Ball & Roller Bearings

Transcription

1 Ball & Roller Bearings CAT. NO. B1E-

2 1 Structures and types A 1 Outline of selection A 14 Selection of type A 16 4 Selection of arrangement A 5 Selection of dimensions A 4 Boundary dimensions 6 A 46 and numbers 7 Tolerances A 5 8 Limiting speed A 78 9 Fits A 8 Internal 1 clearance A 9 11 Preload A 16 1 Lubrication A Materials A 1 16 Failures Shaft and 14 housing design A 15 A Handling A 1 Technical section Open type B 8 68, 69, 16, 6 6, 6, 64 Shielded/sealed type B Z, RU RD, RS Locating snap ring type B N NR Extra-small & miniature B 8 (flanged type B 44) Double-row B 5 [4, 4] Deep groove ball s Single-row B 6 79, 7, 7, 7, 74 ACH9, ACH Matched pair B 9 DB, DF DT Double-row B 14,, 5, RS, 5...RS Four-point contact B 1 [6...BI, 6...BI] Angular contact ball s Open type B 16 1, 1, Sealed type B RS...RS Extended inner ring type B 148 [11, 11] Adapter assemblies B 15 Self-aligning ball s Single-row B 158 NU1, NU, NU, NU NU, NU, NU, NU4 Thrust collars B 184 [HJ] Double-row B 194 NN NNU49 Cylindrical roller NU NJ Metric series B 4 Inch series B 6 9,,, 1,,,, D, 1,, IS R, RR RH, RHR RHA NUP N NF NN NNU Single direction B 5 511, 51, 51, 514 5, 5, 54 5U, 5U, 54U Needle roller and cage ass'y B 88 Drawn cup type B 4 TDO type B 8 TDI type B 96 46, 46, 46T, 46T 46T, 46TD, 46T [45, 45] B 6 Adapter assemblies B Withdrawal sleeves B 8 9,, 4, 1, 41,, 1, Machined ring type B 44 Double direction B 6 5, 5, 54 54, 54, U, 54U, 544U Thrust B 44 B 68 [9, 9, 94] Stud type track rollers (cam followers) B 45 Yoke type track rollers (roller followers) B 454 (Miniature one-way clutches) B 46 Bearing specification tables Tapered roller s s Spherical roller s Thrust ball, Spherical thrust roller s Needle roller s B 47 B 49 B 5 B 51 B 518 B 54 Split type B 544 [SN, SSN, SD] One-piece type B 57 [V] Ball s for units B 58 Ball units Plummer blocks Ceramic & series C 1 Vacuum ball s, ceramic s, self-lubricating clean ball s, linear ball s for vacuum K-series super thin section ball s C 7 Bearings for machine tool spindles (for support of axial loading) C 47 Precision ball screw support s and units C 65 Full complement type cylindrical roller s for crane sheaves C 71 Rolling mill roll neck s C 81 Bearings for railway rolling stock axle journals C 19 Linear ball s C 149 Accessories C 16 Special purpose s Supplementary tables D 1 D 8 Supplementary tables Tecnopoint srl Tel Fax info@tecnopointonline.it

3 BALL & ROLLER BEARINGS CAT. NO. B1E- Tecnopoint srl Tel Fax

4 Publication of Rolling Bearing Catalog Today s technology-based society, in order to utilize the earth s limited resources effectively and protect the environment, must strive to develop new technologies and alternate energy sources, and in that connection it continues to pursue new targets in various fields. To achieve such targets, technically advanced and highly functional rolling s with significantly greater compactness, lighter weight, longer life and lower friction as well as higher reliability during use in special environments are sought. This new-edition catalog is based on the results of wide-ranging technical studies and extensive R&D efforts and will enable the reader to select the optimal for each application. In addition to standard s, this catalog provides information on a variety of s for specific purposes, such as ball units, plummer blocks, and JTEKT EXSEV series (s for extreme special environments). JTEKT is confident that you will find this new catalog useful in the selection and use of rolling s. JTEKT is grateful for your patronage and look forward to continuing to serve you in the future. The contents of this catalog are subject to change without prior notice. Every possible effort has been made to ensure that the data herein is correct; however, JTEKT cannot assume responsibility for any errors or omissions. Reproduction of this catalog without written consent is strictly prohibited Tecnopoint srl Tel Fax info@tecnopointonline.it

5 Contents Technical section 1 Rolling structures and types 1-1 Structure... A 1 1- Type... A 1 Outline of selection... A 14 Selection of type... A 16 Selection of 4 arrangement... A Selection of dimentions 5-1 Bearing service life... A 4 5- Calculation of service life... A 4 5- Calculation of loads... A Dynamic equivalent load... A Basic static load rating and static equivalent load... A Allowable axial load for cylindrical roller s... A Applied calculation examples.. A 41 Boundary dimensions and numbers 6-1 Boundary dimensions... A Dimensions of snap ring grooves and locating snap rings... A Bearing number... A 48 Bearing tolerances 7-1 Tolerances and tolerance classes for s... A 5 7- Tolerance measuring method.. A Limiting speed 8-1 Correction of limiting speed...a Limiting speed for sealed ball s...a Considerations for high speed...a Frictional coefficient (refer.)...a 79 Bearing fits 9-1 Purpose of fit...a 8 9- Tolerance and fit for shaft & housing...a 8 9- Fit selection...a Recommended fits...a 84 Bearing internal clearance 1-1 Selection of internal clearance...a 9 1- Operating clearance...a Preload Purpose of preload...a Method of preloading...a Preload and rigidity...a Amount of preload...a 18 Bearing lubrication 1-1 Purpose and method of lubrication...a Lubricant...A Bearing materials 1-1 Bearing rings and rolling elements materials...a 1 1- Materials used for cages...a 14 Shaft and housing design 14-1 Accuracy and roughness of shafts and housings...a Mounting dimensions...a Shaft design...a Sealing devices...a 19 Handling of s 15-1 General instructions...a Storage of s...a Bearing mounting...a Test run...a Bearing dismounting...a Maintenance and inspection of s...a Methods of analyzing failures...a 14 Examples of failures...a 144 Specification tables [Standard s] Contents... B Deep groove ball s... B 4 Angular contact ball s... B 5 Self-aligning ball s... B 14 Cylindrical roller s...b 154 Tapered roller s...b Spherical roller s...b Thrust ball s...b 48 Spherical thrust roller s... B 66 Needle roller s... B 74 Ball units... B 46 Plummer blocks... B 54 [Special purpose s] Ceramic & EXSEV series... C 1 K-series super thin section ball s... C 7 Bearings for machine tool spindles (for support of axial loading)... C 47 Precision ball screw support s and units... C 65 Full complement type cylindrical roller s for crane sheaves... C 71 Rolling mill roll neck s... C 81 Bearings for railway rolling stock axle journals... C 19 Linear ball s... C 149 Locknuts, lockwashers & lock plates... C 16 Supplementary tables 1 Boundary dimensions of radial s... D 1 Boundary dimensions of tapered roller s... D 5 Boundary dimensions of single direction thrust s... D 7 4 Boundary dimensions of double direction thrust ball s... D 9 5 Dimension of snap ring grooves and locating snap rings... D 11 6 Shaft tolerances... D 15 7 Housing bore tolerances... D 17 8 Numerical values for standard tolerance grades IT... D 19 9 Greek alphabet list... D 1 Prefixes used with SI units... D 11 SI units and conversion factors... D 1 1 Inch/millimeter conversion... D 5 1 Steel hardness conversion... D 6 14 Surface roughness comparison... D 7 15 Viscosity conversion... D 8 Tecnopoint srl Tel Fax info@tecnopointonline.it

