Narrow Belt Sorter

Overview

A narrow belt sorter carries product on a deck of several parallel narrow belts and diverts it with pop-up rollers that rise through the gaps between those belts. Product rides flat across the Narrow Belt Deck until it reaches its assigned Pop-Up Roller Station, where a bank of skewed rollers lifts a few millimetres above the belt plane and pushes the item onto a branch lane. The narrow-belt layout gives a flat, continuous carrying surface that handles small flats, polybags and padded mailers more reliably than wide single-belt or roller sorters, while still moving cartons up to 30 kg.

Narrow belt sortation occupies the band between gentle wheel diverters and high-rate shoe or cross-belt sorters. It is favoured in parcel and e-commerce operations because the closely spaced belts support small and irregular items without letting them dip into gaps, and because the divert is quiet and low-impact. Rates of 80 to 150 cartons per minute per lane are typical, with multiple divert stations along one carry line.

Carrying Deck

The Narrow Belt Deck uses six to ten Narrow Carry Belt runs, each 50 to 75 mm wide, spaced so the divert rollers can rise between them. Each belt slides over a Belt Slider Bed bed that keeps the carrying surface flat and supports the product load. At the discharge end every belt runs over a Belt Tail Pulley. The Side Guide Rail rails square product as it enters so each item arrives at its divert station aligned to the belt direction.

Because the belts are narrow and closely spaced, the gap any single item bridges is small. This is what lets the machine carry document mailers, jiffy bags and small cartons that would dip into the rollers of a roller diverter. The flat plane also keeps labels facing up for the scanner.

Divert Stations

Each Pop-Up Roller Station holds rows of Divert Roller units skewed to the divert angle, mounted in a pivoting Roller Carrier Frame. When the bank is flush, product passes over the rollers on the belts. When the Lift Mechanism raises the carrier 6 to 12 mm, the rollers clear the belt plane and contact the underside of the product. A Roller Drive Belt beneath the bank spins the rollers, so the product is driven off at a vector that combines line speed and divert speed. Keeping the rollers spinning before they touch the load avoids the jolt that a passive divert would impose.

Drive and Divert Drive

The Belt Drive System turns every carry belt from a single lagged Belt Drive Pulley on a common shaft, powered by a Carry Gearmotor of 2.2 to 5.5 kW through a Gearbox Housing. A Belt Take-Up Unit at each end tensions the belts so they track straight and grip the drive pulley.

The diverts have their own Divert Roller Drive. Angled lower belts driven by a Divert Gearmotor and trimmed by a Servo Motor spin the divert rollers only when their station is raised. Independent divert drive lets the divert speed be matched to product type without changing line speed, which matters when the same line sorts both light flats and heavy cartons.

Pneumatics and Lift Timing

The Pneumatic Supply deliver clean dry air at 6 bar through a Filter-Regulator Unit. A Solenoid Valve Bank holds one fast solenoid per station, and local Air Reservoir tanks keep supply pressure steady when several stations fire in a burst. A Pressure Sensor reports pressure to the controller. The Lift Air Bag in each lift inflates to raise the carrier and the Coil Spring returns it flush when the valve exhausts. Fast and repeatable lift timing sets the minimum gap the machine needs between consecutive items.

Controls, Tracking and Scanning

The Control System run on a PLC that tracks each item from scan to divert using a Belt Position Encoder reading belt position. A Variable-Frequency Drive regulates each motor. The Scanner & Sensing Array reads routing barcodes with top and side Barcode Imager units and confirms gaps with Photo-Eye Sensor sensors. A Bare PCB carrying an Microcontroller handles the high-speed sensor interface and feeds tracking events to the PLC, which fires the correct divert solenoid as each item reaches its window.

Structure, Variants and Use

The Structural Frame is welded steel on adjustable legs with Sheet Metal Panel guarding over the drives. Versions differ in belt count, belt spacing and divert angle. Tighter belt spacing handles smaller flats, while wider spacing and stronger lifts handle heavier cartons. Diverts can be left-hand, right-hand or both from one line.

Common uses are e-commerce shipping sortation, parcel induction to chutes, returns grading and routing to packing stations. The narrow-belt format is chosen wherever a mix of small flats and cartons must run on the same line at high rate without items dipping into gaps or labels being scuffed during divert.