THE DESIGNING OF THE BEARINGS CONFIGURATION
               Table 12 shows the most typical hardness curve, the required hardness value is the Vickers harness
           transformed from the related tension value.
               The minimum quenching hardness is mainly related with the diameter of the rolling body , the strain
           of the materials , the core hardness of the materials and the quenching method.
               For the case of tray , the its stable load reaches Co  (Hertz tension PH=4000N/mm2) , its required 
           quenching hardness will be decided by the following formulas:
               Surface quenching
            Eht≥0.078.Dw  .............................................( 42)    
               Flame or induction quenching
             Rht≥140.Dw/Rp0.2    ........................................(43)

                 Eht                       mm
              Effective surface quenching hardness depth
                 Rht                       mm
              Quenched hardness penetrating depth (for flame or induction quenching)
                 Dw                        mm
              Diameter of the rolling body
                 Rp0.2                    N/mm2
              0.2% of the material central elastic limit tension
              When the load is less than P=Co or Dw>100mm, experiments show that the quenching hardness depth can be less than the
            results of formulas (42) or (43).The quenched hardness must not be less than 0.3mm after final abrasion.
             
                The surface precision of the tray
             The selection of the surface precision of the tray is depended on the operational condition requirements 
        of the bearings. To fully develop the load capacity of the bearing, the roughness of the tray surface should
        be Rz1(Ra0.2). For lower requirements, the surface  roughness can be lowered down to Rz4(Ra0.8).But for those
        operation which needs higher stability and low noise , the tray should be ground or super ground so that the 
        minimum ripple surface can be reached.
            The dimensional tolerances between the needle and retainer assembly and  the punched outer ring tray are
        shown in the technical remarks before the dimension table of this brochure . the dimensional tolerances of the
        trays of the needle bearings without inner ring are shown in Table 16. The round tolerances will be no greater 
        than 25% of the associated dimensional tolerances while the parallel tolerances are 50%.
            When needle and retainer assembly is used, the width of the tray , after the subtraction of the chamfered 
        sized ( or the radium of the circular angle) , should be enough to ensure that the full width of the retainer 
        will have enough guiding surface .

               To reach the rigidity and load capacity the highest possibly while the spaces used can be saved as much
          as possible,  CJSRTL bearings without rings are recommended. The rolling bodies are directly on the shaft or
          rolling in the bearing holes such as the needle and retainer assembly, non-inner needle bearings and punched 
          outer ring needle clutches etc. Special attention should be paid to the followings points:
               Material
               To fully reach the load capacity of the bearing, be sure that its surface hardness should be 670?40 HV 
          during the selection of the roll bearing tray materials with enough quenched hard depth .Its purity  requi-
          rements are the same as generally high quality steel. The following steels are specially recommended for the
          rolling body tray materials.
                lThoroughly quenched steel
           In special cases, these rolling bearing steel can be surface quenched.
                lSurface quenched steel
               When selecting the materials, the hardness at the center should be considered besides the quenching
           hardness. During surface quenching treatment, first selection should be those with fine grain structure 
           and its effective quenched hard depth in compliance with formula (42).
                lFlame quenched steel or induction quenched steel
               the flame or induction quenching can be only effected tray position on the machined parts. The pre-
           condition of selecting material is still the quenchable hardness. Tempering process should be made before
           quenching hardness treatment.

 The surfaced quenched , flame 
quenched or induction quenched 
trays must get enough quenched 
hard depth Ht beside its surface
hardness of 670-40HV(for surface
quenching, the effective hard
depth is Eht, while the 
quenching hardness penetrate 
depth should be Rht for flame or
induction quenching. The defini-
tion of quenching hard depth is: 
the vertical distance between the
surface and the place where the 
hardness is 550HV.

                The organizational structure inside the commonly standard bearing materials will change with the
           operational temperature exceeds + 120℃ which will cause the variation of the bearing size. Therefore, 
           to ensure the normal operation of the bearings  under high temperature , the bearings must go through
           dimensional stability treatment . In  this case , we  must also consider the decrease of the material
           hardness caused thence. For small bearings,the dimensional stability requirements usually are not very
           high . But to guarantee the  stability combination  and the initial radical clearance of the big scale
           bearings, at least the inner rings should be dimensional stabilization treated. This can be expressed
           with different additional codes as per the different operational temperature requirements.

