Basic Parameters for Crane Selection

Lifting load, rated capacity, maximum working radius, maximum lifting height — these parameters are critical for developing lifting plans and technical solutions.

Components of the lifting load: The weight of the object being lifted (equipment or structure) in its hoisted state plus the weight of the slings and rigging hardware (for mobile cranes, this typically also includes the weight of the hook block and the weight of the hoist rope hanging from the boom tip to the hook). For example, the lifting load for a crawler crane is the sum of the weight of the equipment being lifted (including any reinforcements and lifting lugs), the weight of the slings (rope slings), the weight of the hook block, and the weight of the hoist rope hanging from the boom tip.

2. Calculated Load

(1) Dynamic Load Factor
A coefficient that accounts for the additional load impact on the lifting equipment caused by the motion of the crane during hoisting. In lifting engineering calculations, this influence is factored in using the dynamic load factor. Typically, the dynamic load factor is taken as K₁ = 1.1.

(2) Imbalanced Load Factor
When two or more lifting devices (such as multiple cranes or multiple pulley systems) jointly lift a single load, additional loads may act on the cranes, the load, and the rigging due to their relative motion, or because the devices may not work in perfect synchrony, causing each branch not to share the load exactly as intended. In lifting engineering, this effect is accounted for by the imbalanced load factor. Typically, the imbalanced load factor is taken as K₂ = 1.1 to 1.25.

(3) Calculated Lifting Load
The calculated lifting load (abbreviated as the calculated load) is equal to the dynamic load factor multiplied by the lifting load. In lifting and rigging engineering, the calculated load is commonly used as the basis for design calculations. In the design of lifting operations involving multiple cranes lifting a single piece of equipment, the calculated load for one crane, taking into account the effects of load motion and load imbalance, is generally calculated using the following formula:
Qj = k₁ × k₂ × Q

Where:

• Qj — Calculated load;
• k₁ — Dynamic load factor;
• k₂ — Imbalanced load factor;
• Q — Lifting load assigned to one crane, including the weight of the equipment and the rigging hardware.

3) Rated Capacity

(1) The maximum lifting capacity of the crane at the selected boom length and working radius must be greater than the calculated lifting load (Qj).

(2) When two lifting devices are used simultaneously to lift a single load, it is preferable to use cranes of the same type or with similar performance characteristics. The load should be distributed rationally based on the lifting capacity of each device. The total lifted weight should not exceed 75% of the sum of the allowable lifting capacities of the two devices. The load on any single lifting device should not exceed 80% of its safe working load.

Maximum Working Radius
The maximum working radius is the crane’s maximum lifting radius, which corresponds to the radius at its rated capacity.

Maximum Lifting Height
The maximum lifting height must satisfy the following requirement:
Hm > H₁ + H₂ + H₃ + H₄

Where:

• Hm — Lifting height to the sheave at the boom tip of the crane (m);
• H₁ — Height of the equipment (m);
• H₂ — Rigging height from the top of the equipment to the hook (including the height of the rope, spreader beam, shackles, etc.) (m);
• H₃ — Height from the top of the foundation or anchor bolts to the bottom of the equipment during installation (m);
• H₄ — Height of the foundation or anchor bolt top (m).