TIMKEN tapered roller bearing clearance setting method

TIMKEN tapered roller bearings can be set during installation. It is because of this unique characteristic that the bearing clearance can be adjusted to meet the optimum range of application conditions to obtain the best bearing performance and system performance. Tapered roller bearings have the following advantages in setting clearance: while meeting application performance requirements, optimizing bearing clearance and extending bearing life Setting proper bearing clearance can increase the stiffness of the system, for example, suitable clearance Allows for better gear contact and longer gear life Bearing inner ring and outer ring can be separated, and the clearance of the installed bearing can be set during the assembly machine, so wider tolerances of the shaft and the housing can be accepted. A variety of ways to quickly set the clearance of tapered roller bearings. You can manually set the clearance, preset clearance or automatically set the clearance. Five common methods for automatically setting clearances (namely SETRIGHTTM, ACRO-SETTM, PROJECTASETTM, TORQUE-SETTM, and CLAMP-SETTM) each have many implementation methods, considerations, and advantages. See Table 1. The design of bearing clearance For tapered roller bearings, "set clearance" refers to a certain amount of axial clearance or preload (axial interference) of a mounted bearing. The structure of the tapered roller bearing determines that it can be easily adjusted and optimized during assembly.

  Unlike other types of rolling bearing models, tapered roller bearings do not require specific clearance values ​​by tightly controlling the fit of the shaft or housing when setting clearance. Since the tapered roller bearings are mounted in pairs (Fig. 1), their play depends mainly on the relative axial position of the two rows of bearings. The three main types of bearing clearance: Axial clearance - first apply a small axial force to the shaft in one direction, then apply this force again in the opposite direction, apply a force while swinging or rotating the shaft, roller The axial clearance between the raceway and the raceway can produce a measurable axial movement (the bearing bearing area is less than 180 degrees) preloading - axial interference between the roller and the raceway, so the shaft is as described above The method can not be measured when measuring the axial movement can measure the rolling resistance of the shaft rotation (loading area greater than 180 degrees) zero clearance - the gap between the axial gap and preload, no gap and no preloading assembly and The bearing clearance set in the process of adjusting the bearing is called a cold installation clearance, and the cold installation clearance is adjusted before the equipment is put into operation.

The clearance during operation is called the "working clearance" of the bearing. The working clearance is the result of the change in clearance caused by the thermal expansion and deformation of the bearing during operation. The cold installation clearance needed to achieve the best working clearance varies from application to application. The best clearance can usually be determined based on application experience or testing. However, the exact relationship between cold installation clearance and working clearance is often unknown, and can only be estimated based on existing knowledge and experience. If you want to obtain recommendations for bearing cold mounting clearance for specific applications, please contact Qingdao Ruijing Mechanical and Electrical Equipment Co., Ltd. bearing sales engineer. In general, the ideal bearing operating clearance is close to zero for maximum bearing life. Most bearings set an axial gap as an initial clearance during cold installation. When the equipment reaches a stable operating temperature, the clearance will be as close as possible to the required clearance - close to zero.

  Mounting clearances for certain applications may be set to preload to increase the stiffness or axial positioning of high-stress components, which would otherwise be subject to excessive flexing and eccentricity. Over pre-tensioning in the working state must be avoided, otherwise the bearing's fatigue life will be significantly shortened. In addition, excessive pre-tightening during operation generates a large amount of heat, which can lead to lubrication problems and premature bearing damage. The bearing area is the physical measurement of the arc carried by the raceway and directly reflects the number of rollers bearing the load. For a single-row tapered roller bearing, the maximum service life is approximately 225 degrees. Figure 2 graphically illustrates the relationship between L10 life and operating clearance of a bearing on a (cantilever) gear shaft. The ideal working clearance that maximizes the life of the bearing system is usually in the interval from near zero to slight preload. When manually setting the bearing clearance for small and medium-sized equipment production, if the precision of the bearing clearance is not high and the bearing clearance is mainly axial clearance, the manual method can often be used to set the bearing clearance, usually without special tools and measuring tools. , charts or fixtures, but there are requirements for the skills and judgment of the assembly workers. For example, a non-drive wheel of a conventional truck using a single adjustment nut design (fig. 3). During manual adjustment, the wheel is turned while tightening the adjustment nut until it feels that the rotation begins to have resistance. Then adjust the nut back 1/6 to 1/4 turn, align the nearest locking hole or retract to a small axial gap just enough to allow the wheel to rotate freely. Then adjust the lock nut in this position. Workers' skills and judgments need to be used to determine when the wheel starts to rotate when it is rotating. The more complicated and/or heavier the equipment is, the higher the level of skill and judgment of the worker is.

 For complex, large-scale or mass-production applications, manually setting the play may be too cumbersome, inaccurate, unreliable or time consuming. Timken designed a preset clearance bearing assembly and automatic clearance setting method as an alternative to manual setting of clearance. Preset clearance bearing assemblies Many applications use or require a double row or tightly coupled paired bearing assembly. This depends on the design and operating characteristics of the machine (such as the effects of thermal growth, high loads, etc.). To facilitate setting the bearing clearance in this case, we often use a preset clearance bearing assembly. The preset clearance bearing assembly has various forms. However, most are generally referred to as spacer bearings (Figure 4). Most preset clearance bearings are manufactured and supplied with spacers. The spacers are custom-built according to the bearings and are used to control the internal clearance (reference types 2S and TDI). Therefore, these custom or "grinding" spacers cannot be used interchangeably with other bearing assemblies. There are some preset clearance components, such as type SR or TNA, that allow the use of interchangeable spacers and/or bearing components. The purpose of designing these interchangeable assembly components is to tightly control the important tolerances that affect the bearing clearance. Therefore, these components can be randomly selected for use. Preset clearance bearings are manufactured with specific (unmounted) Internal clearance or factory clearance (BEP). The factory clearance is determined based on the installation clearance range required for a particular application. The installation clearance range of the bearing is determined strictly according to the influence of the shaft and bearing seat assembly and BEP. It is usually only required that the bearing and the rotating part are tightly fitted (shaft or bearing seat). The result is an expected installation clearance range of less than 0.008". The assembly clearance of the components of the interchangeable parts is usually greater than the range of installation clearances of the "paired" spacer assemblies. Usually the preset clearance bearing assembly is used when installing. It is very simple, just use the spacers to properly clamp the bearing components.

  Application of a typical preset clearance bearing assembly Preset clearance TIMKEN bearing assemblies are widely used in various industrial devices. Such as: planetary gears, bolts or connecting rod positions, gearbox idler gears, fan hub axles, pumps and idler shafts, pulleys, conveyor idlers, winch drums, fixed and floating positions of mining equipment, propulsion and slewing drives, Large gearbox drive.