ZHONGYUAN Drawworks for Drilling Rigs

1

JC40

Main Frame: Q345R Forged Carbon Steel (Shot-Peened); Gearbox Gears: 20CrMnTi Alloy Steel (Carburized & Quenched, Surface Hardness HRC 58-62); Brake Disc: 42CrMo Alloy Steel (Induction-Hardened); Drum: 35CrMo Alloy Steel (Welded & Stress-Relieved); Seals: NBR Rubber

1. Gear tooth pitting and scuffing due to insufficient lubrication and load fluctuation during drill string lifting; 2. Brake disc thermal fatigue and cracking from long-term continuous braking (temperature exceeding 350°C); 3. Drum surface wear from friction with steel wire rope (wire rope wear debris accumulation); 4. Frame corrosion from high humidity and rainwater exposure in onshore open-air drilling sites

1. Use gear oil with anti-wear and anti-scuff additives (ISO VG 460), replace oil every 800 operating hours, and install magnetic oil filters to remove metal debris; conduct gear mesh inspection monthly and adjust backlash to 0.15-0.30mm; 2. Implement intermittent braking during long hoisting operations to allow brake disc cooling (maintain temperature ≤250°C); inspect brake disc for cracks using dye penetrant testing (DPT) every 500 operating hours, and grind the surface if roughness Ra >0.8μm; 3. Regularly inspect steel wire rope for wear (replace if diameter reduction exceeds 3%) and apply anti-wear grease to the drum surface; ensure proper rope winding alignment to avoid uneven wear; 4. Apply anti-corrosion primer and topcoat (epoxy resin) to the frame annually, install a rain cover for open-air installations, and drain accumulated water in the gearbox monthly

2

JC40D

Main Frame: Q345R Forged Carbon Steel (Shot-Peened); Gearbox Gears: 40CrNiMoA Alloy Steel (Nitrided, Nitride Layer Depth 0.3-0.5mm); Brake Disc: 42CrMo Alloy Steel (Double-Sided Induction-Hardened); Drum: 42CrMo Alloy Steel (Forged & Stress-Relieved); Drive Motor Shaft: 42CrMo Alloy Steel; Seals: FKM/Viton Rubber

1. Nitride layer peeling on gear surfaces due to improper gear oil viscosity (too low) and high-speed operation; 2. Drive motor shaft wear at bearing seats due to vibration from uneven load distribution; 3. Brake system leakage caused by seal degradation from high-temperature brake dust; 4. Electrical component failure in the enhanced drive system due to moisture ingress

1. Use gear oil with viscosity ISO VG 460-680 (adjust based on ambient temperature: 460 for 0-40°C, 680 for 40-60°C); monitor gearbox temperature (normal range ≤80°C) and investigate any abnormal rise; inspect nitride layer for peeling every 6 months using UT; 2. Balance the drill string before hoisting to reduce load unevenness; check motor shaft bearing clearance monthly (maximum allowable clearance ≤0.05mm) and replace bearings if worn; 3. Clean brake dust from seal surfaces weekly to prevent abrasive wear; replace seals with FKM/Viton variants annually or if leakage is detected; 4. Install a waterproof and dustproof cover for the drive system’s electrical cabinet; maintain cabinet internal relative humidity ≤60% using a dehumidifier, and inspect electrical connections for corrosion quarterly

3

JC40DB

Main Frame: Q345R Forged Carbon Steel (Shot-Peened & Anti-Corrosion Coated); Gearbox Gears: 40CrNiMoA Alloy Steel (Carburized & Nitrided); Brake Disc: 42CrMo Alloy Steel (Ceramic-Coated); Drum: 42CrMo Alloy Steel (Forged & Chrome-Plated); Dual-Drive Shafts: 40CrNiMoA Alloy Steel; Seals: FKM/Viton Rubber

1. Gear tooth wear from uneven load distribution between dual drives; 2. Ceramic coating peeling on brake discs due to impact from falling debris during drilling operations; 3. Chrome plating wear on the drum surface from misaligned steel wire rope; 4. Frame weld joint fatigue from cyclic load and vibration in complex onshore drilling sites

1. Calibrate dual-drive load distribution monthly to ensure deviation ≤5%; use torque monitors to track drive shaft load in real time; inspect gear teeth for wear using a tooth thickness gauge every 400 operating hours; 2. Install a protective guard over the brake disc to prevent debris impact; inspect ceramic coating for peeling monthly and re-coat if damaged; avoid over-braking (limit braking force to ≤80% of rated capacity); 3. Adjust steel wire rope guide rollers to ensure proper alignment (deviation ≤2°); apply high-pressure lubricating grease to the drum surface every 200 operating hours; 4. Conduct magnetic particle testing (MPT) on frame weld joints every 1000 operating hours to detect fatigue cracks; relieve residual stress in weld joints via post-weld heat treatment if cracks are found (temperature 600-650°C, holding time 2 hours)

