Importing and modifying a new mini excavator from China

[LouNY]

A suction strainer is a very important part of a system it will protect your pump from large debri that could destroy a pump.
A return filter with a bypass will help to maintain clean hydraulic fluid.

 

[D'oh]

I agree with the Strainer Filter being very important., It Directly protects the Pump from any debris that gets into the Tank, the Spin On Return Filter cleans the Oil that has already gone all through your system.

A 10 Micron In Tank (Suction) would diminish Flow Rates, so I would leave the 100 Micron In Tank the way it is.

When I put my Plow Truck through the Ice, Insurance wrote off my Truck but not my Plow. I drained the Pump (which was clean anyways) of water, however the Swing 1 way Cylinders, actual had water in them that took many Oil Changes to get the water out.

Once anything is In, it takes alot to get it out.

 

[dfkrug]

Most of our tractors come with a steel mesh 100u suction filter in the bottom of the hydraulic oil sump. It does keep the manufacturing debris out of the pump, which is good.

However, it can cause problems, too. Esp when you get water in the oil, which is very hard to remove. I have had a few tractors that I acquired with water in the oil. This problem can be especially bad when starting the machine in sub-freezing weather, where water emulsion has frozen solid on the suction filter mesh. In that case, suction can cause pump cavitation, and even collapse and break the suction filter into pieces.

 

[Rich B1]

I am not trying to start an argument….just relating personal experience with suction strainers,

I spent my entire career (43 years) working for a company that built excavators. I spent a lot of those years heavily involved with hydraulic troubleshooting.

I came to loathe suction strainers on any type of suction line attached to a pump. Mainly due to lack of maintenance issues, but also due to inherent cavitation on some piston pump installations that could go from stand by flow (6 - 8 GPM) to near full flow (80+ GPM) very rapidly. The pump failure could be rather catastrophic from the cavitation over time.

Eventually, our pump supplier quietly dropped the requirement for suction strainers. And pumps quit failing.

 

[jaylast]

^^ I wonder how applicable cavitation is for these comparable tiny gear pumps?
Makes sense imo to have something to trap anything foreign right where it's introduced. Even just a screen in fill hole.

Brandonb, which are you considering, agt?
Here's pics of my stock one from diggit (nuoman, leking).
It might not flow full return well- this one is filtering 2 functions of 8 but I guess all fluid eventually goes thru it. Same premise as a cooler that cools but doesn't restrict full flow.
Translate shows the manufacturer- might be helpful to whomever you are buying from. It's beside the slew motor on the 'firewall'

 

[D'oh]

I could see that happening with a Piston Pump, but the Gear type Pumps that we have, Starvation would be better than What Ever going through the Pump. No 43 years of experience but 9 Years in Farm Machinery and -35F temps

 

[jaylast]

You can certainly move some of the functions around by switching hoses

Thinking of doing this for Boom and bucket to test the theory. Boom shouldn't feel the touchiest when it's the largest cylinder

 

[dfkrug]

Thinking of doing this for Boom and bucket to test the theory. Boom shouldn't feel the touchiest when it's the largest cylinder

I switched mine cuz I am used to the ISO pattern, which my backhoe has.

The boom control is quite jerky cuz it is very heavy, relative to total machine weight, and the flow rate is too high.

The lift force with the boom is amazingly high with the RV set properly (2400-2500psi). There are many test demonstration vids on Utube now, and one shows one of these 1.2-1.5T minis lifting another mini.

 

[Agitator]

For what it's worth - and hoping to add to the general bank of knowledge here: I figured out the root of the my machine's engine fading & surging / lack of power was. It turns out that it was fuel starvation. Once my gas tank gets to be 1/3 full or less, the fuel flow is really unreliable - especially since my entire property is hilly, so there's no really level area where I'm working. The gas was sloshing in the tank and it just wasn't getting the fuel it needed. For the moment, I'm making sure it's got a full tank, but I've ordered a small electric fuel pump online and will be installing that, tied to the ignition switch. Don't know if anyone else has needed to do that, but thought it would be worth mentioning.

