Importing and modifying a new mini excavator from China

[dfkrug]

I replaced the hydraulic return line to the tank with the filtration system shown above.
The original fitting on the tank had 2 lines returning fluid. One was out of the stack
valve, and the other smaller hose came out of the distribution valve (photo).

The distribution valve allows the house to rotate 360 degrees, while providing hydraulic
power to the tracks and the dozer blade. I have never had one of these valves opened
up. Anyone else work with these?

I kept the distribution valve drain hose on the tank fitting, and I used the original return port
on that fitting for a capillary-type fluid temperature gauge. The fluid can heat up very
fast on a hot day, especially when using the track motors.

I opted to use the passive temp gauge, rather than an electric one since the engine puts out
so little charging power. The gauge is installed where the diesel fuel fill cap used to reside.
It works well.

Note the metric grade 12.9 bolts used in the last photo. The maker did not cheap-out on any
of the fasteners used on this machine.

 

[BigBlue1]

Why do you call it a 'house' when on a tractor it is called a 'station'? Is it an excavator term or is it your term for any equipment operator location?

 

[dfkrug]

Why do you call it a 'house' when on a tractor it is called a 'station'?

Yes, it is a standard excavator term. On the bigger ones, it is usually enclosed. The big diff from
a tractor is that it rotates. I suspect that term goes all the way back to "steam shovels".

Mine has a "FOPS/ROPS" on the house. (Falling Object/RollOver Protective Structure).

 

[dfkrug]

The ROPS/FOPS comes in the crate, but not attached. Here I am installing it.

It is quite substantial, with 2mm (.075") steel canopy. I installed the masts, with
the 12.9 bolts provided, but the folding section was heavy enough that I needed
my forklift.

After a bit of chamfering to clear the welds with my angle grinder, it went right in.

Some similar units to mine are sold without the rollover protection, or it is smaller,
or at additional cost. If you remove the steel canopy, it looks like the top section
will fold down and clear the boom. That is how they work on brand-name units of
this size. I have not tried it.

Now if it only had a cupholder and cellphone holder.....

 

[BigBlue1]

Thanks for the continued updates and pics.

How is this mini-excavator meeting your needs? In your first post you mentioned wanting it for improving trails on hills. Have you been able to use it for that yet?

Rob

 

[dfkrug]

Thanks for the continued updates and pics.

How is this mini-excavator meeting your needs? In your first post you mentioned wanting it for improving trails on hills.
Have you been able to use it for that yet?
/QUOTE]

Fair question, Rob.

I have used it just a bit on one of my trails. Our climate here in the coastal rainforest is such that we get no
rain from JUN-SEP, so the soil is very dry. It is harder to dig, and impossible to compact. Turns to dust.
I pretty much have to wait until I get some rain in prob OCT before I can do any real work. If I pump
water from the creek using a trash pump, or bring it downhill from my water tank, then it will be
a lot more work.

A couple of things I discovered is that I Can go up inclines of >40%. Not easy, but it works. I
remember seeing a spec for a name-brand mini-X where the "gradability" is only 27%. I did
have to disable my low-oil shutoff switch in the engine to do this.

It is also easy to get a rock between the track and a wheel, which will stop you.

 

[dfkrug]

Next is the air cooling system. As shown before, the original engine ducts air, driven by
the flywheel fan, into the house on the left side. You can see the 5.5" round weldment
to which a large-diameter corrugated rubber duct attaches (first photo, left side).

You can see a smaller hose in the same photo, which is used as a cold-air intake for
combustion.

I had to cut those out to clear the new hyd pump installation on that side, as well
as fabricate a new cooling-air duct on the right side. Where I cut out the existing
duct, I mounted a small 12V fan (2nd photo).

I made the new air duct with some scrap steel I had, and connected it to the rubber
hose. On the right side of the house, I adapted the duct to the engine's pull-start mounts.
Leather was riveted on to cover up all the gaps.

 

[downsizingnow48]

I was studying the photo of the machine from the side. The thumb mounting bosses look very substantial and it looks like there is a hydraulic circuit headed that way on the boom. Was there a thumb option?

From the description of your terrain, you might be in the market for a tilt bucket.

Also, I do not see a seat belt? In rough going I have sometimes thought of getting a suspension seat and even a 5 point restraint system to keep from getting tossed around. And that has no tires to soften the jolts.

 

[dfkrug]

I was studying the photo of the machine from the side. The thumb mounting bosses look very substantial and it looks like there is a hydraulic circuit headed that way on the boom. Was there a thumb option?

From the description of your terrain, you might be in the market for a tilt bucket.

