RKB Tapered roller Bearings Double Row
RKB double row taper roller bearings can take up heavy loads and are stiff.
Suitable for combined radial and axial loads, they locate axially the shaft in both directions with the stated axial end play (also defined as BEP – Bench End Play) or given preload.
The basic styles are two-row converging TDI configuration and two-row diverging TDO configuration.
Rings and rollers are made of high chrome through hardening steels or case hardened carburizing alloy steels depending on the application.
Cages for RKB double row taper roller bearings are stamped pressed steel. A steel pin-type cage, which allows a larger complement of rollers for higher capacity, is also available.
This style of bearing set simplifies design and reduces the danger of bearing clearance changes due to axial shaft expansion.
It is important the definition of the proper internal play related to the application.
RKB bearings in TDI configuration have a double cone assembly and two single cups and they are generally supplied with a cup spacer.
The cup spacer of each bearing is face ground after accurate measurement of the distance between adjacent cup faces to obtain a predetermined internal play. Consequently, spacers or components may not be interchanged. An annular groove and lubrication holes are included in the spacer. The contact angle converges, so the use of these bearings will not appreciably increase the rigidity of the shaft mounting.
RKB also produces the taper roller steep contact angle TDIS version with higher thrust capacity (while the radial one is reduced) than the TDI type, normally used as back-up thrust bearings in rolling mills.
These TDIS bearings have combination of face slots (e.g. N, N1, N2, etc.) and bore keyway for locking the cone on the shaft.
Also, helical groove in the bore and lubrication grooves inside faces of double cone and/or retention sleeve with annular groove and lubrication holes can be provided.
RKB bearings in TDO configuration have a double cup, two single cone assemblies and can be supplied with a shaft supported cone spacer.
The spacer for individual cones is face ground to obtain the desired internal play for the assembly. So, also in this case, spacers and components may not be interchanged. An annular groove and oil holes are included in the cone spacer.
The TDO style bearings are mainly used in a floating cup mounting. So, the counterbored hole in the cup is for a drilled dowel pin which prevents rotation of the loosely fitted double cup. Additional features of a lubrication groove and oil holes in the double cup for simplified lubrication through the outer ring are included (suffix CD). However, this style of bearings is usually lubricated through the shaft by use of oil holes and a groove in the cone spacer.
In the TDO type the contact angle diverges, so the rigidity of the shaft mounting is increased to resist overturning moments.
Bearing sets with steep contact angle and intermediate ring, pierced rollers and steel pin-type cage (TDOS design), bearing sets with extended inner rings which abut each other (TDONA and TDONASW designs), bearing sets with heavy wall cup (TNASWH design) and bearing sets with shields of pressed steel (TDO 4422 design) are also in RKB manufacturing program.
Most of TDI and TDO double row taper roller bearings are produced with inch dimensions as per American AFBMA 19/1974 and as per RKB standard practice, dimensional and running accuracy grade is in accordance with class 2 or 4.