Thursday, February 14, 2008

The Gears that Power the Roosevelt Island Tram

Cool photo of Roosevelt Island Tram gear works. I've noticed on several occasions recently young children staring intently at these Roosevelt Island Tram station gears as they power the Tram on it's journey over the East River. Sometimes the kids even persuade their parents to wait for the next tram so they can watch the moving gears during it's trip to and from Manhattan.

Sometimes the gears fail to move. Here is Popular Mechanics description of the mechanical system failure that caused the April 18-19 2006 failure of the Roosevelt Island Tram.
MECHANICAL SYSTEM: The main drive unit (A) failed when a malfunction in the AC/DC power converter caused three 800-amp fuses to blow. The spring-activated emergency brake on the rim of the main-drive bull wheel (B) prevented the haul rope from moving the cars along the track ropes. The backup diesel hydrostatic drive (C) stalled when it could not release the brake or reach running speed. Ultimately, it was a rescue drive (D) powering a separate haul rope on independent bull wheels that made it possible to retrieve the passengers.