Pulley Ridge Pulley Ridge Pulley Ridge is a mesophotic coral reef system off the shores of the continental United States. The reef rests on sunken barrier islands and lies 100 miles west of the Tortugas Ecological Reserve and stretches north about 60 miles at depths ranging from 60–80 meters. Pulley Ridge was originally discovered in 1950 during a dredging operation conducted by an academic group from Texas. While well known to fishermen, this remarkable habitat remained undiscovered by scientists until 1999 when the U.S. Geological Survey (USGS) and graduate students from the University of South Florida happened upon it. This reef system,
Elevator poor energy efficiency. Gearless traction machines are low-speed (low-RPM), high-torque electric motors powered either by AC or DC. In this case, the drive sheave is directly attached to the end of the motor. Gearless traction elevators can reach speeds of up to , A brake is mounted between the motor and gearbox or between the motor and drive sheave or at the end of the drive sheave to hold the elevator stationary at a floor. This brake is usually an external drum type and is actuated by spring force and held open electrically; a power failure will cause the brake