Automating cable yarder skyline shifting
ANEW SKYLINE CARRIAGE THAT ALLOWS A YARDER OPERATOR to perform a skyline shift in a matter of seconds from the comfort of his cab is in an advanced phase of development. A prototype of the carriage has already been constructed by Gisborne-based Awdon Technologies Ltd and recently performed in-forest demos in the North Island, but it requires further refinement before going into production.
The Skyshifter Twin Winch Tail Hold Carriage is another product of the Steepland Harvesting programme devised by the former Future Forest Research organisation, now renamed Forest Growers Research (FGR), and backed by the government’s Primary Growth Partnership (PGP) fund.
Shifting the skyline is a time consuming, difficult and potentially hazardous task, but with the Skyshifter, it can be simply undertaken remotely from the yarder cab.
Don Scott, of Awdon Technologies, has spent much of the past year developing the Skyshifter, among other projects. Don spoke to a group of farm foresters at a demonstration organised by FGR in April, saying: “The idea behind it is that when you are grappling you need to move sideways to grab the wood.
“How it works is that it’s got two winches in a box, with each winch line going to a stump (tail hold), so then it can pull the skyline across by up to 60 metres. Ultimately, I’d like to get it so that it can do 100 metres or even 150 metres and to move even faster than it does now – currently it takes 40 seconds to move 10 metres, which is still pretty good.
“This one is just a prototype and the next one I build will be different and a lot more exciting and less heavy.”
The prototype currently weighs around 3.5 tonnes, including the small engine to power the winches, plus all the rope on board.
Spencer Hill, FGR project leader for the Skyshifter development, says: “This is about being able to set up and log for two or three days without anyone near the skyline.”
With the yarder up to 600 metres away and the Skyshifter suspended between the skyline and the two winch lines to a pair of tail hold spars, it is suspended off the ground. This enables the yarder operator to work within a large triangle, grappling logs over a huge area before moving to a completely new position. Maximum pull on the skyline is limited to around 10 tonnes.
Spencer says: “Because when you are grappling there will be no one near it for two days, in theory you can log a two-shift scenario, so it opens up the opportunity for extended shifts, or night operation.”
While the Skyshifter has been field tested in a hauler operation since it was built, FGR says the next step is to put it through its paces in real production trials over a longer period of time and FGR is currently looking for a suitable crew to take up the challenge.
The Skyshifter Twin Winch Tail Hold Carriage built by Awdon Technologies.