In the process of purchasing a crane, the business manager usually asks some questions such as:
1.How many hours the cranes will be used per day? by average level
2.How many lifting times per hour by average level? etc.
These questions are prepared for the selection of cranes. Through these questions, the sales manager selects the corresponding crane solution. You will get a crane quotation with work duty marked as A5/M5, A3/M3, etc. Maybe you will be very curious about what these grades represent? Today, we will elaborate on what the work duty of the crane hoisting is, what it affects, and how to calculate and select the appropriate crane working duty.
What Is Crane Hoist Duty Classification?
Crane hoist duty classification helps determine how often and how heavily a crane can be safely used. It ensures:
Longer equipment life – Prevents overloading and wear
Better safety – Reduces breakdowns and accidents
Cost efficiency – Matches the right crane to the job
The classification depends on two main factors:
Load Spectrum – How heavy the loads are (Light to Very Heavy)
Daily Operating Time (Usage Time)– How many hours the crane works per day
How to Determine the Load Spectrum
The load spectrum is based on how much weight the crane lifts regularly:
| Classification | Load Type | Typical Use Case |
|---|---|---|
| Light (M3/1Bm) | Mostly light loads, occasional full load | Warehouses, small workshops |
| Medium (M4/1Am) | Mix of light and medium loads | Construction sites, factories |
| Heavy (M5/2m) | Frequent full loads, heavy use | Steel plants, shipyards |
| Very Heavy (M6+/3m+) | Almost always full loads | Mining, heavy industry |
Calculating Daily Operating Time
The formula to find the average daily operating time is:
t = (2 × N ×H × T) / (V × 60)
Where:
N = Work cycles per hour (e.g., 5 lifts/hour)
H = Average lifting height (meters)
T = Daily working hours (e.g., 8-hour shift)
V = Hoisting speed (meters per minute)
Example Calculation:
If there is a crane which load spectrum is heavy, a crane lifts 5 times/hour (N=5), average height (H=3m), works 16 hours/day (T=16), and speed (V=5 m/min):
t=(2×5×3×16) / (5×60)=1.6 hours/dayt=5×602×5×3×16=1.6 hours/day
This means the crane's duty class is M5 (GB A5 / FEM 2m).
International Duty Class Comparison
Different countries use different codes:
| ISO/BS/DIN | China (GB) | Europe (FEM) | USA (CMAA) |
|---|---|---|---|
| M3 | A3 | 1Bm | A |
| M4 | A4 | 1Am | B |
| M5 | A5 | 2m | C |
| M6 | A6 | 3m | D |
Crane Hoist Duty Classification
In the process of purchasing a crane, the business manager usually asks some questions such as:
1.How many hours the cranes will be used per day? by average level
2.How many lifting times per hour by average level? etc.
These questions are prepared for the selection of cranes. Through these questions, the sales manager selects the corresponding crane solution. You will get a crane quotation with work duty marked as A5/M5, A3/M3, etc. Maybe you will be very curious about what these grades represent? Today, we will elaborate on what the work duty of the crane hoisting is, what it affects, and how to calculate and select the appropriate crane working duty.
What Is Crane Hoist Duty Classification?
Crane hoist duty classification helps determine how often and how heavily a crane can be safely used. It ensures:
Longer equipment life – Prevents overloading and wear
Better safety – Reduces breakdowns and accidents
Cost efficiency – Matches the right crane to the job
The classification depends on two main factors:
Load Spectrum – How heavy the loads are (Light to Very Heavy)
Daily Operating Time (Usage Time)– How many hours the crane works per day
How to Determine the Load Spectrum
The load spectrum is based on how much weight the crane lifts regularly:
| Classification | Load Type | Typical Use Case |
|---|---|---|
| Light (M3/1Bm) | Mostly light loads, occasional full load | Warehouses, small workshops |
| Medium (M4/1Am) | Mix of light and medium loads | Construction sites, factories |
| Heavy (M5/2m) | Frequent full loads, heavy use | Steel plants, shipyards |
| Very Heavy (M6+/3m+) | Almost always full loads | Mining, heavy industry |
Why Does Duty Classification Matter?
Safety compliance – Avoid fines and accidents
Better maintenance planning – Know when to service the crane
Cost savings – Don't buy an over-spec crane for light jobs
3 Tips to Choose the Right Class
Choosing the right crane duty class ensures safety, efficiency, and cost savings. Always check:
Check Loads (load spectrum): how heavy the loads are (use our load chart).
Count Hours (Daily operating time): how long the crane works.
Match to Our Models(International standards): See our Duty Class Guide PDF for quick picks.
Why Buy from Minecrane Brand?
✅ 15-year warranty on M5+ cranes
✅ Free inspection to confirm your duty class
✅ Custom upgrades
View Minecranes Product Line：
FEM Standard Overhead Cranes
125kg- 500 ton Gantry Cranes
European Standard Electric Hoist
New Design Rubber Tyre Gantry Crane
