Underband rollers

Bottom rollers

The "bottom rollers" are the idlers that are installed in the bottom run of the conveyor belt system and carry only the empty conveyor belt. 
Since they are installed in the lower run, they are often also called " Lower run rollers ". Because of the affiliation with a conveyor belt system, all idlers in such a system are often referred to by a collective term " conveyor belt idlers ".

In the bulk material conveyor belt systems, the bottom belt idlers are usually equipped with support rings. Why is it so and why we prefer to use polyurethane for this? - You can find out here.

For detailed information on idler dimensions, please refer to "Dimensions and designs".

Quality classes of lower belt pulleys in comparison

We have defined three quality classes ("Compact", "Compact Plus" and "Premium"), which we recommend as the optimal solution depending on your application-specific case. Each quality class corresponds to the type of operating conditions on site and the requirements placed on the idlers, respectively, also the manufacturing effort.

Quality class
Support roller shell
Pipes	Welded, dimensionally rolled steel pipes according to EN 10305-3	Welded, dimensionally rolled steel pipes according to EN 10305-3; with narrowed tolerances (Küpper standard)	Welded, dimensionally rolled steel pipes according to EN 10305-3; with narrowed tolerances (Küpper standard)
Materials	Steel S235JR according to EN 10025-2	Steel S235JR according to EN 10025-2	Steel S235JR according to EN 10025-2
Bearing housing (roller bottoms)
type	Deep drawn part	Forged part or cast part	forging
Materials	steel DD13 according to EN 10111	steel C15 according to EN 10267-2 or S235JR according to EN 10025-2 or grey cast iron EN-GJL-200 according to EN 1561	steel C15 according to EN 10267-2 or S235JR according to EN 10025-2
Bearing seat	IT7	IT7	IT7
axles
type	full axle	full axle or bending hollow axle	Full axle or rigid hollow axle
Materials	Round steel according to EN 10277	Round steel according to EN 10083-2 / Tube according to EN 10305-3	Round steel according to EN 10083-2 / Tube according to EN 10305-3
Bearing seat	IT9	IT6	IT6
Bearing
Factory	AKT	AKT	AKT
Bearing type	Deep groove ball bearing	Deep groove ball bearing	Deep groove ball bearings
Bearing sizes	6204 - 6306	6306 - 6312	6306 - 6312
Sealing	2Z	2Z	2Z
Bearing air	C4	C4	C4H
Tolerance classes	P0	P0	P5
Cage	Plastic cage	Plastic cage	Plastic cage
Lubrication	50 - 60% of free bearing volume	50 - 60% of free bearing volume	Application specific design
Sealing
type	QLR Hybrid Gasket	QLR Hybrid Gasket	QLR Hybrid Gasket
Running characteristicsSupport rings / lining
type	Support rings	Support rings or 4-fold packages	Molded roller shell
Material	rubber, alternatively PU	PU	PU