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During the transfer the STS-106 payload to Atlantis on Launch Pad 39-B, a technician turns a switch to move the Payload Ground Handling Mechanism (PGHM). The mechanism is located inside the Payload Changeout Room (PCR) of each shuttle launch pad’s Rotating Service Structure. The PGHM (pronounced pigem) removes payloads from a transportation canister and installs them into the orbiter. It is essentially NASA’s largest fork-lift.