Also, I do not see a seat belt? In rough going I have sometimes thought of getting a suspension seat and even a 5 point restraint system to keep from getting tossed around. And that has no tires to soften the jolts.

The unit came with a mechanical thumb, which I have removed. I plan to install a custom
hydraulic thumb and power it with the AUX circuit provided. That is where I did the pressure
test in the video I posted. The control is one of the 8 valves in the valve stack. It is detented,
with the idea that it will be used with a hydraulic PHD. The PHD is optional.....I think
it was $1K or so. No other hyd options are sold. I will also convert the detented AUX valve
to spring-centered. Parts are on order.

There IS a seat belt, tho I had not used it in the vids. You are right that that would help with
getting jerked around. I have found that tracked skid steers jerk you around in a similar
way, when turning.

 

[Agvg]

I can really understand that you choose a gasoline engine if the alternative was a 1 cyl diesel, the noise level one those are horrible.

 

[dfkrug]

I can really understand that you choose a gasoline engine if the alternative was a 1 cyl diesel, the noise level one those are horrible.

Some of them ARE pretty loud. The ChangChai engine seems to have been sold around the world
for small equipment like generators. I imagine you see them in Norway.

I do not have much experience with 1-cyl diesels, tho I had a couple of Volvo Penta MD-1 7hp
engines last year. I was hoping to get one running...they were from the early 60s, out of a
small sailboat. Last I heard it running in the boat, it was loud, and low-RPM. You had to
hold the decompression valve open, spin it with the starter-motor, then let go, and hope it
started.

It prob ran at barely over 1000RPM, and the piston had FOUR rings, 2 compression, and 2 for
oil.

 

[ruffdog]

I have not noticed any noise reduction material in the China mini EX.

 

[Agvg]

Only a 10hp? The unit must be pretty small. I would be thinking a Kubota or Yanmar in the 23hp range. Keep us updated with pics....interesting.

A 3.5t machine often are around 30hp, so 23hp would be total overkill in a such a light machine.

 

[Agvg]

I have not noticed any noise reduction material in the China mini EX.

Seems like the 1cyl Yanmar clone is the original engine and that's so loud, has a generator set here with that engine and can't imagine have that noise in my ear hour after hour. There a reason why this nice silent 3cyl diesels are used, the barly makes sound in a proper designed housing. How high rpm are you running on?

 

[100 td]

You had to hold the decompression valve open, spin it with the starter-motor, then let go, and hope it
started.

Not too many engines left with the old starter/generators on them..............

 

[dfkrug]

How high rpm are you running on?

I run my gas engine at maybe 2500RPM. 3600 is too fast, given the size of the
pump. At idle, there is a bit of resonance inside the house, causing the rear cover
to hit the counterweights. Does not sound good, but goes away at higher RPMs. I
will need to put some padding in there the next time it is off. The buyer in Utah
actually cut up the rear cover and made it into a hinged door, like you see on a
Bobcat skidsteer.

As for noise level, with and without the body mounted, there is not a lot of difference.
I do wear hearing protection. There is no sound-deadening material anywhere.

 

[Agvg]

The Penta is water cooled and that helps a lot, this Chinese engine with horizontal cylinder seems interesting never seen it here and they also has the Yanmar clone that i have on my genset, wonder if its a license of anything.

We don't use so much small engines as you in the US, 3 phase electric power is everywhere so we use a lot of quite large motors.

 

[Agvg]

With some job you should be able to take the noise level down, 1 cyl gas can be tiring if you sit for hours.

 

[majorwager]

AGVG,

Must disagree w/ your assessment of a one cylinder w/ regard to engine noise. ChuckE2009, you tube channel, just bought a 10hp, believe it is 10 hp, one cylinder Yanmar. It is a used engine, sticker shows engine rebuild in 2010. Engine did not look much older than rebuild date. Think he was told by seller, engine had been mated to a genset. Must have racked up significant operating hours. Anyway he and mechanic Steve had it running on the bench w/ no muffler, was NOT loud at all. It is one of his very recent videos.

His visual experience is considerably at varience w/ that which you have reported. BTW, I have a 1 cylinder kohler - deere lawn mower and a 1 cylinder B and S troy built walk behind mower. I have NO noise concerns at all w/ either. Do Norwegians have sensitive hearing? Likly must keep things quiet, listening for those Ruskie subs operating off the coast?


DFKRUG,
Did the manufacturer provide hydraulic pump specifications? Max RPM's?, gpm output graph across the RPM spectrum? Believe you shared pressure reading when your gauge was connected to the aux. Circuit.

 

[Agvg]

But it wasn't at 3000rpm.