What REVS are best for smooth operation of my Mini Excavator?
ฝัง
- เผยแพร่เมื่อ 28 ก.พ. 2023
- Should I run the Chinese Mini Excavator at full revs or not? Some say run them flat out, others say slow and easy. Let's try to find out what works best.
UHI UME12 Mini Excavator:
www.unitedheavyindustries.com... - แนวปฏิบัติและการใช้ชีวิต
Great vid mate. I have the 1 tone version. About 1.5 years old now. They are rough and jerky but I found the lower revs definately work better. Go through less juice too. Beats using a shovel 😉
Yes I have found the lower revs work for me. In tougher material I still need to go higher but still happy with the performance after 2 years. Cheers Dave
Another good video Dave you explain things well. Like you say it comes down to the operator and what you get used to. I see a lot of advice given on TH-cam, often conflicting advice but the more time you spend on your machine the more you sort out what works for you on your machine at your place, each to his own. Your UME12 is still looking like it's just come out of the factory, good on you for looking after it. Cheers.
I would assume that the valves of the swing boom are not symmetrical. A manufacturing deviation. Valve dimensions are critical in terms of performance. I once worked on a servo control for a hydraulic elevator. We could not get good control in each direction (up & down) until we examined the control valves and found one that was VERY slightly out of spec.
High revs for tracking, mid to high for working and digging, low revs for technical stuff or working close to a building or something. The controls arnt bad on these for being mechanical controls. At least on the rhinoceros brand diggers which are similar to UHI ones.
Yep I would agree with all of that.
Hey mate, cheers for the video, made some good points, gonna get the 12p model, and like you said more expensive machines have piston pumps as opposed to gear pumps, but that’s where the price difference comes in👌, these are perfect for hobby farms and work where you can spend more time👍
the reason the swing boom moves quicker in one direction than the other has to do with the hydraulic cylinder. when it extends it has nearly twice the volume of fluid to fill the piston than when it retracts, every function is like this simply from the mathematics of the volume of fluid. extending the ram uses more volume which gives more power but at a slower rate.
The are so many variables that can come into this. The first is that many youtube viewers are seeing jerkiness associated with Chinese excavators based on views of the single cylinder diesel versions that seem to dominate the youtube do-it-yourselfer community videos.
I'd say that the single cylinder diesel ones definitely require higher revs to operate smoothly because of their lack of low down torque and their "one pulse" single piston nature plus the fact that there are no accumulators or dampers in these direct acting control valve arrangements to smooth out the hydraulic flow/pressures. The three cylinder ones such as the one in this video seem more capable of operating smoothly at lower revs because of their stronger low down torque and the fact that they provide three power "pulses" spread across the same time that a single pot one makes only one "pulse".
That said, the tests in this video here are very controlled, lightly loaded, and use very precise hand movements of the levers to feather the valves and thus it all looks pretty smooth at both high and low revs but in my experience of the exact same machine it is not all so smooth when you put it into proper practical operation, loaded and operating at an acceptable professional workspeed.
Try digging say a one hundred metre trench at full revs where the flow of operation requires some hand speed on the controls and you'll find it much more difficult to feather the controls to the degree that you can get the smoothness exhibited in this test and you'll actually find the whole thing a lot more violent as the point on the controls where it progresses from lightly feathered to full-on is very small. That's where the advantage of the multi-cylinder engine comes in here over the single cylinder one, multi cylinder version will work quite effectively at say half way between idle and full (I operate mine at three clicks from idle on the throttle pawl as a general rule) and you can operate it much more smoothly at half or less revs whilst still maintaining an acceptable work pace.
Even then, you do need to ensure you have enough revs that one function doesn't steal priority over another cos with only one pump driving everything, these machines don't have the inbuilt calibrated and balanced rates of comparative movement between boom and stick that is built into makes like Kubota (that use a separate pump stage and separate valve body for each of those two functions) hence it is more of a juggling act on the levers with the UME12 to get it right.
I agree with that Dave. I should have tested it with a heavier load and it some tougher working conditions. I am putting in a 100 metre french drain soon so will try the higher and lower revs test again then. Cheers Dave.
Good video, it's important to note diesel engines do not like to be run at low revs.
The reason it's jerking about, is you haven't got your blade down. With the boom at full extension its bound to bounce!!!!