1

JC50

Main Frame: Q460C Forged Carbon Steel (Shot-Peened); Gearbox Gears: 40CrNiMoA Alloy Steel (Carburized & Quenched); Brake Disc: 42CrMo Alloy Steel (Induction-Hardened, Thickness Enhanced to 30mm); Drum: 42CrMo Alloy Steel (Forged, Chrome-Plated); Bearing: 316L Stainless Steel; Seals: FKM/Viton Rubber

1. Drum deformation and chrome plating peeling due to overloading (exceeding 50T) and uneven load distribution during drill string lifting; 2. Gearbox bearing wear and seizure from contaminated lubricating oil; 3. Brake disc thermal cracking from long-term heavy-load braking (temperature exceeding 400°C); 4. Frame corrosion from salt spray in near-shore drilling environments

1. Strictly operate within the rated load (≤50T); use load cells to monitor hoisting load in real time and install overload protection devices (trigger at 110% rated load); inspect drum for deformation using a laser measuring tool every 500 operating hours, and re-chrome plate if plating wear exceeds 0.1mm; 2. Use lubricating oil with cleanliness grade NAS 7; replace oil filters every 400 operating hours and conduct oil analysis (particle count, water content) quarterly; replace bearings if abnormal noise or temperature rise (≥90°C) is detected; 3. Implement forced air cooling for the brake disc during heavy-load operations to maintain temperature ≤300°C; inspect brake disc for cracks using DPT every 400 operating hours, and replace if cracks exceed 5mm; 4. Apply marine-grade anti-corrosion coating (epoxy resin + polyurethane topcoat) to the frame every 6 months; install a salt spray protection cover for near-shore installations, and clean the frame with fresh water weekly to remove salt residues

2

JC50DB

Main Frame: Q460C Forged Carbon Steel (Shot-Peened & Anti-Corrosion Coated); Gearbox Gears: 40CrNiMoA Alloy Steel (Carburized & Nitrided); Brake Disc: 42CrMo Alloy Steel (Ceramic-Coated); Drum: 42CrMo Alloy Steel (Forged & Nitrided); Dual-Drive Shafts: 40CrNiMoA Alloy Steel; Seals: FKM/Viton Rubber (High-Pressure Rated)

1. Dual-drive shaft synchronization failure due to uneven torque distribution; 2. Gear tooth fatigue cracking from long-term heavy-load cyclic operation; 3. Ceramic coating peeling on brake discs due to thermal shock (rapid cooling after high-temperature braking); 4. Seal leakage in the gearbox due to high internal pressure from load fluctuations

1. Calibrate dual-drive torque distribution monthly to ensure synchronization deviation ≤3%; install torque sensors on each drive shaft for real-time monitoring; inspect drive shaft couplings for wear every 300 operating hours; 2. Conduct ultrasonic flaw detection (UT) on gear teeth every 600 operating hours to detect fatigue cracks; avoid rapid load changes (limit load rise rate to ≤5T/s); 3. Avoid rapid cooling of the brake disc (e.g., spraying water directly) after high-temperature operation; allow natural cooling to ≤150°C before maintenance; inspect ceramic coating for peeling monthly and re-coat if damaged; 4. Install pressure relief valves in the gearbox (set pressure 0.6MPa) to prevent overpressure; inspect seals for leakage weekly and replace with high-pressure rated FKM/Viton variants if necessary; check gearbox ventilation system monthly to ensure unobstructed air flow

1

JC70

Main Frame: Q690D Forged Carbon Steel (Shot-Peened & Stress-Relieved); Gearbox Gears: 40CrNiMoA Alloy Steel (Carburized & Quenched, Tooth Profile Grinding); Brake Disc: 42CrMo Alloy Steel (Double-Sided Induction-Hardened, Thickness 35mm); Drum: 42CrMo Alloy Steel (Forged, Nitrided); Bearings: 316L Stainless Steel (High-Load Rated); Seals: FKM/Viton Rubber (High-Temperature & High-Pressure Rated)

1. Gear tooth wear and fatigue cracking from extreme heavy-load cyclic operation (70T rated load); 2. Drum nitrided layer wear and deformation from long-term friction with heavy steel wire rope; 3. Brake system failure due to thermal overload (temperature exceeding 450°C) during deep well hoisting; 4. Frame weld joint fatigue from high vibration in deep drilling operations

