Today’s heavy lift cranes weigh almost as much as the loads they lift, which means getting them to the job site can be a challenge.
Not only do crane companies need to be experts in the field, they need to be experts in federal and state Department of Transportation requirements for getting equipment to the job site. Even a small company traveling within its own state has to deal with load limits on roads and bridges. They have to know about special vehicle registration, when permits are required, and what permits are required. They need to know when to remove weight from the crane, and how to transport the boom and counterweights separately. Larger companies, traveling over state lines, need to know the subtle differences in requirements from state-to-state or may be faced with large fines, travel delays, or accidents.
Extra planning is required if any part of the travel is off-road or on non-paved roads. The travel plan could call for removing weight from the crane in order to stay within weight requirements on public-paved roads. When going off-road, it may be necessary to use wood, metal or cement matting over the full route of travel, or in extreme cases, building a road that can handle the weight of a crane.
It is always important to consider ground support around the entire working area, not just where the load will be lifted.
It is common to think that if the ground is firm enough under the outriggers toward the lift, then the crane will be supported. However, this 500 ton All-Terrain crane has several tons of counterweight being supported by the outriggers on the opposite side of the crane.
If the crane swings over an outrigger, thousands of pounds per square inch of pressure impacts the float and the ground beneath it. Generally, the times three rule for blocking is adequate, but the actual load pressure on the ground for a crane configured similarly must be calculated. Additionally, a compaction test should be conducted to determine ground support.
After obtaining this information, a proper size blocking can be chosen for lifting the load safely.
Read the entire story at Vertikal.net.