6 1. Rolling structures and types 1-1 Structure Rolling s (s hereinafter) normally comprise rings, rolling elements and a cage. (see Fig. 1-1) Rolling elements are arranged between inner and outer rings with a cage, which retains the rolling elements in correct relative position, so they do not touch one another. With this structure, a smooth rolling motion is realized during operation. Bearings are classified as follows, by the number of rows of rolling elements : single-row, double-row, or multi-row (triple- or four-row) s. Deep groove ball Outer ring Ball Inner ring Cage Thrust ball Tapered roller Shaft race Ball Cage Cage Housing race Outer ring Roller Inner ring Note) In thrust s inner and outer rings and also called shaft race and housing race respectively. The race indicates the washer specified in JIS. ) Rolling element Rolling elements may be either balls or rollers. Many types of s with various shapes of rollers are available. Ball Cylindrical roller (L W D W )* Long cylindrical roller (D W L W 1D W, D W > 6 mm)* Needle roller (D W L W 1D W, D W 6 mm)* Tapered roller (tapered trapezoid) Convex roller (barrel shape) * L W : roller length (mm) D W : roller (mm) ) Cage The cage guides the rolling elements along the rings, retaining the rolling elements in correct relative position. There are various types of cages including pressed, machined, molded, and pin type cages. Due to lower friction resistance than that found in full complement roller and ball s, s with a cage are more suitable for use under high speed rotation. 1- Type The contact angle (α) is the angle formed by the direction of the load applied to the rings and rolling elements, and a plan perpendicular to the shaft center, when the is loaded. α = α α = 9 Fig. 1-1 Bearing structure 1) Bearing rings The path of the rolling elements is called the raceway; and, the section of the rings where the elements roll is called the raceway surface. In the case of ball s, since grooves are provided for the balls, they are also referred to as raceway grooves. The inner ring is normally engaged with a shaft; and, the outer ring with a housing. Bearings are classified into two types in accordance with the contact angle (α). Radial s ( α 45 )... designed to accommodate mainly radial load. Thrust s (45 < α 9 )... designed to accommodate mainly axial load. Rolling s are classified in Fig. 1-, and characteristics of each type are described in Tables 1-1 to 1-1. A A 1 Tecnopoint srl Tel Fax info@tecnopointonline.it

7 1. Rolling structures and types Radial ball Radial Deep groove ball Angular contact ball Four-point contact ball Single-row Single-row Double-row Matched pair or stack Double-row Bearings classified by use [Automobile] Wheel hub unit Clutch release Water pump Tensioner unit Self-aligning ball Universal joint cross Radial roller Rolling Thrust ball Thrust Cylindrical roller Needle roller Tapered roller Spherical roller Thrust ball Angular contact thrust ball Single-row Single-row Single-row Single direction Single direction Double-row Double-row Double-row with aligning seat race Double direction Double direction Four-row Four-row with aligning seat races Railway rolling stock Electric equipment Business equipment Construction equipment Industrial equipment Steel industry equipment Paper manufacturing equipment [Aircraft] Axle journal Integral unit Crane sheave Split for continuous casting Jet engine Plastic pulley unit Slewing rim Back-up roll unit for hot leveler Swimming roll triple ring Thrust roller Cylindrical roller thrust Needle roller thrust Others Ball unit Plummer block Tapered roller thrust Spherical thrust roller Single direction Double direction Stud type track roller (cam follower) Yoke type track roller (roller follower) Linear ball (linear motion ) Fig. 1-(1) Rolling s Fig. 1-() Rolling s A A Tecnopoint srl Tel Fax info@tecnopointonline.it

8 1. Rolling structures and types Table 1-1 Deep groove ball s Table 1- Angular contact ball s Single-row Double-row Single-row Matched pair Double-row Open type Shielded type Non-contact sealed type Contact sealed type Extremely light contact sealed type With locating snap ring Flanged type For highspeed use Back-to-back arrangement Face-to-face arrangement Tandem arrangement ZZ RU RS 68, 69, 6, 6, 6, (ML) Extra-small, miniature 68, 69, 16, 6, 6, 6, 64 The most popular types among rolling s, widely used in a variety of industries. Radial load and axial load in both directions can be accommodated. Suitable for operation at high speed, with low noise and low vibration. Sealed s employing steel shields or rubber seals are filled with the appropriate volume of grease when manufactured. RK 4 4 Bearings with a flange or locating snap ring attached on the outer ring are easily mounted in housings for simple positioning of housing location. [Recommended cages] Pressed steel cage (ribbon type, snap type single-row, S type double-row), copper alloy or phenolic resin machined cage, synthetic resin molded cage [Main applications] Automobile : front and rear wheels, transmissions, electric devices Electric equipment : standard motors, electric appliances for domestic use Others : measuring instruments, internal combustion engines, construction equipment, railway rolling stock, cargo transport equipment, agricultural equipment, equipment for other industrial uses Outer ring chamfer Outer ring raceway Inner ring raceway Inner ring chamfer Pressed cage (ribbon type) Bearing width Seal Bore Pitch of ball set Outside Groove shoulder Machined cage Locating snap ring Snap ring groove RD Bearing outside surface Bearing bore surface Face NR Pressed cage (S type) Suitable for extra-small or miniature Filling slot Bearing size (Reference) Unit : mm Connotation Bore Outside Miniature Under 9 Extra-small Under 1 9 or more Small size 1 or more 8 or less Medium size 8 18 Large size 18 8 Extra-large size Over 8 With With pressed cage machined cage HAR DB DF DT (With filling slot) 7, 7, 7, 74 Contact angle 7B, 7B, 7B, 74B 4 79C, 7C, 7C, 7C... Contact 15 HAR9C, HARC angle Bearing rings and balls possess their own contact angle which is normally 15, or 4. Larger contact angle higher resistance against axial load Smaller contact angle more advantageous for high-speed rotation Single-row s can accommodate radial load and axial load in one direction. DB and DF matched pair s and double-row s can accommodate radial load and axial load in both directions. DT matched pair s are used for applications where axial load in one direction is too large for one to accept. HAR type high speed s were designed to contain more balls than standard s by minimizing the ball, to offer improved performance in machine tools. Angular contact ball s are used for high accuracy and high-speed ZZ (Shielded) operation. 5 5 Contact angle 4 Axial load in both directions and radial load can be accommodated by adapting a structure pairing two single-row angular contact ball s back to back. For s with no filling slot, the sealed type is available. RS (Sealed) [Recommended cages] Pressed steel cage (conical type single-row : S type, snap type double-row), copper alloy or phenolic resin machined cage, synthetic resin molded cage [Main applications] Single-row : machine tool spindles, high frequency motors, gas turbines, centrifugal separators, front wheels of small size automobiles, differential pinion shafts Double-row : hydraulic pumps, roots blowers, air-compressors, transmissions, fuel injection pumps, printing equipment Outer ring back face Inner ring front face Outer ring front face Inner ring back face Contact angle Load center Pressed cage (conical type) Stepped inner ring Machined cage Counterbored outer ring Ball and ring are not separable. Stand-out( δ ) Stand-out( δ 1 ) Contact angles (Reference) Contact angle Supplementary code 15 C CA 5 AC A (Omitted) 5 E 4 B "G type" s are processed (with flush ground) such that the stand-out turns out to be δ 1 = δ. The matched pair DB, DF, and DT, or stack are available. A 4 A 5 Tecnopoint srl Tel Fax info@tecnopointonline.it

