Cam Followers are either needle roller or cylindrical roller bearings with an extra radially thick outer ring. Depending on their series, Cam Followers may be both separable and non - separable radial bearings.
Cam Followers usually run with their outer ring either directly on a guide track or against a machine surface that is for guidance. Due to their extra - thick outer rings, Cam Followers are able to accept high radial forces as well as shock loads.
Their ability to accommodate axial forces, however, depends on the particular design of the support roller.
Cam Followers are usually exposed to minor misalignments during operation. To minimize the negative effects of such misalignments, (e.g. high edge stresses), Cam Followers are more frequently used with sphered outer rings.
NKE - Cam Followers with parallel (cylindrical) outer diameters are indicated by the suffix "X"
In order to cover as many applications as possible, NKE Cam Followers are available in several different design variants as standard.
To provide simple re-lubrication, all Cam Followers have lubrication holes in their inner rings.
Cam Followers without axial guidance
The most simple design of Cam Followers is provided by the STO - type rollers.
For these rollers the outer ring, inner ring and the needle roller and cage assembly may be fitted separately. Since STO - type Cam Followers do not provide any axial guidance to their needle roller and cage assembly they adequately accept radial loads only.
The axial guidance of outer ring and needle roller and cage assembly must be provided by a suitable design of adjacent machine parts. STO - Type Cam Followers are frequently used without their inner rings, namely RSTO - rollers. The needle roller and cage assembly of RSTO - type Cam Followers run directly onto the shaft surface, which must be designed in an adequate manner, (e.g. hardened and ground).
For detailed guide lines on the design of bearing raceways on shafts see chapter "Design of bearing position" on page 303.
STO and RSTO - type Cam Followers are the only Cam Followers that are satisfactory for operating with oil lubrication.
Unlike the STO - type Cam Followers, the outer ring, and the needle rollers and cage assembly of series NA 22 ..2RS build a unit, whilst the inner ring may be dealt with individually.
NA 22 ..2RS- type Cam Followers also accommodate radial loads only. They also require adequate axial guidance of their outer rings by adjacent parts.
Due to the contact seals, which are integrated in their outer rings, NA 22 ..2RS- type Cam Followers provide the possibility for maintenance - free bearing arrangements.
Sealed Cam Followers, without inner rings, are also produced, namely RNA 22..2RS.
For these types both the needle rollers and the rubbing seals run on the contacting shaft surface.
Cam Followers 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.
Where high axial loads are anticipated effective axial support of side washers must be achieved by the adjacent machine components.
Cam Followers, type STO . .2Z
STO . .2Z - type Cam Followers are designed similar to the STO - type but have two loose side plates to accept axial forces.
These types of Cam Followers 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 STO . .2Z - type Cam Followers must not have any axial play when they are mounted.
Cam Followers, type NATR
The side washers of NATR - type needle roller Cam Followers are pressed into the inner ring to ensure guidance of the outer ring and the needle roller and cage assembly.
Therefore, these roller types are non - separable. NATR - type needle roller Cam Followers are optimum for applications where the rollers are exposed to high radial loads at high speeds.
The sealed Cam Followers, namely, NATR..PP, which feature integrated rubbing seals on each side of the outer ring are very suitable for operating in harsh conditions (e.g. heavy dust, dirt and other contaminates).
Cam Followers, type NATV
NATV-type rollers are identical to the NATR-type except they have no fitted cage (i.e. full complement type).
This enables an increased numbers of needle rollers to be fitted in the available space (i.e. circumferentially and radially). Therefore, significantly higher load ratings are achieved.
NATV type full complement rollers are unsuitable for high speed applications due to the differing kinematic operating condition. Also they must be re-lubricated more frequently.
For applications of harsh operating conditions the sealed support roller, namely, NATV...PP is also available.
NUTR - type Cam Followers
The base internal design of NUTR - type Cam Followers is similar to that of double row cylindrical roller bearings.
Since the outer ring has two shoulders these Cam Followers are able to accommodate greater thrust loads.
NUTR - type Cam Followers are non - separable.
The separate loose ribs of these types are retained using either cupped washers press-fitted into the outer ring or with lamellar rings which sit in the formed circumferential grooves machined in the loose rib outer diameter.
Both methods also act as a gap seal.
Due to to their full complement design, NUTR - type support roller feature a maximum load rating but they must be more frequently re - lubrication.
For extra heavy duty applications, particularly where heavy shock loads occur NUTR - type Cam Followers are available with an extra - radially thick walled outer ring (see sketch).
NKE's extra heavy duty NUTR - type support rollers with increased outer ring wall thickness are identified by the fact that their nominal diameters are included in their designation.
All NKE support rollers are produced with crowned outer ring diameter as standard they are also available with parallel (cylindrical) outer diameters indicated by the suffix "X", see the relevant designs.
Material of seals
Several types of NKE support rollers, such as series NA22...2RS, NATR .. PP and NATV PP.. are also available in sealed versions.
These support rollers feature contacting seals made from a wear - resistant synthetic rubber compound (NBR) that provides an efficient and effective seal against the penetration of impurities or the escape of grease.
The synthetic rubber used for these contacting seals is satisfactory for operation temperatures of -30deg C up to +120 deg C.
All NKE Support rollers are already supplied filled with a high quality, lithium - soaped bearing grease as standard.
This lubricant is adequate for operating temperatures of -30deg C up to +110 deg C.
Although Cam Followers under normal operating conditions usually run maintenance - free, they may require more frequent re - lubrication under certain unfavourable operating conditions such as heavy dust, high speeds, permanent operating temperatures of more than 70 deg C, and the presence of increased humidity etc.
Therefore a NKE Cam Followers feature a lubrication hole in the inner ring to provide the possibility of re-lubricating the rollers, when necessary.
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