Watching a new guy—a "greenhorn"—try to run a tamping rammer machine for the first time is a lesson in biomechanics. The natural human instinct when holding a machine that kicks like a mule is to muscle it. They grip the handlebars with a "death grip," lock their elbows, and try to force the machine down into the dirt. Within fifteen minutes, their forearms are completely pumped out, their lower back is in spasms, and the machine is bouncing erratically out of the trench.
I spend a lot of time retraining this instinct. I teach my crews the "fingertip method." A properly balanced jumping jack is designed to advance itself forward by a few millimeters with every jump. You do not push it down; you simply balance it. I instruct operators to keep a loose, relaxed grip on the isolated handles, keeping their elbows bent and letting their knees act as a secondary suspension system. You use your body weight simply to pivot the machine slightly left or right to guide its path. The goal is to separate your skeleton from the harmonic resonance of the machine. When an operator finally understands this, the job shifts from a brutal wrestling match to a rhythmic, walking dance. The machine does the work; the operator just provides the steering wheel.