            The following factors must be considered in the positioning to the rolling bearings:
                l        ROTATION STATE
                 The rotation state means the movements of the bush rings in relation with the load directions..
                 Rotation load: bearing bush ring rotates while load remains standstill or vise ad versa . Both 
           of these cases belong to rotating load states . Under the rotating loads , if the combination to the 
           shaft or bearing seats is too loose , deviation will  occur on the bearing bush ring position .The-
           refore more compacted combination must be ensured to avoid such position deviation. The heavier the 
           load is , the greater of the bush ring dimension should be and the more compacted combination should
           be chosen.
                Spot load : when bearing bush ring load are still , or when the bearing bush ring and load are
           rotating with the same speed, the two cases are regarded still loads. In this case , comparatively 
           looser combination can be selected because at this time , no position deviation will change on the 
           bearing bush ring.
                Variable load direction: the irregularly changing load , the rocking load or impact and vibrating 
           load are all called variable  load direction, more compacted combination of the two bush rings must be
           selected.
                l   LOAD TYPE AND  NATURE
                For the bush ring of the rotating load or the variable load, the greater the load is, the more 
　　　　　　compacted combination should be.
　　　　　　　　 l THE BEARING TYPE AND SIZE
               Table 14 only shows the bearing seat hole tolerances only used for steel or cast iron bearing seats 
          while Table 15 shows the shaft tolerances for the solid shaft. More compacted combination should be used 
          in  the cases of bearing  seats made of light  metal or the hollow shaft .  The shaft tolerances for the 
          needle bearings without inner rings are listed in Table 16.
              From the factors mentioned above,it is clear that it is impossible to find a selective principle that
          contains all the combination tolerances for all combinations under all factors. Therefore , allthe figures
          listed in the tables will be regarded as reference values only.

Table 15the selective principles for the shaft tolerance limit for inner

ring needle bearings and roller bearings

　　　　　　　　After the tolerance limited of the shaft and the bearing seat is chosen, the  working clearance must be rechecked.
　　　　　　　　Greater radical clearance is needed for tolerances of n6 and p6.
　　　　　　　　Combination should be no greater than k5 for needle ?angular contact bearings.

Table 16 the reference values for the selective shaft tolerance limits of the needle bearings without inner rings

                   1)The tolerance suitable to the bearing seat is up to K7,for the bearing seat tolerance
                above K7 , the clearance must be got through calculation or measuring.
                Mounting  tolerance
                   Bearing bush rings has perfect radical positioning while the bush rings are evenly supported
            on their circular surfaces and widths. These will decisively effect the normal operation and a longer 
            life of the bearing. Therefor the mounting tolerances must be selected very carefully.
                Thedesigning of  the bearing bush ring supporting surface
                   For normal function of the rolling bearings,the surfaces in combination with the bearings(shaft
            and bearing seat holes) must be made as per the appropriate bearing precision grade.
                   The surface dimensional tolerance of the recommended geometric precision value associated with 
            the bearings are listed in Table 17.
                   The contacting surfaces of the divided bearing seats must be de-burred  and chamfered..
             Table 17 the surface dimensional tolerance and geometric precision associated with the bearings

            To prevent the side slip of the needle bearings or the cylindrical roller bearings, the bearings must 
         be positioned in axle direction and be clamped. No axle clamping device are permitted if the combination
         tolerance is compact enough. (see figure 12a which shows the needle bearing of punched outer ring)
            The needle and retainer assembly must have axial directional guide. (see figure 13 and fig 14)
            The designing of the guiding surface
            The side directional guiding surface of the needle and retainer assembly must me machined very care-
         fully  to  ensure on burr existing .  The neighboring faces  must be quenched and ground for high speed 
         operation. There should be a washer added before the stopping ring. (see fig 14)
            The axial directional positioning of the bearing bush ring
            The bearing bush ring is always positioned by the shaft or the retaining shoulder. The retaining shoulder must have enough altitude and
                 be vertical to the axle line of the bearing. Also they must be produced in the same machining of the surface combined with the bearing bush
                 ring.
                        The circular angle and the cutter exit groove must be in compliance with the regulation in the transit parts between the retaining shoulder
                and the surface combined with the bearing.
                        The circular angle or the cutter exit groove will ensure the whole face of the bearing bush ring be supported by the retaining shoulder ,
                so attention must be paid to the minimum value of he chamfered angle ?s given in the dimension list.
                        If the bearing is used as the fixed end support and bears the axial direction load, the both ends of  the bush ring must be fixed tightly (see
                figure 16,17 18), especially for the case of the inner ring of the separation inner ring  (Nk1b , see fig 16 and SL04 , fig 24) and the cylindrical 
                roller bearing divided outer ring series SL01(Figure 17 or 18) , series SL11 and SL12. In these cases, the two ends must be closed clamped.
                        Fir the single directional positioned bearing ( Figure 19 and 20 ) ,   it will be enough to have the one end of the retaining edge supported 
                where the axial directional load is effected on the bearing bush ring.
                       The support height of the retaining edge of the cylindrical roller bearings under the axial direction load should be increased to the size of d1 
                or D1 (see dimension list)

