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Cam followers series

  • Ohne Exzenter
  • With eccentric

T-axial disc seal (KR...PP)
or
open (KR...)
+ cage

T-axial disc seal (KRE...PP)
or
open (KRE...)
+ cage

T-axial disc seal (KRV...PP)
or
open (KRV...)
full complement

T-axial disc seal (KRVE...PP)
or
open (KRVE...)
full complement

Labyrinth seal (NUKR...)
full complement

Labyrinth seal (NUKRE...)
full complement

Protected lip seal (PWKR...2RS)
full complement
with center flange

Protected lip seal (PWKRE...2RS)
full complement
with center flange

Production options for cam followers

KIS cam followers are based on needle roller or cylindrical roller bearings. Instead of an inner ring, they are fitted with a solid pin that acts as an inner ring replacement and is equipped with a fastening thread. They are available in single-row or double-row designs with needle roller and cage assemblies or full complement rolling elements.

KIS offers various versions based on your requirements. We’re happy to advise you on the optimal solution for your specific needs.

  • Special dimensions

  • Optimised internal design (especially for applications with high radial loads)

  • Application-specific material solutions, surface treatments and coating variants

  • Profiling & tilting

    Profiling & design of the outer ring lateral surface

    Cam followers are characterised by line contact between the rolling elements and the raceway, as well as between the crowned outer ring surface and the counter raceway.

    As a rule, cam followers are shaped in such a way that they make optimum contact with the guide rail. To achieve this, they have a round surface (spherical lateral surface) along their longitudinal axis. This is important as the cam follower and the guide rail are not always perfectly aligned, which can lead to a skewed position. The round shape of the roller distributes the pressure better and there are no sharp pressure points or wear at the edges (edge wear).

    However, this also reduces the contact surface between the roller and the guide rail. To compensate for the resulting higher pressures, the guide rail must be made more stable.

    The KR...PP, KRV...PP, NUKR, NUKRE, PWKR...2RS and PWKRE...2RS series have an optimised crown radius R=500mm as standard. The distribution and the maximum value of the local contact pressures are decisively influenced by the extended modification of different profiling. With lower degrees of profiling, the pressure distribution is more even, but this results in increased edge stresses, particularly at higher angles of inclination.

    Application-specific advantages include the following:
    • Avoidance of edge wear, especially with tilting

    • Reduction of the Hertzian pressure

    • Higher nominal service life of outer ring and counter raceway

    • Reduced wear and reduced pitting in the tribological system

    • Ratio of acting load and radial deflection (stiffness) is positively influenced

    • Significantly lower friction coefficient at low and high relative speeds

    • Faster transition to the area of fluid friction to achieve maximum service life

    • If required, our cam followers can also be produced with a cylindrical lateral surface, e.g. for applications that require high rigidity and where there are no errors in terms of skewing and tilting.

      Profilierung Verkippung

      Generation of axial loads

      In the case of cam followers with a cylindrical outer ring, particularly high edge stresses occur between the outer ring and the mating track in the event of tilted running. Due to the rolling elements with line contact (needles or cylinders), cam followers are generally less able to absorb the axial forces resulting from this positioning error than, for example, track rollers with balls. A spherical or crowned outer ring profile reduces the sensitivity.

      The following guide values can be regarded as the limit of the tilt angle:

      Cylindrical profile <= 0.1°
      Spherical profile <= 0.25°

      In the illustration, the axis of the bolt is inclined in relation to the raceway. The amount of axial load is a function of the angle of inclination and is generally low. At best, the outer ring rests on the raceway over its entire length. Slight misalignment can occur with an inclined pin axis as long as the angle is within the bearing clearance. Excessive misalignment can be seen on the contact surface of the outer ring after a short period of operation. This condition leads to an internal roller pressure load, which can be compensated for by using a crowned outer ring. As cam followers are self-supporting devices, misalignment also occurs if the pin deflects under load. Misalignment is unavoidable in this case and shortens the service life of cam followers and impairs their sealing ability. KIS cam followers have been further developed to optimize this condition. They have greater roller end support and can better absorb the resulting axial forces and significantly increase the service life.

