Used TBM Buying Guide: Inspect Cutterhead, Main Bearing and Seals First

Metro programmes across South Asia are pushing TBMs into mixed-face and high-water-table alluvial soils, where EPB machines must hold face pressure while resisting abrasion. New machines are scarce and lead times stretch, so buyers increasingly weigh refurbished units. The economics only work when the machine is assessed as a complete system — cutterhead, drive, conveyor and hydraulics together — rather than a shield hull with a head bolted on. Inspection discipline is what separates a serviceable asset from an expensive resale problem.

Start at the cutterhead: check for structural cracks, worn or ovalised cutter housings, deformed spokes and poor field repairs, then measure main bearing clearance and sample lubricant for metal content. Inspect main drive and tail seals for scoring, verify screw conveyor wear liners and shaft flighting, and pressure-test hydraulic circuits. Electrical cabinets, the segment erector and thrust cylinders deserve the same scrutiny. Ask for measured values with photographs, not verbal assurances.

Refurbishment scope drives the risk profile. A credible supplier documents bearing and seal replacement, hydraulic overhaul and cutterhead retrofit — hard-facing, housing upgrades for larger disc cutters, or geometry changes for abrasive ground — before quoting. Working from the Deyang TBM cluster, OUSUN supplies interchangeable disc cutters, seals, segment bolts and screw conveyor parts on roughly 2–4 week lead times, and offers new or refurbished EPB, slurry and hard-rock machines.