LARGE SIZE BALL & ROLLER BEARINGS LARGE SIZE BALL & ROLLER BEARINGS General Bearings LARGE SIZE BALL & ROLLER BEARINGS

1 Selection of bearing dimensions ⋅⋅⋅ 4 3 Bearing fits ⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅ 35 2 Bearing tolerances ⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅⋅ 17 4 Internal clearance ⋅⋅⋅⋅⋅⋅⋅⋅ 47 7 Examples of failures ⋅⋅⋅⋅ 70 6 Bearing materials ⋅⋅⋅⋅⋅⋅⋅⋅ 66 Technical data Deep groove ball Angular contact ball Cylindrical roller Tapered bore Full complement cylindrical roller bearings for crane sheaves inch series TDIS (For axial support) TDIT (Tapered bore) T⋅⋅⋅, THR⋅⋅⋅ 2THR⋅⋅⋅ For screw down spindle THR⋅⋅⋅X For screw down spindle Bearing specification tables Tapered roller bearings Spherical roller bearings Thrust ball bearings Tapered...

Koyo. LARGE SIZE BALL & ROLLER BEARINGS Value & Technology

Technical data Publication of LARGE SIZE BALL & ROLLER BEARINGS We are pleased to offer you this newly issued Koyo large size rolling bearing catalogue. Bearing specification tables The conventional large size rolling bearing catalogue has been thoroughly revised. This catalogue includes information such as the latest bearing types, bearing numbers, and technical data. We are confident that this catalogue will help every people engaged in design and maintenance of machinery. This catalogue also shows bearings intended for special purposes. If you have any inquiry for selection of bearings, please...

1. Selection of bearing dimensions 1-1 Bearing service life When bearings rotate under load, material flakes from the surfaces of inner and outer rings or rolling elements by fatigue arising from repeated contact stress. This phenomenon is called flaking. The total number of bearing rotations until flaking occurs is regarded as the bearing "(fatigue) service life". "(Fatigue) service life" differs greatly depending upon bearing structures, dimensions, materials, and processing methods. Since this phenomenon results from fatigue distribution in bearing materials themselves, differences in bearing...

1. Selection of bearing dimensions 1-2-3 Correction of basic dynamic load rating for high temperature use and dimension stabilizing treatment In high temperature operation, bearing 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 bearings used in high temperature operation, the basic dynamic load rating should be corrected by multiplying the basic dynamic load rating values specified in the bearing specification...

b) Fatigue load limit Cu Fig. 1-2 Life modification factor aISO Fig. 1-3 Life modification factor aISO (Radial ball bearings) (Radial roller bearings) For regulated steel materials or alloy steel that has equivalent quality, the fatigue life is unlimited so long as the load condition does not exceed a certain value and so long as the lubrication conditions, lubrication cleanliness class, and other operating conditions are favorable. For general high-quality materials and bearings with high manufacturing quality, the fatigue stress limit is reached at a contact stress of approximately 1.5...

1. Selection of bearing dimensions The lubricant forms an oil film on the roller contact surface, which separates the raceway and the rolling elements. The status of the lubricant oil film is expressed by viscosity ratio κ, the actual kinematic viscosity at the operating temperature ν divided by the reference kinematic viscosity ν1 as shown in the following equation. Loads affecting bearings includes force exerted by the weight of the object the bearings support, transmission force of devices such as gears and belts, loads generated in equipment during operation etc. Seldom can these kinds of...

1. Selection of bearing dimensions 1-4 Dynamic equivalent load Bearings are used under various operating conditions; however, in most cases, bearings receive radial and axial load combined, while the load magnitude fluctuates during operation. Therefore, it is impossible to directly compare the actual load and basic dynamic load rating. The two are compared by replacing the loads applied to the shaft center with one of a constant magnitude and in a specific direction, that yields the same bearing service life as under actual load and rotational speed. This theoretical load is referred to as the...

1. Selection of bearing dimensions Mean dynamic equivalent load When load magnitude or direction varies, it is necessary to calculate the mean dynamic equivalent load, which provides the same length of bearing service life as that under the actual load fluctuation. The mean dynamic equivalent load (Pm) under different load fluctuations is described using Graphs (1) to (4). P1p n1t1 + P2p n2t2 + ⋅⋅⋅ + Pnp nntn ⋅⋅⋅⋅⋅⋅⋅⋅⋅ (1-14) n1t1 + n2t2 + ⋅⋅⋅⋅⋅⋅ + nntn (3) Fluctuation forming sine curve P Symbols for Graphs (1) to (4) Pm : mean dynamic equivalent load P1 : dynamic equivalent load applied for...

1. Selection of bearing dimensions Koyo 1-5-3 Safety coefficient The allowable static equivalent load for a bearing is determined by the basic static load rating of the bearing; however, bearing service life, which is affected by permanent deformation, differs in accordance with the performance required of the bearing and operating conditions. Therefore, a safety coefficient is designated, based on empirical data, so as to ensure safety in relation to basic static load rating. 2. Bearing tolerances Bearing tolerances and permissible values for the boundary dimensions and running accuracy of bearings...