How to determine the rated load of an electric hoist

How to determine the rated load of an Electric Hoist

Introduction
As a lifting device widely used in the industrial field, the determination of the rated load of an electric hoist is crucial to ensure the safe operation of the equipment, improve work efficiency, and extend the service life of the equipment. If you are building an independent website for electric hoists for international wholesale buyers, providing a detailed and professional guide on determining the rated load of electric hoists will help enhance customers' trust in you and their understanding of your products. This article will explore in depth the key factors and steps for determining the rated load of an electric hoist.

1. Understand the basic parameters of electric hoists
Before determining the rated load of an electric hoist, you first need to be familiar with some of its basic parameters:
Lifting height: refers to the maximum distance that an electric hoist can lift a heavy object vertically. Different working scenarios have different requirements for lifting height. Generally speaking, the lifting height of an electric hoist has a wide range, ranging from a few meters to tens of meters.
Lifting speed: that is, the speed at which an electric hoist lifts a heavy object per unit time. The selection of lifting speed should be determined according to the actual work needs. Usually the lifting speed is between 5m/min and 30m/min. When the lifting speed is greater than 6m/min, a speed regulating device or soft start control device should be adopted.
Operating speed: For electric hoists with operating mechanisms, the operating speed is also one of the parameters that need to be considered. It affects the horizontal movement efficiency of the electric hoist. Generally, the allowable deviation of the operating speed is ±15% of the nominal value (slow speed is not assessed).

2. Key factors for determining the rated load
Working level
The working level of the electric hoist is one of the important bases for determining the rated load. According to the provisions of GB/T3811, the working level of the electric hoist lifting mechanism is divided into 8 levels from M1 to M8, and the load state is divided into L1-light, L2-medium, L3-heavy, L4-extra heavy, corresponding to different nominal load spectrum coefficients Kn and utilization levels T and total design life h.
For example, for electric hoists with lower working levels, such as M1 and M2, they are suitable for intermittent service, and their rated loads are relatively small; while for electric hoists with higher working levels, such as M7 and M8, they can withstand heavier loads and more frequent use, and the corresponding rated loads will also be larger.
**Load state
Light load (L1): In actual use, if the electric hoist mainly bears a lighter load, has a shorter working cycle and a lower operating frequency, then an electric hoist with a lower rated load can be selected. For example, in the light material handling of some small warehouses or workshops, it may only be necessary to select an electric hoist with a rated load of 0.5t or 1t.
Medium load (L2): This is a more common load state, suitable for general industrial production environments, such as the handling and assembly of parts. Usually, an electric hoist with a rated load of about 2t to 5t can be selected.
Heavy load (L3): For places where heavy equipment, raw materials or finished products need to be lifted frequently, such as machining workshops, construction sites, etc., electric hoists with larger rated loads, such as 10t, 15t, etc., should be selected.
Extra heavy load (L4): In some special heavy industrial fields, such as steel mills, port terminals, etc., electric hoists with larger rated loads are required, even up to tens or hundreds of tons.
** Operating environment
Temperature: The working environment temperature of the electric hoist is generally - 20℃ to + 40℃. If the working environment temperature exceeds or falls below this range, it may affect the performance and life of the electric hoist, and even cause the equipment to malfunction. When used in high or low temperature environments, it may be necessary to reduce the rated load or take special protective measures.
Humidity: When the working environment humidity is high, such as in coastal areas or humid workshops, the electrical equipment of the electric hoist is easily damp, affecting the insulation performance. At this time, an electric hoist with a higher protection level should be selected, or the equipment should be treated with moisture-proof treatment, and the rated load should be appropriately reduced to ensure safety.
Corrosive environment: If the electric hoist is used in places with corrosive gases or liquids such as chemical industry and papermaking, its metal structural parts and electrical components are susceptible to corrosion, reducing the strength and reliability of the equipment. In this case, it is necessary to select an electric hoist with anti-corrosion performance, and appropriately reduce the rated load according to the degree of corrosion.
Matching of lifting height and running speed
According to the process requirements of actual work, reasonably select the lifting height and running speed to match the rated load. If the lifting height is high and the running speed is slow, it may lead to reduced work efficiency; conversely, if the lifting height is low and the running speed is too fast, it may affect the stability and safety of the equipment, thereby limiting the determination of the rated load.
Consideration of safety factor
The safety factor is an important indicator to ensure the safe operation of the electric hoist. Generally, the nominal working pressure of the compression spring of the lifting mechanism brake of the electric hoist should meet the level 2 accuracy in GB1239, the breaking load of the reducer body should be at least 8 times the rated load, and the breaking load of the hook housing should be at least 5 times the rated load. When determining the rated load, these safety factor requirements must be fully considered to ensure the safety and reliability of the equipment during operation.

