An Automatic Hydraulic Roll off Stop is designed to prevent a lift truck from accidentally driving off a dock lift platform when the platform is in the raised position.
An Automatic Hydraulic Roll off Stop is a hydraulic operated hinged barrier that is installed on the end of the dock lift platform opposite to the end of the platform that the truck is loaded/unloaded. With the dock lift in the fully lowered position the Automatic Hydraulic Roll off Stop is at rest in the lowered, level position.
The lift truck drives across the level Automatic Hydraulic Roll off Stop onto the lowered platform of the dock lift. As soon as the dock attendant activates the dock lift up button a hydraulic cylinder automatically powers the Roll off Stop hinged barrier upward into the almost vertical position behind the lift truck on the dock lift platform, creating the barrier.
This link leads to a photograph (shown in orange) of an Automatic Hydraulic Roll off Stop https://www.pentalift.com/solutions/automatic-hydraulic-roll-off-stop/
The hinged barrier design prevents the lift truck from accidentally driving off the back of the dock lift platform when the platform is in any raised position. The Roll Off Stop also prevents the lift truck from driving off the back of  the platform in the raised position due to slippery or icy conditions on the platform or if the lift truck experiences brake failure. The Roll off Stop does not prevent fork lift run off on the end of the platform opposite to the end it is installed on.
Only when the dock lift platform is returned to the fully lowered position does the Roll off Stop automatically lower and return to the level position. Roll off Stop cylinder is simply teed into the hydraulic lines feeding the lift cylinder of the dock lift. With the dock lift in the fully lowered position and the Roll off Stop lowered into the level position the lift truck can now safely drive off the dock lift platform.
For information on any Pentalift product please contact the Pentalift Sales Department.