be considered that misalignments of bearing rings in operation produce a considerably higher noise.
Tolerances
Deep groove ball bearings are generally manufactured to the normal tolerance class P0.
At request, they can also be manufactured to the tolerance classes P6, P5 or P4.
The values of tolerances are given in chapter 3 on page 24.
Radial and axial clearance
Deep groove ball bearings are generally manufactured with normal radial clearance. At request, they can also be manufactured with radial clearance different from the normal one, according to ISO 5753. The values of radial clearance are given in table 1.
Paired bearings can be manufactured with axial clearance (suffix A) or preloaded (suffix L). Values for axial clearance and preload are given in table 2.
If a certain axial clearance is prescribed, this has to be measured and marked on the bearing by A, followed by clearance actual value.
Cages
Deep groove ball bearings are generally fitted with cages of pressed steel sheet.
Cages of glass fibre reinforced polyamide 6.6 are also suitable if the operating temperature doesnt exceed + 120 0C. They have reduced weight, low coefficient of friction and are noiseless in operation. Large-sized bearings are fitted with machined brass cages.
Cage design and some technical data are given in table 3.
Bearing minimum radial load
A minimum load must be applied on a deep groove ball bearing so that they can operate correctly, especially in case of operating under heavy loads.
The forces of inertia which occur in bearing as well as the friction in lubricant influence negatively the operating conditions and can cause detrimental sliding movements between balls and raceways.
Minimum radial load depends on the bearing size, speed and lubricant viscosity at operating temperature. It can be roughly calculated from the equation:
Frmin= 0, 01 Cr, (Cr = basic dynamic radial load).
Equivalent dynamic radial load
Deep groove ball bearings can take also radial and axial combined loads.
For deep groove ball bearings, single or paired in tandem arrangement DT, equivalent dynamic radial load can be calculated using the equation:
Pr = Fr, kN, when Fa/Fr e
The greater the axial load, the greater the contact angle of these bearings.
Factors e, Xand Ydepend on the ratio f0Fa/C0r- Factor fo can be determined using the diagram in the bellow figure, as a function of dimension series and mean diameter (d+ D)/2. Fa is the axial load and Coristhestaticbasicloadofthe bearing.
The values of factors e, X, Y which depend on the bearing clearance can be determined from table 4, corresponding to the values of the ratio f0Fa/C0r- The values in table 4 apply to bearings mounted with normal fit, i.e. shafts manufactured to tolerance class j5 or k5 and housing in J6, respectively.
Equivalent static radial load
For deep groove ball bearings, single or matched in tandem (DT), equivalent static radial load can be calculated using the equations:
P0 = Fr, kN, when Fa/Fr 0, 8
For bearings matched in DB or DF arrangement, it can be calculated from:
P0 = Fr + 1, 7Fa, kN
Axial load
If deep groove ball bearings are purely axial loaded, the axial load should not exceed 0, 5 Cor- In case of small-sized bearings and bearings of light series (diameter series 8, 9, 0 and 1), the axial load should not exceed 0, 25 C0r.
Heavy axial loads cause a significant decrease of bearing rating life. In such cases, we recommend you to consult our experts.
Abutment dimensions
For a proper location of bearing rings on the shaft shoulder and housing shoulder, respectively, maximum shaft (housing) connection radius ru max should be less than minimum bearing mounting chamfer rs min.
The shoulder should have the proper height corresponding to maximum bearing mounting chamfer.
The values of the connection radius (ru) and support shoulder height (hu) as functions of mounting chamfers are given in table 6.
Self-aligning ball bearings have a common sphered raceway in the outer ring. This feature allows angular misalignment of the shaft relative to the housing. Therefore self-aligning ball bearings are particularly used in case of bearings where misalignment can occur from errors in mounting or from shaft bending. Double row self-aligning ball bearings are manufactured both with cylindrical bore and tapered bore (taper 1:12). Self-aligning bearings with tapered bore can be delivered, at request, with adapter sleeves.