9 1. Rolling structures and types Table 1- Four-point contact ball s One-piece type Two-piece inner ring Two-piece outer ring Table 1-4 Self-aligning ball s Cylindrical bore Tapered bore Sealed Table 1-5 Cylindrical roller s Single-row Double-row Four-row 6BI 6BI (6BO) (6BO) Radial load and axial load in both directions can be accommodated. A four-point contact ball can substitute for a face-to-face or back-to-back arrangement of angular contact ball s. Suitable for use under pure axial load or combined radial and axial load with heavy axial load. This type of possesses a contact angle (α) determined in accordance with the axial load direction. This means that the ring and balls contact each other at two points on the lines forming the contact angle. [Recommended cage] Copper alloy machined cage [Main applications] Motorcycle : Transmission, driveshaft pinion-side Automobile : Steering, transmission Contact angle ( α) Load center α Two-piece outer ring Pressed cage (staggered type) Two-piece inner ring Bore (u d) K (Taper 1 : 1) 1, 1 11, 11 1, 1 extended inner ring type, RS RS RS Spherical outer ring raceway allows selfalignment, accommodating shaft or housing deflection and misaligned mounting conditions. Tapered bore design can be mounted readily using an adapter. Pressed steel cage staggered type 1, 1,...RS,...RS snap type, Power transmission shaft of wood working and spinning machines, plummer blocks Large end of tapered bore (u d 1 ) Bearing width (B) Small end of tapered bore (u d) NU NJ NUP N NF NH NN NNU NU1, NU (R), NU (R), NU4 NU (R), NU (R) NU, NU Since the design allowing linear contact of cylindrical rollers with the raceway provides strong resistance to radial load, this type is suitable for use under heavy radial load and impact load, as well as at high speed. N and NU types are ideal for use on the free side: they are movable in the shaft direction in response to changes in position relative to the shaft or housing, which are caused by heat expansion of the shaft or improper mounting. Cylindrical bore Tapered bore NNU49 NNU49K NN NNK (FC), (4CR) NJ and NF types can accommodate axial load in one direction; and NH and NUP types can accommodate partial axial load in both directions. With separable inner and outer ring, this type ensures easy mounting. Due to their high rigidity, NNU and NN types are widely used in machine tool spindles. [Recommended cages] Pressed steel cage (Z type), copper alloy machined cage, pin type cage, synthetic resin molded cage [Main applications] Large and medium size motors, traction motors, generators, internal combustion engines, gas turbines, machine tool spindles, speed reducers, cargo transport equipment, and other industrial equipment Rib Machined cage Grinding undercut Roller set bore Rib Grinding undercut Pressed cage (Z type) Roller set outside Mainly use on rolling mill roll neck Lubrication groove Lubrication hole Machined cage Center rib Rib Center rib Rib Pressed cage (snap type) (d 1 = d + 1 B) 1 Lockwasher Locknut Adapter sleeve Adapter assembly Loose rib Thrust collar Loose rib Spacer Guide ring Pin type cage (suitable for large size s) Removal groove A 6 A 7 Tecnopoint srl Tel Fax info@tecnopointonline.it

10 1. Rolling structures and types Table 1-6 Machined ring needle roller s Single-row Double-row Table 1-7 Tapered roller s Single-row Double-row Four-row With inner ring Without inner ring Sealed With inner ring Without inner ring NA49 NA59 (NQI, NQIS) RNA49 RNA59 (NQ, NQS) NA49UU NA69 RNA69 In spite of their basic structure, which is the same as that of NU type cylindrical roller s, s with minimum ring sections offer space savings and greater resistance to radial load, by using needle rollers. Bearings with no inner rings function using heat treated and ground shafts as their raceway surface. [Recommended cage] Pressed steel cage [Main applications] Automobile engines, transmissions, pumps, power shovel wheel drums, hoists, overhead traveling cranes, compressors (Reference) Many needle roller s other than those with machined ring are available. For further details, refer to the section, "needle roller Lubrication groove specification table". Outer ring Lubrication hole Inner ring Pressed cage Needle roller and cage assemblies Standard Inter mediate Steep contact angle contact angle contact angle 9JR JR CR DJ JR JR CR DJR JR JR CR 1JR 1JR JR CR JR Flanged type TDO type TDI type Mainly used on rolling mill roll necks Tapered rollers assembled in the s are guided by the inner ring back face rib. The raceway surfaces of inner ring and outer ring and the rolling contact surface of rollers are designed so that the respective apexes converge at a point on the center line. Single-row s can accommodate radial load and axial load in one direction, and double-row s can accommodate radial load and axial load in both directions. This type of is suitable for use under heavy load or impact load A (45T) 46A (46T) (47T) (4TR) Bearings are classified into standard, intermediate and steep types, in accordance with their contact angle (α). The larger the contact angle is, the greater the resistance to axial load. Since outer ring and inner ring assembly can be separated from each other, mounting is easy. Bearings designated by the suffix "J" and "JR" are interchangeable internationally. Items sized in inches are still widely used. [Recommended cages] Pressed steel cage, synthetic resin molded cage, pin type cage [Main applications] Automobile : front and rear wheels, transmissions, differential pinion Others : machine tool spindles, construction equipment, large size agricultural equipment, railway rolling stock speed reduction gears, rolling mill roll necks and speed reducers, etc Bearing width Rib Drawn cup needle roller s Stud type track roller (cam follower) Yoke type track roller (roller follower) Outer ring Same as contact angle Outer ring angle Pressed cage (window type) Lubrication Anti-rotation groove pin hole Double outer ring Lubrication hole Pin type cage Overall width of inner rings Inner ring spacer Inner ring Double inner ring Contact angle ( ) α Load center Roller small end face Inner ring front face rib Outer ring small inside Front Back face face Front face Back face Overall width of outer rings Outer ring spacer with lubrication holes and lubrication groove Center rib Outer ring width Inner ring width Stand-out Roller large end face Inner ring front face rib Inner ring back face rib A 8 A 9 Tecnopoint srl Tel Fax info@tecnopointonline.it