1. Conduct UT on gear teeth every 300 operating hours to detect fatigue cracks; use gear oil with anti-fatigue additives (ISO VG 680); replace oil every 600 operating hours and conduct oil analysis quarterly; adjust gear backlash to 0.20-0.35mm per OEM specifications; 2. Use high-strength steel wire rope (minimum breaking strength ≥120T) and inspect for wear every 100 operating hours (replace if diameter reduction exceeds 2%); apply molybdenum disulfide-based lubricating grease to the drum surface every 150 operating hours; inspect drum nitrided layer for wear using a hardness tester monthly; 3. Install a water-cooled brake system to maintain disc temperature ≤350°C during deep well hoisting; inspect brake pads for wear every 200 operating hours (replace if thickness ≤5mm); conduct DPT on brake discs every 300 operating hours to detect cracks; 4. Conduct MPT on frame weld joints every 800 operating hours to detect fatigue cracks; reinforce weld joints with additional welding if necessary; install vibration dampers between the drawworks and rig platform to reduce vibration transmission (vibration amplitude ≤0.5mm/s)

2

JC70D

Main Frame: Q690D Forged Carbon Steel (Shot-Peened & Anti-Corrosion Coated); Gearbox Gears: 40CrNiMoA Alloy Steel (Carburized & Nitrided); Brake Disc: 42CrMo Alloy Steel (Ceramic-Coated); Drum: 42CrMo Alloy Steel (Forged & Chrome-Plated); Enhanced Drive Motor: 42CrMo Alloy Steel Shaft; Seals: FKM/Viton Rubber; Electrical Components: IP65 Protection Rating

1. Enhanced drive motor overheating due to high-power output (exceeding 200kW) in long-term operation; 2. Gearbox seal leakage due to high internal pressure and temperature; 3. Ceramic coating peeling on brake discs due to impact from heavy debris; 4. Electrical component failure in the drive system due to moisture and dust ingress in harsh drilling environments

1. Install a forced liquid cooling system for the drive motor to maintain temperature ≤85°C; monitor motor current and power in real time (avoid continuous operation at ≥90% rated power); inspect motor windings for insulation damage quarterly using a megohmmeter (insulation resistance ≥1MΩ); 2. Install pressure relief valves in the gearbox (set pressure 0.8MPa) and check for proper operation monthly; inspect seals for leakage weekly and replace with high-temperature/high-pressure rated variants if necessary; 3. Install a heavy-duty protective guard over the brake disc to prevent debris impact; inspect ceramic coating for peeling monthly and re-coat if damaged; avoid over-braking (limit braking time to ≤30 seconds for continuous operation); 4. Ensure electrical components meet IP65 protection rating; install a dustproof and waterproof cover for the drive control cabinet; maintain cabinet internal temperature ≤50°C using a cooling fan; inspect electrical connections for corrosion and tightness quarterly

3

JC70DB

Main Frame: Q690D Forged Carbon Steel (Shot-Peened & Anti-Corrosion Coated); Gearbox Gears: 40CrNiMoA Alloy Steel (Carburized, Nitrided & Tooth Profile Grinding); Brake Disc: 42CrMo Alloy Steel (Ceramic-Coated & Cooled); Drum: 42CrMo Alloy Steel (Forged, Nitrided & Chrome-Plated); Dual-Drive Shafts: 40CrNiMoA Alloy Steel (Forged); Seals: FKM/Viton Rubber (High-Performance); Dual-Drive Control System: IP67 Protection Rating

1. Dual-drive system synchronization failure due to high vibration and load fluctuation in deep drilling; 2. Gear tooth wear from uneven load distribution between dual drives; 3. Drum surface wear from misaligned heavy steel wire rope; 4. Dual-drive control system failure due to salt spray and moisture ingress in offshore drilling

1. Calibrate dual-drive synchronization monthly using laser alignment tools (synchronization deviation ≤2%); install real-time vibration monitors (alarm at vibration amplitude ≥1.0mm/s); inspect drive shaft couplings for wear every 200 operating hours; 2. Use torque sensors to monitor load distribution between dual drives (deviation ≤3%); inspect gear teeth for wear using a tooth thickness gauge every 300 operating hours; adjust gear meshing alignment if necessary; 3. Install automatic wire rope alignment guides to ensure deviation ≤1°; inspect wire rope for wear and alignment every 100 operating hours; apply high-pressure lubricating grease to the drum surface every 150 operating hours; 4. Ensure dual-drive control system meets IP67 protection rating; apply marine-grade anti-corrosion coating to external control components; install a waterproof and dustproof cabinet for control modules; clean control system connectors with contact cleaner quarterly and apply anti-corrosion grease