Buying a Used TBM: Cutterhead, Main Bearing and Seal Inspection Guide

For buyers supporting Southeast Asia's dense metro and rail programmes, a used EPB or slurry TBM can shorten procurement — but only if the inspection is honest. Start at the cutterhead: check cutter housings for ovalisation, hardfacing wear, and cracks in hub and spoke welds. Then the main bearing: oil sampling, vibration history, backlash, and the main bearing seal, the most failure-prone assembly on a soft-ground machine. Finish with screw conveyor flights, casing wear, discharge gate, hydraulic cylinder scoring and electrical insulation readings.

Refurbishment scope should be defined as a level, not promised as a word. Typical work covers bearing and seal renewal, hydraulic hose and valve replacement, motor overhaul, control panel upgrades, and structural repair to shield, tail skin and articulation joints. Cutterhead retrofit is where decisions matter most: moving from 17-inch to 18- or 19-inch cutters, replacing housings, adding wear plates and hardfacing. In karst and mixed-face ground, that extra wear protection pays back quickly.

Lead time is the commercial argument. A new-build machine is measured in many months; a correctly refurbished unit, backed by spares delivered in roughly 2–4 weeks, often returns to site far sooner. Risk drops when the supplier works at OEM scale — OUSUN, in Deyang, Sichuan, supplies disc cutters, seals, screw conveyor parts and hydraulic/electrical spares for EPB, slurry and hard-rock machines. In humid climates, insist on corrosion treatment, moisture-protected electrics and fresh sealed lubrication. Contact [email protected].