Special Maintenance Requirements for Electric Forklifts in Low-Temperature Environments (SOP-Level Implementable Plan)

Low-temperature environments significantly impact core components of electric forklifts such as batteries, hydraulic systems, and transmission mechanisms. Maintenance must focus on four core objectives: anti-icing, range preservation, wear reduction, and fault prevention. Targeted measures are formulated based on winter environmental characteristics. Below are systematic and quantifiable maintenance requirements:

I. Battery System: Core Anti-Freezing + Capacity Protection (Top Priority for Winter Maintenance)

1. Charging Process (Directly Affects Battery Life and Range)

2. Storage and Usage

• Daily Storage: Prioritize storage in a warm warehouse (temperature ≥5℃). If unavailable, install a battery insulation cover (insulation thickness ≥5mm, thermal conductivity ≤0.04W/(m·K)) to reduce heat loss.
• Long-Term Storage (Over 7 Days): Supplementary charging once a week to maintain 70%-80% battery capacity (avoid irreversible capacity loss from deep discharge storage). Disconnect the main battery switch to reduce static power consumption.
• Lithium Battery Special Protection: Activate low-temperature preheating function (available on some high-end models). If unavailable, start the forklift periodically to generate battery self-heating (operate for 5-10 minutes each time; avoid no-load high speed).

II. Hydraulic System: Anti-Viscosity + Anti-Leakage + Anti-Icing

1. Hydraulic Oil Replacement and Maintenance

• Oil Selection: Replace with low-temperature dedicated hydraulic oil meeting specifications: "Pour point ≤-25℃, kinematic viscosity (40℃) ≥40mm²/s" (Recommended models: ISO VG 32 or VG 46 low-temperature grade, e.g., Shell Tellus LT 32, Mobil DTE 10 Excel 46).
• Oil Change Cycle: Complete oil change before winter. Thoroughly drain old oil (including hydraulic tank, pipelines, and cylinders) to avoid mixing with new oil, which impairs low-temperature performance.
• Daily Inspection: Check hydraulic oil level (between dipstick marks) before daily operation. Inspect oil quality (no turbidity, moisture, or impurities) weekly. Replace immediately if abnormal viscosity is detected.

2. Hydraulic System Anti-Freezing and Operation

• Pre-Operation Preheating: After starting the forklift, perform no-load lifting and tilting operations for 5-10 minutes (3-5 cycles) to raise hydraulic oil temperature above 10℃ before load operation (avoid hydraulic pump wear from high viscosity at low temperatures).
• Anti-Icing Measures: Install insulation sleeves on hydraulic tanks and wrap exposed pipelines with insulation cotton (thickness ≥8mm). Release hydraulic system pressure to 0MPa after daily operation to prevent residual oil from freezing and blocking pipelines due to sudden temperature drops.
• Leakage Inspection: Inspect hydraulic pipelines, joints, and oil seals weekly (low temperatures cause cold shrinkage and hardening, leading to leakage). Replace seals promptly if leakage is found (use low-temperature resistant seals, e.g., fluororubber).

III. Transmission and Travel System: Friction Reduction + Anti-Jamming

1. Lubricating Oil Replacement

• Transmission/Drive Axle: Replace with low-temperature dedicated gear oil meeting specifications: "Pour point ≤-30℃, viscosity index ≥120" (Recommended models: GL-4 75W-90 or GL-5 80W-140 low-temperature grade). Shorten oil change cycle by 30% compared to normal temperature (lubricating oil ages faster in winter).
• Steering System: Replace with low-temperature power steering fluid (pour point ≤-25℃). Check steering rod and ball joint clearance (cold shrinkage may increase clearance, affecting steering accuracy). Adjust or replace components if clearance exceeds 0.5mm.

2. Tires and Travel Mechanism

• Tire Inspection: Clean ice, snow, and gravel from tire treads before daily operation. Check tire pressure (increase by 0.1-0.2MPa compared to normal temperature to avoid excessive contact area and accelerated wear from low-temperature pressure drop).
• Tire Selection: Replace with snow tires or anti-slip tires (tread depth ≥15mm, rubber hardness ≤60 Shore A) for low-temperature environments (≤-10℃) to improve grip (prevent skidding risks).
• Travel Mechanism Lubrication: Grease wheel bearings and steering knuckles weekly with low-temperature grease (recommended: lithium-based grease with dropping point ≥180℃ and low-temperature performance ≤-20℃) to avoid poor lubrication from component cold shrinkage.

