Altra precision ensures flawless performance in new World Trade Center lifts

One World Trade Center (1 WTC) is the tallest building in a new complex built on the site of the 9/11 attacks in New York City. At 105 storeys and a symbolic 1,776ft high (representing the year of the United States Declaration of Independence), it is also the tallest building in the Western Hemisphere and the fourth tallest building in the world.

As a new, prestigious and very high-profile building, it is one of the most sought-after addresses in the world. Access to the exclusive upper floors is via high-speed lifts, which, travelling at nearly 30ft a second, can transport passengers from ground level to their chosen floor in about 30 seconds. In order to ensure a smooth and reliable ride, components from two of Altra Industrial Motion’s leading power transmission brands, TB Wood’s and Nuttall Gear, have been specified.

The elevator OEM at 1 WTC ordered sheave/shaft assemblies from TB Wood’s for use on both express and service elevators. These were custom-made in fine grain, high-tensile cast iron, and delivered in six sizes from 46in to 62in. They weighed up to 7,000lb, with up to 16 grooves sized to accommodate 1-inch cables. To satisfy the specification requirements the components were delivered with a 40-year, maintenance free operating life.

Nuttall Gear supplied 7in diameter x 23.25in long custom shafts for the sheave assemblies. Special alloy, high-carbon 1045 steel was used to meet performance specifications and finish machining included dual-grease channels and intersecting holes. Along with very precise machining tolerances, shafts were individually balanced, prior to assembly with the sheaves, to ensure high quality performance.

TB Wood’s also provided bearing covers which, together with bearings and seals, completed the assembly components. Once finished, each assembly was balanced prior to shipping. To ensure proper performance, individual assemblies were balanced again after installation in the 1 WTC building.

Nuttall Gear has a long-standing reputation for the design and manufacture of unique, custom-engineered gear drives for parallel, right angle or vertical input shaft arrangements. Its extensive experience with complex precision-machined gearing and shafts was crucial for meeting the close tolerance requirements for the 1 WTC elevator project. Its parent group, Altra, is active in over 70 countries and produces a wide range of mechanical power transmission products, particularly for critical applications. It also supplies a wide range of power and motion components to high-volume manufacturers.