The overhead trolley conveyor is the workhorse of coating lines and foundries. Knowing its parts helps you specify, compare and maintain one.
In this guide
How an Overhead Trolley Conveyor Works
An overhead trolley conveyor is a chain conveyor whose chain is carried by trolleys running on a track. Attachments below the trolleys hold hooks, load bars or carriers. A drive unit pulls the chain round a closed loop, and a take-up keeps it tensioned as it wears or expands with heat.
Main Components
01Track
Either an I-beam, whose lower flanges carry the trolley wheels, or an enclosed box track with the chain inside. I-beam suits heavy and hot duty; enclosed track suits dusty areas and lighter loads.
02Chain
Drop-forged rivetless chain such as X-348, X-458 or X-678 is standard on I-beam conveyors. It flexes horizontally and vertically and can be taken apart without tools.
03Trolleys and Attachments
Trolleys carry the load on two wheels with sealed or high-temperature bearings. Pendants, hooks and load bars hang below; load bars spread heavy parts over two or more trolleys.
04Drive and Take-Up
A caterpillar or sprocket drive moves the chain, with overload protection. The take-up keeps tension constant; in ovens it must absorb thermal growth.
05Curves and Inclines
Roller turns guide the chain round horizontal bends; vertical curves change elevation. Each curve adds chain pull, so routes with fewer bends need smaller drives.
Where Trolley Conveyors Are Used
- Powder coating and paint lines through pretreatment, booth and oven
- Foundries and forging shops moving hot castings
- Assembly loops with steady flow
- Storage and cooling loops
Limits and How to Overcome Them
All carriers on a trolley conveyor move together. If one station needs more time, the line must slow down for everyone. Where that matters, a power and free conveyor adds a free track so carriers can stop and wait, or an electric monorail gives every carrier its own drive.
