SUPPORT ROLLERS WITH AXIAL GUIDANCE
These types of supporting rollers are able to accommodate additional thrust loads as they occur, due to aligning errors or if rollers run out of line.
That is why no extra external guiding surfaces are required.
Support rollers with axial guidance that, except support rollers belong to the series STO_2Z, are not separable. They are ready to mount and are particularly suitable for applications in which it can not derive lateral guide surfaces.
Where high axial loads are anticipated effective axial support of side washers must be achieved by the adjacent machine components.
Definition of identification :
NATR = support roller with axial guidance , full complement
NATR_PP = support roller with axial guidance with contact seals on both sides
NATV = support roller with axial guidance , full complement
NATV_PP =support rollers with axial guidance for difficult working conditions
NUTR = support roller with axial guidance, derive from bearings Double row cylindrical roller bearings , full complement
Support rollers belong to the series STO_2Z are designed similar to the STO, but have two loose side plates to accept axial forces but have two lateral loose washers which provide for the axial guidance of the group consisting of the inner ring , the cage and the rollers . These types of support rollers are separable, this enables simple mounting of the rollers due to the separable parts.
Particular attention must be paid to the adequate axial clamping of loose side washers during mounting. The side plates of this type of rollers must not have any axial play when they are mounted.
Support rollers belong to the series NATR have the side washers pressed into the inner ring to ensure guidance of the outer ring and the needle roller and cage assembly. Therefore, these rollers types are non separable. Support roller of these series are optimum for applications where the rollers are exposed to high radial loads at high speeds and this can lead to axial stresses due to misalignments or inclined axis operation .
They can contain a relatively large amount of grease, they can work for long periods before requiring a re-lubrication . When there are difficult working conditions the support rollers , of series NATR , can be equipped with contact seals on both sides ,identified as NATR_PP.
Support rollers belong to these series are full complement ( they have no fitted cage ) and, also, they may also be provided with contact seals on both sides .
These support rollers are unsuitable for high speed applications due to the differing kinematic operating condition.
Also they must be re-lubricated more frequently.
For applications that work in difficult conditions , support rollers are supplied with sealed support ; series NATV_PP.
The base internal of the support rollers of this series is similar to that of double row cylindrical roller bearings. Since the outer ring has two shoulders these support rollers are able to accommodate greater thrust loads. Support rollers belong to these series are non-separable.
Two -shaped laminations at "L " , forced in the outer ring and that going to break into a circumferential space created on the non- inner ring integral jokes , hold together the various parts and form an effective labyrinth seal. Support rollers belong to these series are suitable for very high radial loads , as well as for axial shocks.
Support rollers of series NUTR can work at higher speeds of the MATV support rollers , but they need to be re-lubricated frequently.
Several types of support rollers , such as series , are also available in sealed version. NA22_2RSR , NATR_PP e NATV_PP, are available also the version with gaskets.
These support rollers feature contacting seals made from a wear - resistant synthetic rubber compound ( NBR ) that provides an efficient and effetcive seal against the penetration of impurities or the escape of grease.
The synthehic rubber used for these contacting selas is satisfactory for operation temperatures of -30°C up to +120°C.
All support rollers are already supplied filled with a high quality, lithioum - soaped bearing grease as standard.
The lubricant is adequate for operating temperatures of -30°c TO +110°C
Therefore support rollers feature a lubrication hole in the inner ring to provide the possibility of re-lubricating the rollers, when necessary.
It must be considered where relubrication is necessary, with a satisfactory grease, the force of pressure to re-grease must be of a level not to cause permanent damage to either the seals or shields.
Support rollers with cages fitted , normally have pressed steel cages as standard.
Only small support rollers without axial guidance (series STO and RSTO) are fitted with solid polyamide 6,6 (TVP) , as standard.
Support rollers are produced to normal tolerance class ( PN ) as standard .
Support rollers are produced to normal internal clearance group ( CN ) as standard.
ITS Italia may want to pay attention to the fact that the existing lubrication hole on the inner ring comes to find , after installation , in the download area of the wheel.
The surfaces against which it must flow the outer rings of the roller without axial guide ( series STO , RSTO , NA22_2RSR and RNA22_2RSR ) must be machined with turning faint , no flaws and clean.
If the surfaces are not hardened must have an extension at least equal to half of that of the outer ring side face ; however if they are hardened may have less extension .
The wheels without inner ring ( RSTO and RNA22_2RSRS ) must have an axial clearance of at least 0.2 mm between the guide surfaces .
For support rollers with axial guidance to be subjected to high loads , we recommend providing a support for the entire side wall of the side washers .