11 1. Rolling structures and types Table 1-8 Spherical roller s Table 1-9 Thrust ball s Convex asymmetrical roller type Cylindrical bore Convex symmetrical roller type Tapered bore With flat back faces Single direction With spherical back face With aligning seat race With flat back faces Double direction With spherical back faces With aligning seat races R, RR RH, RHR RHA K or K 9R, R (RH, RHA), 1R (RH, RHA), R (RH, RHA), 1R (RH) 4R (RH, RHA), 41R (RH, RHA), R (RH, RHA), R (RH, RHA) Spherical roller s comprising barrel-shaped convex rollers, double-row inner ring and outer ring are classified into three types : R(RR), RH(RHR) and RHA, according to their internal structure. With the designed such that the circular arc center of the outer ring raceway matches with the center, the is self-aligning, insensitive to errors of alignment of the shaft relative to the housing, and to shaft bending. This type can accommodate radial load and axial load in both directions, which makes it especially suitable for applications in which heavy load or impact load is applied. The tapered bore type can be easily mounted/ dismounted by using an adapter or withdrawal sleeve. There are two types of tapered bores (tapered ratio) : 1 : supplementary Suitable for code K series 4 and : 1 supplementary Suitable for series code K other than 4 and 41. Lubrication holes, a lubrication groove and antirotation pin hole can be provided on the outer ring. Lubrication holes and a lubrication groove can be provided on the inner ring, too. [Recommended cages] Copper alloy machined cage, pressed steel cage, pin type cage [Main applications] Paper manufacturing equipment, speed reducers, railway rolling stock axle journals, rolling mill pinion stands, table rollers, crushers, shaker screens, printing equipment, wood working equipment, speed reducers for various industrial uses, plummer blocks Convex asymmetrical roller Outer ring Rib Inner ring Center rib Machined cage separable prong type Convex symmetrical roller Guide ring Pressed cage Rib Convex symmetrical roller Guide ring Large end of tapered bore (u d 1 ) Machined cage (prong type) Anti-rotation pin hole Small end of tapered bore (u d) U 5U 54U This type of comprises washer-shaped rings with raceway groove and ball and cage assembly. Races to be mounted on shafts are called shaft races (or inner rings); and, races to be mounted into housings are housing races (or outer rings). Central races of double direction s are mounted on the shafts U 54U 544U Single direction s accommodate axial load in one direction, and double direction s accommodate axial load in both directions. (Both of these s cannot accommodate radial loads.) Since s with a spherical back face are self- aligning, it helps to compensate for mounting errors. [Recommended cages] Pressed steel cage, copper alloy or phenolic resin machined cage, synthetic resin molded cage [Main applications] Automobile king pins, machine tool spindles Machined cage Bore (u d) Outside (u D) Shaft race Housing race Aligning surface radius Pressed cage Aligning surface center height Aligning housing race Bearing height Adapter sleeve R, RR type RH, RHR type RHA type Lubrication groove Lockwasher Locknut Adapter sleeve Locknut Lock plate Withdrawal sleeve Outer ring guided machined cage Lubrication hole (Shaft 18 mm) (Shaft mm) (For shaker screen) Shaft race back face Housing race back face chamfer Raceway contact Shaft race back face chamfer Housing race back face [Remark] The race indicates the washer specified in JIS. Aligning housing race Race height Aligning seat race Central race Aligning seat race A 1 A 11 Tecnopoint srl Tel Fax info@tecnopointonline.it

12 1. Rolling structures and types Table 1-1 Cylindrical roller thrust s Table 1-11 Needle roller thrust s Table 1-1 Tapered roller thrust s Table 1-1 Spherical thrust roller s Single direction Separable Non-separable Single direction Double direction (THR...R) This type of comprises washer-shaped rings (shaft and housing race) and cylindrical roller and cage assembly. Crowned cylindrical rollers produce uniform pressure distribution on roller/raceway contact surface. Axial load can be accommodated in one direction. Great axial load resistance and high axial rigidity are provided. [Recommended cages] Copper alloy machined cage [Main applications] Oil excavators, iron and steel equipment (TPW) (TPWS) (TPWWS) (TPK) (TVK) The separable type, comprising needle roller and cage thrust assembly and a race, can be matched with a pressed thin race (W) or machined thick race (WS). The non-separable type comprises needle roller and cage thrust assembly and a precision pressed race. Axial load can be accommodated in one direction. Due to the very small installation space required, this type contributes greatly to size reduction of application equipment. In many cases, needle roller and cage thrust assembly function by using the mounting surface of the application equipment, including shafts and housings, as its raceway surface. Pressed steel cage, synthetic resin molded cage Transmissions for automobiles, cultivators and machine tools (T) (THR) (THR) This type of comprises tapered rollers (with spherical large end), which are uniformly guided by ribs of the shaft and housing races. Both shaft and housing races and rollers have tapered surfaces whose apexes converge at a point on the axis. Single direction s can accommodate axial load in one direction; and, double direction s can accommodate axial load in both directions. Double direction s are to be mounted such that their central race is placed on the shaft shoulder. Since this type is treated with a clearance fit, the central race must be fixed with a sleeve, etc. [Recommended cages] Copper alloy machined cage [Main applications] Single direction : crane hooks, oil excavator swivels Double direction : rolling mill roll necks This type of, comprising barrel-shaped convex rollers arranged at an angle with the axis, is self-aligning due to spherical housing race raceway; therefore, shaft inclination can be compensated for to a certain degree. Great axial load resistance is provided. This type can accommodate a small amount of radial load as well as heavy axial load. Normally, oil lubrication is employed. Copper alloy machined cage Hydroelectric generators, vertical motors, propeller shafts for ships, screw down speed reducers, jib cranes, coal mills, pushing machines, molding machines Machined cage Shaft race Housing race Cylindrical roller Pressed cage Molded cage Needle roller Race Race [Remark] The race indicates the thrust washer or washer specified in JIS. Tapered roller Machined cage Roller large end Shaft race Rib Housing race Roller small end Housing race Convex roller Machined cage Shaft race Housing race Cage guide sleeve Machined cage Central race Housing race A 1 A 1 Tecnopoint srl Tel Fax info@tecnopointonline.it

