What are the safety features of wire rope electric hoists?

What are the safety features of wire rope electric hoists?

1. Equipment structural safety features

1.1 Hook safety device
The hook of the wire rope electric hoist is a key component, and its safety device is crucial.
The hook is usually equipped with an anti-unhooking device, which can effectively prevent the object from accidentally slipping during the lifting process. According to relevant statistics, the incidence of accidents of objects slipping can be reduced by more than 90% when the anti-unhooking device is properly installed and used.
The material and manufacturing process of the hook also directly affect its safety. High-quality hooks are made of high-strength alloy steel. After strict heat treatment process, their tensile strength can reach more than 1000MPa, which can withstand greater tension and ensure the safe lifting of objects.
1.2 Wire rope and drum design
The wire rope and drum are the core components of the wire rope electric hoist. Their design and selection play a decisive role in the safety of the equipment.
The selection of wire rope is crucial. Generally speaking, the breaking force of a wire rope is several times its working force. For example, for an electric hoist with a rated lifting capacity of 1 ton, the breaking force of its wire rope is usually more than 5 tons. The twisting process of the wire rope will also affect its performance. The use of advanced twisting processes can improve the flexibility and wear resistance of the wire rope and extend its service life.
The design of the drum is equally important. The diameter and length of the drum should match the specifications of the wire rope to ensure that the wire rope will not be tangled during the winding process. The surface of the drum is usually processed with spiral grooves. This design can guide the wire rope to be wound neatly, reduce friction and wear between the wire ropes, and improve the service life and safety of the wire rope.

2. Operational safety features
2.1 Operator qualification requirements
The operator of the wire rope electric hoist must have the corresponding qualifications and capabilities to ensure the safe operation of the equipment.
Qualification certification: The operator must undergo professional training and obtain relevant operation certificates, such as special equipment operation certificates. According to statistics, the error rate of operators who have received professional training and hold a certificate is more than 80% lower than that of untrained personnel.
Health requirements: Operators should be in good health and have no defects in vision, hearing, reaction ability, etc. For example, operators with a vision lower than 0.8 will have a greater impact on their ability to observe and judge the operating status of the equipment, which is easy to cause safety accidents.
Experience requirements: It is also necessary to have certain operating experience. Experienced operators can master the operating skills of the equipment more skillfully and detect and handle abnormal situations in a timely manner. Data shows that experienced operators can shorten the equipment failure handling time by more than 30% on average compared with novice operators.
2.2 Pre-operation inspection process
Pre-operation inspection is an important part of ensuring the safe operation of wire rope electric hoists.
Appearance inspection: Check whether the appearance of the equipment is obviously damaged, deformed or worn. For example, check whether the hook has cracks or deformation, and whether the wire rope is broken or worn. According to relevant research, appearance inspection can find more than 60% of potential problems of equipment.
Electrical system inspection: Check whether the electrical circuit is intact, whether the insulation is good, and whether the electrical components such as motors and controllers are working properly. Electrical failure is one of the important reasons for abnormal operation of equipment. Electrical system inspection can effectively reduce the incidence of electrical failures and ensure the safe operation of equipment.
Braking system inspection: Check whether the brake is sensitive and reliable, and whether the braking distance meets the requirements. The brake is a key component to ensure the safe operation of the equipment, and its performance directly affects the braking effect of the equipment. For example, for an electric hoist with a rated lifting capacity of 5 tons, the braking distance should be controlled within 50 mm to ensure that the equipment can stop quickly during emergency braking.
Lubrication system inspection: Check whether the lubrication system of the equipment is working properly and whether there is enough lubricating oil at the lubrication point. Good lubrication can reduce the wear of equipment components, extend the service life of the equipment, and also ensure the normal operation of the equipment. Regular inspection of the lubrication system can reduce equipment failures caused by poor lubrication and improve the safety and reliability of the equipment.

