Ultra-High-Thrust, Extreme Heavy-Duty Anti-Vibration Design
The barrel is fabricated from high yield-ratio quenched & tempered alloy steel forgings or ultra-heavy-wall tube, with FEA-optimized wall thickness and barrel-to-end transition. The piston rod is a large-diameter solid forging, precision hard-chrome plated (HV900–1100, Ra≤0.1μm). All critical welds undergo 100% UT/MT with stress relief. Bench fatigue testing confirms over 1.5 million full-load grip cycles without deformation or cracking under the intense vibration of continuous rock cutting and shoe reaction impact.
Exceptional Clamping Retention
Once pressurized, the cylinder is locked by an integrated dual pilot-operated check valve or counterbalance valve. Even during continuous boring lasting several hours without hydraulic supply, piston drift remains under 1.5 mm per 24 hours, preventing gripper slippage that would cause thrust misalignment or cutterhead deviation.
Variable Clamping Force for Multi-Ground Adaptation
Through a proportional pressure reducing valve or load-sensing system, clamping force can be precisely adjusted according to the rock mass UCS. In weak ground, excessive crushing and wall collapse are avoided; in hard, competent rock, adequate reaction force is ensured — balancing advance rate and ground protection.
Specialized Rock-Dust-Resistant High-Pressure Sealing
The gland exterior features multiple wipers, a stainless steel scraper ring, and a labyrinth seal. The main seal is a polyurethane + filled PTFE composite with hydrolysis resistance, supplemented by an accumulator buffer chamber to absorb high-frequency pressure pulsations. In aggressive environments of rock dust, cuttings, and fissure water spray, it guarantees zero leakage over long tunnel drives.
Ultra-Low Breakaway for Smooth Response
Low-friction guide rings and specialized seals keep breakaway pressure under 0.4 MPa. The cylinders grip and retract smoothly — no stick-slip or judder — ensuring precise shoe-to-wall contact and avoiding eccentric loading or localized stress concentration.
Comprehensive Anti-Corrosion & Temperature Resistance
External surfaces are finished with moisture-resistant epoxy. The piston rod is available with hard chrome, Ni/Cr alloy plating, laser cladding, or ceramic thermal spray. Seals can be upgraded to high-temperature grades; all fasteners are stainless steel, adapting to high geothermal and corrosive groundwater environments.
Intelligent Monitoring & Maintenance-Free Pivots
Pressure sensors and linear displacement sensors can be integrated to monitor real-time clamping force and extension of each shoe, supporting TBM main control system diagnostics and early warning. Standard self-lubricating composite bushings in both clevises eliminate daily greasing and provide long life under high loads and frequent stepping.
