Pallet Chain Conveyor

Overview

A pallet chain conveyor moves loaded pallets by dragging them on two or three strands of heavy roller chain. Where a roller conveyor needs a smooth, flat load base, a chain conveyor grips the rough bottom boards of a wooden or plastic pallet directly, so it handles the heavy, uneven, sometimes wet loads that come off production lines and out of warehouses. It runs slowly and powerfully, carrying a full pallet of well over a tonne, and it is built heavy and anchored to the floor because the drive must overcome that weight and the chains pull hard.

The conveyor is a Frame and Supports carrying a Drag Chain Set that runs over the Shafts and Sprockets and rides on the Wear Strips. A Drive Unit powers the head shaft, Stops and Centering position the pallet at work stations, and the Electrical and Controls panel runs the machine and coordinates it with the equipment around it.

Frame and supports

Because a pallet conveyor carries concentrated heavy loads and reacts a high drive torque, the Frame and Supports is far stiffer than a light-duty bed. Two Side Beam members run the length and carry the chain rails and shaft bearings, tied square by Cross Tie braces. The frame stands on Base Plate feet bolted down with Floor Anchor fixings, because the chain pull and sudden stops would walk an unanchored conveyor across the floor. The whole structure is sized so it does not flex under a pallet, since flex would let the chains run unevenly and wear.

The drag chains

The Drag Chain Set is what actually carries the pallet. Two or three Chain Strand runs of heavy roller chain run the length of the conveyor, spaced to support the pallet under its bottom boards. Each strand is built from Chain Link side plates, Chain Roller rollers that ride the wear strip and engage the sprocket teeth, and hardened Chain Pin pins that take the bearing load. Top Carry Attachment tabs grip the pallet and drag it forward, and a Master Link closes each strand into a loop. Chain Guide rails keep the strands on track. Running on the chain top surface, the pallet is dragged rather than rolled, which is why this conveyor tolerates damaged or irregular pallet bases that a roller conveyor would snag on.

Drive, shafts, and sprockets

The Drive Unit delivers the high torque needed to start a loaded conveyor. A heavy Gearmotor through a helical-bevel reducer turns the drive shaft, joined by a Drive Coupling and held against the reducer reaction by a Torque Arm. The drive turns the Shafts and Sprockets. A Drive Shaft carries the driven Chain Sprocket wheels that pull the chains, and an idle Idle Shaft supports the return sprockets. Both shafts run in Pillow Block bearings bolted to the frame, each a Ball Bearing in a Block Housing sealed against dust. The sprockets set the chain pitch line and must stay aligned so the strands share the load.

Wear strips and tensioning

The chains do not run on the bare frame. They ride on Wear Strips, where a Wear Strip of polymer or hardened steel takes the wear of the loaded chain on the carry run and a Return Strip supports the empty chain underneath. These strips are replaceable, so the chain wears them rather than the frame, and swapping a worn strip is far cheaper than rebuilding the structure. Over time the chains stretch, so a Chain Take-up at the idle shaft pulls the slack out to keep the chains on their sprockets and stop them whipping.

Stops, centering, and station handling

A pallet conveyor rarely runs nonstop; it indexes pallets between stations and must hold them accurately for transfer or robot pickup. The Stops and Centering do this. A Pop-up Stop rises between the chains to catch a pallet, using a Stop Cylinder to lift a Stop Blade and a Shock Absorber to take the impact gently so the load does not jolt. A Centering Unit unit then squares and centers the pallet, and Position Sensor devices confirm it is present and located. This lets the conveyor present a pallet repeatably to a wrapper, labeler, or stacker crane.

Controls, safety, and use

The Electrical and Controls system runs the conveyor from a Control Panel with a VFD that gives a soft start under heavy load and lets the conveyor index precisely. Emergency Stop switches drop power, and the panel interlocks the conveyor with neighbors so pallets pass between machines without collision. Pallet chain conveyors are the standard transport at the heavy end of material handling: end-of-line palletizing, stretch wrapping, transfer to and from automated storage, and movement of full pallets around a plant. They are slower and heavier than roller conveyors, but they carry loads and tolerate pallet conditions that lighter conveyors cannot, which is why they anchor pallet-handling systems.