Dave, of the back of you videos I bought the same UME12 and one thing im struggling with is greasing it all. If you have a guide on greasing the baby that would be another great video for the novices out there. Thanks again for another great video.
No problems I can do a video on greasing. Stay tuned! Cheers Dave.
Hi Dave. Good experiment and observations. I learned some things. I will try your experiment and compare with my CX-15B as soon as our rainy season is over, here in Oregon. I have the pilot controls located near the seat and have commented before on your channel about the jerkiness. I notice that you are able to move your joysticks very slowly. One other thing I want to try was suggested by @DieselandIron was to use just the finger tips with the hands above the joysticks to operate the controls - rather than gripping the joysticks with your palms. Anyway, thanks for posting this video!
Hello again Patrick. Is your digger a chinese one or the CASE CX-15B?
You can use a fingertip technique on some short throw pilot control excavators but it's physically impossible to do on a UME12 (and many other "forward control" style machines) because the arc of throw at the top of the levers on a UME12 is at least 8 inches and that's quite uncomfortable to do with even a wrist plus finger movement if gripped at the very top of the lever - that means that limiting this machine to just finger movement control is not really on unless you grip it at almost its base. If you want avoid having to move your whole arm when controlling a UME12 you need to grip the lever further down and use your wrist to control it but the reality is you'll still likely end up using a combination of forearm and wrist........
He's not using a UME12 but if you watch the bloke in the attached video at around 7:40 you'll see him grasping the lever knob with his fingers but still having to control it with his arms and wrists and it demonstrates how bad some of these chinese machines can be................
th-cam.com/video/FhUVYcCC6vU/w-d-xo.html
Rather than all spool controls, the 'newer' style trickling down into the smallest machines utilizes pilot/solenoid valving for the two joysticks iirc. Along with the split style pump it's potentially to give much finer and smoother control
I have the same machine, and it is very jerky on boom down unless you are smoothly stick out at the same time. I presume it's all about diverting the oil to something else so boom down becomes smoother. I wonder if it's possible to put a restrictor on the oil flow on boom down to smooth things out. My slew is to fast I reckon, also has a lot of play in the slew. Swing motor coming out this weekend to check for play in the keyway on the pinion gear.
Thanks Martin. Maybe worth checking the bolts that hold down the slew motor. I saw a video of another brand of Chinese mini digger that had the bolts come loose and caused similar problems. Cheers Dave.
Don't go to all the trouble of taking out the slew motor just to check the soundness of that joint until you've checked the play from underneath. My UME12S has quite a bit of slop in the slew too (enough that trying to take say an extra half a bucket width off the edge of a trench dug by the 200mm bucket is difficult to do accurately because the play will just allow the bucket to slip sideways off the edge of the trench back towards the middle as it goes down hence I've got to lightly slew the house at same time as making the digging stroke to take up the lost motion so I can keep the bucket at the right position as it cuts down).
It's possible to access the pinion gear from underneath the machine to tell if it is moving on the motor drive shaft. In my case I can tell that my pinion gear is solidly held on the shaft but there is play between the pinion gear and the ring gear (slew gear/swing gear) and no doubt some play within the motor itself (and whatever slew brake is in there) that compounds into a noticeable amount of lost motion in the house. It's only an issue (for me) when digging narrow trenches or when inch perfect lateral accuracy is necessary, other actions like loading a trailer from a heap or grading it doesn't really affect.
Another great video. I awesome that a bigger machine would be smoother? Larger pump?
Yep the larger machines have bigger pumps. More expensive machines can have more than a single pump for different functions. As JC has mentioned here, some have gear driven pumps and some have piston pumps.
Enjoy your vids Dave. Very informative and pitched in a very humble manner. I recently acquired an AGT one tonner at auction and am trying to ascertain who in Australia sells attachments 25mm pins. Any suggestions pls? Thks.
Hello Wayne. You could call 'UHI' or maybe try 'Digger King' for attachments. Normally they are sold in a package deal but I did see racks full of attachments at UHI when I was last there. The mini excavators up to 1.5 tonne should all have the 25mm pins. I think they change to 30mm on the 1.7 tonne and above. Cheers Dave.
Thks Dave-much appreciated.@@TreeChangeFarmer
I have a mini with pilot controls - it's very, very twitchy when using the swing function - I need to reduce orifice size or something. I've run excavators for 30 years and figured I'd easily get the hang of any machine, but it's a bugger.
can try searching for an adjustable flow valve...
