Features/Benefits Provided: Flux Vector Variable Frequency Drives Precision Lifts & 4 Pick Points Two Five Ton Auxiliary Monorail Trolleys Remote Controlled

The bridge crane designed and built by North American Industries (NAI) is entrusted to lift $35 million dollar prototype engines at a jet engine test facility. The crane lifts the engines into special engine stands which enable engineers and technicians to work on them and make the necessary developmental changes. NAI built the double girder bridge crane, with an 87’ span riding on a 90’ runway. Due to the weight, size, and unequal weight distribution of the loads, a precise four-point lift is required; therefore, the crane has four remote controlled 15 ton wire rope hoists.

The hoists are mounted on one trolley with four pick points which can lift the jet engines up to 26ft 2in above the ground. Flux vector variable frequency drives are used to monitor the position and speed of each hoist and to control the hoists for precision lifting. Hooks have to be positioned to within one eighth of an inch. Attached to each hook block, the hoists also have an adjustable turnbuckle (a metal device that can be adjusted for length or tension) capable of plus or minus two inches of adjustment.

When the jet engines are lifted up to the test facility, the turnbuckles can be adjusted manually to ensure the precision necessary to connect them to the stand. The crane also has two 5 ton auxiliary monorail trolleys which ride on the bottom flange of each cross girder, used for handling smaller equipment mounted to the engine, such as intakes and instrumentation.

When the engines need to be fired up and run for testing purposes, they are transported several hundred yards from the facility and mounted to a test tower, which incorporates additional lifting equipment supplied by NAI in the form of jib cranes. Once mounted, the engines are run to test the changes made by the engineers.

Proud Member of the Crane Manufacturers Association of America


80 Holton St.
Woburn, MA, 01801
Phone: (800)847-8470 or (781)897-4100 Fax: (781)729-3343
info@naicranes.com
www.naicranes.com