                The operational reliability and the life time of the bearing mainly depends on the effective protection of its sealing unit against the
                      entering of the dirt and vapor and the leakage of the lubrications. The applicable conditions should be taken into account when selecting 
                     the sealing type.
                              Non contacting sealing is mainly used in the following cases: the place where sealing friction must be avoided in high speed circular
                    movement, the sealing friction is hoped to be avoided under hgih temperature. Gap sealing will get good sealing result for lubricating grease .
                   The gap sealing back flow design (the groove, centrifugal ring , spiral groove etc) will help this sealing to be used in the case of lubrication oils.
                                  The slit of the simple gap sealing is 0.1-0.2mm. the slit in the permissive space range can be as long as possible. Those with ring--
                    shape groove (fig 21) will help to improve the sealing effect.
                                   Labyrinth sealing (fig 23) has better effect. To avoid pump absorption phenomenon, the slit of the radical expansion can not be very
                     narrow  .  A better result will be got with grease in the slit . Generally speaking ,  the lubrication grease should be the same as that used in the
                     bearing  ,  or at least the densification agents for the lubrication grease must be the same .  If  the above mentioned requirements can not be 
                    satisfied due to the sealing medium, special sealing grease should be used. In this case, separating space should be provided so tha the sealing 
                    grease will not enter into the bearing.

              Contacting sealing
                  Contacting sealing is usually better than the non contacting sealing. In contacting sealing,the 
          sealed surfaces contact is kept by pre-tension. Therefore, the friction heat thus caused will limit the 
          permissive circular speed . In operation , a bigger initial friction surface will decrease drastically . 
          The sealed combination surfaces should be lubricated as well, or abrasion loss will occur.
                  Seal lip sealing (Fig 24-Fig 27). This kind of sealing is applicable to the oil lubrication and 
          grease lubrication  with the circular speed of  12m/s . If the purpose of the sealing is to prevent the 
          sealing lubricant leakage from the bearing seat,the seallip should be fitted inward while if the purpose 
          is only to prevent the dirt from entering into the bearing unit, leas lip should be fitted outward.
                 Rotating shaft sealing: As per DIN3760 (Fig 27) this is a king of seal lip sealing which are very
          effective for many kinds of bearing units. 

Fig24 seal lip sealing , series pp

lRTL sealed needle and cylindrical roller bearings

    (Fig 24) is seal lip sealed bearing (suffixed "RS"or "P" , no additional sealing space is required 
in this structure . This kind of bulk sealing is applicable to the sealing unit without pressure need . 
In general operational condition, it can prevent dirt from entering the bearing and the leakage of lu-
bricating grease. In re-lubrication, the used grease can be drained out from here.

            Felt  lubrication
               This lubrication is used in the case of a circular speed less than 4m/s. Felt sealing ring and the 
        ring groove are all standardized in DIN5419. Felt sealing unit must be dipped into the hot oil (about + 80℃)
        before mounting.
               There must be no scratches or scores on the combination face. If there is no spiral trails after
        surface grinding, better sealing result will achieved. The recommended roughness is Rz1-Rz4 or Ra0.2-Ra0.8. 
        the surface hardness must be no less than 450HV. When the circular speed exceed 4m/s, the minimum should 
        reach 600HV. There must be guiding chamfered angle at the ends of contacting sealing combination surfaces 
        so that seal lips will not be turned over in mounting.
             The lubricating grease should be coated onto the seal lips and the combination surfaces before fitting
        to avoid the dry friction in the first rotation of the shaft. If double lip sealing or several sealed units 
        are mounted, the lubricating grease should be filled into the gaps in between.
             If the sealing purpose is mainly to prevent the lubricant leakage from the bearing, the seal lip should
        be fitted inward while the outward fitted lips will help preventing the dirt outside from entering . also, 
        the used lubricants can be drained out when lubricate again.
             When the sealing unit is to be pressed into the bearing seat hole, pressing pole should be used to 
        ensure alignment of the center and vertical to the axle. In case there is a sharp angle at the surface top
        end of the sealing unit combination, associated auxiliary sleeve should be used. The diameter of the 
        assembling sleeve should be a little bigger than the diameter of the sealing unit combination surface with
        a long guiding chamfering angle.(about 15℃)
             The roughness of the RTL inner (IR series) ring tray is very small and its surface is suitable for the
        combination path of the lubrication seal lip. When it is used for oil lubricating sealing, to get better 
        sealing effect, the inner ring should be machine without spiral scores (IR...EGS), and a chamfered angle to 
        prevent the seal lip from being scraped.