Track Runner Bearings

Track runner bearings are designed to run on all types of tracks and to be used in cam drivers, conveyor systems, etc. These bearings have a thick-walled outer ring, which enable them to accommodate shock loads, while reducing distortion and bending stresses.

The outer ring running surface is crowned as standard. This is beneficial for applications where angular misalignment relative to the track may occur or where edge stresses need to be minimized. With the exception of single row cam rollers, track runner bearings are also available with a cylindrical (flat) outer ring running surface.

SKF supplies track runner bearings greased, sealed and ready to mount.

SKF supplies track runner bearings in many different types and designs, and for a wide variety of operating conditions and applications. The assortment comprises:

• cam rollers (fig), internal design based on ball bearings
• support rollers (fig), internal design based on needle or cylindrical roller bearings
• cam followers (fig), internal design based on needle or cylindrical roller bearings

Cam rollers

Single row cam rollers SKF single row cam rollers (fig) are based on deep groove ball bearings in the 62 series. They are supplied greased and capped with a sheet steel reinforced acrylonitrile-butadiene rubber (NBR) contact seal on both sides.

Double row cam rollers SKF double row cam rollers (fig) are based on double row angular contact ball bearings in the 32 dimension series and have a 30� contact angle. They are supplied greased and capped with a sheet steel shield on both sides, which extends into a recess on the inner ring.

Lubrication SKF cam rollers are supplied greased. They are filled with the appropriate amount of a high-quality grease under clean conditions. The technical specifications of the grease are listed in the table.

Relubrication requirements Single row cam rollers are greased for the life of the bearing and cannot be relubricated.

Double row cam rollers are also greased for the life of the bearing under normal operating conditions. If subjected to moisture or solid contaminants, or if they run for long periods at temperatures above 70 �C (160 �F) they should be relubricated. When relubricating double row cam rollers, the grease should be applied slowly to avoid damaging the shields. For relubrication, SKF recommends SKF LGMT 3 grease.

Relubrication facilities SKF supplies all inner rings for double row cam rollers with one lubrication hole. If suitable ducts are provided in the pin, the bearings are easy to relubricate.

For additional information about greases, refer to the section Lubrication.

Bearing data

Dimension standards Single row cam rollers:

ISO 15:1998, dimension series 62, except for the outside diameter

Double row cam rollers: ISO 15:1998, dimension series 32, except for the outside diameter

Profile of the outer ring running surface Single row cam rollers:

Radius = 400 mm

Double row cam rollers:

3057.. C design Cylindrical (flat)

3058.. C design Radius = 400 mm

Tolerances Normal, except:

diameter of the crowned running surface: twice the Normal tolerance

Values for Normal tolerance class: ISO 492:2002

Internal clearance Normal

Single row cam rollers:

Values: ISO 5753-1:2009, table

Double row cam rollers:

Values 32 A series: table

Internal clearance values are valid for unmounted rollers under zero measuring load.

Loads

Dynamic loads Compared to a typical rolling bearing, where the outer ring is fully supported in a housing, a cam roller has only a small contact area between its outside diameter and the track. The actual contact area depends on the applied radial load and the profile of the runner surface. The distribution in the bearing, which affects load carrying ability. The basic load ratings listed in the product tables take this into account.

The ability to accommodate dynamic loads depends on the requisite life, but it is also important to consider the strength of the outer ring. Therefore, the value of the maximum permissible dynamic radial load Frmax should not be exceeded.

Static loads The permissible static load for a cam roller is determined by the smaller of the values F0rmax and C0. If requirements for smooth running are below normal, the static load may exceed C0, but should never exceed the maximum permissible static radial load F0rmax.

Axial loads Cam rollers are intended for predominantly radial loads. If an axial load acts on the outer ring, as when the cam roller runs against a guide flange, it will produce a tilting moment and the service life of the cam roller may be reduced as a consequence.

Minimum load Frm = 0,0167 C0

The weight of the components supported by the bearing, together with external loads, generally exceeds the requisite minimum load. If this is not the case, the bearing must be subjected to an additional radial load.

Equivalent dynamic bearing load Single row cam rollers:

P = Fr when Fa/Fr = e

P = 0,56 Fr + Y Fa when Fa/Fr > e

Double row cam rollers:

P = Fr + 0,78 Fa when Fa/Fr = 0,8

P = 0,63 Fr + 1,24 Fa when Fa/Fr > 0,8

Equivalent static bearing load Single row cam rollers:

P0 = 0,6 Fr + 0,5 Fa when P0 = Fr

P0 = Fr when P0 < Fr

Double row cam rollers:

P0 = Fr + 0,66 Fa

where

C0 = basic static load rating [kN]

e = limit for the load ratio depending on the relationship f0 Fa/C0

f0 = calculation factor

Fa = axial load [kN]

Fr = radial load [kN]

Frmax = maximum permissible dynamic radial load [kN]

F0rmax = maximum permissible static radial load [kN]

Frm = minimum radial load [kN]

P = equivalent dynamic bearing load [kN]

P0 = equivalent static bearing load [kN]

Y = calculation factor for the axial load, depending on the relationship f0 Fa/C0

Design of associated components

Pins Cam rollers generally operate under conditions of stationary inner ring load. For this type of load, and if easy displacement of the inner ring is required, the pin or shaft should be machined to tolerance class g6.

For additional information, refer to the section Raceways on shafts and in housings.

Support surfaces Cam rollers that must accommodate heavy axial loads should be supported over the entire inner ring side face (fig) and the support surface should be dimensioned according to diameter d1. The value for the dimension d1 is listed in the product tables.

Guide flanges For rails or cams with guide flanges, the recommended flange height ha (fig) should be:

ha = 0,5 (D – D1)

This helps to avoid damage to the seals or shields fitted in the outer ring. The values for the outer ring diameters D and D1 are listed in the product tables.

Bearing terminology | Y-bearings | Deep groove ball bearings | Needle roller bearings | Combined cylindrical roller/taper roller bearings | Cylindrical roller bearings | Angular contact ball bearings | Combined needle roller bearings | Spherical roller bearings | Tapered roller bearings | Thrust ball bearings | CARB� toroidal roller bearings | Cylindrical roller thrust bearings | Angular contact thrust ball bearings | Tapered roller thrust bearings | Needle roller thrust bearings | Track runner bearings | Spherical roller thrust bearings | Indexing roller units | Backing bearings for cluster mills | Other SKF rolling bearings | Bearing accessories | Engineering products | Mechatronics