scope:

Description of Driving Event:

The 175-ton and two 250-ton VAB cranes are used to perform solid rocket booster (SRB) stacking, external tank (ET)/SRB mate, and orbiter/ET mate. The 250-ton and 175-ton cranes operate on crane rails 466 feet and 168 feet above the VAB floor, respectively. Crane motions are controlled from the console of the crane cab. The cab is equipped with four master switches which control movement of main and auxiliary hoist load blocks and trolley and bridge travel. The main and auxiliary hoist and trolley and bridge drives are redundant configurations utilizing motor-generator sets that supply energy to the DC final drive motors.