Rated load of electric hoist: key points and in-depth analysis

Rated load of electric hoist: key points and in-depth analysis
In the industrial field, electric hoists are indispensable material handling equipment, and their rated load is a core parameter that buyers are extremely concerned about. The following is a detailed introduction to the rated load of electric hoists:

1. Definition of rated load
Rated load refers to the maximum weight that an electric hoist is allowed to lift under normal working conditions. It is a key indicator to measure the load-bearing capacity of an electric hoist, ensuring that the equipment operates safely and reliably within the specified load range.

2. Common rated load ranges and corresponding specifications
Small electric hoists: The rated load is generally between 0.05 tons and 3 tons. For example, a 0.05-ton electric hoist is usually used for some light lifting work, such as lifting small parts and tools in small factories or repair workshops; a 1-ton electric hoist is more widely used and can be used to lift some medium-sized mechanical parts, packaged goods, etc.
Medium electric hoists: The rated load is usually around 5 tons to 10 tons. 5-ton electric hoists are often used for lifting materials on production lines in factory workshops, stacking and handling goods in warehouses, etc.; 10-ton electric hoists can be used to lift larger equipment, molds, and heavier goods.
Large electric hoists: The rated load can reach 16 tons, 20 tons, or even higher. These large electric hoists are mainly used for lifting heavy equipment in large industrial projects, handling large steel structures, etc., such as lifting large pipes, containers, equipment components, etc. in power plants, petrochemical plants, shipyards, etc.

3. Factors affecting rated load
Types of electric hoists:
Wire rope electric hoists: The lifting capacity is generally between 0.3 tons and 80 tons. The rated load is determined by factors such as the strength of the wire rope and the winding capacity of the drum. The material, diameter, and twisting method of the wire rope will affect its load-bearing capacity, and thus affect the rated load of the electric hoist.
Chain electric hoist: The rated load range is usually around 0.1 tons to 60 tons. The quality of the chain, the connection method and the load-bearing capacity of the sprocket are the key factors affecting its rated load. The material, strength grade and surface treatment of the chain will affect its load-bearing capacity.
Motor power: The greater the motor power, the greater the traction force that can be provided to lift heavier objects, thereby increasing the rated load of the electric hoist accordingly. However, factors such as the motor's overload capacity and heat dissipation performance also need to be considered to ensure that the motor can operate stably and reliably under the rated load.
Transmission mechanism: It includes transmission components such as reducers, gears, chains or wire ropes. The efficiency, strength and reliability of the transmission mechanism directly affect the rated load of the electric hoist. An efficient transmission mechanism can reduce energy loss and improve lifting capacity; while transmission components with sufficient strength can withstand larger loads to ensure that the electric hoist works normally under the rated load.
Structural design: The overall structural design of the electric hoist, such as the layout of the lifting mechanism, the operating mechanism of the trolley, the strength and rigidity of the hook, etc., will affect its rated load. Reasonable structural design can optimize the load distribution and improve the carrying capacity and stability of the equipment.

4. Methods for determining the rated load
Theoretical calculation: According to the parameters such as the motor power, transmission efficiency, breaking tension of the wire rope or chain of the electric hoist, the theoretical rated load is calculated by mechanical formula. For example, for a wire rope electric hoist, the rated load can be calculated based on the breaking tension of the wire rope divided by the safety factor, combined with the traction of the motor and the efficiency of the transmission mechanism.
Test verification: In the actual production process, manufacturers usually conduct strict type tests on electric hoists, including static load tests and dynamic load tests. The static load test is generally carried out by lifting the electric hoist about 100 mm from the ground at 125% of the rated load for 10 minutes to check whether there are any abnormal conditions such as permanent deformation and cracks in the components of the electric hoist; the dynamic load test is to repeatedly lift and move the electric hoist left and right with the rated load weight to test the normal reliability of its mechanical transmission part, electrical part and connection part, and verify and determine the actual rated load of the electric hoist through the test results.

5. Precautions for rated load and actual use
Overloading is strictly prohibited: Overloading will cause the motor of the electric hoist to overload and heat, accelerate the wear of mechanical parts, reduce the service life of the equipment, and may even cause serious safety accidents, such as hook breakage, wire rope or chain breakage, heavy objects falling, etc.
Consider the safety factor: In actual use, the appropriate safety factor should be selected according to different working environments and load characteristics. For example, in special cases such as lifting high temperatures, corrosive or dangerous goods, the use ratio of the rated load should be appropriately reduced to ensure higher safety.
Regular inspection and maintenance: Regularly conduct comprehensive inspection and maintenance of electric hoists, including checking the wear of wire ropes or chains, deformation and cracks of hooks, sensitivity of brakes, operating status of motors, etc. Timely discover and deal with potential problems to ensure that electric hoists always maintain good working performance under rated load.