      Lubrication

      Two tribological systems and therefore two contact conditions must always be determined separately:

      • The rolling elements and the rolling element raceway
      • The outer race and the counter race

      Cam followers have relubrication options via the pin of the bearing, depending on the design. In series with an eccentric, the eccentric ring covers the radial lubrication hole of the pin. For this reason, relubrication must be carried out via the end faces.

      The following conditions influence the relubrication cycles:

      • Loads
      • speeds
      • frequency of direction changes
      • Contamination or cleanliness of the environment
      • Temperatures (from 70°C shorter relubrication cycles)
      • Internal geometry
      • Cage or full complement or needle roller (à shorter relubrication cycles)

      The maximum amount of grease that a bearing can accommodate is a function of the free space available inside the bearing. This means that it is the volume that is created between the outer rolling element raceway and the inner rolling element raceway, minus the volume of the rolling elements and the additional space that may be available due to sealing concepts, two rolling element raceways, etc. Ideally, relubrication should be carried out regularly, even if the initial filling still has full lubricating properties.

      In cam followers with needles the large number of needles takes up most of the available space, leaving little room for the lubricant. It primarily fills the cavity between neighbouring rolling elements and the inner or outer raceway. The main cause of premature wear is a lack of lubricant. The greater the grease filling, the longer the product will last in most common applications. Excess grease is carried to the outside as a protective function by centrifugal force and with the help of the sealing lip structure (incl. groove geometry).

      In cam rollers with cylinders as rolling elements, the cavities between the rollers and the raceways are larger, although there are fewer of them. However, there is additional space for lubricant in the area between the roller pairs and between the rollers and seals. As a result, there is up to four times more grease in cam rollers of the same size than in cam rollers with needles.

      For KIS cam followers, an EP-additivated, fully synthetic high-performance grease (consistency class NLGI 2) is used as standard, which has been specially developed for use in applications subject to high radial loads (even in highly oscillating operation). It combines the advantages of a synthetic base oil and a special lithium complex thickener with those of a state-of-the-art additive package.

      It is an excellent choice due to its wide temperature range, high mechanical stability and exceptional load-bearing capacity. The effort required for a reliable grease supply is significantly reduced by using this product. The lubricant can be used with grease guns, automatic relubrication systems and centralised lubrication systems.

      All lubricants suitable for rolling bearing lubrication can be used to lubricate the counter raceway. However, there are also applications in which the counter raceway must remain unlubricated. If lubrication is not possible, wear must be expected, particularly under high loads and high reciprocal speeds. In these cases, please contact our technical support team.

      Relubrication cycles can only be determined under operating conditions. At the latest, however, when the first traces of tribocorrosion can be recognised in the tribological system.

      Sealing variants and axial guidance of the outer ring

      Our product portfolio includes open and double-sided sealed variants. Depending on the series, low-contact T-axial disc seals or contacting labyrinth seals and protected lip seals seal the inner system.

      Properties of the sealing variants:

      Seals protect the tribological system of the bearings against loss of lubricant, prevent the ingress of contaminants and guarantee relatively low-friction operation.

      There are further design differences between cam followers with cylinders and needles as rolling elements. One of the most important is the axial guidance of the outer ring. The outer ring is guided between the two flanges and rubs against one or both flanges under axial load. To prevent direct metal contact between the outer ring surfaces and the retaining flanges of the bolt and the end disc, the T-axial disc seal usually has a radial extension that extends into the gap between the outer ring and the flange or end disc. The radial extension thus acts as a plastic thrust washer. In order to fulfil this function, the seal material must have good load absorption and be rigid enough for the application.

      These requirements demand material properties that are in contrast to conventional sealing materials, which focus on the flexibility and bending of the sealing lips. Consequently, the T-axial disc seals are gap seals that rely on a lubricant barrier as a sealing function and therefore on relubrication. During running-in, the centrifugal force causes excess grease to enter the gap seals. At a constant speed, this inflow stops until the next relubrication cycle.