IV. Brake System: Anti-Freezing + Sensitivity Preservation

• Brake Fluid Replacement: Replace with low-temperature brake fluid (DOT 4 or DOT 5.1, freezing point ≤-40℃) to prevent brake line freezing from excessive moisture (brake fluid water content ≤0.5%; replace if exceeded).
• Air Brake System (Diesel Hybrid/Partial Electric Forklifts Only): Drain water from air reservoirs and dryers before daily operation. Check anti-freezer operation (add dedicated antifreeze with concentration ≥50%) to prevent brake failure from frozen pipelines and valves.
• Brake Clearance Adjustment: Cold shrinkage of metal components may reduce brake shoe and drum clearance (normal clearance: 0.3-0.5mm). Test brake performance before daily operation. Adjust clearance promptly if brake drag or abnormal noise occurs.

V. Electrical System: Anti-Condensation + Anti-Short Circuit

• Wiring Inspection: Inspect battery connections, motor control wires, and sensor cables weekly (low temperatures cause hardening and cracking). Apply conductive paste to connectors (prevent oxidation) and wrap exposed wires with insulation cotton (avoid condensation-induced short circuits).
• Battery Terminals: Clean oxide from terminal surfaces (wipe with 10% sulfuric acid solution, rinse with water, and dry). Apply petroleum jelly or dedicated protectant (prevent corrosion from low-temperature humidity).
• Lights and Instruments: Check headlights, turn signals, and brake lights daily (low visibility in winter fog and snow). Verify normal instrument display (focus on alarm information such as battery temperature, voltage, and hydraulic oil temperature).
• Heating System (If Equipped): Inspect cab heater and battery preheating device operation. Air outlet temperature ≥30℃, preheating time ≤10 minutes (ensure driver comfort and battery preheating effect).

VI. Body and Structural Components: Anti-Corrosion + Anti-Cold Shrinkage Deformation

• Cleaning and Rust Prevention: Clean ice, snow, and salt from the body surface after daily operation (especially for outdoor-stored forklifts; salt accelerates metal corrosion). Wipe dry with a dry cloth. Apply low-temperature rust-preventive oil (pour point ≤-20℃) to key parts (e.g., mast, pins).
• Mast Inspection: Inspect mast rails and chains weekly (low temperatures cause chain stiffness). Apply low-temperature chain oil (strong adhesion, anti-freezing) and adjust chain tension (sag ≤20mm).
• Structural Component Clearance: Inspect welds of frames and masts (low temperatures may cause weld cracking). Retighten connecting bolts (e.g., wheel bolts, mast bolts) to standard torque (increase by 5%-10% compared to normal temperature to prevent loosening from cold shrinkage).

VII. Pre/Post-Operation Daily Maintenance Procedures (Mandatory)

1. Pre-Operation (5-Minute Quick Check)

• Environment Preheating: If the forklift is stored outdoors, move to a warm warehouse for 20-30 minutes of preheating (or idle for 10 minutes).
• Three-Fluid Inspection: Battery voltage (≥90% of rated voltage), hydraulic oil level, brake fluid level.
• Function Test: Perform 3 cycles of no-load hydraulic operations (lifting, tilting). Test brake performance and steering flexibility.
• Safety Check: Tire pressure and tread, lights, and brake line icing.

2. Post-Operation (10-Minute Final Maintenance)

• Cleaning and Organization: Remove ice/snow from the body and tires, and condensation from the battery surface.
• Status Reset: Lower forks to the lowest position, straighten steering, and turn off the main power.
• Storage Protection: Store in a warm warehouse (priority) or cover with an insulation cover. Fully charge the battery.
• Recording and Feedback: Fill out the "Winter Forklift Maintenance Record Form" to document battery voltage, operating status, and abnormalities.

VIII. Key Consumables and Tool Preparation (Ensure Maintenance Implementation)

IX. Prohibited Items (Avoid Equipment Damage from Improper Operation)

- Strictly Prohibited Charging when the battery is frozen or electrolyte is insufficient.

- Strictly Prohibited Using normal-temperature hydraulic oil or gear oil (prone to system jamming and component wear at low temperatures).

- Strictly Prohibited Heating batteries or hydraulic tanks with open flames (risk of explosion and fire).

- Strictly Prohibited Long-term no-load high-speed operation below -10℃ (motor overheating and sudden range drop).

-Strictly Prohibited Long-term storage with deep discharge in winter (irreversible battery capacity loss).

By implementing the above targeted maintenance measures, the failure rate of electric forklifts in low-temperature environments can be reduced by over 60%, battery range retention rate increased to over 85%, and hydraulic system response speed maintained at approximately 90% of normal temperature, providing guarantee for safe and efficient winter operations.