1. Failure Analysis of Shield Machine Bearings

The cutterhead main support, flange base and tail hinge of shield machines are supported by large spherical roller bearings, the core force-bearing components of shield equipment. Bearings operate under underground mud-water, gravel impact, eccentric load from posture correction, groundwater immersion and round-the-clock tunneling. Common failures include abrasive wear caused by mud and sand intrusion, fatigue spalling from hard rock impact, roller fracture under eccentric load, rust & grease failure from groundwater, indentation deformation under long-term low-speed heavy load. Main bearing failure requires cutterhead disassembly and frame hoisting for overhaul lasting 10–20 days, bringing huge safety risks of face collapse & water inflow and enormous daily shutdown cost. Conventional bearings have short service life leading to frequent shield overhaul and high renovation cost.

2. Graded Reinforcement Advantages of NMT Shield Machine Bearings

NMT optimizes spherical roller structure, high-purity bearing steel, high-strength cage, multi-layer mud-water composite seal, tunneling-specific clearance and water-resistant anti-silt grease targeting mud intrusion, rock impact, eccentric load, water rust and low-speed heavy load, divided into economical sealed type for earth pressure balance shields, reinforced waterproof type for slurry shields, anti-shock heavy-duty type for hard rock TBM, extra-large main bearing for river-crossing shields and hinge bearing for shield articulation, for retrofitting & OEM replacement of CRCHI, Herrenknecht, Komatsu, Hitachi and domestic shield machines.

Reinforced Self-Aligning Spherical Roller Structure: Widened double-row spherical rollers achieve up to 4° angular compensation to balance eccentric load during shield turning & posture adjustment; thickened rollers expand contact area under low speed to enhance radial & axial bearing capacity against instantaneous impact from cobbles and hard rock.

ESR Ultra-High-Purity Bearing Steel: ESR electroslag remelting bearing steel with multiple high-temperature stabilizing tempering for minimal permanent deformation under long-term compression. Deep hardened working surface resists abrasion from silt and gravel, tough matrix inhibits crack propagation, service life 4 times longer than ordinary bearings for all-weather underground tunneling.

One-Piece Machined Brass Cage: CNC solid brass cage with exceptional rigidity, no deformation or fracture under severe vibration, mud moisture and alternating impact, accurate roller positioning to prevent roller scattering and cutterhead spindle jamming accidents.

Labyrinth + Multi-Seal Mud-Water Barrier System: Steel dust cover + double-lip silt-resistant NBR oil seal for EPB shields; extended labyrinth mud baffle + quadruple FKM waterproof oil seal + inner grease baffle for slurry shields to block high-pressure mud backflow and grease leakage; metal wear-resistant sleeve + composite multi-seal for hard rock TBM for severe gravel impact conditions.

Tunneling Customized Internal Clearance: C3 enlarged clearance for cutterhead main bearings to compensate vibration & thermal deformation; C4 oversized clearance for tail hinge bearings to buffer large turning deformation & vibration; standard clearance for fixed flange base bearings to stabilize fuselage structure.

Pre-Filled Water-Resistant Silt-Proof EP Grease: Resists emulsification under high water pressure, strong oil film adhesion against mud washing, centralized refueling cycle extended 4 times to reduce seal disassembly maintenance.

3. Shield Machine Position-Based Selection Guide

Cutterhead Main Spindle Bearing (Core Load): Labyrinth mud-water sealed C3 clearance brass cage waterproof heavy-duty bearing for mud, impact and eccentric load tunneling conditions.

Shield Tail Articulation Bearing: C4 large clearance waterproof dust-proof spherical roller bearing to buffer fuselage turning deformation and vibration.

Fuselage Flange Fixed Support Bearing: Standard clearance wear-resistant waterproof bearing to stabilize shield structure and reduce overall vibration.

EPB Shield Cutterhead Auxiliary Bearing: Economical triple silt-proof sealed bearing for dry muck tunneling.

Hard Rock TBM Main Bearing: Reinforced thick raceway anti-shock bearing for high-frequency impact from hard rock crushing.

Direct dimensional replacement without modification to cutterhead flange or chocks, easy disassembly with shield workshop overhead crane and hydraulic tools for overhaul.

4. Precision Manufacturing & Factory Inspection

Mirror super-finishing for spherical raceways and rollers reduces frictional heat under low-speed heavy load; high-precision machining of sealing mounting surface improves labyrinth tightness to block fine silt ingress; low-temperature stress relief tempering eliminates permanent deformation under long-term heavy load & mud immersion. All products pass high-pressure mud spray waterproof test, silt erosion abrasion test, eccentric turning impact fatigue test, groundwater immersion rust test, ultimate static load test and clearance grading with official material certification and mud-condition performance certificates. Pre-filled dedicated shield long-life grease simplifies assembly and overhaul after cutterhead integration.

5. Assembly & Construction Company Maintenance Cost Reduction

Fully dimensionally interchangeable with original bearings of Herrenknecht, CRCHI, Komatsu, Hitachi and other imported & domestic shields for modification-free direct replacement, compatible with hot mounting and cold pressing for on-site overhaul by shield maintenance teams. Factory preset tunneling heavy-load clearance and multi-layer mud-water seal eliminate on-site mud baffle installation, gap calibration and seal reinforcement, cutting emergency main bearing overhaul duration by 70%. Rapid tunneling resumption avoids safety hazards of face collapse, water burst and huge liquidated damages for project delay. Extended bearing service cycle reduces shield overhaul frequency, spare parts procurement and construction downtime expenditure.

6. Global Application Scenarios

Main bearing accessories for EPB and slurry shields in urban metro tunnels; waterproof heavy-load main bearings for large-diameter river & sea crossing slurry shields; anti-shock wear-resistant bearings for hard rock TBM mountain tunnels; heavy-duty support bearings for rectangular shields and pipe jacking machines for urban utility tunnels; wear-resistant waterproof bearing upgrading for aging shield overhaul and shield remanufacturing projects.

7. Spot Stock & Customized Service

Spot inventory for conventional spherical roller bearings for shield supports for fast delivery for medium sizes, rapid deployment for extra-large diameter main bearings for super-large shields. Custom non-standard waterproof heavy-duty spherical roller bearings available via drawing, dimension and tunneling condition customization for super-large shield non-standard flange bearings, ultra-deep underwater high-pressure waterproof shield bearings, explosion-proof electrical supporting bearings and compact narrow hinge bearings. Professional construction machinery bearing engineers provide customized selection solutions based on shield model, tunneling stratum (clay/cobble/hard rock), maximum buried water pressure, turning frequency and impact load intensity, solving mud abrasion, rock impact spalling, turning overload fracture, water-induced rust and excessive cutterhead swing failures. Extend the overall shield overhaul cycle and comprehensively cut tunneling shutdown loss, equipment overhaul cost and comprehensive spare parts operation cost for tunnel construction enterprises.