Mini-excavator tipping point

hayden · Oct 7, 2011

I recently got a Kubota KX121 mini excavator. I love the machine and am slowly getting comfortable with it, but still don't have a good sense of it's tipping point on slopes. Initially it made me very nervous traveling up and down slopes. I would creep along with the dozer blade down low ready to stop me, and the bucket close to the ground, also as a crutch in case I started tipping.

As I use it more and more, it seems to be more stable than my butt cheeks tell me, but I really don't want to find it's limits the hard way. It's very stable while digging, and even when I manage to start it tipping, it's a long way from going over - much less so than a tractor which seems close to the point of no return as soon as it starts tipping.

So the question is, how stable are these things traveling up and down hills, and what technique do you use for max safety? Do you descend boom-first or do you go down backwards? What about ascending?
What about traversing a hill where you are tipping sideways rather forward or backward?

Thanks.

By the way, the first day I had it I got it totally stuck in a swamp. The exhaust was gurgling up from under water. I now have a good feel for the sinkage limits.

yankeerider · Oct 7, 2011

Descend boom first. With the bucket in front and close to the ground, it will serve to limit the tipping once the bucket contacts the ground. Ascending is more iffy for me. I tend to swing the house so the blade is behind me, extendthe boom as far forward as possible to keep the cg low, and proceed in that fashion. Particularly if you are going to work on that slope, you want the blade on the low slide so you can use it to level the machine. So far this has worked for me, even in snow/ice where I had to use the bucket for assist because the tracks couldn't bite. If still in doubt, I'll swing the boom to the downhill side (after backing to where it feels safe to swing) then reverse up the slope with the knowledgethat the boom extended low and far will allow the bucket to guard agaist tipping just as on descent. I am still new to this, and there are some slopes on my property I consider too steep to safely work.

I am very cautious about traversing slopes, avoiding it as much as possible. Here I will swing the house 90 degrees to the direction of travel, keeping the bucket within a foot of the ground as a "tip stop." I figure if the boom is in anyother position, it can't be used to stop tipping.

hayden · Oct 8, 2011

One thing I've noticed while descending boom first, is that I'll hit a sudden down pitch and the machine will top forward with the boom stopping it as expected. But then to experiment I'll lift the boom back off the ground and and continue to move forward, even throwing in a few abrupt stops to see how much the machine will tip forward. So far, although it tips forward, it continues to appear to be going nowhere which has increased my confidence, and is leading me to believe these are more stable than my butt is telling me.

I'm interested that you extend your boom as far forward as possible while descending. I've been puzzling over that. Getting the bucket within a foot or so of the ground to act as a crutch makes lots of sense, but the further forward the boom, the further forward (lower too) the center of gravity. If I just use the blade as a crutch, wouldn't it be better to have the boom fully retracted to move weight aft?

Ken45101 · Oct 8, 2011

^^^ What he said.

Blade behind and low going up slopes, boom fully extended in front and low. I'm on some fairly steep slopes and it's always been stable.

Going downhill, boom and bucket in front.

Going across slopes? That's where the mini ex excels: dig yourself a flat trail! :thumbsup: Here is a photo of my 121 cutting a trail:

Of course there are always limits to everything. They use big excavators to dig pipeline trenches up and down the mountains. When it gets too steep, they cable them to bulldozers on top to hold them. My son's outfit had one come in for repair: a cable broke and the excavator rolled down the mountain. Pretty heavy damage. The ROPS was bent but protected the operator.