Custom Heavy Duty Gear Drives Bascule Lift Bridge

The Blynman Bridge in Gloucester, Massachusetts recently underwent a major rehabilitation including new gear drives. The bascule lift bridge crosses a small canal that connects the Annisquam River to Gloucester Bay. With over 8,000 openings per year and over 14,000 vehicle crossings per day, this 107-year-old bridge is one of the most active in the East Coast of the USA.

In order to meet the bridge’s heavy-use operation requirements, Nuttall Gear was selected to provide two custom primary drives (one for each bascule leaf). Working closely with the bridge engineering firm, Nuttall engineers were able to provide significant contributions to the drive design concepts during development.

The enclosed parallel-shaft, helical gear drives feature an input rating of 15 HP @ 1,800 RPM, reduction ratio of 50:1 and output torque rating of 40,000 in.lbs.

The custom-designed differential reducers met project requirements including fabricated steel housings, load testing to 150% full load at 100% rated speed, through-hardened gearing, and inspection of all welds by a Certified Weld Inspector (CWI).

Download a PDF of this article