Over Under Conveyor can maximize use of valuable floor space

Over Under Conveyors (sometime abbreviated to Over-N-Under) are making a comeback, with Ultimation engineering a number of new systems recently. This style of conveyor is a derivative of the overhead chain conveyor family, with one unique difference. Over-Under style chain systems have the main product delivery path underneath, and the chain return path overhead. This over-under style therefore has a very compact footprint. Manufacturing engineers like the over under conveyor design because it enables more productive use of all available floor space.

Over and under conveyor

Gravity, powered, or power and free versions of Over and Under Conveyors

Over and under conveyors can be simple gravity feeding systems where parts move under their on weight downhill to an unload station. More sophisticated systems can be motorized with a drive. And if parts are required to automatically stop, start or accumulate in a buffer situation, then power and free technology can be used. Feeding parts into and out of robot weld or assembly cells is a common application for this style of buffer system.

Fast to integrate with 3D design and Webb Unibilt enclosed track components

Each system that Ultimation engineers starts in a ‘virtual assembly plant’ where customers can visualize the new conveyor system as it is designed and developed in 3D CAD technology. Robot load and reach studies are performed using the digital models, and likewise Ultimation’s team checks that any human interface with the conveyors and parts follows all ergonomic guidelines for safety and ease of use.


Many systems use Jervis Webb Unibilt enclosed track conveyor track and components. Ultimation’s engineers will then perform important Finite Element Analysis (FEA) simulations on any overhead structures and complete any electrical engineering of the systems.

“Customers  really appreciate being able to see their new system in a 3D rendering and digital model before it is produced for them” said Ultimation Project Manager, Mike Herzog. “They can look for any issues with nearby equipment, study how their robots or operators will interface with the conveyor, and optimized their floor space much more easily.”

“Once we build the conveyor, it typically requires less adjustment at the final buy-off stage as the customer knows exactly what they will be receiving.”

The over-under style conveyor has been in use for decades. With today’s modern 3D tools, engineering and building them has become much faster and easier, and they are sure to have a bright future.

Over under power and free conveyor

The actual system built for the customer

The Webb Unibilt component set is ideal for these kind of applications as the chain enables tight turns due the unique design of the chain system which incorporates side guide rollers within the chain. Unibilt is available in hand push style, motorized and power and free. It can be installed in an overhead configuration, inverted or in a combination of overhead and inverted as is the case with these over/under systems.

Need help learning about other conveyor types, which types to use and how to specify them? This step by step guide will help.