3. Steps to determine the rated load
Clearly define the use requirements
Fully communicate with the purchaser to understand its specific use scenarios, working cycles, operating frequencies, load characteristics and other information. For example, the purchaser is using it for material handling in the production workshop or for lifting heavy objects on the construction site; is it intermittent work or long-term continuous operation; is it lifting light materials or heavy equipment, etc.
Analyze the working level and load state
Determine the working level and load state of the electric hoist according to the use requirements. Combined with the classification of working levels and load states mentioned above, select the appropriate combination of working levels and load states to preliminarily determine the range of the rated load.
Consider the use environment factors
Evaluate the impact of environmental factors on the rated load of the electric hoist based on the climatic conditions and working environment characteristics of the purchaser's area. If the use environment is relatively harsh, such as high temperature, high humidity, strong corrosiveness, etc., the rated load should be appropriately reduced, and corresponding protective measures and equipment selection should be recommended.
Matching lifting height and running speed
According to the actual work process and efficiency requirements, determine the appropriate lifting height and running speed, and match them with the rated load. Ensure that the electric hoist can safely carry the corresponding load while meeting the lifting height and running speed requirements.
Verify safety factor
According to relevant standards and specifications, check whether the various safety factors of the selected electric hoist meet the requirements. For example, whether the strength and reliability of key components such as brakes, reducers, and hooks meet the regulations to ensure that the equipment can operate safely and stably under the rated load.
Provide selection suggestions and solutions
Combining the above factors, provide buyers with specific product selection suggestions, including the model, specification, rated load and other parameters of the electric hoist. At the same time, a variety of solutions can be provided for customers to choose from, and the advantages and applicable scenarios of each solution can be explained in detail.

4. Case analysis
Case 1: Small machinery processing plant
Usage requirements: The factory mainly processes and produces small mechanical parts. It needs an electric hoist for the transportation of raw materials and semi-finished products in the workshop. The working cycle is 8 hours a day, the operation frequency is moderate, the lifting height is about 5 meters, and the running speed does not need to be too fast.
Determine the rated load: After analysis, it is determined that its working level is M3-M4 and the load state is L2. Considering the requirements of lifting height and running speed, combined with the actual situation of the workshop, it is recommended to use an electric hoist with a rated load of 3 tons. At the same time, considering the general environment of the workshop, no special protective measures are required.
Case 2: Coastal port terminal
Use requirements: The port terminal needs an electric hoist for loading and unloading large containers and heavy equipment. The working environment is humid and accompanied by salt spray corrosion. The working cycle is long and it operates almost all day. The lifting height is about 20 meters and the running speed requirement is high.
Determine the rated load: According to its usage scenario, the working level is determined to be M7-M8 and the load state is L4. Due to the harsh working environment and the presence of corrosive factors, it is necessary to use an electric hoist with a high protection level and anti-corrosion performance, and appropriately reduce the rated load. After comprehensive consideration, it is recommended to use a heavy-duty electric hoist with a rated load of 50 tons, and take corresponding anti-corrosion measures, such as stainless steel materials, special protective coatings, etc.

5. FAQ
Q: Can the rated load of the electric hoist exceed its specified value?
A: No. The rated load of the electric hoist is strictly designed and calculated. Using it beyond the rated load will cause the equipment to be overloaded, resulting in serious accidents such as motor burning, brake failure, hook breakage, etc., which will not only damage the equipment, but also endanger the life safety of the operator.
Q: How to ensure that the load of the electric hoist in actual use does not exceed the rated load?
A: First of all, when purchasing an electric hoist, the rated load should be accurately determined according to the actual use needs. Secondly, during use, it is necessary to strictly follow the operating procedures to avoid overloading. In addition, safety devices such as overload limiters can be installed. When the load approaches or reaches the rated load, an alarm will be issued and the power supply will be cut off in time to prevent overloading accidents.
Q: What should I do if the rated load of the electric hoist is not enough?
A: If it is found that the rated load of the existing electric hoist cannot meet the actual work needs, it should be stopped in time, and the use needs should be re-evaluated to select an electric hoist with a larger rated load. Do not modify or overload the electric hoist without permission to avoid safety accidents.

6. Conclusion
Determining the rated load of the electric hoist is a complex and critical process, which requires comprehensive consideration of working level, load status, use environment, lifting height and running speed matching, safety factor and other factors. Through the detailed explanation and case analysis of this article, we hope to help you better provide accurate and reasonable rated load determination solutions for international wholesale buyers, thereby improving the safety, reliability and work efficiency of the electric hoist and enhancing your competitiveness in the market. In actual applications, it is recommended to work closely with professional technicians or suppliers to ensure that the selection and use of electric hoists comply with relevant standards and specifications and meet the actual needs of customers.