Crane Customized


Selection of ISO Standard for Crane Working Class

The working level of a crane is one of its main technical parameters. The size of the working level is determined by two capabilities: one is the frequency of use of the crane, which is called the crane utilization level; the other is the size of the load that the crane bears, which is called the load state of the crane.

  1. Utilization Class of the Crane

During its effective lifespan, a crane has a certain total number of work cycles. A work cycle of crane operations begins with the preparation to lift a load and ends with the completion of lifting the next load. The total number of work cycles characterizes the utilization level of the crane and is one of the basic parameters for classifying cranes. The total number of work cycles is the sum of all the work cycles a crane performs during its specified lifespan.

The total number of work cycles is related to the crane's frequency of use. For convenience, the total number of work cycles is divided into 10 utilization classes (U0 to U9) within its possible range, as shown in follow table 1.

C lass of utilizationTotal number of crane working cycles, C
U0C ≤ 1.6 × 104
U11.6 × 104 < C ≤ 3.15 × 104
U23.15 × 104 < C ≤ 6.3 × 104
U36.3 × 104 < C ≤ 1.25 × 105
U41.25 × 105 < C ≤ 2.5 × 105
U52.5 × 105 < C ≤ 5 × 105
U65 × 105 < C ≤ 1 × 106
U71 × 106 < C ≤ 2 × 106
U82 × 106 < C ≤ 4 × 106
U94 × 106 < C ≤ 8 × 106
Table 1 Classes U of total numbers of crane working cycles , C
  1. Load State of the Crane

The load state is another fundamental parameter for classifying cranes. It indicates the extent of the load borne by the crane's primary mechanism, the hoisting mechanism. The follow table 2 lists the load states of cranes, each numerically representative of a corresponding nominal state of loading.

State of loadingLoad spectrum factor KpRemarks on the use of crane
Qp0Kp ≤ 0.0313Cranes which hoist usually very light loads and the rated load very rarely
Qp10.0313 < Kp ≤ 0.0625
Qp20.0625 < Kp ≤ 0.125Cranes which hoist the rated load occasionally and , normally, light loads
Qp30.125 < Kp ≤ 0.25Cranes which hoist the rated load fairly frequently and , normally, moderate loads
Qp40.25 < Kp ≤ 0.50Cranes which hoist the rated load frequently and , normally,
heavy loads
Qp50.50 < Kp ≤ 1.00Cranes which are regularly loaded close to the rated load
Table 2 Classes Qp of load spectrum factors , Kp
  1. Working Class of the Crane

The working class of a crane, or its classification, is determined by the crane's utilization class (Table 1) and the crane's load state (Table 2). The working class of a crane is denoted by the symbol A and is divided into 8 levels, from A1 to A8. Any level higher than A8 is collectively referred to as A8.

Classes Qp and load spectrum factor KpClasses U and total number of work cycles
Class QpDesign value of load spectrum factor KpU0U1U2U3U4U5U6U7U8U9
Table 3 Classes A for group classification

Where the Qp and U classes are not specified and only the A class is given , the design calculations shall be based on the number of full load cycles , Cf, as given in the table 4.

A- classDesign number of full load cycles , i .e . Kp = 1 Cf
A021 000
A012 000
A04 000
A18 000
A216 000
A331 500
A463 000
A5125 000
A6250 000
A7500 000
A81 000 000
A92 000 000
A104 000 000
A118 000 000
Table 4 Design basis by classes



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