Importing and modifying a new mini excavator from China

[dfkrug]

The hydraulic oil tank also features a very convenient sight glass just like the one
for the fuel tank. It is also a hefty 4mm-wall steel tank. The machine welds
look great.

The first photo here shows the tank and pump on the right side of the house
chassis, as it originally was made. The system features a steel mesh suction
filtration system, but no return-to-tank pressure filtration system. That was my
first major upgrade. Suction filtration is not a good solution to oil contamination
problems on any hydraulic equipment. The inlet screen looks like a 100-micron screen
without any bypass valve to avoid cavitation.

The filter chamber has a very nice large opening, sealed with an O-ring. This
allows inspection and cleaning of the tank. The suction filter is large, and even
comes with a Neodymium magnet attached.

I had to siphon out the hyd fluid before removing the tank since the drain plug
needs to be removed for clearance. Draining the oil thru the drain plug is not
easy unless the house is rotated to clear the tracks.

I bought a return filtration system from our friends at SurplusCenter, along with
a spare filter. Their Zinga 25GPM system features 10-micron filtration with a bypass
valve and 3/4" NPT threads. Only a bit over $30 for the manifold and 2 filters.

I chopped up a 3/4" steel pipe nipple to make the new bung hole in the tank.

Tho there was clearance to install the filter in a downward configuration, hidden
under the floorboard, I opted to install it so that it penetrated the floor for
easy replacement. This was an easy upgrade, and I am encouraging the factory
to make this change. I suspect that with 100u suction-only filtration, the life
of the pump will be limited to a few hundred hours.

 

[ArlyA]

We've got items from the Surplus center as well and do like that shop. You can email them a qestion and get rear answers. Your mini excavator from China, looks better built than I had expected. I found them for about $4000 (no shipping from China) and I believe that was with a 11hp motor. Thanks for posting the photos and videos, especially of it at work.

 

[dfkrug]

Your mini excavator from China, looks better built than I had expected. I found them for about
$4000 (no shipping from China) and I believe that was with a 11hp motor.

I am trying to point out the good things I have discovered, as well as improvements that are necessary, IMO.

If you delete all the options and shipping, you can get this unit FOB in the low $4000s range as you found.

As for the return-oil filtration kit, I bought my first kit from SurplsCntr back in the 90s for my CADDigger. For
the Chinese minis, I suspect that the next size up has this feature already. One factory has verified this for their 1.6T
and bigger units. I sure wish all the makers provided more technical details.

Here is another good quality feature of my XN08: Look at the massive frame-mounted contactor (starter solenoid)
in my first photo of my last post. I used that instead of the engine-mounted small contactor that came with
my new engine.

 

[dfkrug]

In test fitting my new engine, I could see that it was a different shape than the diesel
it replaces. It was not going to fit between the frame rails with the output shaft pointed
right, where the hydraulic pump was originally located. So I had to position the engine
where the pump would be on the left side instead.

The maker provided 1/2" thick mounting plates with large holes to support 8 rubber
isolator mounts. Nice. I welded on 2 transverse brackets to attach to the engine base.
I cut out a small chunk of one frame rail to avoid interference with the pump inlet
fitting and hose. I wanted to mount the engine and pump as low as possible to avoid
any chance of sucking air from the tank.

BTW, the pump is some Chinese brand that I have never heard of, but it is all-steel, not
like the aluminum ones I have purchased most recently.

 

[dfkrug]

Next comes the engine coupler I had to make.

The maker provided a spline adapter for the pump for a direct-coupling. I was hoping to
use something like a Lovejoy coupler (photo), but clearance was tight, and it
would not fit inside the provided pump-to-engine mount. That mount lined up perfectly
with the bolt holes on my engine.

So, I decided to weld up a direct coupling. First, I chopped nearly 2" off the crankshaft,
and used that to help align the 1" keyed coupler I needed. Instead of buying 1" keyed
coupler stock, I bought a sprocket with a wide 1" keyed bore. Sprockets are usually cheaper
than coupling stock, and they have a wider boss for easier welding.

