Recreational vehicles seem like an interesting expensive toy to have.  One customization that most have is an LCD or LED monitor to watch cable TV, play games or surf the web. I was designing a system to raise and lower the screen from the ceiling in a motor controlled fashion, this is handy especially if it is a large screen and you don’t want to manually handle the unit.  Using the motor to both raise and lower the screen drains the battery on the vehicle. Manually handling the delicate screens to stow them into the roof can also cause damage.  Going through the details of the design, I realized we could use the motor to raise the monitor to be stowed flush with the ceiling and use gravity along with a rotary viscous danper and friction hinge to lower the unit from the ceiling.  We have saved the vehicles battery by not using the motor to lower the screen. So the sequence is :the dropping is controlled by the RVD and when in the approximate viewing position the friction hinge allows fine manual adjustment to suit the users preferences.  I am sure there are other interesting applications for the rotary viscous damper.  If anyone has specific application they would like to discuss please contact me at