Light in a dark time
World Trade Center backup generators crafted in Waukesha

By Brandon Anderegg

Sept. 11, 2019

 Waukesha engine L5792DSI was recovered from the World Trade Center and now sits in the Waukesha Engine Historical Society.
Courtesy of the Waukesha Engine Historical Society

WAUKESHA — When the World Trade Center was attacked on 9/11, five Waukesha V12 diesel generating units kicked on in an attempt to supply emergency power to the collapsing towers.

A total of six engines and generators, all of which were assembled in the Waukesha Engine Factory, were located in sub-basement 6, which was the lowest level on the west side of Tower One, according to the Waukesha Engine Historical Society website.

Early videos of the attack suggest the engines and generators may have only run for a brief period since lights were on in parts of the building and complex as the towers started to come down, according to the WEHS website.

The engines weigh a whopping 15 tons each, measuring 18 feet long by eight feet high and eight feet wide. Five of them were shipped to New York during the construction of the WTC in the early 1970s while a sixth was added later on.

As the towers collapsed, a set of Waukesha engines and generators came online at the Federal Reserve Bank, which is just blocks away from the WTC. Four Waukesha diesel engine generator packages for emergency and standby power activated due to the disruption of the area’s power grid on 9/11.

These engines became the primary power supplier for the next two weeks while a loyal crew stayed with the engines 24/7, according to the WEHS website.

On February 26, 1993, a bomb planted by terrorists exploded in the underground garage of the north tower. Following the bombing, the units ran for 3 hours and 10 seconds before the generator room started to fill up with water from broken piping, according to the WEHS website.

After the water rose to the crankshaft centerline area, the engines were manually switched off. Distributor personnel stayed with the engines until the water level was too high and then felt their way to the exit in total darkness, according to the WEHS website.

Of the six engines, three were declared unsalvageable and immediately scrapped, said Dennis Tollefson, WEHS Board member. Two are being rebuilt while the sixth engine is held at the Waukesha Engine Historic Society, Tollefson added.

Unfortunately, the engine is not available to the public due to its sheer size, Tollefson said. However, the engine has made an appearance over the years at events such as Waukesha’s Fourth of July Parade and Veterans Day Parade. The engine was also on display at the Memorial Center in downtown Milwaukee.

To read more about the Waukesha Engine Historical Society, visit