13 . Outline of selection Currently, as design has become diversified, their application range is being increasingly extended. In order to select the most suitable s for an application, it is necessary to conduct a comprehensive study on both s and the equipment in which the s will be installed, including operating conditions, the performance required of the s, specifications of the other components to be installed along with the s, marketability, and cost performance, etc. In selecting s, since the shaft is usually determined beforehand, the prospective type is chosen based upon installation space, intended arrangement, and according to the bore required. Next, from the specifications are determined the service life required when compared to that of the equipment in which it is used, along with a calculation of the actual service life from operational loads. Internal specifications including accuracy, internal clearance, cage, and lubricant are also selected, depending on the application. For reference, general selection procedure and operating conditions are described in Fig. -1. There is no need to follow a specific order, since the goal is to select the right to achieve optimum performance. q Bearing type, arrangement w Bearing dimension e Tolerance class r Fit and internal clearance ( Operating conditions to be considered) ( Other data) Installation space Load magnitude, types and direction of application Rotational speed Running accuracy Rigidity Misalignment Mounting ease Bearing arrangement Noise characteristics, friction torque Marketability, cost performance Reference page No. A 16 A Specifications for installation Recommended service life Dynamic equivalent load Static equivalent load, safety coefficient Rotational speed Bearing boundary dimensions Basic dynamic load rating A 8 A 4 A 8 A 46 A 4 Basic static load rating A 8 Allowable axial load A 4 (for cylindrical roller with rib) Running accuracy (runout) Noise characteristics, friction torque Rotational speed Bearing tolerances A 5 Load magnitude, types Operational temperature distribution Materials, size and tolerances of shaft and housing Fit A 8 Difference in temperature of inner and outer rings Rotational speed Preload A 16 Bearing tolerances A 5 Bearing internal clearance A 9 Comparison of performance of types Example of arrangement A 18 A 1 t y u i Countermeasure for special Lubrication, lubricant, Cage type, material environmental condition sealing device Rotational speed Noise characteristics Conditions of application site abnormal temperature, sea water, vacuum, chemical solution, dust, gas, magnetism Lubrication Special materials A 1 Special heat treatment A 6 (dimension stabilizing treatment) Special surface treatment Lubricant A 118 (Reference) ceramic & series C 1 Operating temperature Rotational speed Lubrication Lubricant Sealing device Limiting speed Grease service life A 111 A 118 A 19 A 78 A 11 Mounting and dismounting, mounting dimension Mounting and dismounting A 1 Mounting dimensions A 16 Final determination of and associated aspect Fig. -1(1) Bearing selection procedure Fig. -1() Bearing selection procedure A 14 A 15 Tecnopoint srl Tel Fax info@tecnopointonline.it

14 . Selection of type In selecting s, the most important thing is to fully understand the operating conditions of the s. The main factors to be considered are listed in Table -1, while types are listed in Table -. Table -1 (1) Selection of type Table -1 () Selection of type Items to be considered Selection method Reference page No. Items to be considered Selection method Reference page No. 1) Installation space Bearing can be installed in target equipment ) Load Load magnitude, type and direction which applied ) Rotational speed 4) Running accuracy Load resistance of is specified in terms of the basic load rating, and its value is specified in the specification table. Response to rotational speed of equipment in which s will be installed The limiting speed for is expressed as allowable speed, and this value is specified in the specification table. Accurate rotation delivering required performance Dimension accuracy and running accuracy of s are provided by JIS, etc. 5) Rigidity Rigidity that delivers the performance required When load is applied to a, elastic deformation occurs at the point where its rolling elements contact the raceway surface. The higher the rigidity that s possess, the better they control elastic deformation. When a shaft is designed, its rigidity and strength are considered essential; therefore, the shaft, i.e., bore, is determined at start. For rolling s, since wide variety with different dimensions are available, the most suitable type should be selected. (Fig. -1) Since various types of load are applied to s, load magnitude, types (radial or axial) and direction of application (both directions or single direction in the case of axial load), as well as vibration and impact must be considered in order to select the proper. The following is the general order for radial resistance ; deep groove ball s < angular contact ball s < cylindrical roller s < tapered roller s < spherical roller s Since the allowable speed differs greatly depend-ing not only upon type but on size, cage, accuracy, load and lubrication, all factors must be considered in selecting s. In general, the following s are the most widely used for high speed operation. deep groove ball s, angular contact ball s, cylindrical roller s Performance required differs depending on equipment in which s are installed : for instance, machine tool spindles require high running accuracy, gas turbines require high speed rotation, and control equipment requires low friction. In such cases, s of tolerance class 5 or higher are required. The following are the most widely used s. deep groove ball s, angular contact ball s, cylindrical roller s In machine tool spindles and automobile final drives, rigidity as well as rigidity of equipment itself must be enhanced. Elastic deformation occurs less in roller s than in ball s. Rigidity can be enhanced by providing preload. This method is suitable for use with angular contact ball s and tapered roller s. A 46 A 18 (Table -) A 81 A 18 (Table -) A 78 A 18 (Table -) A 5 A 18 (Table -) A 16 6) Misalignment (aligning capability) 7) Mounting and dismounting Width series Diameter series Dimension series Operating conditions which cause misalignment (shaft deflection caused by load, inaccuracy of shaft and housing, mounting errors) can affect performance Allowable misalignment (in angle) for each type is described in the section before the specification table, to facilitate determination of the self-aligning capability of s. Methods and frequency of mounting and dismounting required for periodic inspection Deep groove ball Angular contact ball Self-aligning ball Cylindrical roller Needle roller Tapered roller Spherical roller Internal load caused by excessive misalignment damages s. Bearings designed to absorb such misalignment should be selected. The higher the self-aligning capability that s possess, the larger the angular misalignment that can be absorbed. The following is the general order of s when comparing allowable angular misalignment : cylindrical roller s < tapered rollers < deep groove ball s, angular contact ball s < spherical rollers, self-aligning ball s Cylindrical roller s, needle roller s and tapered roller s, with separable inner and outer rings, are recommended for applications in which mounting and dismounting is conducted frequently. Use of sleeve eases the mounting of self-aligning ball s and spherical roller s with tapered bore Fig. -1 Radial dimension series A 18 (Table -) A 18 (Table -) A 16 A 17 Tecnopoint srl Tel Fax info@tecnopointonline.it

