Forestry: Zero swing

By: Patrick Cox, Photography by: Patrick Cox


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Forestry Low centre of gravity for those steep climbs Forestry

Back in the late eighties I was given the opportunity to purchase a 20-tonne excavator and attach a Hultdins 850 felling head on the end of the stick.

Forestry: Zero swing
A blank canvas for your guarding package

This was the first production Hultdins felling head in New Zealand. The guarding package was an uncertified ROPS cab and sidewalks, track guards and nothing else. Since then, in the short space of twenty years, we now send machines to the tree face looking like tanks.

That 20-tonne digger took a beating, but it survived to finish a full life as a harvesting machine. But at the time, it was a dream to convince one of the manufacturers to send an excavator to New Zealand, as a box of bits, so you could put it together without that big bum hanging out the back.

There were many occasions while felling in amongst the standing trees, when you were required to slew yourself out of trouble, only to forget and come to a screaming halt as your long tailswing wacked into a standing tree, on these occasions I asked the question, "Why have we put these catwalks on, as they only make the machine wider?"

Today, wishes have been answered with purpose-built self-leveling zero-swing harvesters available from a number of manufacturers. But if a purpose-built harvester is not in your order book and you just want an excavator for skid work, loading trucks or shovel logging, then what do you buy? Once again safety could play a big part in your decision-making. Would a zero-swing excavator make a good choice?

A few weeks ago I had occasion to visit a logging crew. The make-up was very normal, with a tight skid site when working with limited available space. They had two excavators, four guys on the skid processing, and a skidder pulling up to the edge of the landing.

Standing there, I asked the question: What had changed in the last twenty years? Not a lot in my opinion. We have just added technology and upgraded our guarding packages.

Watching the excavators manoeuver around the skid, operating close to the trucks, log stacks and men has the operator on red alert at all times. A zero-swing machine would have to be considered a good option in situation like this. The operator would have peace of mind, the men on the landing would feel safer and the zero swing would create more space.

Contractors are entering new territory with the new generation zero-swing excavators and engineering companies will also be entering new ground trying to sell guarding packages. This is an opportunity for the contractor to order what he wants, rather than what has been accepted.
When engaging engineers to add extra guarding to a standard excavator for bush work, I have to ask the question — are some of these companies selling more than what is required to do the job? Are they adding too much weight to the machine and will this have any long-term effects on the final drives and track gear?

The over development of track guards, and the wear problems from such, means that when your chains need replacing there is a good possibility you will have to replace the shoes as well.

It is interesting to note the new Volvo ECR305 zero swing is leaving the factory with well-built track guards, strengthened front idlers and is already half a metre off the ground. Why would you want this machine to be made higher and wider? How much space do you want under your machine? Are you being sold on an idea that is not completely necessary?

Sometimes it appears buyers are going for high and wide just because this has become the accepted thing to do, rather than essential for that particular operation. The purpose-built harvester by Tigercat has put a lot of emphasis on low centre of gravity to give the machine stability when felling. Volvo, in the development of its ECR305, has also kept the weight down low, for better climbing and stability. The benefit of this is your operator gets a better ride and more comfort. This equates to better production and ultimately a better return for the owner.

So now when you, the purchaser, have to make the decision on your guarding package, the time might have come for change. Order what you want, not what the engineers are trying to sell you. For those that have already switched to zero-swing excavators, their first comments are, 'I don't have to worry where my bum is anymore'. Everything swings inside the tracks, allowing the operator to work in confined spaces.

As the contractors continue to make advances towards a safer environment in the work place, will the forest owners see the benefits of zero swing and start to make it compulsory in all bush undertaking, gradually bringing them in over the next ten years? Who knows? The manufacturers themselves might decide these are the excavators of the future and start to phase out the manufacture of full tail-swing excavators [That's a big call, Mr Cox — Ed].

Guarding packages are here to stay, but modifications will need to change to suit each individual machine. It probably should be cheaper to do on zero-swing machine as there is less visible machine to guard, but to retain that zero swing, the sidewalks would have to go, as putting these on defeats the purpose.

How many times have you been on a logging site and observed a machine with a back door missing? It could stay like this for months and never does it take a knock again because the operator is conscious that it is missing. With the massive guarding packages on our modern machines, does this give an operator license to be a bit more reckless, thinking he is now bulletproof? Not good thoughts. Excellent operators should always be excellent operators, no matter what their machine is wrapped in.

The New Zealand logger is an inventive person and is always looking for a better way to do the job. Will the new 35-tonne Volvo ECR305 be the new toy on the skid site or hauler pad? A machine such as this would have to be a good option and it will be interesting to watch the inventive guarding packages appear on zero-swing excavators.

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