Hydraulic Powered Bridge Plate : This design uses a hydraulic cylinder that is installed under the lifts platform to both raise and lower the hinged bridge plate. A dock lift equipped with this feature typically has a 4 button hand held pendant control; dock lift up, dock lift down, bridge plate up, bridge plate down. This option eliminates any physical lifting or lowering of the bridge plate.
This link, Page 7 shows a hydraulic powered bridge plate. View PDF