      However, it is important to ensure that the axial loads on the radial extension of the T-axial disc seal are not too high in order to avoid steel-on-steel contact, where abrasive and/or adhesive wear on the contact surfaces would have a negative impact on the service life. In the case of cylinders as rolling elements, the end faces act as a guide for the outer ring. Although this is again a steel-on-steel sliding contact with comparable loads, this condition is optimised by the simpler lubrication conditions. The rolling movement of the cylinders transports new lubricant into the contact area with each revolution. The shoulders with the undercuts at both ends of the outer ring prevent lubricant leakage with the lip seals.

      Cam follower

      Seal

      KR

      Open version

      KR..-PP

      T-axial disc seal on both sides

      KRE..-PP

      T-axial disc seal on both sides

      KRV..-PP

      T-axial disc seal on both sides

      NUKR

      Labyrinth seal on both sides

      NUKRE

      Labyrinth seal on both sides

      PWKR..-2RS

      Protected lip seal on both sides

      PWKRE..-2RS

      Protected lip seal on both sides

      Rotational speeds

      The permissible speeds specified on the data sheets are empirical values. They are not generally exact values and can deviate upwards or downwards depending on the operating conditions of the rotary solution under real conditions and can therefore be modified.

      As the speed increases, the bearing temperature also rises due to the heat generated at the contact surfaces between the cage, raceways and rolling elements, which can ultimately lead to increased wear in the tribological system. It is therefore necessary to keep the speed of a bearing below a certain limit value in order to ensure safe operation over a long period of time. As the heat generated is roughly proportional to the sliding speed at the contact surface, this sliding speed is an indicator that indicates the limit of the permissible speed.

      • Speed limits (including the associated permissible operating temperature) depend largely, but not exclusively, on the following factors:
      • Rolling element guidance (especially when entering the load zone)
      • Lubrication
      • Bearing type
      • Main loads
      • Cooling conditions
      • Sealing
      • Intermittent or continuous operation
      • Radial clearance
      • Counter raceway (incl. lubrication)

      Face guidance requires a length-to-diameter ratio of the rolling elements of 2.8 or less in order to guarantee optimised alignment when entering the load zone. Needles, on the other hand, have a much larger ratio and can neither be guided on the end face nor absorb axial loads. They rely on the crowned outer ring surface to correct misalignment. This means that cam rollers with cylinders as rolling elements can operate in higher speed ranges and needles exhibit small misalignments when entering the load zone, which leads to sliding movements and promotes heat generation.

      The permissible speeds stated on the data sheets are empirical values. They are not generally exact values and may deviate upwards or downwards depending on the operating conditions and application of the rotary solution under real conditions and may therefore be modified.

      The speeds must be reduced or determined more precisely for

      • Loads > 0.05 * C0r w
      • Bearing variants with needles as rolling elements
      • Difficult lubrication conditions (incl. counter raceway)
      • High sealing requirements (higher contact friction)
      • Tight radial internal clearance tolerances
      • Additional axial loads
      • Insufficient heat dissipation
      • Need for a high-viscosity lubricant

      Oil-lubricated cam followers can generally be operated at a 50% higher speed than grease-lubricated solutions, whereby the rolling element guidance has a much greater influence on the maximum speed. Intermittent operation can also further increase this value.

      In the case of a sealed cam roller with cylinders, the speed is limited by the maximum permissible surface speed of the seal.

      Cage-guided (usually plastic) rolling elements also reduce internal friction and offer a larger lubricant reservoir than full complement (needle roller) variants. However, lower load ratings must now be taken into account, as fewer and shorter rolling elements are used due to the cage volume.

      Temperature ranges

      The maximum values shown in the following table are only permissible for short periods. If the values are permanently elevated, an application-specific analysis is essential.

      Operating temperature

      Open or with labyrinth seal from °C

      up to °C

      With protected lip seal from °C

      up to °C

      With plastic cage from °C

      up to °C

      T-axial disc seal from °C

      up to °C

      Operating temperature

      -30

      +140

      -30

      +120

      -30

      +120

      -30

      +100

      Dimensions & tolerances

      The dimensional and running tolerances correspond to the tolerance class Normal according to ISO 492, for KR, KRE and KRV according to ISO 7063.