Sealed self-aligning ball bearings
Self-aligning ball bearings are also available in a sealed version with seals at both sides. The seals are made of gasoline, oil and wear-resistant synthetic rubber. Sealed bearings are delivered filled with a certain grease quantity. Sealed bearing operating temperatures are between -30?C and +80?C. Grease service life is much reduced if bearing operates at a temperature higher than + 80?C (see Chapter 5). Sealed bearings are greased for the entire operating period, relubrication not being necessary. Sealed bearings washing or heating before mounting in assembly is not allowed.
Self-aligning ball bearings with extended inner ring
Self-aligning ball bearings with extended inner ring of series 112 and 113 are used in applications where high accuracy is not necessary and generally, they can be mounted directly on rolled shafts. The bore manufactured to tolerance class J7 allows fast mounting and dismounting. The innerring has a groove for bearing axial location which can be done by means of a screw or pin.
Dimensions
Overall dimensions of self-aligning ball bearings are in accordance with ISO 15.
Misalignment
Self-aligning ball bearings allow within certain limits an angular misalignment of the outer ring in relation to the inner ring, without detrimental effects in bearing unit. Approximate values for permissible misalignment, under normal operating conditions are given in table 1.
Tolerances and radial clearance
Bearings of serial production are manufactured to normal tolerance class and with normal radial clearance. Tapered bore bearings of serial production are also manufactured with radial clearance C3. Self-aligning ball bearings with extended inner ring are manufactured with radial clearance C2 and normal clearance. At request, these bearings can also be manufactured to other tolerance classes and with smaller or larger radial clearance. The bore of self-aligning ball bearings with extended inner ring is manufactured to tolerance class J7. Bearing tolerances are given on page 24 and the values of radial clearance are given in tables 2 and 3.
Equivalent dynamic radial load
Pr = Fr + Y1Fa, kN, when Fa/Fr e The values of factors e, Y1 and Y2 which depend on bearings are given in bearing tables.
Equivalent static radial load
P0r = Fr + Y0Fa, kN The values of the factor Y0 which depends on bearing are given in bearing tables.
Axial load on bearings with adapter sleeve
If self-aligning ball bearings are mounted with adapter sleeves on smooth shafts, without side location, their axial carrying capacity depends on the friction between the sleeve bore and shaft. Permissible axial load can be precisely enough determined using the equation:
Fa max = 3 B d
where:
Fa max maximum permissible axial load, N
B bearing width, mm
d bearing bore diameter, mm
Cages
Self-aligning ball bearings are generally fitted with pressed cages of sheet. At special request, when bearings operate under fluctuating loads, at high speeds and where large sizes are required, machined brass cages are recommended to be used. Glass fibre reinforced polyamide 6.6 cages are also suitable if the operating temperatures do not exceed +12CTC. They have low weight, a low coefficient of friction and are noiseless while running. Cage design and technical data are given in table 4.
Single row angular contact ball bearings are manufactured in various constructive versions, with various contact angles, depending on the application. Bearings series 72B and 73B for general applications have a contact angle a = 40?. Bearings series 718, 719, 70 and 72 generally used for tool-holders, have phenol resins (textolite) cages or machined brass cages. Those with bore diameters up to d = 100 mm are manufactured to tolerance classes P5, P4 and P2 and have a contact angle of 15? (C) and 25? (A) respectively.
Single row angular contact ball bearings can take only one direction axial loads. When being radially loaded, in bearing occurs an axially acting load which has to be compensated. For this reason, a bearing or paired bearings are mounted on each shaft end. Single row angular contact ball bearings with B suffix have a contact angle a = 40? and are suitable in case of heavy loads. These bearings are not dismountable and their use at relatively high speeds is allowed. Pair mounting of bearings as shown in figures on page 119 is used when the load carrying capacity of a single bearing is inadequate (tandem arrangement), respectively when axial loads have to be taken in both directions (DB or DF arrangements). In case of DT tandem arrangement , the contact lines are in parallel. Radial and axial loads are uniformly distributed on both bearings. The bearing pair can take axial loads in only one direction. Therefore, a third bearing should take axial loads in the opposite direction. In case of DB arrangement, the contact lines diverge towards the bearing axis and form letter O. Axial loads are taken in both directions, but only by one single bearing for each direction. DB arrangement is considered to be a relatively stiff arrangement and can also take tilting moments. The contact lines of DF arrangement converge towards the bearing axis and form letter X. Axial loads are taken in the same way as in case of DB arrangement, but the arrangement is not so stiff and it is less suitable for taking tilting moments
Universal design
Single row angular contact ball bearings of universal design are suitable for DB, DF and DT arrangements. Bearings of universal design are manufactured to more accurate tolerance classes and can be matched if the mounting conditions UA, UO and UL are observed. The values of clearance or preload are obtained when the shaft is manufactured to tolerance class j5 and the housing bore to tolerance class J6.