3. Electrical safety characteristics
3.1 Insulation performance requirements
The insulation performance of the wire rope electric hoist is a key factor in ensuring the safety of operators and equipment.
From the perspective of national standards, the insulation resistance of electric hoists should meet the safety standards of relevant electrical equipment. For example, in a dry environment, its insulation resistance should not be less than 1MΩ, and in a humid environment, the insulation resistance should not be less than 0.5MΩ to ensure the safety and reliability of the electrical system.
The selection of insulating materials is crucial. High-quality insulating materials can effectively prevent electrical short circuits and leakage accidents. At present, many wire rope electric hoists use high-performance insulating materials, such as polyester films, which have good insulation and heat resistance and can maintain stable insulation effects under different working environments.
Regular testing of insulation performance is essential. Through regular testing of the insulation performance of electric hoists, problems such as insulation aging and breakage can be discovered in time, and corresponding measures can be taken to repair or replace them, thereby avoiding safety accidents caused by reduced insulation performance. According to relevant statistics, the electrical failure rate of electric hoists that are regularly tested for insulation performance is more than 60% lower than that of equipment that has not been tested.
3.2 Leakage protection device
The leakage protection device is an important guarantee for the electrical safety of wire rope electric hoists.
The function of the leakage protection device is to quickly cut off the power supply in a short time when a leakage fault occurs in the equipment to prevent the current from causing harm to the human body. Generally speaking, the action current of the leakage protection device should be set below 30mA, and the action time should be less than 0.1 second to ensure that the power supply can be cut off in time and effectively when leakage occurs to protect the personal safety of the operator.
The reliability of the leakage protection device is crucial. A high-quality leakage protection device can accurately detect the leakage signal and respond in time. At present, some advanced leakage protection devices on the market use advanced electronic technology and intelligent algorithms, which can effectively avoid false operation and leakage operation, and improve the reliability and accuracy of leakage protection.
Regular inspection and maintenance of the leakage protection device is the key to ensure its normal operation. Regular inspection and maintenance of the leakage protection device can timely discover problems with the device, such as decreased sensitivity, poor contact, etc., and repair or replace it in time to ensure that the leakage protection device is always in good working condition. According to relevant research, the failure rate of regularly maintained leakage protection devices is more than 70% lower than that of unmaintained devices.

4. Limit and brake safety features
4.1 Upper and lower limit devices
The upper and lower limit devices of the wire rope electric hoist are key components to ensure that the equipment operates within the safe travel range.
The role of the limit device: The upper and lower limit devices can effectively prevent the hook from exceeding the safe travel range during operation. When the hook approaches the upper or lower limit, the limit device will automatically cut off the power supply to stop the equipment from running, avoiding collision between the hook and the drum or the ground, thereby protecting the safety of the equipment and operators. According to statistics, the occurrence rate of hook collision accidents can be reduced by more than 70% with effective upper and lower limit devices.
The type and accuracy of the limit device: There are two common limit devices: mechanical and electronic. The mechanical limit device realizes the limit function through the mechanical structure, and its structure is simple and reliable; the electronic limit device realizes the limit control through sensors and electronic circuits, and has the advantages of high accuracy and fast response speed. At present, the electronic limit device used in advanced wire rope electric hoists can achieve millimeter-level accuracy, which can more accurately control the travel of the hook and ensure the safe operation of the equipment.
4.2 Reliability of the braking system
The braking system is one of the core safety devices of the wire rope electric hoist, and its reliability is directly related to the safe operation of the equipment.
Type and performance of brake: Wire rope electric hoists usually use electromagnetic brakes or mechanical brakes. Electromagnetic brakes have the advantages of fast response speed and good braking effect, and can brake quickly when the equipment is powered off or in an emergency; mechanical brakes rely on mechanical structures to achieve braking, and have the characteristics of simple structure and high reliability. Regardless of the type of brake used, its braking distance and braking time must meet the relevant safety standards. For example, for an electric hoist with a rated lifting capacity of 3 tons, its braking distance should be controlled within 30 mm and the braking time should be less than 0.2 seconds to ensure that the equipment can stop quickly and safely during emergency braking.
Maintenance and inspection of the braking system: Regular maintenance and inspection of the braking system is the key to ensuring its reliability. Maintenance includes checking the wear of the brake, adjusting the brake clearance, etc. to ensure the normal operation of the brake. Inspection requires a comprehensive evaluation of the performance of the braking system, including indicators such as braking distance, braking time, and braking stability. According to relevant statistics, the failure rate of brake systems that are regularly maintained and inspected is more than 85% lower than that of systems that are not maintained and inspected.

5. Operational safety features

5.1 Prohibition of tilting and slanting
Tilting and slanting is a strictly prohibited operation method during the use of wire rope electric hoists. This operation method has great safety hazards.

Force analysis: When tilting and slanting, the wire rope forms a certain angle with the vertical direction, and the tension on the wire rope will increase. According to the principle of trigonometric function, when the angle is 30 degrees, the tension on the wire rope will increase by about 17.3%; when the angle reaches 45 degrees, the tension will increase by about 41.4%. This increased tension will cause the stress on the wire rope to exceed its design range, which may easily cause the wire rope to break and cause safety accidents.

