How to Select the Appropriate Bridge Crane Based on Working Level?

How to Select the Appropriate Bridge Crane / overhead crane Based on Working Level?

The core principle for selecting a bridge crane based on its working level is "matching working conditions, choosing the higher level over the lower," avoiding using low-level equipment for high-load operations while also avoiding blindly selecting high-level equipment and wasting costs. Specifically, follow these steps:

Step 1: Determine the Working Level of Your Own Working Conditions
First, determine the required overall working level and the working level of key mechanisms (the hoisting mechanism is the core and usually has the highest requirements) using the ISO 4301 international standard.

For example: In a machining workshop, there are approximately 50 hoisting operations per day, an average of 300 working days per year, and a design life of 15 years. The total number of cycles N = 50 × 300 × 15 = 22.5 × 10⁴, corresponding to a utilization level of L4/U4. The load is mainly 50% of the rated lifting capacity, rarely fully loaded, resulting in a load condition of H2/Q2. Therefore, the final overall working level of the crane is A4.
Step 2: Matching Equipment Configuration and Performance According to Working Level Cranes of different working levels have clear differences in core components, structural strength, and protective design, requiring targeted selection:
 

Crane working class range	Typical application scenarios	Key points for equipment configuration selection
A1~A3 (Light)	Warehouses, finished goods warehouses, and maintenance workshops operate intermittently at low frequency with minimal load fluctuations.	1. Lifting Motor: A standard asynchronous motor is sufficient; no frequency converter is required. 2. Reducer: A soft-tooth surface reducer meets the requirements and is more cost-effective. 3. Structural Components: Steel plate thickness can be selected according to the lower limit of national standards; no additional reinforcement is required. 4. Control Method: Ground-based wired control is preferred for its high cost-effectiveness.
A4~A5 (Intermediate)	The machining and assembly workshop operates at a moderate frequency of 8 hours per day, occasionally at full capacity.	1. Lifting Motor: Variable frequency speed control motor is recommended for smooth starting and reduced impact. 2. Reducer: Hardened gear reducer offers better wear resistance and a longer lifespan. 3. Structural Components: The main beam can adopt a hollow or off-center box-type structure, balancing strength and weight. 4. Safety Devices: Standard configuration includes a lifting capacity limiter and travel limit switch; wireless remote control is optional.
A6~A8 (Heavy/Extra Heavy)	Metallurgical, port, and heavy production lines operate continuously at high frequency, often at full load.	1. Hoisting Motor: A high-power variable frequency motor with overheat protection is required. 2. Reducer: Heavy-duty hardened gear reducer or planetary reducer with strong load-bearing capacity. 3. Structural Components: The main beam adopts a standard box-type structure with thickened steel plates; welds require flaw detection. 4. Safety Devices: A complete set of high-end safety devices (overload alarm + power failure, windproof anchoring, buffer, emergency braking), with dual backup of cab control and wireless remote control. 5. Protective Design: A heat insulation layer is required for high-temperature environments; anti-corrosion coating is required for corrosive environments.