Hi there! New to this forum, and new to mini excavators in general. I've got a very small Komatsu PC08-UU mini excavator (0.8T) and my question is: It seems like the rotate function of this thing is pretty weak. Is this normal? I feel like with the bucket extended the rotate motor could probably only put out like, 200-300lbs of force, tops. Maybe even less. A strong person could for sure stop the machine from rotating on the base. It works fine and has low hours (under 1000) and is in quite good shape otherwise, so I'm not sure if this is an actual defect with the machine or is just to be expected. If this is a problem... how do I fix it?
Here's a picture of it holding up my other, even smaller excavator: a Kobelco SS1.
So, I did some more reading and it looks like this is pretty normal functionality for the slew/rotate function on compact excavators, and that it wears them out to try and use them to backfill/push things that way. Good to know. Next question - is it normal, if I park the machine with the bucket off the ground, for the hydraulics to "leak" and lower the bucket to the ground? Probably loses an inch every few minutes. I feel like this is probably also normal behaviour but I know so little about these machines. Thanks for any insight!
For the swing, you don't want anymore turning force that it takes to move the crawler part of the machine. That isn't saying that you machine isn't capable of more force. You would need hydraulic pressure gauges and someone knowledgable on checking and adjusting pressures to know for sure if you machine is capable of more. The gradual settling of the implements is normal to a point. Some leakage in the cylinders is necessary to facilitate lubrication of the packing rings. Generally I don't see settling an inch a minute as being much of a problem.
Thanks for the reply john! Looks like it's all good then.
Ok, another question on this machine: Is it normal for the "boom" to not be as powerful as the "stick" or the bucket? I was using the machine to move an air compressor yesterday and I couldn't lift it with the boom, which I figured should be the most powerful part of the machine! It has the biggest cylinder and is built from the thickest steel. I had to lift the boom up far and then push the stick away from me and uncurl the bucket to lift the compressor. This is my first machine, so I'm not really familiar on if this is normal behavior or not. Is it possible that the hydraulics are set wrong?
When the Japanese machines hit North America, boom power was always a complaint. American machines were set up with enough power to tip the machine. The Japanese engineers figured that being able to tip the machine accomplished nothing and made the machine inherently unsafe. Their machines were set up for stability. Just the same you should check your pressures as all hydraulic pressures are dependent on springs that gradually fatigue and need to be reset. A new machine set to factory specs usually needs a tune up at around 3,000 hours and it will generally stay about the same for the next 7 or 8,000 hours.
Also had the same problem with a customer, pressures checked out good, tweeted it up just a little, changed out boom cylinder to a smaller diameter, with same stroke, 600 kilos was no problem with arm complete extened
So a smaller cylinder gave it more power? I figured the opposite would be the case. Maybe there are different cylinder setups? New to hydraulics. Definitely seems to have tons of power in the bucket and stick, and a reasonable amount of power to push down with the boom, just not a ton to pull up. Assuming I can't get a manual for this thing, any idea what ballpark the pressures should be? This machine has only 400 hours on it, but I think is about 15 years old. Looked like it had sat for a long time when I bought it.
Your going to have to explain how a smaller cylinder will achieve more lifting power. Physics don't work that way.
Sorry I meant larger diameter, didn't realize I put smaller in, my mistake