Double row angular contact ball bearings

Double-row ball bearings of oblique contact correspond by their own construction and function to pair of one-row ball bearings with oblique contact in „O“ – type configuration. They have rather deep orbits on both rings and are may not be disassembled. In case of „E“ type construction, a filling opening is made on one side.

With optimal size of the balls and their conformity to the raceways relatively high load ratings are achieved. They can carry axial and radial loads in both directions
and are suitable even for high rotation rate. In case of “E” type bearings assembling, it must be done so that the prevailing axial force acts on the ball row on the side without the filling groove.

Double row angular contact ball bearings


 

Design specification

Main dimensions

Main dimensions of double row angular contact ball bearings specified in the dimension tables are in accordance with the international standards ISO 15. The bearings are commonly produced in the basic P0 tolerance class. Double row angular contact ball bearings are very sensitive to the misalignment of the rings.

Bearings with shields or seals

Double row angular contact ball bearings with sealing on one or on both sides are manufactured with metal shields (Z, -2Z) or with seals (RS, -2RS). The sealing rings made of rubber, vulcanized on metal reinforcing ring, provide an effective friction type sealing. The bearings are manufactured in the design with a seal and a flat collar of the inner ring (RS, -2RS).
Bearings with seals are suitable for operation within the temperature range from -30°C to 110°C.
Bearing deliveries with sealing capacity within 180°C (RS2, -2RS2), or eventually delivery of bearings with other sealing design, must be negotiated in advance.
Bearings sealed on both sides (-2Z, -2RS) are filled with a quality lubricant the properties of which usually ensure the lubrication during the whole bearing life under normal operating conditions. The bearings of this design cannot be relubricated. They can be used within the operating temperature range from -30°C to 110°C. The delivery of bearings with different lubricant should be discussed with the supplier in advance.

Lubrication

For bearings sealed on both sides, the designation of the lubricant filling different from standard lubricant is indicated by a symbol combination. The first two letters indicate the operating temperature range (a symbol in accordance with STN 02 4608) and the third identifies the lubricant name.

TL – Lubricant for low operating temperatures (from -60°C to 100°C)
TM – Lubricant for medium operating temperatures (from -30°C to 110°C)
TH – Lubricant for high operating temperatures (from -40°C to 250°C)
TW – Lubricant for low and high operating temperatures (from -40°C to 150°C)
Note: The symbols of lubricants for medium operating temperatures need not to be marked on the bearings.

Cage

The single row deep groove ball bearings of the basic design are equipped with a pressed cage made of steel sheet, guided on balls, which is not designated. The cages for double row angular contact ball bearings are manufactured in two version in dependence on the inner construction of the bearing. (see picture).

Double row angular contact ball bearings

In special cases the bearings are produced with different types of cages: bearings with a solid polyamide cage (TNH, TNGH), with a solid cage of textite (TB). The supply of these bearings should be discussed in advance.

Tolerances

Single row deep groove ball bearings are produced in tolerance classes P0 and P6. For special arrangements requiring high precison or for arrangements with a high rotation speed, the bearings with higher tolerance classes P6, P5 and P4 are used. The bearings with higher tolerance class P6E are used for rotating electric machines. The limit values of deviations in tolerances and the operation are specified in ISO 492.

Bearing clearance

Normally produced double-row ball bearings with oblique contact have normal axial clearance which is not marked. For special cases, the bearings with reduced axial clearance (C2) or enhanced axial clearance (C3, C4, C5) are supplied.

Vibration level

Commonly produced double row angular contact bearings have standard vibration level specified by the manufacturer. For special arrangements with silent running bearings with reduced vibration level (C6) are produced.

Combination of symbols

The symbols for the tolerance classes, internal bearing clearances and vibration levels are combined with the simultaneous omission of the symbol C in the second and the following bearing special characteristics e. g.:

P6 + C3 = P63
C3 + C6 = C36
P6 + C3 + C6 = P636

3205 P63
3205-2RS C36
3205-2Z P636


Misalignment

The misalignment of the rings is not admissible for double row angular contact ball bearings. The misalignment causes additional load of the bearing and the durability is lowered.

Radial equivalent dynamic load

Double row angular contact ball bearings:

P = Fr + 0,73.Fa
P = 0,67.Fr + 1,41.Fa

for Fa/Fr ≤ 0,68
for Fa/Fr > 0,68


Designation

The designation of basic designs and common modifications of the bearings are specified in the dimension tables. Modification of the basic design is designated with additional symbols according to STN 02 4608. The meaning of the most used symbols for single row deep groove ball bearings is in the table.

SymbolExample of DesignationMeaning
-RS3205RSSeal on one side adhering to a flat surface of the inner ring
-2RS3307-2RSSeal on both sides adhering to a flat surface of the inner ring
-Z3206-ZMetal shield on one side
-2Z3208-2ZMetal shields on both sides adhering to a flat surface of the inner ring
TNH3309TNHPlastic cage guided on balls
P63205 P6Higher tolerance class than standard
P53307E P5Higher tolerance class than P6
C23304 C2Radial clearance less than normal
C33305-2Z C3Radial clearance greater than normal
C43307-2RS C4Radial clearance greater than C3
C53206-2Z C5Radial clearance greater than C4
C63305 C6Reduced vibration level