Improve input controls on excavator?!

[MaxG]

I bought an excavator to do some land management (stumps, lantana, clean-ups). It's a self-imported electric 2.5t excavator from China.
I am happy with it in principle. However, the controls are shocking. I can nicely operate the boom and stick on my back-hoe, but these controls are jerky, not allowing for precision work. E.g., one of my prime movements is scraping, that is running the bucket or rake parallel to the ground, which seems impossible to achieve with this machine.

Long story short: Can these controls be improved? (for a reasonable price)

I read a few posts on this forum; this one talks about wire-controlled valves... which I have on the FEL on the tractor, and which allow for fine control.
I have not much of an idea of valves and hydraulic parts, as I never had to deal with it (as in diving into design details; other than replacing the odd hose on the tractor).
However, I can work with electronics. (Meaning, if there is cost-effective to use servo controlled valves via joystick input?)

Are there specific servo valves, or other types I need to look at.
In the quoted post it is also talked about a flow restrictor (means most likely a flow control valve).

Any hints appreciated. E.g. cost, complexity, best approach?!

 

[4570Man]

I’m assuming by the profile picture that it’s a Chinese excavator. Every video that I’ve seen of those are super jerky. Cheap valve body’s are jerky. Flow restrictions might help but there’s not much else to do. A quality valve bank would cost more than the excavator.

 

[MaxG]

I’m assuming by the profile picture that it’s a Chinese excavator. Every video that I’ve seen of those are super jerky. Cheap valve body’s are jerky. Flow restrictions might help but there’s not much else to do. A quality valve bank would cost more than the excavat

Hmm, do you mind explaining this a bit more?

Is the issue the 'valve bank' or is it the control (valves). I have valves in the controls (as far as I can tell; see photo of the underside of the control stick). Not sure, if these operate the (real) valves or not. Or are the joystick valves it?

 

[4570Man]

Hmm, do you mind explaining this a bit more?

Is the issue the 'valve bank' or is it the control (valves). I have valves in the controls (as far as I can tell; see photo of the underside of the control stick). Not sure, if these operate the (real) valves or not. Or are the joystick valves it?

It’s most likely the actual valves. Good ones can operate smoothly and cheaper ones tend open all or nothing.

 

[MaxG]

It’s most likely the actual valves. Good ones can operate smoothly and cheaper ones tend open all or nothing.

Thanks for getting back to me.

However, it is still not clear to me if there are two sets of valves; e.g. the valves under the stick, and the actual actuator valves for the cylinders? (Or the stick valves control the cylinders?)

---

OK, I am starting to watch Youtubes on hydraulics. They talk about pilot valves and the valve block. Meaning there are two valves (of sort) for moving cylinders.
I assume, the stick has the pilot valves and the valve contains the spool for the cylinder movement.

Coming back to my original question: where is the jerkiness originating from? The pilot valve or the actuator valve in the valve block?

I do not have a pressure gauge (yet), but I can regulate the hydraulic pump speed. I understand the pressure is pretty constant across the speed range, but the flow changes as speed changes (increased speed, increases the flow).

I haven't done much work on the new digger; in fact, I worked it for ten minutes so far... my neighbour has a 3t Sany, which has excellent stick/boom control. I could immediately run the bucket run parallel to the ground.
What I will do is more experimenting with different pump speeds and how this affect the stick/boom movements.

I then learn more about these hydraulics to figure out what can be done to improve the or rather get rid of the jerkiness.

 

[oldnslo]

How do your present joysticks connect to the main valves that operate the cylinders? Are there small hydraulic (pilot) lines connecting joystick to main valves or mechanical linkage? From your description suspect hydraulic pilot lines.

If hydraulic pilot I would start by installing gauges in those lines to see if joy sticks ramp pilot pressure up smoothly or does pilot pressure just jump up. Not sure what the pilot pressure will be but would suspect 500 PSI or less.

 

[MaxG]

The digger came without any documentation! Not a single page.
I have no clue where the oil filter is, what type; fuses and sizes, etc.
A big learning curve (I am not afraid of), but hydraulics won't be learned in a day
I will eventually create a separate post with my experience about purchasing this digger.

I am going to operate the machine today and see what I can do from a human input perspective.
I have to figure out what pieces of metal to remove, to 'find' whatever valves there are and take some photos.
I will draw up electrical and hydraulic plans as I go... simply to be able to service the digger as needed.

You said "install gauges". Do you mean get a bunch and install them in the pilot lines, or get one and move it from one line to the next? I reckon the latter.

 

[oldnslo]

I would get one gauge to start with to monitor the pilot pressure. For main system pressure suspect you will need 3,000 PSI gauge so might want to get one of each if ordering parts. I also suspect machine will be metric or BSPP style threads so will probably also need some adapters of unknown size.

 

[rScotty]

I would get one gauge to start with to monitor the pilot pressure. For main system pressure suspect you will need 3,000 PSI gauge so might want to get one of each if ordering parts. I also suspect machine will be metric or BSPP style threads so will probably also need some adapters of unknown size.

