How to Lock and Release the Rok Ratchet Lift Up Support

Commonly used for supporting and adjusting the angle of table tops such as drafting tables and headrests. Ratchets may also be installed at one end to allow for transformation from a bed to a sofa, or can also be fitted on both ends to provide a vertical lift (similar to a hospital bed for back pain). Wherever a tilt-lift is needed, the Rok Ratchet will be your best bet.

Includes upper and lower mounting plate
Allows vertical lift function with multiple adjustment points
12 different settings
Automatically locks lid in place when fully opened
Made of steel with zinc finish
8-1/2" L x 8-1/2" H x 1" W
220 lb. Static load rating
Requires #8 screws (not included)

NOTE:
The range of motion depends on how close they are to the pivot point, but the maximum operating arc is 112 degrees from horizontal. Also, a hinge must be used at the pivot point (not included). We recommend two butt hinges or a piano hinge.

[Thornspyre]

Im planning to make a fold-down table (or fold up, in a canal boat, my idea is that it will be folded down 95% of the time, but i want to be able to lift it up and have it lock in place (without dropping our dinners into our laps) safely
In case im not making it clear this will be fitted to a wall and be folded down most of the time, but will be folded up to use at dinner time etc
 I understand i may have to use 2 of them, as i doubt 1 could take the weight, or simply having a second as a failsafe
Will this work for that, or do i need something else?
Its hard even googling this stuff when youve no idea what a manufacturer may have named it