Return Idler

Return idler is also know as Bottom idler, as per the drawing and customer requirements, we are manufacturing return idlers.

A return idler’s technical specifications define its design, materials, and performance to support the empty conveyor belt on its return path. Unlike carrying idlers, which support the loaded side, return idlers are designed to handle lighter loads but must be robust enough to withstand the environment and provide long service life.

Key Technical Specifications

1. CEMA Class Rating and Dimensions

Like other conveyor components, return idlers are classified by the Conveyor Equipment Manufacturers Association (CEMA) standards (B, C, D, E, and F). The CEMA class specifies the maximum belt tension and load capacity the idler can handle. For return idlers, this is based on the weight of the belt itself and any minor “carryback” material that adheres to it.

The belt width is a fundamental dimension, as the return idler must span the entire width of the belt to prevent sagging. Common belt widths range from 18 to 96 inches.

2. Construction and Materials

Most return idlers are flat return idlers, consisting of a single steel roller mounted on a frame. This design is simple, effective, and economical. However, other types are available for specific applications:

• Steel Roll: The roll is a simple steel tube. Its thickness is specified to provide the necessary strength without being overly heavy.
• Rubber Disc Return Idler: For applications with sticky or abrasive materials, the steel shell is replaced with a series of rubber or polymer discs. These discs help to clean the belt of “carryback” material and reduce wear.

The shaft diameter is a critical parameter, sized to prevent deflection under the combined tension of the belt and its own weight. It must be compatible with the bearings and the mounting brackets on the frame.

3. Seals and Bearings

The sealing system is arguably the most important component of a return idler. Located on the underside of the conveyor, the idlers are highly susceptible to contamination from dust, moisture, and fine materials. A robust sealing system, often a multi-stage labyrinth seal, is essential to protect the internal bearings and extend the idler’s operational life.

The bearings are typically deep-groove ball bearings, selected based on their load-carrying capacity and rated for a specific service life, often measured in thousands of hours.