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Deep Groove Ball Bearings with Filling Slots

Single row deep groove ball bearings with filling slots have a filling slot in both the inner and outer ring enabling more and larger balls to be incorporated than in standard deep groove ball bearings.

Deep groove ball bearing with filling slots

Filling slot bearings have a higher radial load carrying capacity than bearings without filling slots, but their axial load carrying capacity is small. They are also unable to operate at such high speeds as bearings without filling slots. Depending on the main application for which they are used, deep groove ball bearings with filling slots have a cage (fig) or no cage (fig).

Deep groove ball bearing with filling slots and cage

Deep groove ball bearing with filling slots without cage

The smaller sizes, which are mainly used for automotive gearboxes and are identified by a standard designation, incorporate a cage. The standard assortment of these bearings comprises

  • basic design open bearings
  • shielded bearings
  • bearings with a snap ring groove.

The large-size bearings which are designed for heavily loaded, slowly rotating applications are without cage.

Basic design bearings

Basic design bearings with filling slots are open. Those bearings that are also produced in shielded version may have seal recesses in the outer ring, for manufacturing reasons (fig)

Shielded bearings

SKF deep groove ball bearings with filling slots are available with shields on one or both sides, designation suffixes Z or 2Z. The shield forms a narrow gap to the inner ring shoulder (fig).

Bearings up to and including sizes 217 and 314 are filled with high-quality NLGI class 2 grease with a polyurea thickener, that can be used at temperatures between 30 and +150 C. The base oil viscosity is 115 mm2/s at 40 C and 12,2 mm2/s at 100 C.

Larger bearings are supplied with a high-quality NLGI class 3 grease with a lithium thickener, that can be used at temperatures between 30 and +120 C. The base oil viscosity is 98 mm2/s at 40 C and 9,4 mm2/s at 100 C.

The quantity of grease fills some 25 to 35% of the free space in the bearing. The bearings are lubricated for life and are maintenance-free. The grease life can be estimated according to the method explained for single row deep groove ball bearings (section "Sealed bearings - Grease life") using diagram 2 for bearings up to and including size 217 and 314 (grease GJN) or diagram 1 for larger bearings (grease MT33). Calculations can be made with the program "Grease life for sealed bearings".

Shielded bearings should not be washed or heated above 80 C before mounting.

Shielded bearings are primarily intended for applications where the inner ring rotates. If the outer ring rotates, there is a risk that the grease will leak from the bearing at high speeds.

Details regarding the suitability of shields for various operating conditions can be found in table 1.

Bearings with a snap ring groove

For easy, space saving axial location of the bearing in the housing, SKF deep groove ball bearings with filling slots are available with a snap ring groove in the outer ring, designation suffix N (fig). The appropriate snap ring is shown in the product table with designation and dimensions and may be supplied separately or already mounted on the bearing, designation suffix NR.

SKF deep groove ball bearings with filling slots and snap ring groove can also be supplied with a shield on the side opposite the snap ring groove or with two shields (fig).

Large-size deep groove ball bearings with filling slots, without cage

These special SKF deep groove ball bearings have been developed for heavily loaded bearing arrangements where movement is of a slewing nature, e.g. the support bearing arrangement of converter drives. The bearings may be of the full complement type (without cage) (fig), or the balls may be separated by separator or spacer rings (fig), or spacers (fig).

Normally the rings are made of standard bearing steel but may also be made of hardenable steel.

DimensionsThe boundary dimensions (with cage / without cage) of the bearings identified by a standard designation (i.e. not a drawing number) are in accordance with ISO 15:1998.

The dimensions of the snap ring groove and snap rings follow ISO 464:1995.

TolerancesSKF deep groove ball bearings with filling slots are produced to Normal tolerances. The tolerances are in accordance with ISO 492:2002.

Internal clearanceSKF deep groove ball bearings with filling slots are manufactured with Normal radial internal clearance. The large-size bearings are supplied with either Normal or C3 clearance.

The values for radial internal clearance are in accordance with ISO 5753:1991 and are valid for unmounted bearings under zero measuring load.

MisalignmentThe conditions concerning misalignment of the outer ring with respect to he inner ring are the same for deep groove ball bearings with filling slots as for standard bearings. However, the filling slots limit the angular misalignments to 2 to 5 minutes of arc. Any greater misalignment may lead to the the balls running over the edges of the filling slot. This will cause increased bearing noise and reduced bearing service life.

Cages, separatorsSKF deep groove ball bearings with filling slots are fitted with a riveted pressed steel cage, ball centred, no designation suffix (fig).

The large-size bearings which are not of the full complement type have either separator rings (fig) or plastic separators (fig) to keep the balls apart.

Minimum loadTo achieve satisfactory operation, deep groove ball bearings with filling slots, like all ball and roller bearings, must always be subjected to a given minimum load, particularly if they are to operate at high speeds or are subjected to high accelerations or rapid changes in the direction of load. Under such conditions, the inertia forces of the balls and cage, and the friction in the lubricant, can have a detrimental influence on the rolling conditions in the bearing arrangement and may cause damaging sliding movements to occur between the balls and raceways.

The requisite minimum radial load to be applied to deep groove ball bearings with filling slots can be estimated using

where

Frm = minimum radial load [kN]

kr = minimum load factor (see product data)

? = oil viscosity at operating temperature [mm2/s]

n = rotational speed [r/min]

dm = mean diameter of bearing

= 0,5 (d + D) [mm]

When starting up at low temperatures or when the lubricant is highly viscous, even greater minimum loads may be required. The weight of the components supported by the bearing, together with external forces, generally exceeds the requisite minimum load. If this is not the case, the deep groove ball bearing must be subjected to on additional radial load.

Equivalent dynamic bearing loadP = Fr + Fa

provided Fa/Fr = 0,6 and P = 0,5 C0.

If the axial load Fa > 0,6 Fr then deep groove ball bearings with filling slots are unsuitable for the application and bearings without filling slots should be used instead.

Equivalent static bearing load

P0 = Fr + 0,5 Fa

provided Fa/Fr = 0,6.

If the axial load Fa > 0,6 Fr then deep groove ball bearings with filling slots are unsuitable for the application and bearings without filling slots should be used instead.

Supplementary designationsThe designation suffixes that occur most frequently with deep groove ball bearings with filling slots are listed below with their definitions.

snap ring on the opposite side of the shield
DesignationFeatures
C3Radial internal clearance greater than Normal
NSnap ring groove in the outer ring
NRSnap ring groove in the outer ring, with appropriate snap ring
ZShield of pressed sheet steel on one side of the bearing
2ZZ shield on both sides of the bearing
ZNRShield of pressed sheet steel on one side of the bearing and snap ring groove in the outer ring with
2ZNRZ shield on both sides of the bearing and snap ring groove in the outer ring with snap ring


Deep groove ball bearings | Single row deep groove ball bearings | Basic design bearings | Sealed bearings | Bearings with shields | Bearings with low-friction seals | Bearings with contact seals | ICOS oil sealed bearing units | Grease life | SKF Energy Efficient (E2) deep groove ball bearings | Deep groove ball bearings with filling slots | Stainless steel deep groove ball bearings | Double row deep groove ball bearings

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This page is still under construction. All bearing information remains the property and copyright of SKF Group.