OMT Manufacturing Co. Pvt. Ltd Kolhapur, Maharashtra

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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 the normal tolerance class ISO and AFBMA, respectively (for bearings with inch dimensions). 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/2tgα where α 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. cash for credit 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 doesn’t 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 don’t 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 58…65 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, 07…0, 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, 1…0, 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.