      Possible deviations from ISO 492 can be found in the individual technical KIS data sheets.

      Tolerances for coated bearings

      For coated cam followers, the tolerances are increased by the thickness of the special coating selected.

      kis-dimension-tolerance

      Bearing clearance

      Cam followers are designed with a tighter radial clearance in order to extend the load zone. The standard is approximately C2 (Group 2) or CN.

      The radial internal clearance values correspond to DIN 620-4:2004 (ISO 5753-1:2009) and apply to cam followers in an unloaded, force-free state (without elastic deformation)

      Radial internal clearance for support rollers and cam followers

      Nominal diameter of the bore
      d
      mm
      over

      Up to

      Radial internal clearance
      C2 (Group 2)
      µm
      min.

      max.

      C3 (Group 3)
      µm
      min.

      max.

      C4 (Group 4)
      µm
      min.

      -

      Wert

      Wert

      Wert

      20

      45

      35

      60

      50

      75

      24

      30

      0

      25

      20

      45

      35

      60

      50

      75

      30

      40

      5

      30

      25

      50

      45

      70

      60

      85

      40

      50

      5

      35

      30

      60

      50

      80

      70

      100

      50

      65

      10

      40

      40

      70

      60

      90

      80

      110

      65

      80

      10

      45

      40

      75

      65

      100

      90

      125

      80

      100

      15

      50

      50

      85

      75

      110

      105

      140

      100

      120

      15

      55

      50

      90

      85

      125

      125

      165

      120

      140

      15

      60

      60

      105

      100

      145

      145

      190

      Dimensioning

      Possible methods for calculating the rating life are the nominal and modified nominal rating life calculation in accordance with DIN ISO 281 and the extended calculation of the modified reference rating life in accordance with DIN ISO 281-4.

      The basic rating life is the number of revolutions reached or exceeded by 90 % of a sufficiently large number of identical bearings at constant load and speed before the first signs of material fatigue occur.

      These methods are described under load-bearing capacity and service life. For support and

      cam rollers, the following values are used:

      • for Cr the effective dynamic load rating Cr w
      • for C0r the effective basic static load rating C0r w
      • for Cur the effective fatigue limit load Cur w

      The service life is the service life actually achieved by a support roller, cam roller or track roller and can deviate significantly from the calculated nominal service life.

      Deviations between the nominal service life and the service life are due to wear or fatigue:

      • misalignment between the track roller and the mating track
      • deviating operating data
      • Too small or too high operating clearance
      • Very high impact loads, static overload
      • Contamination of the track roller
      • Operating temperature too high
      • Insufficient lubrication
      • Oscillating bearing movement with very small swivel angles that cause rippling
      • Wear between the outer ring shell surface and the counter raceway
      • Vibration stress and ripple formation
      • Preliminary damage during assembly

      Due to the variety of installation and operating conditions, the service life cannot be calculated exactly in advance and can be estimated most reliably by comparison with similar installation cases.

      Connecting structure for cam followers

      Bore tolerance H7: results in a clearance fit, as the tolerance of the shaft diameter without eccentric is h7, with eccentric h9

      • Insertion chamfer on the mounting hole: maximum 0.5x45°
      • The contact surfaces for the cam rollers must be flat, at right angles and sufficiently high. The strength of the nut contact surface must be sufficiently high.
      • Cam followers must be secured axially with a hexagon nut. These are not included in the standard scope of delivery and must be ordered separately or noted on the respective data sheet. The strength and roughness of the nut contact surface must be selected so that settling effects do not lead to a loss of preload force.
      • For highly loaded applications or strong vibrations, special fastening variants (e.g. self-locking nuts) or an interference fit with bolt diameter h7 must be selected.
      • The position of the radial lubrication hole is marked on the face of the roller journal. It must not be located in the loaded zone and should not be positioned 180° from the most heavily loaded zone in order to ensure a sufficient supply of lubricant.

