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Discover how RACO electric actuators are utilized for lock bar systems for bridge construction.
Discover the distinct advantages of RACO Electric Linear Actuators and how they push the boundaries of engineering innovation.
Willis Tower Observation Deck Overview
In January 2009, the Skydeck at the Willis Tower in Chicago was opened to the public after a major renovation. First opened June 22, 1974, the Skydeck still maintains the highest observation deck in the United States, standing at 1,353 feet above ground level.
Located on the tower’s 103rd floor, the observation level can be reached by elevator in about 60 seconds. Once there, the Skydeck offers unobstructed views in every direction. On clear days, tourists can see up to 50 miles away and enjoy Eastern views across Lake Michigan into Indiana or Northern views into Wisconsin.
RACO Electric Actuator’s Function/Role
The innovative Skydeck renovation included the installation of four glass viewing boxes that protruded outside of the buildings profile. This gives people the chance to step into the box, known as The Ledge, and have the ability to look straight down to the street below. These awe inspiring views evoke feelings of both beauty and fear as one stands on nothing more than a sheet of glass.
Each box extends 4.3 feet over Wacker Drive and retracts back into the tower on a trolley system to allow for cleaning or during unsuitable weather conditions. The Ledge consists of six 250-pound glass panels. Each panel is comprised of three layers of 0.5-inch-thick glass that are fully tempered for durability. The glass panels have a laminated smooth finish so they stay together if shattered. The Ledge is suspended from three steel girders above and rolls on two girders below. This near-invisible support system was designed to bear a weight of 5 tons, with minimal use of any structural steel to support the perimeter of the box.
RACO International, LP provided four type T1T4 electric actuators that operate the locking pins which are engaged once the boxes are moved into position. This safety feature ensures that the skyboxes remain locked in place whether they are extended outside of the building or retracted inside.
The variable-frequency-drive actuators have a 7.79-inch stroke and a speed of 0.66 inch per second. They use a digital integrated EPS 06 with 4- to 20-milliamp output signal, and limit detecting capability to ensure repeatable, uniform and precise positioning of the pins. In case of a power loss, each actuator is also equipped with a hand wheel for manual operation. The actuators integrate easily into a PLC and only consume energy during operation, making them environmentally friendly.