15 . Selection of type Table - Performance comparison of type Deep groove ball Angular contact ball Matched pair or stack Singlerow Doublerow Four-point contact ball Selfaligning ball Cylindrical roller NU N NJ NF NUP NH NN NNU Needle roller (machined ring type) Tapered roller Singlerow Double-row, four-row Spherical roller Thrust ball With With flat aligning back seat faces race Double direction angular contact thrust ball Cylindrical roller thrust Needle roller thrust Tapered roller thrust Spherical thrust roller Reference page No. Radial load Load resistance Axial load Combined load radial and axial * * * * Vibration or impact load High speed adaptability High accuracy Low noise level/low torque Rigidity Misalignment Inner and outer ring separability * * A16 A78 A16, 5 A111 A16 A16 A17 Description before specification table Arrangement Fixed side Free side * A A Remarks A pair of s mounted facing each other. *DT arrangement is effective for one direction only. *Filling slot type is effective for one direction only. *Nonseparable type is also available. A pair of s mounted facing each other. *Double direction s are effective for both directions. *Non-separable type is also available. Reference page No. A4 B4 A5 B5 A6 B5 A6 B14 A7 B154 A8 B74 A9 B A1 B A11 B48 C47 A1 A1 B74 A1 A1 B66 Excellent # Good Fair Unacceptable Both directions One direction only Acceptable Acceptable, but shaft shrinkage must be compensated for. A 18 A 19 Tecnopoint srl Tel Fax info@tecnopointonline.it

16 4. Selection of arrangement As operational conditions vary depending on devices in which s are mounted, different performances are demanded of s. Normally, two or more s are used on one shaft. Fixed side Free side When fixed and free sides are not distinguished Bearings for vertical shafts Table 4-1 Bearings on fixed and free sides Features This determines shaft axial position. This can accommodate both radial and axial loads. Since axial load in both directions is imposed on this, strength must be considered in selecting the for this side. This is employed to compensate for expansion or shrinkage caused by operating temperature change and to allow ajustment of position. Bearings which accommodate radial load only and whose inner and outer rings are separable are recommended as free side s. In general, if non-separable s are used on free side, clearance fit is provided between outer ring and housing to compensate for shaft movement through s. In some cases, clearance fit between shaft and inner ring is utilized. When intervals are short and shaft shrinkage does not greatly affect operation, a pair of angular contact ball s or tapered roller s is used in paired mounting to accommodate axial load. After mounting, the axial clearance is adjusted using nuts or shims. Bearings which can accommodate both radial and axial loads should be used on fixed side. Heavy axial load can be accommodated using thrust s together with radial s. Bearings which can accommodate radial load only are used on free side, compensating for shaft movement. In many cases, in order to locate shaft positions in the axial direction, one is mounted on the fixed side first, then the other is mounted on the free side. Recommended type Deep groove ball Matched pair or stack angular contact ball Double-row angular contact ball Self-aligning ball Cylindrical roller with rib (NUP and NH types) Double-row tapered roller Spherical roller Separable types Cylindrical roller (NU and N types) Needle roller (NA type, etc.) Non-separable types Deep groove ball Matched pair angular contact ball (Back-to-back arrangement) Double-row angular contact ball Self-aligning ball Double-row tapered roller (TDO type) Spherical roller Deep groove ball Angular contact ball Self-aligning ball Cylindrical roller (NJ and NF types) Tapered roller Spherical roller Fixed side Matched pair angular contact ball (Back-to-back arrangement) Double-row tapered roller (TDO type) Thrust + radial Example No. Examples 111 Examples 116 Examples 17 and 18 Example Ex. 1 Ex. Ex. Ex. 4 Ex. 5 Ex. 6 Ex. 7 Table 4- (1) Example arrangements Bearing arrangement Recommended application Fixed side Free side Suitable for high-speed operation; used for various types of applications. Not recommended for applications that have center displacement between s or shaft deflection. More suitable than Ex. 1 for operation under heavy load or impact load. Suitable also for high-speed operation. Due to separability, suitable for applications requiring interference of both inner and outer rings. Not recommended for applications that have center displacement between s or shaft deflection. Recommended for applications under heavier or greater impact load than those in Ex.. This arrangement requires high rigidity from fixed side s mounted back to back, with preload provided. Shaft and housing of accurate dimensions should be selected and mounted properly. This is recommended for operation at high speed or axial load lighter than in Ex.. This is recommended for applications requiring interference of both inner and outer rings. Some applications use double-row angular contact ball s on fixed side instead of matched pair angular contact ball s. This is recommended for operations under relatively small axial load. This is recommended for applications requiring interference of both inner and outer rings. This is recommended for operations at high speed and heavy radial load, as well as normal axial load. When deep groove ball s are used, clearance must be provided between outside and housing, to prevent application of radial load. This arrangement is most widely employed. This arrangement can accommodate partial axial load as well as radial load. Application example Medium size motors, air blowers Traction motors for railway rolling stock Steel manufacturing table rollers, lathe spindles Motors Paper manufacturing calender rollers, diesel locomotive axle journals Diesel locomotive transmissions Pumps, automobile transmissions A A 1 Tecnopoint srl Tel Fax info@tecnopointonline.it

