I recently was approached for a special application which required damping and/or friction in one rotary direction and close to zero resistance in the opposite direction. It made me realize that I should start highlighting the options available for the rotary viscous dampers and friction hinges. If you look at Rotary Viscous Dampers (RVD) and friction hinges as the core technologies and one way clutches, torsion springs, cams and linkages like four bar linkages as options, you realize the myriad o convenient mechanisms that you can design for your application. For example the lid that lifts easy but stays exactly where you need it can be done by combining a friction hinge with a zero backlash one-way clutch. Pictured above. So there are many engineering situations where we can think of our product as a modular design system which there is a menu of items to choose. If you need some guidance please contact us at www.mmtech.us.