      Assembly

      Great care must be taken when installing cam rollers to ensure trouble-free running:

      • Cam followers must be protected from dust, dirt and moisture. Contamination can lead to increased wear and premature failure
      • Do not overcool cam rollers. Condensation may lead to corrosion in the bearings and bearing seats
      • Keep the assembly area dust-free and clean
      • Check the axle seat for dimensional, shape and positional accuracy and cleanliness
      • Lightly oil the seating surfaces of the bearing rings or rub in solid lubricant
      • Apply lubricant to the bearings after installation
      • Final functional check of the bearing

      Depending on the application, the following tools are suitable:

      • Induction heating devices in compliance with the manufacturer's instructions regarding seal and lubricant
      • Heating cabinets with heating up to +80 °C
      • Mechanical or hydraulic presses: Use mounting sleeves that are in contact with the entire circumference of the bearing ring end faces
      • Hammers and mounting sleeves: Apply blows centred on the sleeve

      Cam followers with eccentrics allow the fitter to adjust the radial position of the bearing relative to its carrier housing. This is particularly useful when several cam roller bearings are carrying a load and inaccuracies during assembly prevent the standard bearings from distributing the load evenly. Eccentric adjustment can also reduce wear on raceways.

      • Do not transfer installation forces via the rolling elements
      • Do not damage seals
      • No impacts on the bearing rings


      The removal option should already be taken into account when designing the bearing position. For reuse:

      • Avoid direct impacts on the bearing rings
      • Avoid dismounting forces via the rolling elements
      • Only clean bearings when they have been removed
      • No hard flame


      • If possible, fit the cam followers using an assembly press as shown in the illustration
      • Do not hit the thrust collar of the roller stud
      • The lubrication hole must not be located in the loaded zone and is labeled on the collar side of the roller stud.

      • Fit the grease nipple before fitting the bearings
      • Drive-in grease nipples are supplied with the cam followers. These must be pressed in correctly before fitting the bearings. Only the enclosed grease nipples may be used.
      • For lubricating the cam rollers with the central lubrication adapter.
      • If lubrication is applied via the locating bore, the axial lubrication holes in the cam roller must be sealed with the grease nipples before installation.

      Cam followers must be secured axially with a hexagon nut. The slot or hexagon at the end of the roller pin allows the bearing to be fixed with a spanner when the fixing nut is tightened and the eccentric adjusted. Special locking washers or self-locking nuts to DIN 985 can also be used in the event of strong vibrations.

      Axial mounting, important to note:

      The tightening torque of the fastening nuts must be adhered to in order to ensure the permissible radial load. If it cannot be maintained, an interference fit is required. In the case of self-locking nuts, an increased tightening torque and the nut manufacturer's instructions must be observed.

      The highest point of the eccentric is marked on the roller journal side, where the radial lubrication hole is also located.

      • Cam followers each have a lubrication hole for relubrication:
      • on the collar side of the roller journal
      • on the end face on the thread side, from an outside diameter of 22 mm
      • on the shaft of the roller stud, from outer diameter 30 mm with additional lubrication groove

      Commissioning and relubrication, important to note:

      • Cam followers with an eccentric cannot be relubricated via the shaft, as the eccentric ring covers the lubrication hole.
      • For lubrication, only use grease guns with needle point nozzles that have an opening angle of 60°.
      • Before commissioning the lubrication holes and supply lines, they must be filled with grease to prevent corrosion, and lubrication can be carried out at the same time.
      • Lubrication is made more difficult if a rolling element is positioned above the radial lubrication hole. For this reason, relubrication must be carried out when the bearing is at operating temperature and rotating, as well as before standstill and before longer interruptions in operation.
      • The same lubricant must be used for relubrication as for the initial lubrication. If this is not possible, the miscibility and compatibility of the lubricants must be checked. Relubrication is carried out until a fresh grease collar forms at the sealing gaps. The old lubricant must be able to escape from the bearing unhindered.

      Do you have any further questions?
      Please contact us.