6. Selection of rated loads in different application scenarios
Manufacturing factories: Material handling on the production line, such as lifting parts in automobile manufacturing plants, lifting raw materials and finished products in machining workshops, etc., should select electric hoists with appropriate rated loads according to the specific material weight and handling frequency. Generally, electric hoists of 1 to 3 tons can be selected for small parts; for medium-sized engines, transmissions and other parts, electric hoists of 5 to 10 tons can be selected; and for large equipment components or molds, electric hoists with rated loads of 16 tons or even larger are required.
Warehouse logistics: In the stacking and handling of warehouse goods, if the weight of the goods is relatively light, such as packaged electronic products, daily necessities, etc., an electric hoist with a rated load of 1 ton to 5 tons can be used. For some large hardware and building materials warehouses, when handling heavier goods such as steel and wood, electric hoists with a rated load of 10 tons to 20 tons are required.
Construction industry: In the construction process, electric hoists with larger rated loads are usually required for lifting building materials such as concrete components, steel structures, large formwork, etc. For example, in the construction of high-rise buildings, electric hoists with a rated load of 20 tons or even larger may be required to lift heavy prefabricated components.

7. Relationship between rated load and other parameters of electric hoists
Lifting height: Generally speaking, when the rated load of the electric hoist is constant, the higher the lifting height, the longer the required wire rope or chain length, and at the same time, higher requirements are placed on the size and strength of the drum or sprocket. Higher lifting heights may limit the rated load of electric hoists, because longer wire ropes or chains will generate greater deadweight and inertia, affecting the lifting capacity and stability of the equipment.
Lifting speed: There is a certain mutual influence between lifting speed and rated load. Under the condition of a certain motor power, the higher the lifting speed, the smaller the rated load that can be lifted. This is because the higher the lifting speed, the greater the power the motor needs to output to overcome the inertia and friction of the heavy object. When the rated power of the motor is exceeded, the rated load of the electric hoist will be limited.
Working level: The working level of the electric hoist is divided according to its frequency of use and load conditions. The rated load of the electric hoist will also be different at different working levels. For example, for electric hoists with higher working levels, their design and manufacturing standards are higher, and they can withstand more frequent and heavier lifting operations, and the corresponding rated load will be larger; while for electric hoists with lower working levels, they are mainly used in some light or moderate use occasions, and the rated load is relatively small.

8. Rated load characteristics of special electric hoists
Explosion-proof electric hoists: The rated load range is usually similar to that of ordinary electric hoists, but due to its special explosion-proof design, it has higher requirements for the sealing and protection of motors, electrical components and mechanical parts. When used in flammable and explosive dangerous environments, such as chemical plants, gas stations, coal mines and other places, the selection of its rated load should not only consider the weight of the hoisted objects, but also ensure that the equipment can operate reliably under the premise of explosion-proof safety. Generally, the use ratio of the rated load will be appropriately reduced to improve safety.
Metallurgical electric hoists: Specially used for lifting special objects such as high temperature and red-hot metals, its rated load is relatively large, generally between 5 tons and 100 tons. Metallurgical electric hoists use high-temperature resistant materials and special insulation measures to ensure that heavy objects can be safely lifted in high-temperature environments. Due to the extremely high temperature of the hoisted objects, the performance requirements for the hook, wire rope, pulley and other components of the electric hoist are more stringent. At the same time, it is also necessary to be equipped with complete safety protection devices, such as limiters and brakes, to prevent safety accidents caused by damage to components due to high temperature.
Electric hoists for nuclear power plants: Nuclear power plants have extremely high requirements for safety performance, and the rated load of the electric hoists they use is generally determined according to the specific lifting requirements of nuclear power plant equipment. These electric hoists need to strictly follow the safety standards and specifications of nuclear power plants during the design and manufacturing process, use highly reliable materials and advanced manufacturing processes to ensure stable and reliable operation in complex radiation environments, and have multiple safety protection measures and fault diagnosis functions to ensure the safe operation of nuclear power plants.
The rated load of the electric hoist is one of its core parameters. Buyers need to consider a variety of factors when choosing to ensure that the equipment can meet actual use requirements and operate safely and reliably. By deeply understanding the relevant knowledge of rated load, we can better play the important role of electric hoists in industrial production and improve the efficiency and safety of material handling.