What pressure do you think it operates at? Without documentation its hard to know. I'd say go higher on the gauge. 5000 psi guages are standard.

 

[oldnslo]

What pressure do you think it operates at? Without documentation its hard to know. I'd say go higher on the gauge. 5000 psi guages are standard.

no clue but doubtful small Chinese unit would run high pressure pumps. My best guess would be similar to utility tractors in 2500 PSI range
can use 5,000 PSI if he wants just to be safe and not wrap a gauge

 

[MaxG]

I have since operated the digger for some 10 hours. I am better with the controls now; ran 'rake' (boom and stick) at the same time. The machine has no arm-rests, which leads to the jerkiness when the machine start moving due to (mostly) boom movements.

The digger has (as I understand it) a three stage pump (see image)... again, this is an electric digger, hence, the pump is driven by an electric motor... which I run at half speed (no rpm meter, hence, I can only guess).

I have been looking at gauges on AliExpress, but have not yet settled on which type/range of gauge(s) to get. While I could just buy a gauge, I want a permanent solution. Meaning, I'd like to add a pressure sensor somewhere, and add a display, which also shows values from additional sensors I am putting in; e.g.; oil temperature, operating hours, battery data.

Coming to the gauge suggestion:
a) where do I best measure the pump pressure?
b) where should I measure pilot pressure? I can measure it on the control inlet or each outlet.

Huh, 'oldnslo' said it:
If hydraulic pilot I would start by installing gauges in those lines to see if joy sticks ramp pilot pressure up smoothly or does pilot pressure just jump up. Not sure what the pilot pressure will be but would suspect 500 PSI or less.

I have yet to 'find' the valve block, and create hydraulic and electrical schematics.

 

[rScotty]

Fascinating machine. My hat is off to you for getting it.

Easiest place to put the meter to get real information would be in the high pressure line between the pump and the control valve. That will enable you to look at real pressure in every circuit and combination plus the relief valves.

I don't know of any way to measure pilot or regeneration directly in a way that it would mean anything.
Inexpensive valves may have neither.

Amazon has hydraulic test gauge kits for under $75. I doubt you could make your first kit with various types of fittings much cheaper.
If you like a test port position just put a "hydraulic T" there and either cap it or run a small high pressure hose to where ever suits. Terminate in a $20 gauge. You can leave the gauge inline indefinitely. I have left mine on the JD for 30+ years now.
Most gauges have too much damping to catch spikes.

One simple solution to the tame the controls from jumping might be to put a pressure reservoir on a T in the main pressure line. Adjust it to add variable damping to the entire system.

rScotty

 

[oldnslo]

Pump shows 25MPa or 25 Mega Pascal which is 250 Bar or 3,625 PSI for rated pressure. What we do not know is what pressure is each section running at. Like stated It is three section gear pump so would have three separate pressure lines which are the smaller lines labeled out on the pump as shown in the picture.

 

[Seven Gables]

For gauges you should get at least 2 , a 1k psi for testing pilot pressure and 5k for working hydraulics . I bought a three gauge kit from amazon mainly for the gauges and the test lines that go to gauges. You’ll end up buying individual fittings to tap the test line into your system at various locations.
You’re pumps 3 outlet ports are most likely; main pump for 3 cylinders on boom/arm and boom swing cylinder. 2nd pump usually supplies swing motor and dozer blade . 3rd pump is your servo/pilot pump.
I’d first check the pilot pressure going into boom valve, T in at valve or dead head gauge into pilot line. Operate boom lift and see if pilot pressure smoothly increases with lever stroke, most pilot systems on mini excavators max around 500psi.
System servo pressure is tested by teeing in a gauge at pilot filter outlet. Main pump system pressure T in at pump outlet, DoNot deadhead a gauge at pump!
Does your pilot circuit have a accumulater? Should be between pilot filter and pilot lock out solenoid, it helps take the pulsations out of pilot flow.
Some more good pictures of workings under the hood would help.
Getting some good pressure readings is first best step in diagnosis

 

[MaxG]

I am still deciding on the gauge kit... and am aiming for 'inside' pictures, once I figured out if there is some 'easy' way to access what is under the foot plate (floor).

Thanks, Seven Gables, for providing an idea what the three pumps are most likely for.

I have asked for a 10% refund today due to missing documentation. Will see how that goes. The supplier went as far as removing name plates; I have never seen such a thing. They did not (at least) provide the component supplier's manuals.

Again, I am happy with the machine, or what I got for the money I paid, but the missing manual will cost me lots of time to create. It also hampers efforts to improve the machine, or tap into the communication between battery and its management system.
I think I mentioned that I want to install a permanent oil pressure sensor and temperature sensor. I will relocate the battery display, or may leave it where it is but with a protective cover/screen, and create my own display with a micro-controller gathering the sensor and communication data.
What will hamper my progress with the digger is the fact that I am owner-building a passive house, which needs another year of my time to complete it (and has priority). However, I will see what I can do and will post here as I progress.

Thank you all for your input so far, I do appreciate it.