I put the female splined adapter on the lathe and made an alignment cut to help with
welding the two halves together straight. The 1" stub from the crankshaft was used inside
the sprocket hub to make sure both parts were concentric. I then welded and cut off the sprocket.

The paint job is always last, but usually necessary.

Even with a direct pump coupling, I needed to make a spacer to create some extra clearance on
the pump-to-engine mount. So I cut a 3/8" ring out of some scrap steel plate. The final photo shows
the completed left side pump installation.

 

[dfkrug]

All the hydraulics on this machine are metric sizes, and proved one of the bigger
challenges of this project. I got the adapters I needed from our friends at Discount
Hydraulic Hose in PA, but they were spendy, and one I could not find at all. I had
to make the adapter for the small hose that provided flow from the AUX circuit on the
dipper.

Standard-length new SAE hoses worked fine for me, so I did not have to have any
custom hoses made. The cost of adapters was higher than the whole filtration system.

 

[radios1]

seriously, this is more of a make work project/hobby type deal, which can be fun for that aspect, but requires a lot of work that most people don't have the machines for.. so for them, it would cost much more to have this done, than just buy an excavator that is fully assembled, and working..

 

[majorwager]

radios,

I disagree. The excavator would have been functional W/ deletion of the many modifications elected by the OP. True he chose to present the appearance of a hobby project, simply because he has the time, ability, and desire to perform the mods. I have not studied the engine to pump connection, but there may have been a simpler, less precise but More $$ solution. The OP may have desired to build his own excavator, but the tractive drive system and boom construction were too intensive. If my goal was to just get the machine functional, it would already have most of the trail work complete.

The OP has a sense of perfection and pride so this project BECAME A JOINT VENTURE between construction and equipment build/mods. Filtration was optional. Had it been his desire, an EPA approved diesel engine might be available to mate to the existing hydraulic drive. Another point missed, is the OP desire to employ his adaptive abilities to short circuit unnecessary cost overruns. Based upon his initial investment, the budget likely supported more elaborate accessory ready made purchases, but where is the fun in that? Showing how ones ingenuity defeated the money grinch, is the stuff that can occupy a whole cocktail hour or campfire outing, and them some.

Which is preferable? a buddy stops over, says nice machine, did you buy it all put together? Answer A, yea kinda, just bought a bunch of pre-engineered stuff and bolted it on. Answer B, well actually I hand fabricated all these components, machined that, adapted that, extended this, ARE You getting the big PICTURE?

NONE of this diminishes the painstaking effort to purchase and import a piece of equipment from china as an INDIVIDUAL.

 

[dfkrug]

seriously, this is more of a make work project/hobby type deal, which can be fun for that aspect, but requires a lot of work that most people don't have the machines for.. so for them, it would cost much more to have this done, than just buy an excavator that is fully assembled, and working..

Indeed it WOULD cost more to have this work done, versus buying a ready-made machine. IF you could buy
one. Our pals in Canada or Australia can certainly buy it ready-made. As I mentioned above, the closest
I was able to get to a ready-made unit was at about $10K for a used high-hour machine from a dealer
out of state.

I am offering up my design work and modifications currently to 2 Chinese factories (gratis) who have expressed
interest in making these changes so they can sell more units into the US. I will help them, plus I have
at least one person in mind as an importer here in CA who would retail and repair these units.

 

[dfkrug]

Let me share a similar solution to the problem of importing one of these units without an
engine.

Charlie in OR brought one in before I did and he ran into the same EPA buzzsaw. He bought
a Predator 420 from an ubiquitous HarborFreight store, and installed it without doing anything
to the hydraulics at all. The engine was shoe-horned in at an angle so the pump could
remain where it was originally. A LoveJoy coupler was used, which is longer and costs more
than what I did. He had to make a different pump mount so it would clear.

The upshot of his approach is that the engine sticks out the back, so the rear bodywork can not
be reinstalled. He was able to get up and running fairly quickly however. Cooling issues also
made it so he could not enclose the engine. I elected a different approach, but I understand
why Charlie went this way.

There are 2 others in the US I have spoken with who have substituted gas engines for the
original diesel: one in Utah, and one is NE. Since they have not sent me pix or provided
details, I don't have much to share on those mods.