Risk of equipment damage: Tilting and slanting will also cause damage to other parts of the electric hoist. For example, it will cause abnormal lateral force on components such as the drum and hook. Long-term use will cause problems such as drum deformation and hook damage. According to statistics, equipment damage accidents caused by crooked lifting account for about 30% of the total equipment damage accidents, which seriously affects the service life and safety of the equipment.
Accident case: An accident caused by crooked lifting occurred in a factory. When the operator was lifting the heavy object, he pulled the electric hoist crookedly for convenience. As a result, the wire rope suddenly broke, and the heavy object fell, injuring a nearby worker, causing serious casualties and economic losses. This accident once again reminds us that crooked lifting is strictly prohibited, and the lifting operation must be carried out strictly in accordance with the operating procedures.
5.2 Restrictions on the suspension and movement of heavy objects
During the operation of the wire rope electric hoist, there are strict safety restrictions on the suspension and movement of heavy objects. These restrictions are to ensure the safety of equipment and personnel.
Restrictions on the suspension of heavy objects: The heavy object must be firmly hung on the hook, and the hanging position must be correct to avoid eccentric loading. If the heavy object is not firmly hung or there is eccentric loading, the hook and wire rope will be subjected to uneven tension, which may easily lead to problems such as hook deformation and wire rope breakage. For example, when the overload of the heavy object reaches 20% of the rated lifting capacity, the maximum tension on the hook will increase by about 30%, greatly increasing the probability of equipment damage and accidents. Therefore, the suspension of the heavy object must be carefully checked before lifting to ensure that it meets safety requirements.
Restrictions on the movement of heavy objects: During the lifting process, the speed and direction of the movement of the heavy object are also restricted. The lifting and lowering speeds of the electric hoist should be kept stable, avoiding too fast or too slow. Generally speaking, the lifting speed should be controlled at about 10 meters per minute, and the lowering speed should be controlled at about 15 meters per minute. Too fast speed will cause the heavy object to generate a large inertial force, which is easy to cause equipment out of control and accidents. At the same time, the heavy object should maintain vertical movement during the movement to avoid lateral swing. If the heavy object swings laterally, the operation should be stopped immediately and the lifting should be continued after the heavy object is stable. According to relevant research, accidents caused by excessively fast movement speed or lateral swing of heavy objects account for about 25% of the total number of lifting accidents, so the restrictions on the movement of heavy objects must be strictly observed.
Safety distance requirements: When lifting heavy objects, a certain safety distance should also be maintained. A safety distance of at least 1 meter should be maintained between the heavy objects and the surrounding personnel, equipment and other obstacles to prevent the heavy objects from colliding with them during movement, causing casualties and equipment damage. For example, at a construction site, because the operator did not maintain a sufficient safety distance, the hoisted heavy objects collided with the nearby scaffolding, causing the scaffolding to collapse and causing multiple injuries. This accident reminds us that we must always pay attention to the safety distance during the lifting process to ensure the safety of the lifting operation.

