How to Calculate the Lifting Speed of an Electric Hoist?

How to Calculate the Lifting Speed of an Electric Hoist?

For consumers in the international wholesale procurement market, understanding the lifting speed of an electric hoist is crucial for ensuring work efficiency and safety. This blog will provide a comprehensive guide on calculating the lifting speed of an electric hoist.

I. Basic Concepts and Importance of Lifting Speed
A. Definition of Lifting Speed
Lifting speed refers to the vertical displacement speed of the electric hoist's hook or lifting trolley within a unit of time, typically measured in meters per minute (m/min).
B. Significance of Lifting Speed
Work Efficiency: An appropriate lifting speed can enhance work efficiency. For instance, in workshops or construction sites handling heavy loads, a faster lifting speed can save time and improve productivity.
Safety Assurance: Reasonable lifting speed ensures operational safety. Excessive speed may cause instability in lifting and increase safety risks. Conversely, excessively slow speeds may affect work progress.
Equipment Service Life: Proper lifting speed helps extend the service life of the electric hoist. Excessively high speeds can lead to motor overload, increased wear and tear of components, and reduced equipment lifespan.

II. Factors Affecting Lifting Speed
A. Electric Hoist Specifications
Motor: The motor's power and rated speed significantly impact lifting speed. Generally, higher motor power and rated speed result in faster lifting speeds. For example, a 20-ton electric hoist with a 15kW motor and 960r/min rated speed has a lifting speed of 4m/min.
Transmission System: The transmission ratio of the reducer and other transmission components affects the lifting speed. A lower transmission ratio increases the lifting speed.
B. Load Weight
Under the same motor power and transmission ratio, the lifting speed decreases as the load weight increases. For instance, when an electric hoist lifts a rated load and a light load, the lifting speed under the light load is faster than under the rated load.
C. Power Supply and Voltage
Stable power supply and appropriate voltage are essential for achieving the rated lifting speed. If the voltage is too low, the motor's output power decreases, resulting in slower lifting speeds or even failure to lift the load. Conversely, excessively high voltage may damage the motor.
D. Working Environment
In harsh working environments, such as high temperatures, low temperatures, or humid conditions, the motor's performance may decline, leading to reduced lifting speed.

III. Calculation Methods for Lifting Speed
A. Theoretical Calculation Method
Formula: The basic formula for calculating lifting speed is v = π × D × n / (i × 60), where v is the lifting speed (m/min), D is the drum diameter (m), n is the motor's rotational speed (r/min), and i is the total transmission ratio of the transmission system.
Example: Consider a 5-ton electric hoist with a drum diameter of 0.2m, a motor rotational speed of 960r/min, and a total transmission ratio of 30. The lifting speed is calculated as follows: v = π × 0.2 × 960 / (30 × 60) ≈ 0.32m/min.
B. Measurement Method
Tools and Equipment: Use a steel tape measure to measure the lifting distance and a stopwatch to record the time taken.
Steps:
Attach a weight of known mass to the electric hoist's hook.
Measure a vertical distance of 1m or more from the ground using the steel tape measure.
Start the electric hoist and lift the weight at a constant speed. Use the stopwatch to record the time taken to lift the weight over the measured distance.
Repeat the measurement 3–5 times and calculate the average lifting speed.
C. Calculation Based on Motor Power and Load Weight
Formula: The formula P = F × v / 1000 can be rearranged to calculate the lifting speed as v = (P × 1000) / F, where P is the motor power (kW) and F is the lifting force (N). The lifting force F is equal to the load weight G divided by the mechanical advantage of the pulley system.
Example: Suppose a 10-ton electric hoist with a motor power of 7.5kW has a lifting force F = G / 2 = (10,000N) / 2 = 5,000N (assuming a double-block pulley system with a mechanical advantage of 2). The lifting speed is calculated as v = (7.5 × 1000) / 5,000 = 1.5m/min.
D. Calculation Based on Electric Hoist Model and Parameters
Refer to Manufacturer's Specifications: Manufacturers typically provide detailed specifications for electric hoists, including lifting speed. Users can directly refer to these specifications to determine the lifting speed of the desired model.
Example: For a CD1-type electric hoist with a rated load of 10 tons, the lifting speed can be found in the manufacturer's specifications. For instance, the lifting speed for a CD1-10 electric hoist is approximately 8m/min.

IV. Calculation Examples and Analysis
A. Example 1: Single-Speed Electric Hoist
Assume a 5-ton electric hoist with a motor power of 4kW, a rated voltage of 380V, a motor rated speed of 1,440r/min, a drum diameter of 0.25m, and a total transmission ratio of 40.
Using the theoretical calculation method: v = π × 0.25 × 1,440 / (40 × 60) ≈ 0.3m/min. Through actual measurement, the lifting speed is approximately 0.28m/min. The slight discrepancy between the theoretical and measured values may be due to factors such as mechanical friction and power supply voltage.
B. Example 2: Two-Speed Electric Hoist
Consider a two-speed electric hoist with a rated load of 10 tons. The motor power is 7.5kW, and the rated speeds for the two gears are 960r/min and 720r/min. The drum diameter is 0.3m, and the total transmission ratios for the two gears are 30 and 40, respectively.
For the first gear: v1 = π × 0.3 × 960 / (30 × 60) ≈ 0.48m/min. For the second gear: v2 = π × 0.3 × 720 / (40 × 60) ≈ 0.28m/min.
V. Applications of Lifting Speed Calculation
A. Selection of Electric Hoists
When selecting an electric hoist, users can calculate the required lifting speed based on their specific needs and compare it with the specifications of different models to choose the most suitable one.
B. Work Schedule Planning
Accurate calculation of lifting speed helps plan work schedules. For example, in a workshop requiring the lifting of 10 tons of materials over a height of 5m within 2 minutes, the required lifting speed can be calculated to select an appropriate electric hoist model.
C. Equipment Upgrades and Optimization
By calculating the lifting speed of existing electric hoists, users can identify whether the equipment meets the current production requirements. If the lifting speed is insufficient, measures such as upgrading the motor or adjusting the transmission ratio can be taken.

VI. Precautions for Lifting Speed Calculation
A. Accuracy of Parameters
Ensure the accuracy of parameters such as motor power, rated speed, drum diameter, and transmission ratio to enhance the reliability of the calculation results.
B. Consideration of Load Weight
When calculating lifting speed, consider the actual load weight. For rated loads and light loads, the lifting speed may vary.
C. Stability of Power Supply
Ensure the stability of the power supply and voltage to avoid deviations in calculation results caused by voltage fluctuations.
D. Regular Equipment Maintenance
Maintain the electric hoist regularly to ensure proper operation of components such as motors and reducers. This helps achieve the rated lifting speed and prolongs the equipment's service life.