Dimensions
Main dimensions of bearings given in tables are in accordance with ISO 15.
Misalignment
In case of single row angular contact ball bearings the conditions regarding the permissible error of alignment of the outer ring relative to the inner ring are as complex as for single row deep groove ball bearings. When the bearings are paired in DB arrangement, angular misalignments of the outer ring in relation to the inner ring can only be accommodated between the balls and raceways by force, leading to a reduction in bearing life.
Tolerances
Single row angular contact ball bearings of series 72B and 73B, with a contact angle a = 40? (B) are generally manufactured to the normal tolerance class. At request, they also can be manufactured to normal tolerance classes P6 and P5. Single row angular contact ball bearings of high accuracy, series 70C, 72C, 70A and 72A, with a contact angle a = 15? (C) and a = 25? are manufactured to tolerance classes SP, P4, UP and P2. The deviations of bore diameter, outside diameter and width of high accuracy single row angular contact ball bearings of universal design (UL) are given in table 1. In case of single row angular contact ball bearings manufactured and delivered in sets of 2, 3 or 4 bearings, outside and bore diameter should be chosen considering the mean tolerance values, which are given on the package.
Contact angle
In case of single row angular contact ball bearings, the efforts between rings and rolling elements (contact points of rolling elements/ outer or inner ring) are transmitted at an angle a (< 90?) to a plane perpendicular to the bearing axis. The value of this angle depends on the magnitude of the raceway radius, rolling element diameter and radial clearance in bearing, when the curvature centres of the raceways in the outer or on the inner ring are in the same plane. The contact angle a can be calculated and verified in accordance with the specifications on page 118.
Axial clearance preload
Axial clearance or preload can be obtained only when single row angular contact ball bearing is mounted in the assembly and depends on the location of the second bearing which assures the shaft axial guiding. Single row angular contact ball bearings series 72B and 73B, paired mounted in DB and DF arrangements are manufactured with normal axial clearance CB, smaller than normal, CA, larger than normal, CC, or with light preload, GA, moderate preload GB, or heavy preload, GC, according to the values given in table 2.
Cages
Single row angular contact ball bearings series 72B and 73B are generally fitted with pressed sheet cages. High precision single row angular contact ball bearings series 70C, 72C, 70A and 72A are fitted with textolite cages (textile fibre reinforced phenol resins). At special request (high speeds, large sizes), bearings series 70C, 72C, 70A and 72A are fitted with machined brass cages. Cages of glass fibre reinforced polyamide 6.6 are also used with good results if operating temperature doesnt exceed +120?C. Cages design and some technical data are given in table 4
Equivalent dynamic radial loadFor single row angular contact ball bearings series 72B and 73B, single and in tandem arrangement the following equations are used:
For bearings in DB or DF arrangement
Pr = Fr + 0, 65Fa, kN, when Fa/Fr 1, 14
In case of paired bearings, Fr and Fa are the loads acting upon the bearings pair. As the load is transmitted from one raceway to the other under a certain angle to the bearing axis, the actual load will cause an axial load. This has to be considered when calculating the equivalent dynamic load, in case of two single bearings or tandem arrangements. The equations needed for calculation are given in table 5, for various arrangements and loading versions. These equations are available for bearings mounted without clearance and without preload (clearance equal to zero).
