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Conveyor belt Load-bearing Idler Set

The Load-Bearing Idler Set (also known as a carrying idler set, troughing idler set, or weight-bearing roller assembly) is the most common and essential component of a belt conveyor system. Installed along the carrying side of the conveyor, these idler sets support the belt and the bulk material being transported, maintaining the proper trough shape while minimizing rolling resistance.

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CHENGGANG

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Product Description

Load-bearing idler sets, also known as troughing idlers, are the primary, structural backbone of any belt conveyor system. Positioned along the conveyor's carrying side, they are responsible for supporting the total weight of both the conveyor belt and the bulk material load, shaping the belt into a trough for greater capacity and stable transport. Their performance is directly linked to the system's efficiency, energy consumption, and operational longevity.

Core Function & Design：

Unlike single return idlers, load-bearing idlers are configured in sets—most commonly 3-roll or 5-roll designs—to create a trough shape. The center roll provides base support, while the inclined wing rolls (at angles of 20°, 35°, or 45°) contain the material and increase cross-sectional load capacity. This design is critical for preventing spillage and maximizing throughput in industries like mining, aggregate, and agriculture.

Key Features & Benefits

Feature	Benefit
Optimized Trough Design	20°, 35°, or 45° angles maximize material capacity while minimizing spillage
Heavy-Duty Steel Frame	Rigid construction maintains roller alignment under full load
Precision-Sealed Bearings	Labyrinth + contact seals prevent dust and moisture ingress
Low Rolling Resistance	Reduces drive motor power requirements and energy costs
Smooth Belt Contact	Precision-ground tube surface minimizes belt abrasion
Interchangeable Design	CEMA / DIN standard dimensions fit existing conveyor structures
Corrosion Protection	Hot-dip galvanized, painted, or stainless steel options
Long Service Life	30,000 – 50,000 hours under normal operating conditions

Available Configurations

Configuration	Trough Angle	Description	Application
20° Troughing Idler	20°	Shallow trough; gentle material containment	Light materials, low belt speeds, fragile products
35° Troughing Idler	35°	Standard industry angle; best balance of capacity and belt life	Most general bulk material handling
45° Troughing Idler	45°	Deep trough; maximum material capacity	High-tonnage conveyors, steep inclines
Variable Trough Idler	Adjustable	Wing rollers can be repositioned to different angles	Test conveyors, custom applications
Flat Load-Bearing Idler	0° (flat)	Single horizontal roller	Flat belt conveyors, light-duty applications

Technical Specifications

Parameter	Standard Range
Belt Width	400 mm – 2400 mm (16" – 96")
Trough Angle	20°, 35°, or 45° (custom angles available)
Roller Diameter	89 mm, 108 mm, 133 mm, 159 mm, 194 mm (3.5" – 7.6")
Roller Wall Thickness	2.5 mm – 5.0 mm (depending on diameter and load)
Shaft Diameter	20 mm – 40 mm (cold-drawn round steel, Grade 45# / C45)
Bearing Type	Deep groove ball bearing (6204, 6205, 6206, 6305, 6306, 6307, 6308)
Bearing Clearance	C3 (standard) for temperature variation
Sealing System	Double labyrinth seal + rubber flinger (dustproof / waterproof)
Grease	Lithium-based grease (NLGI #2)
Frame Material	Heavy-duty steel channel (C-channel or box section)
Frame Thickness	4 mm – 8 mm (depending on load rating)
Mounting	Base plate or channel mount (bolted to conveyor stringer)
Temperature Range	-30°C to +60°C (-22°F to 140°F)

Component Breakdown

Component	Material / Specification	Function
Center Roller	Steel tube, 20° – 45° horizontal orientation	Supports belt center and majority of material load
Left Wing Roller	Steel tube, angled upward (left side)	Forms left side of trough; contains material
Right Wing Roller	Steel tube, angled upward (right side)	Forms right side of trough; contains material
Center Bracket	Fabricated steel plate	Holds center roller; connects to side frames
Side Frames	Steel channel or formed plate	Mount wing rollers; attach to center bracket
Pivot Base (if adjustable)	Steel plate with pivot pin	Allows frame to pivot for belt tracking (self-aligning models)
Mounting Feet	Steel plate with bolt holes	Secures idler set to conveyor stringer
Roller Tube	ERW carbon steel (Q235B or higher)	Direct belt contact surface
Shaft	Cold-drawn round steel (Grade 45# / C45)	Supports roller; transfers load to frame
Bearing	Deep groove ball bearing, C3 clearance	Enables smooth, low-friction rotation
Bearing Housing	Steel casting or precision insert	Holds bearing; pressed into tube ends
Labyrinth Seal	Steel or plastic rings	Prevents dust ingress via tortuous path
Flinger Seal	Rubber	Throws out contaminants; retains grease
End Cap	Steel or plastic	Protects seal from external damage

Trough Angle Comparison

Trough Angle	Material Capacity	Belt Stress	Best Application
20°	Low	Lowest	Fragile materials, low belt speeds, flat conveyors
35°	Medium	Moderate	General purpose; most common angle
45°	High	Higher	High-tonnage, steep inclines, non-abrasive materials

Note: Higher trough angles increase material capacity but also increase belt edge stress. For abrasive materials, a 35° trough is typically recommended.

Load-Bearing vs. Other Idler Types

Feature	Load-Bearing Idler	Impact Idler	Return Idler
Location	Carrying side (full conveyor length)	Loading zones only	Return side
Roller Type	Solid steel tube	Rubber disc or sleeve	Flat or V-return
Impact Resistance	Standard (not for high drop heights)	High (rubber cushioning)	N/A
Self-Cleaning	No	Yes (open disc spacing)	V-return or disc types
Primary Function	Support material load	Absorb impact energy	Support empty belt
Trough Angle	20°, 35°, 45°	20°, 35°, 45°	0° (flat) or 10° (V)

Applications

Industry	Typical Use
Mining	Overland conveyors, underground belt systems, incline conveyors
Aggregates & Quarrying	Crushing/screening plant conveyors, stockpile feed belts
Cement	Raw material feed, clinker conveyors, finished product belts
Power Generation	Coal handling conveyors, ash handling systems
Port & Terminal	Ship loading/unloading, yard conveyors, stacker/reclaimer belts
Bulk Material Handling	Grain, fertilizer, salt, sand, gravel, wood chips, biomass
Steel & Smelting	Ore conveyors, sinter feed, scrap handling
Food Processing	Light-duty stainless steel versions (wash-down capable)

Recommended Idler Spacing

Belt Width	Material Density (light)	Material Density (medium)	Material Density (heavy)
< 800 mm (32")	1.5 m (5 ft)	1.2 m (4 ft)	1.0 m (3.3 ft)
800 – 1200 mm (32-48")	1.5 m (5 ft)	1.2 m (4 ft)	1.0 m (3.3 ft)
1200 – 1600 mm (48-63")	1.2 m (4 ft)	1.0 m (3.3 ft)	0.8 m (2.6 ft)
> 1600 mm (63")	1.2 m (4 ft)	1.0 m (3.3 ft)	0.8 m (2.6 ft)