We’re running a similar machine and when you try to make any commercial progress it becomes a lethal weapon. Pussy footing around with the things and you’d lose money on most jobs. The conclusion is very straight forward, these machines are excellent where space is limited and preferable to a spade and aching arms, but if you’re looking to make any profit, you need to up the specification and the weight. Realistically they were not designed and manufactured for continual use, 5 days each week, especially the single cylinder machines. You must tension the bolts after four hours use and the grease gun will become a very close friend. Overall, many of these Chinese excavators are good value for money. Buy direct from the manufacturer however and you will be left stranded if you have a warranty claim, once they have your money they lose interest. Don’t be tempted to save money by buying direct, false economy.
It's easy to make sweeping statements about these machines' unsuitability for "commercial work". Certainly when you refer to digging operations five days a week eight to ten hours a day you're totally correct but then again, it's hard to believe that anyone with a serious business who has enough earth moving work on their books to support a constant forty to fifty hours a week of digging operations for one digger would actually be looking to buy at this end of the market. With that level of demand for service a business could easily finance the purchase of a new 1.7/1.8 ton Kubota or CAT which would be a sensible move compared to trying to make a 1.2 ton Chinese digger fit the bill.
On the other hand, I'd venture to suggest that the vast majority of people who buy cheap chinese sub 1.2 ton machines are people who buy solely based on the low price for either home/farm/property use or very occasional use as an adjunct to a job like plumbing/electrical etc and for those buyers it's often a case of buy a chinese digger at the cheap end of the market or buy no digger at all.
I often see comments from naysayers on various chinese excavator youtuber's channels telling people "don't buy a chinese cheapy, buy a "cheap" second hand Kubota, Deere, Yanmar etc instead". The problem with this advice is that in a great number of countries around the world, second hand higher end used diggers are few and far between and even when heavily used ones are offered for sale in those countries they are still rarely as cheap as a brand new chinese sub 1.2 tonner.
In Australia the "apples with apples" choice when buying second hand is usually something like a kubota k008 with 2500 to 3500 hours on it with an asking price of around (AUD) 18k to 25k plus no warranty but nearly every bush/pin worn out (second hand prices for the bigger and extremely popular U17 seem to run from AUD 28k to 38k dependent on hours).The very few sub 1000hr k008 kubotas that do pop up will usually be not much lower than the new price which is (AUD) 28k to 30k for the k008 (or around AUD 45k+ for the bigger U17). It's easy to see why many people instead choose a chinese digger direct from factory with no warranty but brand new with no wear at 10k to 14k.
No, the sub 1.2 ton Chinese cheapie digger is not really up to doing "commercial work" five days a week but then nor are the majority of their owners expecting them to be. We generally make them work for us within the confines of their design constraints and the limitations of the price we were able/willing to pay.
The other thing that should be mentioned is that not all the chinese sub 1.2 ton machines are the same underneath (even ones that looks substantially the same). As well as having a huge variation in build quality from the one version to another, there are variations in the operating systems too,. Some have smoother and more progressive direct acting valve systems than others (they do not all use the same valving). That's one advantage of buying from a volume distributor in your own home country, often those businesses have worked with the suppliers/manufacturers over some years to iron out bugs, sort through desired options and specs and improve quality.
@@davejaguar6532 Hi Dave. I appreciate your knowledgeable and in-depth explanations to various commenters, including mine. Thanks for taking the time to do so, as they make a lot of sense and I learn from them.
Hi @ArthurDentZapodBeeb. I've commented a few times here. I have a 1.5 CX-15B Chinese digger also with pilot controls. I had actually purchased the older model with the mechanical controls, but they offered me the new model with the pilot controls at the same price, so I said yes. Maybe my mistake because I also have the same issue you describe of a very twitchy swing and down-boom functions. I've asked the manufacturer for help, but they want me to send a video - which I haven't been able to do. However, I just took off the side panel where the throttle lever is and discovered that the full range of movement from min to max is governed by a cutout in the side panel - about 2 inches. Without the panel, I can further lower the throttle lever another half an inch before the engine starts to complain. When I operated the swing and down-boom functions at this lower level, it was noticeably less twitchy. I don't know if this applies in your case, but maybe something to look into.
Put in larger pump
Hello, sir. Is this machine of reliable quality
Yes, I have had the machine for 18 months and no problems.