Learning the ropes
I’VE BEEN LOOKING FORWARD TO THE ROB Iron Test, as it is my first experience of a winchassist system that uses a bulldozer as the anchor and winching machine, instead of an excavator. I do like the way it’s set up. Very neat and simple. The idea of positioning the ropes close to the ground keeps the downforce low in case it does pull forward, so it digs itself in deeper. It will take a lot to shift that blade, which is kind of comforting when you’re in a 45-tonne machine on the end of a 7/8” wire rope on a hill.
That wasn’t the only thing I found different with the ROB system. On other winch-assist machines, the mechanism to control winching the ropes in and out is done automatically through the travel pedals on the harvester. Not in this one. You’ve got manual triggers on the hand controls.
For someone jumping into the cab for the first time it is something else to think about and I did have to consciously make a decision when wanting to wind the rope in or out. With time in the seat that would become second nature. I made a few trips up and down the slope to familiarise myself with how to match the winching of the ropes with the travel speed of the 909 and it didn’t take long to feel comfortable.
Yes, it would be great if it was integrated into the pedals, but having said that, it works, and it works well. It’s less complicated, too, so maybe something less to go wrong.
So, for the record, the trigger to wind in the rope is on the left-hand control and to wind out you press the trigger on the right.
Fortunately, the controls for the 909 are set up in the Cat pattern, which is very familiar to me, so I didn’t have to think about too much else.
Walking the machine down on that face, you’re not very conscious of the ropes behind you, even though you can see them on the screen, from the rear-facing camera. The slope was not that steep and the 909 had good traction, so it wasn’t necessary to have much tension on the ropes. In fact, it almost felt like I was travelling on the flat, especially with the cab tilted level.
As this was my first time, I did keep a close watch on the screen to see what weight was on the ropes. If it heads into the red then you know you are starting to put more weight on them. So I’m making sure I have the right balance operating the foot pedals for the tracks and the triggers on the joysticks for the winches. You’ve got the two levels on the display to let you know that the winches are synchronised, reading the tonnage on both. It was good to see that when I was winding in, both were in sync.
If they are not in sync there is a dial on the display you can turn up or down to get a higher speed. During one of the test runs, walking up the hill, the 909 was travelling a bit faster than the winches were winding in as I weaved across from one side of the track to the other, so turning that dial I was able to get them to the same speed.
Once I mastered the rope tension and use of the triggers, it was time to try some falling.
I made sure my approach to the tree was right first time, as I didn’t want to back up with the ropes behind me. Once I had the felling head positioned to grab and cut there was no need to lock the winches or anything, just make the cut. It all felt very stable. A couple of times I had some slack in the ropes and felt a bit of movement in the base so it was just a matter of applying some tension to make the machine stable. The felling was made easier with the Duxson head, it’s got good grip and a very fast saw.
I’ve operated a few 909 harvesters and they are never short of slew or lift power. It’s a good feeling to be able to swing the tree as it’s coming down and put it exactly where you want.
On the way back up the slope I did need to use the grapple arms to lift the ropes off the ground and away from stumps and debris. Once I was pointed straight I kept a little more tension in the ropes to help with traction on a few tricky places, but mostly the 909 had enough power and traction to keep climbing.
It was another new experience for me, but an enjoyable one.
NZL