17 4. Selection of arrangement Example Ex. 8 Ex. 9 Ex. 1 Ex. 11 Ex. 1 Ex. 1 Bearing arrangement Fixed side Free side Arrangement in which fixed and free sides are not distinguished Back-to-back Face-to-face Table 4- () Example arrangements Recommended application This is recommended for operations with relatively heavy axial load in both directions. Some applications use matched pair angular contact ball s on fixed side instead of doublerow angular contact ball s. This is the optimum arrangement for applications with possible mounting errors or shaft deflection. Bearings in this arrangement can accommodate partial axial load, as well as heavy radial load. This is optimum arrangement for applications with possible mounting errors or shaft deflection. Ease of mounting and dismounting, ensured by use of adaptor, makes this arrangement suitable for long shafts which are neither stepped nor threaded. This arrangement is not recommended for applications requiring axial load capability. This is the optimum arrangement for applications with possible mounting errors or shaft deflection. This is recommended for operations under impact load or radial load heavier than that in Ex. 1. This arrangement can accommodate partial axial load as well as radial load. Recommended application This arrangement is most popular when applied to small equipment operating under light load. When used with light preloading, thicknessadjusted shim or spring is mounted on one side of outer ring. This is suitable for applications in which rigidity is enhanced by preloading. This is frequently employed in applications requiring high speed operation under relatively large axial load. Back-to-back arrangement is suitable for applications in which moment load affects operation. When preloading is required, care should be taken in preload adjustment. Application example Worm gear speed reducers Steel manufacturing table roller speed reducers, overhead crane wheels General industrial equipment counter shafts Steel manufacturing table rollers Application example Small motors, small speed reducers, small pumps Machine tool spindles Example Ex. 14 Ex. 15 Ex. 16 Ex. 17 Ex. 18 Arrangement in which fixed and free sides are not distinguished Back-to-back Face-to-face Application to vertical shafts Table 4- () Example arrangements Fixed side Free side Free side Fixed side Recommended application This is recommended for operation under impact load or axial load heavier than in Ex. 1. This is suitable for applications in which rigidity is enhanced by preloading. Back-to-back arrangement is suitable for applications in which moment load affects operation. When interference is required between inner ring and shaft, face-to-face arrangement simplifies mounting. This arrangement is effective for applications in which mounting error is possible. When preloading is required, care should be taken in preload adjustment. This is recommended for applications requiring high speed and high accuracy of rotation under light load. This is suitable for applications in which rigidity is enhanced by preloading. Tandem arrangement and face-to-face arrangement are possible, as is back-to-back arrangement. This arrangement provides resistance against heavy radial and impact loads. This is applicable when both inner and outer rings require interference. Care should be taken not to reduce axial internal clearance a critical amount during operation. Recommended application This arrangement, using matched pair angular contact ball s on the fixed side and cylindrical roller s on the free side, is suitable for high speed operation. This is recommended for operation at low speed and heavy load, in which axial load is heavier than radial load. Due to self-aligning capability, this is suitable for applications in which shaft runout or deflection occurs. Application example Speed reducers, automobile wheels Machine tool spindles Construction equipment final drive Application example Vertical motors, vertical pumps Crane center shafts, vertical pumps A A Tecnopoint srl Tel Fax info@tecnopointonline.it

18 5. Selection of dimensions 5-1 Bearing service life When s rotate under load, material flakes from the surfaces of inner and outer rings or rolling elements by fatigue arising from repeated contact stress (ref. A 144). This phenomenon is called flaking. The total number of rotations until flaking occurs is regarded as the "(fatigue) service life". "(Fatigue) service life" differs greatly depending upon structures, dimensions, materials, and processing methods. Since this phenomenon results from fatigue distribution in materials themselves, differences in service life should be statistically considered. When a group of identical s are rotated under the same conditions, the total number of revolutions until 9 % of the s are left without flaking (i.e. a service life of 9 % reliability) is defined as the basic rating life. In operation at a constant speed, the basic rating life can be expressed in terms of time. In actual operation, a fails not only because of fatigue, but other factors as well, such as wear, seizure, creeping, fretting, brinelling, cracking etc (ref. A 144, 16. Examples of failures). These failures can be minimized by selecting the proper mounting method and lubricant, as well as the most suitable for the application. 5- Calculation of service life 5--1 Basic dynamic load rating The basic dynamic load rating is either pure radial (for radial s) or central axial load (for thrust s) of constant magnitude in a constant direction, under which the basic rating life of 1 million revolutions can be obtained, when the inner ring rotates while the outer ring is stationary, or vice versa. The basic dynamic load rating, which represents the capacity of a under rolling fatigue, is specified as the basic dynamic radial load rating (C r ) for radial s, and basic dynamic axial load rating (C a ) for thrust s. These load ratings are listed in the specification table. These values are prescribed by ISO 81/ 199, and are subject to change by conformance to the latest ISO standards. 5-- Basic rating life The basic rating life in relation to the basic dynamic load rating and dynamic equivalent load can be expressed using equation (5-1). It is convenient to express the basic rating life in terms of time, using equation (5-), when a is used for operation at a constant speed; and, in terms of traveling distance (km), using equation (5-), when a is used in railway rolling stock or automobiles. Total revolutions (Time) Running distance L 1 = L 1h = C P 1 6 6n L 1s = πdl 1 (5-) where : L 1 : basic rating life 1 6 revolutions L 1h : basic rating life h L 1s : basic rating life km P : dynamic equivalent load N (refer to p. A 4.) C : basic dynamic load rating N n : rotational speed min 1 p : for ball s p = for roller s p = 1/ D : wheel or tire mm p C P (5-1) p (5-) Accordingly, where the dynamic equivalent load is P, and rotational speed is n, equation (5-4) can be used to calculate the basic dynamic load rating C; the size most suitable for a specified purpose can then be selected, referring to the specification table. The recommended service life differs depending on the machines with which the is used, as shown in Table 5-4, p. A 8. C = P [Ball ] Rotational speed Basic rating life L 1h f n n f h [Roller ] Rotational speed Basic rating life 6n 1 6 1/p (5-4) [Reference] The equations using a service life coefficient ( f h ) and rotational speed coefficient ( f n ) respectively, based on equation (5-), are as follows : L 1h = 5f h p (5-5) Coefficient of service life : C f h = f n (5-6) P Coefficient of rotational speed : 1 f n = 6 1/p 5 6n 1/p = (.n) (5-7) For reference, the values of f n, f h, and L 1h can be easily obtained by employing the nomograph attached to this catalog, as an abbreviated method L 1h f n n f h L 1h [Reference] Rotational speed (n) and its coefficients ( f n ), and service life coefficient ( f h ) and basic rating life (L 1h ) A 4 A 5 Tecnopoint srl Tel Fax info@tecnopointonline.it

