In this document is explained how a “Crane Capacity Index” (CCI) can be determined. The CCI basically is calculated as follows: “Radius * Lifting Height * Capacity”. The result CCI is in Te ∙ m².

To clarify calculations a Liebherr LTM 1100-5.2 is used as an example.

Units:

Distance meter m
Angle degree °
Weight Metric Ton Te
CCI Te ∙ m²

Constraints

‍

‍

In order to get a fair “Crane Capacity Index” we need to set some constraints:

• Base dimensions;
• Lifting height is height of the center of lower sheave
• Maximum radius = Maximum main boom length with angle of 30°.
• Minimum radius = ½*outrigger base
• 360° swing angle
• Only with standard equipment (no heavy lift attachment, center support, etc.)
• Main boom only (no jib, no guyed main boom)
  A: Crane center – pivot point main boom
  B: Height of crane pivot point On standard tires, 100mm between ground and tires
  C: Sheaves distance

For the Liebherr LTM 1100-5.2 the base dimensions are:

‍A = 2.0 m
‍B = 3.83 m
‍C = 1.1 m

Calculations

Minimum radius
Minimum radius = ½*outrigger base

Liebherr LTM1100-5.2:   ½*7.0 = 3.5 m

Maximum radius
Maximum radius = Maximum main boom length with angle of 30°.
Maximum main boom length*cos(30°) + C*sin(30°) – A

Liebherr LTM1100-5.2:   52.0*0.866 + 1.1*0.5 – 2.0 = 43.58 m

Lifting height

Liebherr LTM1100-5.2 (example with 30.1m main boom at 15m radius:

The base formula for the Crane Capacity Index is:

‍

Notes

• The first radius is the minimum radius, then every 5m, till maximum radius. For the LTM1100-5.2 the used radius are: 3.5; 5.0; 10.0; 15.0; 20.0; 25.0; 30.0; 35.0;40.0; 43.6

• For each main boom length at each radius the “Lifting height*Capacity” is calculated.
  At one radius the value of “Lifting height*Capacity” varies with different main boom lengths.
  At each radius the maximum value of “Lifting height*Capacity” is chosen.

• For every main boom length a table is made, for the LTM1100-5.2:
  ‍

‍Tables for boom lengths 11.5; 15,2; 22,7; 26,4; 33,9; 37,6; 41,3; 45,0; 48,8 are not shown.

The tables for every main boom length result in 1 main table with the highest value of “Lifting height*Capacity” at each radius. An extra column is added in which “Lifting height*Capacity” is multiplied by “Radius”:

Finally an average is calculated of al “Lifting height*Capacity*Radius”. This number divided by 100 results in the Crane Capacity Index.

Bron/Source: Esta

‍