Disc Anti Reversing Device
OVERVIEW The Marley external Disc Anti-Reversing Device (ARD) backstop is a custom designed, welded stainless steel assembly that is bolted directly to a Marley Geareducer® with input shaft diameters from 1.125" up to 2.625". Specifically designed for all right-angle Geareducer models the Disc ARD prevents reverse rotation of the fan, Geareducer and motor and can be field installed.


This anti-reversing device prevents standby fans from reverse rotation when duty fans are operating. It also helps eliminate damaging and costly fan “reverse windmilling.”

Under reverse rotation, the eccentric mass of the Disc ARD pawls extend away from the rotating disc and engages the stop bracket catch point, preventing the mechanical equipment from operating in reverse direction.


Genuine Marley OEM parts are precision-engineered to provide you with a reliable product. While other suppliers may offer parts at an initial savings, you risk lowering performance — and losing FM and CTI ratings. Marley OEM parts provide the durability you can trust because we design and manufacture them exclusively for cooling towers.

With plant operation relying on your cooling tower performance, it’s important to select the parts that are among the highest quality available — Marley OEM parts.

  • Designed for all right-angle Geareducers

  • Welded stainless steel assembly

  • Can be field installed

  • Prevents reverse rotation


Marley Cooling Tower Parts