Professionals Answer These Crane Misunderstandings

As a core equipment in engineering construction, the safe operation of cranes is of vital importance. However, many widely spread "common sense" is actually wrong and may even cause serious accidents. Today, let's debunk the 8 most common misunderstandings about cranes and restore the truth with science and facts!

Misconception 1: "It doesn't matter if the overload is a little bit. The equipment has some spare capacity."

The truth is that the rated load of cranes is strictly calculated. Overloading will directly cause structural damage!

Experimental data: Overloading by 10% will shorten the service life of the steel wire rope by 50%, and overloading by 20% May cause deformation of the boom.

Accident case: In 2021, a tower crane collapsed at a construction site due to overloading by 5%, resulting in 3 casualties.

Safety standard: The international standard ISO 4309 clearly stipulates: Any overloading operation is strictly prohibited!

Experts suggest: Install a load limiter to monitor the lifted weight in real time and automatically cut off the operation when overloaded.

Misconception 2: "Long arm = Stronger lifting capacity"

The truth is: The lifting capacity drops sharply as the arm length increases!

Mechanical principle: Torque = weight × distance. If the arm length is doubled, the lifting capacity may drop to 1/4.

Actual measurement comparison

A certain 50-ton truck crane can lift 50 tons when its boom is 10 meters long, but only 8 tons when its boom is 30 meters long!

Dangerous consequence: Blindly extending the arm length may lead to overturning.

Operating Rules: Before starting the operation, it is necessary to review the "Load Curve Table" and strictly follow the norms.

Misconception 3: "The wind speed is not strong, so work can continue."

The truth is: Work must be halted when the wind speed exceeds 12m/s (level 6 wind)!

Wind force influence:

A wind speed of 10m/s can generate a lateral force of 2 tons for a 100-ton crane.

Gusts of wind may cause the load to sway and impact the surrounding structures.

Industry standard: OSHA stipulates that lifting operations are prohibited when the wind speed is ≥12m/s.

Safety measures: Install anemometers to monitor environmental wind force in real time.

Misconception 4: "If the ground looks solid, there's no need to pad it with steel plates."

The truth is that soft ground is one of the main reasons for crane overturning!

Pressure-bearing test: The pressure-bearing capacity of ordinary soil is only 0.2MPa, while that of crane outriggers should be ≥0.8MPa.

Accident analysis: In 2022, a 50-ton crane overturned at a construction site due to the failure to lay steel plates, causing the outriggers to sag.

The correct approach is to conduct a ground compaction test before the operation and lay steel plates of sufficient area.

Misconception 5: "The steel wire rope is a little rusty but still usable."

The truth: Rust can significantly reduce the strength of steel wire ropes!

Scrapping standard (GB/T 5972-2023) :

The broken wires exceed 10%

Diameter wear ≥7%

Severe rust or deformation

Experimental comparison: The breaking tensile force of rusted steel wire ropes may decrease by 30% to 50%.

Inspection method: Regular monthly inspection. Replace immediately if rust is found.

Misconception 6: "Experience is more important than the operation manual"

The truth: 90% of accidents result from improper operation!

Statistical data:

Sixty percent of crane accidents are caused by failure to operate in accordance with the manual.

Only 30% of the operators will read the equipment manual completely.

Typical case: A worker, based on experience, omitted the installation of counterweights, resulting in the overturning of the entire vehicle.

Mandatory regulation: Operators must be certified to work and undergo regular refresher training.

Misconception 7: "Nighttime work only requires lights on."

The truth is that the accident rate at night is three times that during the day!

Risk factors:

Limited vision makes it easy to misjudge distance.

The reaction speed of fatigue operation decreases by 40%.

Safety measures:

High-brightness LED work lights must be equipped.

Additional signalmen need to be added for night operations.

Misconception 8: "A device is safe just because it doesn't alarm."

The truth: The sensor may be faulty, and human eye inspection is irreplaceable!

Real case: At a construction site, due to the malfunction of the torque limiter, the operator failed to visually inspect it, resulting in an overloading accident.

Checklist:

Test the safety devices (limiters, alarms) before daily work.

The equipment is regularly inspected by professional institutions.

The Golden rule of safe operation

Never overload - the load limiter is the last line of defense.

Operate strictly in accordance with the manual - experience cannot replace standards.

Environmental monitoring - wind, land and light are all indispensable.

Regular maintenance - Key components such as steel wire ropes and hydraulic systems must be inspected on time.