Maintenance of Electric Forklifts

The maintenance of electric forklifts is core work to ensure their safe operation, extend service life, and reduce failure rates. It requires a combined mode of "regular preventive maintenance" and "daily fault inspection", covering key systems such as batteries, motors, electronic controls, brakes, steering, and hydraulics. The following details the electric forklift maintenance system from five dimensions: daily inspection, regular maintenance (classified by cycle), key points of key system maintenance, common fault handling, and maintenance safety specifications.

I. Daily Inspection: Mandatory Before Startup (5-10 Minutes)

II. Regular Maintenance: Classified by Cycle (Core Link)

1. Short-Term Maintenance (Weekly/Every 50 Hours)

• In-depth battery inspection: Measure the single-cell voltage of the battery with a multimeter (standard voltage for lead-acid battery cells is 2.1V, with a deviation ≤ 0.05V). If the voltage of a single cell is too low, supplementary charging shall be conducted independently (to prevent "underperforming batteries" from affecting the entire battery pack);
• In-depth brake system inspection: Remove the brake drum/caliper, check the wear of brake pads (replace if the thickness ≤ 3mm), and clean dust on the brake pads (to avoid abnormal noise or brake failure);
• Hydraulic filter cleaning: Disassemble the return oil filter of the hydraulic oil tank, and backwash it with compressed air (0.4MPa). Replace the filter if it is damaged (to prevent impurities from entering the hydraulic pump);
• Lubrication of joints: Apply lithium-based grease (Model GB/T 7324-2010; ordinary grease is prohibited as it easily absorbs dust) to moving parts such as steering knuckles, fork carriage rollers, and mast slides.

2. Medium-Term Maintenance (Monthly/Every 200 Hours)

• Motor and electronic control system:
1. Open the motor protective cover, clean dust inside the motor with compressed air (to prevent motor overheating due to dust accumulation), and check the wear of carbon brushes (replace if the length ≤ 5mm; use carbon brushes of the same model to avoid damaging the commutator);
2. Check the terminal blocks of the electronic controller (e.g., Curtis, Zapi) for no looseness or burning. Measure the input/output voltage of the electronic controller with a multimeter (the input voltage is consistent with the battery voltage when no-load, and the output voltage is stable without fluctuation);
• Hydraulic system pressure detection: Measure the working pressure of the hydraulic system with a pressure gauge (the lifting pressure is generally 15-20MPa, and the tilting pressure is 8-12MPa). If the pressure is insufficient, check for wear of the hydraulic pump or failure of the relief valve;
• Comprehensive tire inspection:
• Solid tires: Check the tread pattern depth (replace if ≤ 2mm) and ensure no delamination or cracks on the tire body;
• Pneumatic tires: In addition to tire pressure, check for no deformation of the rim and no air leakage from the valve (detectable by applying soapy water).

3. Long-Term Maintenance (Quarterly/Every 500 Hours, or Annually/Every 2000 Hours)

• Battery system maintenance:
• Water-added batteries: Conduct "equalizing charging" once a quarter (after charging until the green light is on, continue trickle charging for 2-4 hours to eliminate single-cell voltage deviation);
• Lithium batteries: Measure the battery cycle life with a dedicated detector (the cycle life of lithium iron phosphate batteries is ≥ 2000 times; evaluate whether to replace if it is less than 1500 times), and check whether the BMS (Battery Management System) communication is normal (no error codes);
• Motor insulation detection: Measure the insulation resistance of the motor stator winding to the ground with a megohmmeter (shake meter) (≥ 50MΩ is qualified; dry the motor if < 10MΩ to avoid electric leakage);
• Hydraulic oil replacement:
1. Drain the old hydraulic oil (drain while hot to facilitate the discharge of impurities with the oil), and clean the inside of the oil tank (wipe with lint-free cloth; cotton yarn is prohibited to avoid fiber residue);
2. Add new hydraulic oil (must conform to the model recommended by the manufacturer, e.g., ISO VG 32 for winter and ISO VG 68 for summer). Filter the oil through an oil filter (filtration precision ≤ 10μm) when adding;
• Whole-vehicle wiring inspection: Check the insulation layer of the main wire harness (from battery to electronic controller, and from electronic controller to motor) for no aging or damage, and ensure no looseness of the clamps fixing the wire harness (to avoid short circuit caused by harness friction and damage);
• Structural part flaw detection: For load-bearing parts such as forks, masts, and frames, inspect the welds by visual inspection or penetration testing (PT) for no cracks or weld breaks (repair welding is required if there are cracks; after repair welding, grind to a smooth surface and perform stress relief).

III. Key Points of Key System Maintenance (Core Systems Prone to Faults and Affecting Safety)

1. Battery Maintenance: The "Heart" of Electric Forklifts, Accounting for 30%-40% of Total Costs

• Prohibit "overcharging" (after charging until the green light is on, the maximum trickle charging time shall not exceed 8 hours to avoid battery bulging);
• Prohibit "storage with low charge" (charge immediately when the power is below 20%; storage with low charge for more than 24 hours will cause "sulfation" of lead-acid batteries, leading to irreversible damage);
• Charging environment: Temperature 15-30℃, well-ventilated (charging in enclosed spaces is prohibited to avoid hydrogen accumulation and explosion);
• Special notes for lithium batteries: Prohibit collision or puncture of the battery box. If the battery bulges or leaks, stop using it immediately and contact professional manufacturers for handling (self-disassembly is prohibited to avoid fire).

2. Electronic Control System: The "Brain", Requiring Professional Tools for Fault Inspection

3. Brake System: Safety First, Avoid "Brake Failure"

• Hydraulic brakes (common in medium and large forklifts): Check for no leakage of the master brake cylinder/wheel cylinder, and ensure the brake fluid level is between the scale lines (use DOT3 or DOT4 brake fluid; mixing different models is prohibited);
• Electromagnetic brakes (common in small forklifts): Check the coil resistance of the electromagnetic brake (generally 50-100Ω; replace the coil if the resistance is abnormal), and adjust the brake clearance to 0.1-0.3mm (excessive clearance will cause weak braking).

IV. Common Fault Handling (Rapid Localization and Temporary Resolution)

V. Maintenance Safety Specifications (Avoid Personal Injury)

• Maintenance with forklift stopped: Before maintenance, park the forklift on a flat ground, pull the handbrake, lower the forks to the ground, turn off the key switch, and unplug the battery plug (or turn off the main power switch);
• Battery operation safety:
• Use a dedicated spreader when handling batteries (to avoid crushing injuries caused by manual handling);
• Wear acid-resistant gloves and goggles when touching the battery (to avoid skin/eye corrosion by electrolyte; rinse with plenty of water immediately if contact occurs);
• Hydraulic system safety: Before disassembling hydraulic pipelines, release the pressure first (operate the handle until the forks fall naturally) to avoid injury from high-pressure oil injection;
• High-altitude operation safety: When maintaining the top of the mast, support the mast with a bracket (relying solely on the hydraulic lock is prohibited) to prevent the mast from falling suddenly.

Summary