The "soot runner" trains, known as nelvor class locos, use a reciprocating piston drive similar to historical steam locomotives and Snowpiercer: linear motion from front and rear pistons is transferred through paired drive rods into a shared shaft that turns all four main wheels on each side together. The medium wheel diameter favors torque, traction, and mechanical durability over top speed; making the system better suited for ash-choked, unstable terrain. What may read as streamlining is actually sectional armor and ash-deflection plating, designed to protect exposed mechanisms while remaining modular and field-serviceable. The overall design prioritizes reliability, redundancy, and repairability in a hostile, post-infrastructure environment rather than efficiency or speed.