High quality bulk material rolls

High-quality idlers for bulk material conveyors - the most important quality features

How can you recognize the quality of an idler for bulk material conveyors? High-quality bulk material rollers can be recognized by certain features. The most important feature always remains their long trouble-free service life. In this context, good idlers must always have the lowest possible running resistance, good concentricity and imbalance characteristics, and low noise emissions.

As the topic is not new at all, most parameters as well as the corresponding test methods are already established and standardized. The most important standards to be mentioned here are DIN 22112 and DIN 15207.

We have summarized the most important parameters in a table for you.


Target values

Dimensional accuracy

According to DIN 22112 as well as DIN 15207

Axial displaceability (axial clearance)

According to DIN 22112-2. 
If the axial clearance is too small, the idler will wear prematurely and may even jam. 
If the axial clearance is too large, collisions may occur, for example, with the supporting steel structures.

Bearing clearance and tolerance class of bearings

For deep groove ball bearings: C4 and P0 according to DIN 22112-2


For deep groove ball bearings: Plastic cage according to DIN 22112-2

Bearing seat fits

According to DIN 22112-2

Bearing seals

We use Z-washers on both sides.

Expression resistance

>12kN (according to DIN 22112-2)

Rotary runout
(engl. Total Indicated Runout)

Max. permissible tolerances according to DIN 22112-2. The most stringent requirement here is the equivalent of 0.8mm/m.
Depending on the design, our rollers adhere to 0.7mm/m to ≤0.2mm/m. So we always meet the requirement of DIN 22112-2.

(Effectiveness of seals)

Our seals exceed the requirements of DIN 22112-3 and all other standards.

(Grease properties and quantity)

50 - 60% of the free bearing volume must be filled with lithium saponified grease.

Running resistance (running frictional force) - during start-up and operation

It should be as low as possible, as it has a direct influence on wear of the idlers and belt as well as on the energy requirement of the conveyor system. For bearings up to 6306, see DIN 22112-2. It depends on the diameter of the idler and the bearing size. A value of 10N must not be exceeded in any case.

Balance quality

Our idlers have, depending on the design, the balance quality classes according to ISO 1940 of at least ≤G40 at belt speeds up to 3m/s to ≤G14 at belt speeds up to 10m/s.

Maintenance of the max. permissible bearing misalignment*

Under full load, the bearing misalignment for deep groove ball bearings should not exceed 10 arc minutes (see DIN 22112-2). For spherical roller bearings, up to 2° is permissible.

Calculated bearing life*

We recommend L10 > 60,000h.

Noise emissions

If relevant, the max. sound power level of the idlers must also be considered (see "TA Lärm"). 
Only in the case of operation exclusively during the day at >1km distance to the residential area, no special measures are required - standard rollers can be used.

With our noise-reduced idlerswe achieve a reduction of the sound power level by about 20 dB(A).

* Computational verification of suitability for operation in the concrete conveyor systems.

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