The sound of iron wheels biting into cold cast-iron rails was a sharp, ringing music that cut through the thunder of the Diverter like the strike of an anvil.
With four massive high-pressure screw-jacks running all at once, Master Gault’s wagon drivers had lifted the fifty-ton hard dark metal-steel gate clear of the oak logging sleds. Inch by inch, the heavy timber launching carriage was skidded sideways until its sixteen flanged iron wheels lined up perfectly with the twin tramway tracks embedded in the granite crest.
The tracks had been laid eighty years ago to carry heavy check cranes along the two-mile length of the dam. The rails were heavy sixty-pound bridge steel, mounted on white oak sleepers that had been preserved in hot coal-tar creosote.
The full fifty-ton mass was lowered onto the iron rails. Then, the sleepers groaned, squeezing drops of black creosote from their pores. But the steel held. The flanged wheels seated into the rail heads with a heavy, metal CLACK.
Suddenly, the physical nature of the haul changed fully.
On the crushed shale and mud of the haul-road, static friction had been an enemy that needed three hundred men to overcome. Here, on level iron tracks lubricated by freezing rain, friction virtually vanished. The rolling pushback of fifty tons on steel wheels was less than two thousand pounds.
