Importing and modifying a new mini excavator from China

[dfkrug]

I read in an earlier post that you had a lower volume pump you were going to try on your machine, did you ever try it? I love my new machine but even with the pilot controls, it seems to have way to much flow making it much more jerky than it needs to be. And why would they put on a 2 stage pump with a single output? The pump switching stages during operation can't be good for smoothness and control. It may also make it harder to reduce flow by simply throttling down.

I would love to try a new pump with about 1/2 the flow as the one I have now. In an earlier post you estimated current output at around 6 GPM I believe? I would prefer slower and smoother to the way it operates now, WAY too fast for my taste. I want it to be a more relaxing experience and stress the machine less, I am in no rush.

Yes, I have a smaller pump, but I have not installed it. My early machine has a custom splined coupler, unlike newer units with Lovejoy couplers. This potentially requires that I have to remake my coupler if I change to the new pump. I would love to lower my pump volume a bit, but right now, I am living with the current flow.

Be careful about going too small on the pump. I went down to 5.5cc from 6.5cc. And, the pilot controls require you have 2 pumps, or a flow divider.

You are correct that a 2-stage pump does not make sense. Reports I have seen so far say that the the switch from low to high volume does not seem very noticeable, which indicates the load-sensing pressure setting is close to the system RV pressure. That means it acts like one big pump. For both the pilot controls AND the main valve, you may want a total flow rate greater than mine (6.5cc), but lower than what you have (unknown). So far, this is uncharted territory, AFAIK.

If you try something, please report it. It is easy to figure the GPM flow rate if you have the pump volume and the RPM the engine is turning. If you use the B&S 420cc gas engine, it will work best between 3000 and 3600RPM. I am usually at about 3000. Any of the diesels are happy at about 2000RPM.

 

[JohnnyB24]

I just got the machine and only have about 1 hour on so I definitely don't see the big picture and I am not yet a proficient operator. As soon as I get some hydraulic adapters for the new thumb (M16X1.5 Male O-Ring to M14X1.5 Female) and the weather dries up a bit, I will be heading north to my lake property where it will get a very god workout.

After I return, I will do some mods like replacing the existing internal tank filter with a 10u external one like you recommend. Will that filter alone be enough for the machine or would you also replace that existing ilot filter so all the return fluid is filtered

Yeah, that filter is in the return part of the circuit, draining to tank. That is good, but what is the spec on it, and how do you find replacements for it? At least they addressed this critical need. I would change to a known and serviceable 10u filter setup like what I did above.

Thx for posting the filter pix. I will check again the local EM15 to see if it has this somewhat hidden filter.

Well, curiosity got the best of me and I removed the floor plate for a good inspection. It looks like a small hose goes from the lower left side of the flow divider directly to the input of the filter just below the seat. I say input because of the red arrow on the filter housing. The output of the filter tees off and one hose goes to each of the pilot hand controls. Does that sound like it is a pressure filter?

I plan on taking it apart during my next fluid change for further analysis and hopefully determining what a replacement filter would be.

I would pay a lot of money for a good service manual and a parts list!

 

[dfkrug]

After I return, I will do some mods like replacing the existing internal tank filter with a 10u external one like you recommend. Will that filter alone be enough for the machine or would you also replace that existing ilot filter so all the return fluid is filtered

You could tee the return from the pilot valves to the IN on the return filter you are going to install, and use only one filter.

Looks like they put a hi-pressure filter on the IN line to the pilot controls. Strange. This filter will see the full pressure from the pump, regulated by the pilot RV, which is probably 500-1500psi. A proper return pressure filter usually is designed for no more than 500psi, and that's when it starts to resist flow.

I hope they chose that pilot pressure filter properly.

 

[dfkrug]

I would pay a lot of money for a good service manual and a parts list!

I hear ya. For an additional $20K or so you can get a nice manual and parts list. It will even come with a shiny new Kubota K008 mini-X.

As a minimum, it sure would be nice to know about the pilot valve RV setting, and that supply line pressure filter.

 

[Fixastuff]

This tmis

I hear ya. For an additional $20K or so you can get a nice manual and parts list. It will even come with a shiny new Kubota K008 mini-X.

You don’t have to add hydraulic pick up extensions, hydraulic filters, cut holes in the cab for vents, or be unsafe with no proper rops or fops protection and have nice smooth quiet diesel(I know you can get a Chinese 1 ton with diesel but from what I can most are not).


These things are great for a home owner but let’s not pretend the only difference between these and a name brand mini is only a manual. lol.

Oh yeah your forgot if you talk sweet you can get a hat included for your 20k.

 

[JohnnyB24]

Don't get me wrong, I really love the mini ex and I the more I tear into it and understand how it works, the more I like it. It certainly has fit and finish issues with bolt hole alignment and cover fitment, but overall, its built well and I think they are really an incredible value, especially for person who has a wife that will just not let them buy that expensive Kubota!

I'm retired now, but I spent my career in Aviation maintenance and that world is ALL about proper documentation and detailed procedures. It just seems like these manufacturers are limiting their market simply because of the lack of a basic manual and list of major parts. It just can't be that costly to have a technical writer (or a secretary) compile a list of parts used in building the machine and who made them.

I do actually enjoy working on it though, and it will be fun to customize it in the future to make it better than new. Kind of make it your own I guess. No computer controls and locked down software, If you don't like something, change it!

 

[Rich B1]

Most pilot hydraulic systems on CE I have been involved with have a pilot filter on the supply side. You don’t want crud getting into a joystick.

 

[JohnnyB24]

Most pilot hydraulic systems on CE I have been involved with have a pilot filter on the supply side. You don’t want crud getting into a joystick.

It seems like a good idea to have that filter. I'm thinking or replacing the Chinese housing with one with from Grainger (or similar) which is about the same physical size but has 1/2 ports. I could even tee in a pressure gauge on the filter output port to monitor pilot pressure. The filter Housing is about $50 and replacement elements are $13, not a terrible price and maybe I can find one cheaper. It's 25u so it will still let the primary return filter do the really fine filtering down to 10u as the fluid eventually cycles through the entire system

Of course I will have to deal with metric adapters and that world is still mostly a mystery to me.

 

[JohnnyB24]

I noticed the exhaust was blasting against the rear door of the mini due to the muffler outlet being short and not aligned with the cutout in the rear door. This was causing extra heat buildup and unwanted noise in the engine compartment. It has the BS 420cc

A piece of 1in galvanized pipe was just a bit too large to fit inside the muffler tip but after a touch on the grinding wheel to dull and taper the threads, it fit perfect. Next, a slot was cut in the pipe most of the way through then bent, cut and bent again until the angle of the pipe allowed it to align with the center of my door cut out. Grind off the galvanized coating in the weld area and weld it up.

After threading it in, a pilot hole was drilled and a self tapping screw was added to keep it from vibrating loose since it's not really threaded in.

It was already pretty quiet, but it's even better now.

 

[dfkrug]

I noticed the exhaust was blasting against the rear door of the mini due to the muffler outlet being short and not aligned with the cutout in the rear door. This was causing extra heat buildup and unwanted noise in the engine compartment. It has the BS 420cc

That's a step in the right direction.

Note that the stock muffler also puts out a ton of heat, and it is completely enclosed inside the house.

The off-the-shelf screw-on mufflers I have used are not as quiet as the OEM, and they DO have to be unscrewed to open the rear door or panel, but they do work even better for heat removal.

I can operate my machine without hearing protection, but I may upgrade my muffler to one of those larger rectangular ones commonly seen on 5000W generators.