Importing and modifying a new mini excavator from China

[flix2032]

So the bucket side walls are 5mm thick. There is a reinforcing strip along opening that is 10mm.

Yes it has a hydraulic cooler and since it came with spares I assume there is a suction and return filter in the tank. I have looked around inside and not seen any other place those filters could go. When I get the chance I think I will put in a better return line filter just for the ease of changing it. There is also an accumulator stuck in there.

I have a quick question does this swing motor does it have a cushion valve on it? The smaller BS12 has a swing motor that looks like every other one I have seen pictures of and only has two lines on it. This one has two lines coming from the spool stack and one large line that looks like it goes to the end of the spool stack. At the bottom there looks to be a case drain but I did not trace that out and see where it goes.

 

[dfkrug]

What is in the last photo you posted? Is that the house rotation motor? I see two hoses that connect on the right, and what looks like an adjustable relief valve in the middle.

The RV is a good sign. Look on the other side for its twin. That would indicate double crossover RV, or cushion valve. You will just have to trace the hoses to confirm what you have.

As for case drains, the house motors on the smallest minis all seem to have the fitting on the top center, but only some have a hose connected there. Yours is a bigger machine with more serious motors.

Accumulator is for the pilot controls. You need to locate both RVs for the main and pilot valves. Nice to do all this before it is all dusty in there.

 

[flix2032]

After looking closer there is a second RV. They appear to be built right in to the motor. There are two lines from the spool valve going in then one large line heading back to the end of the spool stack. The small line at the bottom of the motor turned out to lead to the grease zerk that is used to grease the gear.

I just changed the motor oil and the hydraulic fluid. I wish it had come with some sort of manual but I have at least found a PFD from Kabuto for the D772-E. It recommends changing the oil for the first time at 50 hours. But I figured it would not hurt to do it at 25 to make sure I was on top of it.

 

[dfkrug]

After looking closer there is a second RV. They appear to be built right in to the motor.

Good news. You seem to have cushion valves on the house rotation motor.

Next, look for the 2 RVs for the main and pilot hydraulics. At least the main one, and maybe both, will be at the entry side of the main hyd valve stack. You could even have a 3rd pump.

The 2-4T Chinese minis often seem to spec their main stack valve RV at about 2900psi. Pilot RVs may only need 1000-1500psi, but I have not seen anything at all about that from any maker.

As for new engines, I like to change oil within the first 10-15 hours. And the hyd oil right away to get that manufacturing debris out of there.

 

[flix2032]

Here is a pix of some of the stumps I have dug up. Had to get the wife to help pull with the SUV to get them out of the hole. Then I loaded them up on the trailer to move.

 

[flix2032]

Good news. You seem to have cushion valves on the house rotation motor.

Next, look for the 2 RVs for the main and pilot hydraulics. At least the main one, and maybe both, will be at the entry side of the main hyd valve stack. You could even have a 3rd pump.

The 2-4T Chinese minis often seem to spec their main stack valve RV at about 2900psi. Pilot RVs may only need 1000-1500psi, but I have not seen anything at all about that from any maker.

As for new engines, I like to change oil within the first 10-15 hours. And the hyd oil right away to get that manufacturing debris out of there.

After looking around I have found one RV on the main valve stack. There appears to be a place for another one on the other end of the valve stack I think. On the pump there appears to be two adjustments and the hose leading out of that section goes to the pilot controls. Any idea why there would be two adjustments for the pilot controls?

This picture if of the RV on the valve stack.

This of what looks to be a place for another one at the other end of the valve stack.

Here is a picture of the pump body. There is a large soft line that comes in to the pump from the bottom of the tank. Then there is another smaller line that comes in from mid tank that you can see on the left. I would guess that is a return line for the RV? Top right has two adjustments screws and the line is smaller and heads off to the pilot controls. Below that is the main output of the pump and heads off to the valve stack. Any ideas on why two adjustments on the pump? I am going to have to get a pressure gauge and some adapters so I see about checking everything out.

 

[dfkrug]

This of what looks to be a place for another one at the other end of the valve stack.

A lot going on there. You need to "reverse engineer" your hyd system.

I see a name plate on your second photo. It says, "Rhinoceros", which would indicate the Xiniu company, aka Rhinoceros, aka Shandong Landworld. That is where I got my XN08, and it seems to be one of the better makers. Yours might be an XN20. You may want to look at photos and compare.

 

[flix2032]

A lot going on there. You need to "reverse engineer" your hyd system.

I see a name plate on your second photo. It says, "Rhinoceros", which would indicate the Xiniu company, aka Rhinoceros, aka Shandong Landworld. That is where I got my XN08, and it seems to be one of the better makers. Yours might be an XN20. You may want to look at photos and compare.

Yeah I am just going to have to trace it out and lay out a schematic. This is really more of a preventative measure as nothing has broken yet but I would like to understand exactly how it is supposed to work so when something does break I can troubleshoot it.

I have really only run in to two problems so far. The mechanical thumb is made out of very soft metal. I bent it on first use and then braced it after bending it back. But now it just bent again after the brace. I am planning on picking up a hydraulic thumb so I will make sure to see about reinforcing it before I install it.

The other problem I have come across is while trying to turn it often. Not the diesel motor but rather the drive motors just do not have the power to turn. I believe that the tracks were set way to tight (think guitar string tight). I did not have the proper wrench to loosen the jam nut. After finally getting a 45mm wrench I was able to loosen it and decrease the tension on the tracks. This helped but it still stalls out when turning just not as often. It also makes some wonderful sounds if I get a rock in there now. I think I probably need to loosen the tracks a bit more. If that does not work the next step I guess should be to check the hydraulic pressure.

Anyways thanks for all the input.

 

[dfkrug]

If that does not work the next step I guess should be to check the hydraulic pressure.

Your main system pressure is almost certainly low. Just be sure the RV you adjust is not the one for the pilot valves. On the Diggit EM15, the first RV I adjusted did nothing I could tell, so it was for the pilots. That unit also had no technical info.

It is way better to figure out your system when it is clean and pretty. Not so much when dusty, oily, and nasty. You can also anticipate some hose rubbing areas and protect them from a future leak.

 

[drawthree]

Your main system pressure is almost certainly low.

That was my first thought too except he said the machine "stalls out" sometimes. I take that to mean the engine literally is working too hard and stalls under the load and I think upping the system pressure would only make that worse. If by "stalls out" he means the hydraulic bypass is opening then I would absolutely be looking at upping the system pressure.