The axial-radial cylindrical roller bearings (YRT) described in this paragraph are the combination of a double direction needle roller thrust bearing with a cylindrical roller, full complement radial bearing. These bearings withstand radial loads, bidirectional axial loads and tilting moments of large entities in relation to their small overall dimensions. They are units equipped with grease and ready for assembly, which can be done by fixing them with screws or bolts to their adjacent components. Its rings (external, internal and angular) , have through holes indeed. They were originally designed for rotary tables and allow the construction of systems with a high load capacity. They are very rigid and guarantee a remarkable rotation precision to the system. Their use has expanded over the years and are still used in chucks, dividers and metrological and test equipment.
Axial-radial cylindrical roller and needle roller bearings DS-YRT series (See image below) include: a ring (1) which is the fusion of the inner ring of a radial bearing and a shaft washer of an axial bearing ; a washer per shaft (2); a housing washer (3) radially guided by the group (4) of cylindrical rollers; two axial roller assemblies enclosed by brass cages (5). The retaining screws (6) are used to facilitate handling during transport and installation. As already mentioned, in order to be fixed to adjacent parts, the rings are provided with through holes for bolts, with or without counterbore, according to the DIN 912 and ISO 4762 standards.
TECHNICAL FEATURES- TOLERANCES
The overall dimensions of the standard bearings (identified by a standard or non-standard designation
by a drawing number) indicated in the dimensional tables are
identical for both DS-YRT & DS-YRTS executions.
The height of the individual components is chosen so that, after assembly and once the fixing bolts have been tightened, there is an appropriate preload in the axial component. The radial component, which is full complement of rollers, has a slight preload.
Thanks to the large number of long rollers and the type of contact between the rolling elements and the raceways, only small deformations occur in the bearing and, above all, in large types there is a high stiffness.
The table provides indicative values of the radial and axial stiffness and that in the presence of tilting moments.
For bearings fixed as in Fig. 1a these values are within the load admissibility range if the indicated tightening torques are adopted.
The rigidity of the system can be increased by using a support ring similar to the one shown in Fig. 1b
Axis-radial cylindrical roller bearings (YRT) in the standard version are built with
dimensional tolerances class P5, shape precision falls within the limits of class P4
according to DIN 620. Special bearings with tolerances can also be supplied on request
reduced on the H1 dimension, flatness and roundness.
All tolerance values are visible in the table below.
|Position and ,Dimensional tolerances|
|Inner ring||Dimensional tolerances||Tolerance on H1 quote||Planarità e rotondità|
|d (mm)||Outer Diameter||Hole||normal||ristretta||normal||ristretta|
|50||126||0/ -0,011||50||0/ -0,008||0,125||0,025||2||1|
|80||146||0/ -0,011||80||0/ -0,009||0,150||0,025||3||1,5|
|100||185||0/ -0,015||100||0/ -0,010||0,175||0,025||3||1,5|
|120||210||0/ -0,015||120||0/ -0,010||0,175||0,025||3||1,5|
|150||240||0/ -0,015||150||0/ -0,013||0,175||0,030||3||1,5|
|180||280||0/ -0,018||180||0/ -0,013||0,175||0,030||4||2|
|200||300||0/ -0,018||200||0/ -0,015||0,175||0,030||4||2|
|260||385||0/ -0,020||260||0/ -0,018||0,200||0,040||6||3|
|325||450||0/ -0,023||325||0/ -0,023||0,200||0,050||6||3|
|395||525||0/ -0,028||395||0/ -0,023||0,200||0,050||6||3|
|460||600||0/ -0,028||460||0/ -0,023||0,225||0,060||6||3|
|580||750||0/ -0,035||580||0/ -0,025||0,250||0,075||10||5|
|650||870||0/ -0,050||650||0/ -0,038||0,250||0,100||10||5|
|850||1095||0/ -0,063||850||0/ -0,050||0,300||0,120||12||6|