Abstract: The invention herein described is directed to an emergency escape system, such as for use in exiting from a high-rise building. Such system includes a personnel lowering device adapted to be clamped to a vertically mounted I-beam running the full height of the building from which a quick escape is desired. The lowering device, which controls the rate of descent of the user thereof through a contained braking system, includes a (1) spring-biased pivotal clamping mechanism, activated by contact with the outer face of the I-beam, and (2) knurled roller which rolls along said face and drives two drums enclosed in a viscous fluid, such as silicon oil having a viscosity of 300 SSU. As the rate of descent of the lowering device begins to increase through gravity and the weight of the descending personnel, drum RPM increases and fluid shear increases. In a short period of time after the descent begins the fluid shear forces on the roller driven drums are balanced such that the rate of descent is controlled.