9. Crane documentation and markings
9.1 Load charts
9.2 Crane operator's manual
9.3 Crane markings
9.1 Load charts
Load charts, also called rated capacity charts, identify what a crane is able to lift safely.
Load charts must include the information specified in AS 1418.5 Cranes, hoists and winches - Mobile cranes (non-Queensland Government link), be written in English and use metric units. Where the crane has one main load chart, this should be fixed in the operator's cabin in a clearly visible location. Where the crane has numerous load charts (e.g. for different boom and fly jib configurations), the charts should be kept in a book, folder or envelope in the operator's cabin.
Lifting should not take place unless the load charts are in the crane cabin. Although the crane's load moment system may appear to be operating correctly, the load charts must be available to verify that the crane is not being overloaded.
The lifting capacity of a crane is limited by:
- structural strength when the working radius is small; and
- stability when the working radius is greater.
The load charts on most cranes have a bold line or shaded area dividing the chart into two segments. The divided segments shows the crane operator which capacities are limited by structural strength, and which are limited by stability.
Ratings above the line are based on structural strength, while the ratings below the line are based on the stability of the crane. If a crane is overloaded in the structural area of the load chart, a structural or mechanical component of the crane may fail. However, if the crane is overloaded in the stability area of the load chart, the crane may overturn.
The lifting capacities specified on a load chart must never be exceeded, except during testing of the crane by a competent person under controlled conditions.
On some mobile cranes, there may be numerous load charts for differing boom and counterweight configurations. The load charts may be complex and include numerous conditions that must be complied with to ensure the crane can safely lift a load. Two important factors that are often overlooked when reading load charts are:
- The need to subtract the mass of the hook block and lifting slings from the capacity of the crane at the particular radius, unless otherwise noted on the load chart. For example, if the load chart states the crane can lift 20 tonnes at a given radius, but the hook and lifting gear have a combined mass of one tonne, the load to be lifted cannot be greater than 19 tonnes. This issue becomes critical for heavier hook blocks and lifting gear (e.g. spreader beams).
- The need to subtract the mass of the fly jib from the capacity of the main hook when lifting from the main hook on the main boom with a fly jib attached to the boom head, unless this is allowed for and noted on the load chart. Capacities of the main boom are generally based on the fly jib being removed. If this issue is ignored, the likelihood of the crane overturning can be very high.
9.2 Crane operator's manual
The crane operator's manual is to be supplied with the mobile crane. The manual must be written in English, and kept on the crane at all times.
9.3 Crane markings
A mobile crane and its lifting components must be marked permanently and legibly in accordance with the requirements specified in AS 1418.5 Cranes, hoists and winches - Mobile cranes (non-Queensland Government link). The markings must be in English, with values in SI units.
All operator controls must be suitably marked to indicate their function and operation. The markings on the controls must be either in English or international code. The crane's computer is to be compatible with these requirements.
Last updated 21 August 2008