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General Guide for crane use

by editor arbor age

Vermeer Australia’s Arborist Seminar Series, held in November last year, provided plenty of insights and learnings from industry experts.

Joe Harris from Into Trees joined Vermeer Australia for the series to share best practice tips and tricks for using cranes on arborist jobs.

Safety: how cranes work and move in arboriculture
Once your crane is set up onsite, you need to get an idea on how the crane can move, and what work it needs to do. At this point, Joe says the driver will telescope out the boom. “The preferred boom inclination for telescoping is around 70 – 75°, and this is typically what it will be set at for the day. Once the boom length is set, you can’t telescope in or out.”

According to Joe there are four key basic movements a crane can make on a job:
• Hoist up/hoist down – the movement of the cables up and down. Depending on how many cables are through the hook, this will impact the speed of hoisting up/down
• Boom up/down, or luff up/down – the inclination of the boom being increased or decreased
• Float in/out – when your boom is moving up or down, and your hook/hoist is moving the opposite – down/up
• Slewing – best imagined from a bird’s eye view, where your boom is moving around in a circle to either slew right or left.

The importance of good communication between the crane driver and arborist
“Good, clear communication between the crane driver and arborist is really important on a job, particularly from a safety point of view. It can be visual or verbal, but communication must be absolutely spot on.

“Ideally, you want a line of sight between driver and the climber, if possible. But most importantly, you want to be using the correct terms for movement, so the driver knows where to move the boom or hoist,” Joe says.

Key principles of crane rigging
Joe says that the most fundamental rule when working with cranes and trees is knowing that cranes are designed for a static load. “Arborists are used to dealing more with dynamic loads, like cutting a branch and letting it swing to the other side of the tree, and cranes are not designed for this. The most common way to upset your crane driver is getting your calculations for pre-load wrong, or putting dynamic load on the crane, so this needs to be managed throughout the job.”

Accurately estimating the weight of the crane’s lifting load is important, so the crane driver can adequately prepare for the load, and make sure the lift is not over capacity. It’s also important as you need to apply the correct amount of pre-load.

Dismantling using a crane
Most climbing arborists normally approach a dismantle by removing the lower branches first, making their way up the tree, so then there is a clear path as they climb their way down. When using a crane, arborists need to approach this differently.

“With a crane, you want to remove the top branches first. This is because you will need to drop the hook of the crane above the branch and lift it up to remove. Then, you will step your way down the tree so you’re removing the lowest branches last.

“Even if you have a crane on site, it might be preferable for you to start the job using traditional climbing techniques, particularly to clear out the bottom of the tree for your lowering zone,” Joe says.

To find out more about Vermeer Australia, including more information on the Vermeer Australia Arborist Seminar Series, head to www.vermeeraustralia.com.au

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