19 5. Selection of dimensions 5-- Correction of basic dynamic load rating for high temperature use and dimension stabilizing treatment In high temperature operation, material hardness deteriorates, as material compositions are altered. As a result, the basic dynamic load rating is diminished. Once altered, material composition is not recovered, even if operating temperatures return to normal. Therefore, for s used in high temperature operation, the basic dynamic load rating should be corrected by multiplying the basic dynamic load rating values specified in the specification table by the temperature coefficient values in Table 5-1. Table 5-1 Temperature coefficient values Bearing temperature, Temperature coefficient C Since normal heat treatment is not effective in maintaining the original size in extended operation at 1 C or higher, dimension stabilizing treatment is necessary. Dimension stabilizing treatment codes and their effective temperature ranges are described in Table 5-. Since dimension stabilizing treatment diminishes material hardness, the basic dynamic load rating may be reduced for some types of s. Table 5- Dimension stabilizing treatment Dimension stabilizing treatment code S S1 S Effective temperature range Over 1 C, up to 15 C 15 C C C 5 C 5--4 Corrected rating life The basic rating life (L 1 ), expressed using equation (5-1), is (fatigue) life, whose estimate of reliability is 9 %. A certain application requires a service life whose reliability is more than 9 %. Special materials help extend life, and lubrication and other operating conditions may also affect service life. The corrected rating life can be obtained from the basic rating life using equation (5-8). L na = a 1 a a L 1 (5-8) where : L na : corrected rating life 1 6 revolutions estimated reliability (1n) % : the probability of failure occurrence is expressed by n, taking characteristics and operating conditions into consideration. L 1 : basic rating life 1 6 revolutions (estimated reliability 9 %) a 1 : reliability coefficient refer to section (1) a : characteristic coefficient refer to section () a : operating condition coefficient refer to section () [Remark] When dimensions are to be selected given L na greater than 9 % in reliability, the strength of shaft and housing must be considered. (1) Reliability coefficient a 1 Table 5- describes reliability coefficient, a 1, which is necessary to obtain the corrected rating life of reliability greater than 9 %. Table 5- Reliability coefficient a 1 Reliability, % L na a L 1a L 5a L 4a L a L a L 1a () Bearing characteristic coefficient a The characteristic in relation to life may differ according to materials (steel types and their quality), and may be altered by production process, design, etc. In such cases, the life calculation can be corrected using the characteristic coefficient a. JTEKT has employed vacuum-degassed steel as JTEKT standard material. It has a significant effect on life extension which was verified through studies at JTEKT laboratory. The basic dynamic load rating of s made of vacuum-degassed steel is specified in the specification table, taking the characteristic coefficient as a = 1. For s made of special materials to extend fatigue life, the characteristic coefficient is treated as a > 1. () Operating condition coefficient a When s are used under operating conditions which directly affect their service life, including improper lubrication, the service life calculation can be corrected by using a. Under normal lubrication, the calculation can be performed with a = 1; and, under favorable lubrication, with a > 1. In the following cases, the operating condition coefficient is treated as a < 1 : Operation using lubricant of low kinematic viscosity Ball 1 mm /s or less Roller mm /s or less Operation at very slow rotational speed Product of rolling element pitch and rotational speed is 1 or less. Contamination of lubricant is expected Greater misalignment of inner and outer rings is present [Note] When hardness is diminished by heat, the basic dynamic load rating calculation must be corrected (ref. Table 5-1). [Remark] When a > 1 in employing a special material, if lubrication is not proper, a a is not always > 1. In such cases, if a < 1, characteristic coefficient is normally treated as a Service life of system comprising two or more s Even for systems which comprise two or more s, if one is damaged, the entire system malfunctions. Where all s used in an application are regarded as one system, the service life of the system can be calculated using the following equation, = (5-9) L e e e e L 1 L L where : L : rating life of system L 1, L, L : rating life of each e : constant e = 1/9 ball e = 9/8 roller The mean value is for a system using both ball and roller s. [Example] When a shaft is supported by two roller s whose service lives are 5 hours and hours respectively, the rating life of the system supporting this shaft is calculated as follows, using equation (5-9) : = + L 9/8 5 9/8 9/8 L h The equation suggests that the rating life of these s as a system becomes shorter than that of the with the shorter life. This fact is very important in estimating service life for applications using two or more s. As the above explanation shows, since a and a are inter-dependent, some calculations treat them as one coefficient, a. A 6 A 7 Tecnopoint srl Tel Fax info@tecnopointonline.it

20 5. Selection of dimensions 5--6 Applications and recommended service life Since longer service life does not always contribute to economical operation, the most suitable service life for each application and operating conditions should be determined. For reference, Table 5-4 describes recommended service life in accordance with the application, as empirically determined. Operating condition Short or intermittent operation Not extended duration, but stable operation required Intermittent but extended operation Daily operation more than 8 hr. or continuous extended operation 4 hr. operation (no failure allowed) Table 5-4 Recommended service life (reference) Application Household electric appliance, electric tools, agricultural equipment, heavy cargo hoisting equipment Household air conditioner motors, construction equipment, conveyers, elevators Recommended service life (h) Rolling mill roll necks, small motors, cranes 8 1 Motors used in factories, general gears 1 Machine tools, shaker screens, crushers Compressors, pumps, gears for essential use 4 6 Escalators 1 Centrifugal separators, air conditioners, air blowers, woodworking equipment, passenger coach axle journals Large motors, mine hoists, locomotive axle journals, railway rolling stock traction motors 4 6 Paper manufacturing equipment 1 Water supply facilities, power stations, mine water discharge facilities 1 5- Calculation of loads Loads affecting s includes force exerted by the weight of the object the s support, transmission force of devices such as gears and belts, loads generated in equipment during operation etc. Seldom can these kinds of load be determined by simple calculation, because the load is not always constant. In many cases, the load fluctuates, and it is difficult to determine the frequency and magnitude of the fluctuation. Therefore, loads are normally obtained by multiplying theoretical values with various coefficients obtained empirically Load coefficient Even if radial and axial loads are obtained through general dynamic calculation, the actual load becomes greater than the calculated value due to vibration and impact during operation. In many cases, the load is obtained by multiplying theoretical values by the load coefficient. Table 5-5 Values of load coefficient f w Operating condition Operation with little vibration or impact Normal operation (slight impact) Operation with severe vibration or impact Application example Motors Machine tools Measuring instrument Railway rolling stock Automobiles Paper manufacturing equipment Air blowers Compressors Agricultural equipment Rolling mills Crushers Construction equipment Shaker screens f w F = f w F c (5-1) where : F : measured load F c : calculated load f w : load coefficient (ref. Table 5-5) 5-- Load generated through belt or chain transmission In the case of belt transmission, the theoretical value of the load affecting the pulley shafts can be determined by obtaining the effective transmission force of the belt. For actual operation, the load is obtained by multiplying this effective transmission force by the load coefficient ( f w ) considering vibration and impact generated during operation, and the belt coefficient ( f b ) considering belt tension. In the case of chain transmission, the load is determined using a coefficient equivalent to the belt coefficient. This equation (5-11) is as follows ; M F b = f w f D b p W = f w f b (5-11) D p n Table 5-6 Values of belt coefficient f b N N where : F b : estimated load affecting pulley shaft or sprocket shaft N M : torque affecting pulley or sprocket mn m W : transmission force kw D p : pitch circle of pulley or sprocket mm n : rotational speed min 1 f w : load coefficient (ref. Table 5-5) f b : belt coefficient (ref. Table 5-6) Belt type Timing belt (with teeth) V-belt Flat belt (with tension pulley) Flat belt f b Chain A 8 A 9 Tecnopoint srl Tel Fax info@tecnopointonline.it