6. Maintenance and inspection of safety features

6.1 Regular inspection content
Regular inspection is an important means to ensure the safe operation of wire rope electric hoists, and its inspection content includes several key aspects.
Structural component inspection: Check whether the key structural components such as hooks, wire ropes, and drums have abnormal conditions such as deformation, wear, and cracks. For example, the number of broken wires in the wire rope is an important indicator to measure its safety status. When the number of broken wires exceeds 10% of the total number of wire ropes, the wire rope should be replaced. According to relevant statistics, regular structural component inspections can timely discover more than 80% of potential equipment problems and effectively avoid safety accidents caused by component damage.
Electrical system inspection: Check the insulation and contact of the electrical circuits, and whether the electrical components such as motors, controllers, and limit switches are working properly. Electrical failures may cause equipment loss of control or leakage accidents. Regular inspections of the electrical system can reduce the incidence of electrical failures by more than 70% and ensure the safe operation of the equipment.
Braking system inspection: Check the sensitivity and reliability of the brake, and measure whether the braking distance meets the requirements. For electric hoists with different rated lifting capacities, the braking distance has different standards. For example, for electric hoists with a rated lifting capacity of 2 tons, the braking distance should be controlled within 20 mm. Regular inspection of the braking system can ensure that it can brake quickly and reliably in an emergency, reducing the risk of accidents caused by brake failure.
Lubrication system inspection: Check whether the lubrication points of the equipment have sufficient lubricating oil and whether the lubrication system is working properly. Good lubrication can reduce component wear, extend the life of the equipment, and also ensure the normal operation of the equipment. Regular inspection of the lubrication system can reduce failures caused by poor lubrication and improve the safety and reliability of the equipment.
6.2 Maintenance requirements
Maintenance is an important measure to extend the service life of the wire rope electric hoist and ensure its safe operation. Its requirements include the following points.
Cleaning and anti-corrosion: Keep the surface of the equipment clean, regularly remove impurities such as dust and oil, and prevent the equipment from overheating or corrosion due to dirt accumulation. For electric hoists used outdoors, anti-corrosion measures should also be taken, such as applying anti-rust paint, to extend the service life of the equipment.
Component replacement and adjustment: timely replace severely worn components, such as wire ropes, hooks, brakes, etc. At the same time, regularly adjust the mechanical components of the equipment, such as adjusting the tension of the wire rope, the clearance of the brake, etc., to ensure the normal operation of the equipment. Regular replacement and adjustment of components can reduce the equipment failure rate by more than 50%, effectively ensuring the safety of the equipment.
Lubrication and refueling: According to the requirements of the equipment manual, regularly refuel the lubrication points of the equipment to ensure good lubrication of the equipment. Use appropriate lubricating oil, and pay attention to the cleanliness of the lubricating oil to prevent impurities from entering the lubrication system. Good lubrication can reduce component wear and improve the operating efficiency and safety of the equipment.
Recording and archiving: Establish equipment maintenance records, record the content, time and results of each inspection, maintenance and maintenance in detail, and archive them. Through recording and archiving, it is easy to understand the historical status of the equipment, provide a reference for the management and maintenance of the equipment, and also help to discover potential problems in the equipment and take timely measures to solve them.

7. Summary
As a widely used lifting equipment, the wire rope electric hoist has many safety features, which together ensure the safety of the equipment during use.
From the perspective of equipment structural safety characteristics, the safety device of the hook and the design of the wire rope and drum are the key. The anti-unhooking device equipped on the hook can significantly reduce the incidence of accidents of suspended objects falling. Its high-strength alloy steel material and advanced heat treatment process make it extremely tensile and can reliably carry suspended objects. The breaking tension of the wire rope is much higher than the working tension, and the advanced twisting process improves its flexibility and wear resistance; the reasonable design of the drum, such as the appropriate diameter, length and spiral groove, effectively avoids the phenomenon of wire rope disorder, prolongs the service life and improves safety.
In terms of operational safety characteristics, operator qualification requirements and pre-operation inspection procedures are crucial. Operators who have undergone professional training and hold certificates have a significantly lower operating error rate, and healthy and experienced operators can better ensure the safe operation of the equipment. Appearance inspection, electrical system inspection, brake system inspection and lubrication system inspection before operation can timely discover potential problems of the equipment, effectively reduce the failure rate, and ensure that the equipment operates in a safe state.
In electrical safety characteristics, insulation performance and leakage protection devices are the focus. The insulation resistance of the electric hoist meets national standards. High-quality insulating materials and regular inspections can effectively prevent electrical short circuits and leakage accidents. The leakage protection device can quickly cut off the power supply when a leakage fault occurs to protect the safety of the operator. Its reliability and regular maintenance are crucial. High-quality leakage protection devices and regular maintenance can significantly reduce the failure rate.
In terms of limit and brake safety characteristics, the upper and lower limit devices can effectively prevent the hook from exceeding the safe travel range and reduce the incidence of collision accidents; the reliability of the braking system can ensure that the equipment stops quickly and safely in an emergency. Regular maintenance and inspection of the braking system can greatly reduce its failure rate.
The operational safety characteristics emphasize the importance of prohibiting crooked and oblique lifting and heavy object suspension and movement restrictions. Crooked and oblique lifting will increase the tension of the wire rope, leading to equipment damage and safety accidents, while the firm suspension of heavy objects, reasonable moving speed, vertical movement and safety distance requirements can effectively avoid equipment damage and casualties.
In the maintenance and inspection safety features, regular inspections cover structural components, electrical systems, brake systems and lubrication systems, which can promptly detect potential equipment problems; maintenance requirements include cleaning and anti-corrosion, component replacement and adjustment, lubrication and refueling, and record keeping and archiving. These measures can extend the service life of the equipment, reduce the failure rate, and ensure the safe operation of the equipment.
In summary, the safety features of the wire rope electric hoist are fully guaranteed from multiple aspects such as equipment structure, operating procedures, electrical systems, limit brakes, operating specifications, and maintenance inspections. These features work together to form a relatively complete safety system, which effectively reduces the safety risks during the use of the equipment and ensures the safety of personnel and equipment.