As a general rule, the idler components should be treated as follows :


Seals should be multi labyrinth "non-rubbing" type to prevent ingress of dirt, air and moisture. The outer seal should be corrosion resistant.


All idler rollers should be fitted with precision ball or spherical roller bearings, shafts and housings machined to standard I.S.O. limits. One idler bearing shall be positively locked to the shaft and the other free to float.


Stationery shafts should be used and should be of such dimensions that the vital clearance dimensions at the seal are maintained.


Bearing g and seal assemblies must be factory greased and contain not less than 1 cubic inch of grease for bearing lubrication, i.e.: Sufficient to continually operate idlers for a minimum of six years without attention. Sealed off regressing facilities can be provided.

Rolling resistance

The total resistance of idler rollers at the periphery against rotation should not exceed an average of 130gms for medium duty idlers up to 'C' (153mm) diameter and 250gms for heavy duty idlers up to 'V' (178mm) in diameter.

Weather seal

Fire and oil resistant weather seals are essential to protect the seal assembly from rain and hosing down operations.

Roller shells

Are to be precise tubing selected to high tolerances. Housings and shells will be welded to prevent loosening or misalignment under impact conditions. Rollers shall have a corner radius of not less than (3mm) over a full 90* for belt protection.


The balance of rollers is to be within 1 gm/mm on 'C' and 'V' rollers.

Peripheral run-out

Peripheral run-out is not to exceed 0.6mm total indicator reading on trough idlers, with proportionately Low values for return and other idlers.


All rollers are to be factory test run at no less than a simulated conveyor speed of 7.62m/sec


Idler bases must be of steel construction, accommodation drop-in roller shafts in rattle-free slots. Bases to be free of pockets and should shed spill.