Types of overhead conveyors
Types of overhead conveyors. Enclosed track vs. open track overhead conveyor.
Overhead conveyor track cross-sections. Powered vs. free overhead conveyors.
Free or “trolley” overhead conveyor versus a powered overhead conveyor. Synchronous vs. asynchronous overhead conveyors.
Types of overhead conveyors
There are no set “types” of overhead conveyors, as they are often built to address specific needs. As a result, this section will explore the broad categories of overhead conveyor features that differentiate one system from the next. This list is not exhaustive but should cover the primary types of overhead conveyors that are usually seen in plants and should help the reader choose what works best, if interested. Know that any given overhead conveyor exhibits some mix of these traits, so you can understand the huge variety in buyer options.
The first major distinction between overhead conveyors is their type of track. Overhead conveyor chains can be completely enclosed, or an open monorail. Enclosed tracks are less susceptible to environmental decay, especially in applications such as painting where overspray can damage the chain over time. Conversely, open track conveyors are easier to install, taking a more typical I-beam form and opting for trollies instead of a chain, and are generally simpler. Enclosed track overhead conveyors will prevent excess damage, but open track conveyors can hold more weight per carrier, so the choice is ultimately dependent on the characteristics of the conveyed items. Also, open track models are typically only found in straight runs, while enclosed tracks are more suited towards applications that require bends in the conveyor path.
Powered vs. free overhead conveyors
Overhead conveyors can be free to move or can be powered via a motor, depending upon the needs of the project. Free overhead conveyors are moved with user pushing/pulling and are an effective, economical option. Powered overhead conveyors are more often chosen however, as they require no manual labor, can be automated and speed controlled, and are a more organized conveying method. Free overhead conveyors cost nothing to run, but the energy efficiency of powered conveyors is quite impressive. The drives which are used in powered overhead conveyors are typically fractional horsepower motors, which means their energy demand is low, if not negligible. Usually, buyers choose powered models for their increased capacity and ease of use, but free overhead conveyors are great for moving large, heavy materials by hand for detailed work.
Synchronous vs. asynchronous overhead conveyors
Finally, the last designation between overhead conveyors is how items interact during conveying. Synchronous overhead conveyors ensure that the system is non-accumulating, meaning that each item is equally spaced and moves at the exact same time, in “synchronous” movements. This arrangement also means that every item starts and stops together, which allows operators to have command over the whole assembly process via its drive control. In contrast, asynchronous models allow for each item to move independently of the others, and are typically unpowered (though, exceptions exist). There is a newer form of “power and free” overhead conveyors, which exhibit traits of both synchronous and asynchronous conveyors, but note that these are generally more expensive and used for high volume assembly line work.