Viscous Speed Governor
VSG's Provide Simple and Fast Door Control
The simple, lightweight rugged construction a viscous speed governor (VSG) provides reliable performance for numerous industrial applications. The VSG controls rotation of shafts and hinged loads by using silicone-based viscous shearing technology. An inner rotor is surrounded by silicone fluid within the stationary housing. As the shaft rotates, the inner rotor shears the silicone fluid providing resistance and smooth motion. Fluid viscosity of each VSG is selected after considering variables such as the components size, weight, spring assist and desired cycle time.
Ideally suited for the Rolling Overhead and Fire Door Control
In new and retrofit applications, a single VSG can be installed on rolling doors by simply mounting to the keyed door shaft per the original door manufacturer’s instructions. Unlike noisy ratcheting devices, the VSG requires no adjustments during installation or while in-service and can control the closing and opening speed of most large doors. Multiple governors can be used to handle over-sized doors.
Currently in use by most major door manufacturers, the patented VSG meets industry standards outlined by Underwriters Labratory, Warnock Hersey and Factory Mutual. It has passed the 3-hour fire door burn test and conforms to numerous industry standards.