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Outrigger pad selection
Background
A recent review of the dunnage supplied with our plant has resulted in additional dunnage available to meet the crane code of practice for work completed in our typical operating environment. Key risks identify:
- Failure to maintain stability is one of the key factors associated with serious crane incidents
- The use of outriggers on crane borers helps provide greater stability to the crane when lifting loads
- Irrespective of ground conditions, timbers or other means of distributing the load must always be placed under the outriggers.
What do you need to do?
All operators of a crane borer and the holder of a C2 or higher HRWL, should know, understand and complete the requirements for calculating the weight being borne by the outriggers and the minimum area required to safely distribute it.
The ground conditions, mass of the crane and the mass of the load must be considered. This will help determine if you need to carry extra dunnage.
The attached matrix minimum area under outrigger M2 – Crane Borer can be used as quick reference guide showing different loads, ground conditions and the required dunnage.
The equation below, taken from the Mobile Crane Code of Practice 2006 (QLD), is used to calculate the minimum area required to safely distribute the load.
0.65 x (total crane mass + lifted load)
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maximum permissible ground pressure
What dunnage should I use?
Essential Energy use four types of dunnage:
- Composite pads (550x550, 22mm thick,13.5kg) – suitable for crane borers and large EWPs on solid ground. These are also used between the outrigger foot and any cribbed dunnage to evenly disperse the load.
- Composite pads (550x550, 16mm thick, 9.8kg) – suitable for smaller EWPs on solid ground. These are also used between the outrigger foot and any cribbed dunnage to evenly disperse the load.
- Composite pads (1,025x395, 50mm thick, 19kg) – used in pairs these can be placed under the plastic pads to increase the surface area in softer ground conditions.
- Hardwood timber (1,200x200, 75mm thick, 23kg) – more versatile than composite pads but slightly heavier. Can be cribbed to form a large foot for poor ground conditions.
Stability is critical to the safe operation of an EWP and similar to cranes outrigger ground pressure must be considered.
The attached matrix minimum area under outrigger M2 – Elevated Work Platform can be used as a quick reference guide showing different vehicle operating weights, ground conditions and then required dunnage for EWPs.
