To determine whether a forklift has good stability, it is necessary to combine four dimensions: static detection, dynamic testing, working condition verification, and data monitoring. This covers the full scenarios of design parameters, equipment status, and actual operations, forming a scientific evaluation system. Below is a structured and actionable judgment method:
I. Static Detection (Non-operating State, Basic Judgment)
1. Basic Parameter and Structure Inspection
- Center of Gravity & Wheelbase Matching: Refer to the forklift technical manual to verify that the wheelbase and track width comply with the design standards corresponding to the rated load. For electric forklifts with under-mounted or rear-mounted batteries, the center of gravity is lower, resulting in better stability.
- Structural Integrity: Inspect the frame, forks, counterweight, and anti-tip bracket for deformation, cracks, or weld cracking. The wear of fork thickness shall not exceed 10% of the original size; otherwise, the load-bearing stability will be reduced.
- Tire Condition: Tires on the same axle must have consistent specifications, tread patterns, and air pressure, with no bulges, uneven wear, or damage. The wear of solid tires shall be ≤ 5mm; the air pressure of pneumatic tires shall meet the manufacturer’s requirements (insufficient air pressure will cause driving deviation).
2. Effectiveness of Safety Devices
- Start the forklift and test the load display/overload alarm device: When loaded to 110% of the rated load, the alarm shall be triggered immediately, and the hydraulic system shall prohibit lifting.
- Test the tilt alarm, speed limiting/height limiting devices: Tilt the mast to the maximum angle (usually ≤ 12°), and the tilt alarm must respond promptly. After setting the lifting height limit, the forks shall not lift beyond the specified range.
- Braking and Steering System: When the handbrake is engaged, the forklift shall not slip on a 5% slope. The steering shall be free of jamming, with a free play ≤ 10°. Load-sensing steering systems automatically increase damping under heavy loads for smoother steering.
II. Dynamic Testing (Operating State, Core Verification)
Dynamic testing shall be conducted in an open, flat, and hardened area. Operation in crowded areas or narrow passages is prohibited. The test shall be performed with the rated load applied.| Test Item | Operation Method | Stability Judgment Standard |
|---|---|---|
| Straight-line Braking Stability | Drive straight at the rated speed (usually ≤ 10km/h) and perform emergency braking | No sideslip or tail swing of the vehicle; no shaking or displacement of goods; braking distance ≤ manufacturer’s specified value (generally ≤ 3m) |
| Turning Stability | Turn at a speed of 5km/h (turning radius in accordance with manual requirements) | No obvious tilting or lateral swing; no tipping risk of goods on the forks (simulated counterweights may be used); no frequent intervention of the ESP system (if equipped) |
| Slope Operation Stability | Drive and park with heavy load on a 5% slope (both uphill and downhill) | No slipping caused by insufficient power when going uphill; stable braking without rear tilting when going downhill; reliable fixation by handbrake after parking with no sliding |
| Mast Lifting Stability | Lift the forks to the maximum height and idle for 1 minute | No shaking or sinking of the mast; no swinging of goods; no leakage of the hydraulic system; fork sinking amount ≤ 5mm within 1 minute |
III. Working Condition Verification (Actual Operation Scenarios, Final Judgment)
After passing static and dynamic tests, verification shall be carried out in real working scenarios, with focus on high-risk working conditions:- Heavy-load & High-lifting Condition: Transport the rated load, lift it to the commonly used stacking height (e.g., 3m), and drive/turn at low speed. The vehicle shall show no obvious shaking, and the goods shall have no falling risk.
- Unbalanced Load/Long-load Operation Condition: Transport goods longer than twice the fork length (must be fixed with attachments). No unilateral tilting during driving and no abnormal deformation of the mast shall occur.
- Slippery/Complex Site Condition: Drive and brake on slightly oily ground without sideslip. When turning in narrow passages, maintain a stable safe distance between the vehicle and obstacles to avoid collision risks.
IV. Data Monitoring & Long-term Evaluation (Long-term Judgment)
- Equipment Operation Data: Through the forklift’s IoT system (if available), check data such as braking frequency, turning speed, and fork lifting height during heavy-load operations. Frequent emergency braking and high-speed turning will accelerate the decline of stability, and such operations must be corrected in a timely manner.
- Fault & Accident Statistics: Count equipment fault records in the past 3 months. Frequent occurrences of brake failure, steering jamming, fork sinking, or vehicle tilting indicate a significant decline in stability.
- Regular Third-party Testing: Entrust special equipment inspection institutions to conduct static tilt tests and dynamic stability tests annually and issue inspection reports. In the tilt test, the forklift shall not tip over within the specified tilt angle; otherwise, its stability shall be judged as substandard.
V. Typical Signs of Poor Stability
If a forklift exhibits any of the following conditions, it indicates potential stability hazards, and the equipment must be shut down for maintenance immediately:- Obvious tilting or shaking of the vehicle during heavy-load driving, with a tendency to tip over when turning;
- Sideslip or tail swing during braking, or a significant increase in braking distance;
- Severe shaking of the mast after lifting, or unexplained sinking of the forks;
- Failure of the overload alarm or tilt alarm, or frequent uneven wear of tires.