For single row angular contact ball bearings series 70C and 72C with a contact angle a= 15? (C), single or in DT arrangement, the following equations are available:
Pr = Fr, kN, for Fa/Fr e
The values of factor Y depend on the values of the ratio f0 i Fa/C0r and are given in table 6. Factor fo can be found in diagram in page 179 as a function of dimensions series and bearing mean diameter, i represents the number of bearings or bearing pairs in a bearing joint. For bearings in DB and DF arrangements, the following equations are available:
Pr = Fr + Y1Fa, kN, for Fa/Fr e
The values of factors Y1 and Y2 depend on the ratio Fa/Cor and are given
Pr = Fr, kN, for Fa/Fr 0, 68
For bearings in DB and DF arrangement, the following equations are available:
Pr = Fr + Y1Fa, kN, for Fa/Fr e
Values for Y1 and Y2 are given in table 6.
Equivalent static load
For single row angular contact ball bearings series 72B and 73B with a contact angle a = 40?, single and in DT arrangement, the following equation is available:
P0r=0, 6Fr+0, 26 Fa, kN if P0r < Fr, then we consider P0=Fr
For bearings in DB and DT arrangement, the following equation is available:
P0r=Fr + 0, 52Fa, kN
For single row angular contact ball bearings series 70C and 72C, with a contact angle a = 15?, single and in DT arrangement, the following equation is available:
P0r = 0, 5 Fr + 0, 46 Fa, kN
For bearings in DB and DE arrangement, the following equation is available:
P0r = 0, 5 Fr + 0, 92 Fa, kN
For single row angular contact ball bearings series 70A and 72A with a contact angle a = 25?, single and in DT arrangement, the following equation is available:
P0r = 0, 5 Fr + 0, 38 Fa, kN
For bearings in DB and DE arrangement, the following equation is available:
P0r = Fr + 0, 76 Fa, kN
Two V scratches are marked on the outside surface where the runout is maximum, i.e. where the outer ring thickness is maximum, so that the bearings of a set can be mounted in the manufacturing order. The place of maximum runout is marked on the chamfer between the inner ring bore and side face. Thus, the possible fit ovalnesses on the shaft can be compensated. Every set is delivered as an unit, separately packed. In each unit, bearings are singly packed. If distance rings are necessary to be mounted between bearings, they have not to be adjusted when being mounted. There is only one condition to be observed: the inner distance ring width should be equal to that of the outer ring, the side faces being parallel to each other. This can be easily done if both distance rings are simultaneously ground on a grinding and lapping machine. If bearings are mounted with distance rings, the mounting is also done observing the V marked as mentioned above. The cone vertex should be on the ring side opposite to that one on which the load acts (see next figure).
Basic dynamic load of paired bearings
Basic dynamic load given in bearing tables is valid for each single bearing. Basic dynamic load of a paired bearings set can be determined according to the specifications on page 26.
Basic static load of paired bearings
Basic static load of paired bearings can be similarly determined, multiplying the values of Cor in the tables by 2, 3 and 4 respectively.
Bearing speed limit
Single row angular contact ball bearings are used at high speeds. High precision bearings allow operation at higher speeds than those in the catalogue, depending on the oil lubrication system (oil bath, dropping lubrication, oil spot, with oil cooling). The values of speeds for bearings series 72B and 73B, normal tolerance class, without preload are given in this catalogue. In case of preloaded bearings, forsinglemounted bearing and bearings in DB, DFor DTarrangements, speeds should be multiplied by the coefficients in table 7. For bearings series 70C, 72C, 70A and 72A, speeds are given for the tolerance class P4 and light preload. In case of bearings with other values of preloads or arrangements of 3 or 4 bearing sets, the speeds of the bearing of basic design should be multiplied by the values of the coefficients in table 7.
Abutment dimensions
For a proper location of bearing rings on the shaft and housing shoulder respectively, shaft (housing) maximum connection radius ru max should be less than bearing minimum mounting chamfer r1min, r1min Shoulder height should also be properly sized in case of bearing maximum mounting chamfer. The values of the connection radii and support shoulder height are given in table 8.
Shivaji Udyam Nagar, Kolhapur, Maharashtra 