Mac felt the iron catwalk flexing under his work boots like a springboard.
The noise down here was an animal. It wasn’t the steady, predictable hum of a diesel engine idling at a terminal, or the rhythmic rattle of loose leaf springs on an old crosstown municipal bus. It was the sound of twenty thousand pounds of cast iron hitting structural steel twenty times every single second.
The shockwaves traveled straight up the soles of his work boots, through his knees, and into his jaw.
Mac gripped the hot tubular railing with his bare right hand, feeling the heat radiating off the reduction gearbox ten feet below. His mechanical left arm--fitted with its cast-iron Route 04 fare-box housing--hummed with sympathetic resonance, vibrating like an electric buzzer against his collarbone.
“Look at the main reduction arbor, Julian,” Mac yelled over the mechanical roar. “That’s a twelve-to-one planetary reduction gear set in a four-inch cast-iron tub. The flywheel on the input shaft weighs at least twelve tons.”
“Once twelve tons of iron gets up to three hundred RPM, you couldn’t stop it with a brick wall. The kinetic energy alone would carry it through three city blocks.”
Up on the gantry above Unit 3, Otto Kreutz didn’t bother using a microphone or an acoustic speaker.