If anyone has done that, and has particular wisdom to share about how to shoehorn it in, I'd love to hear about it...

 

[dfkrug]

For what it's worth - and hoping to add to the general bank of knowledge here: I figured out the root of the my machine's engine fading & surging / lack of power was. It turns out that it was fuel starvation. Once my gas tank gets to be 1/3 full or less, the fuel flow is really unreliable - especially since my entire property is hilly, so there's no really level area where I'm working. The gas was sloshing in the tank and it just wasn't getting the fuel it needed. For the moment, I'm making sure it's got a full tank, but I've ordered a small electric fuel pump online and will be installing that, tied to the ignition switch. Don't know if anyone else has needed to do that, but thought it would be worth mentioning.

If anyone has done that, and has particular wisdom to share about how to shoehorn it in, I'd love to hear about it...

I certainly have encountered fuel starvation in the past, as I operate on steep hills all the time. I try to bring along a little fuel each time I go back to my worksite, so the tank does not run low. I can go a long time on just a gallon of gas.

If you use an electric fuel pump, you will still need to use the fuel outlet at the bottom of the tank. Same problem.

Note that if you let heat inside the house get out of control, the gas will actually boil, and that may exacerbate the problem.

 

[jaylast]

Agree ^^ Maybe baffle in tank or something? Plumb in and tee a 2nd outlet? Same thing might help the supposed problem with the Agro L12 hydro tank.

dfkrug I finally got 'something' from them about diggit/leking 'YLYX' pump.
9.2ml total displacement (6+3.2)

Considering turning up the cutoff from high to low flow, and turning up stack pressure too. Same or better travel speed would be the goal. With same or better multifunction flow. And more power in curl, boom lift, and travel.
The current transition from slow to fast movement seems to be the jerky part. And the only really challenging function is boom up/down. Considering finding max flow/pressure and then perhaps running a flow control on each hose of boom function.
I almost want to try a 14 or 16gpm 2 stage pump to see how much more fast it operates (and if it is that much more jerky . . . ) The engine seems to have more than enough HP to operate up towards double the flow at full pressure also.

Honestly the entire current system is probably just way better suited to lower rpm more torque diesel.

 

[dfkrug]

I finally got 'something' from them about diggit/leking 'YLYX' pump.
9.2ml total displacement (6+3.2)

Interesting. Did you get any explanation of all the pressure #s on the maker plate? I see 13MPa (1900psi), which I guess is the system RV setting. Seems low, while the 20 and 25MPa #s are crazy high (2900-3600psi).

If you have a 2-stage pump, you should have access to the full 9.2cc pump volume at lower pressures, but if you have a large pump with flow divider as I saw on the Diggit EM15 here, you would not. And I did not sense a flow rate change when operating the EM15 to relief.

 

[jaylast]

Here's goog translate:

CBL-ES06/FS03 two-stage pump technical parameters
1. Displacement: front pump 6ml/r, rear pump displacement 3.2ml/r.
2. The opening pressure of the relief valve is 13MPa. When the system pressure is lower than 13MPa, the front pump and the rear pump supply oil at the same time, and the displacement at this time is 9.2ml/r. When the system pressure is greater than 13MPa, the relief valve opens and the 3.2ml/r rear pump supplies oil. 6ml/r front pump circulation.
3. The rated pressure of the rear pump is 20MPa, and the maximum pressure is 25MPa.
4- Maximum speed 3600r/min. Right rotation.
Yantai Liyouxin Hydraulic Technology Co., Ltd. Technical Quality Department

Compared to two stage pumps on amazon etc, the rv setting (which I still assume is adjustable) is already like 2-3x higher, while the total flow/displace is kinda lowish.
Perhaps after playing with settings it'd be fun to try a 14 or 16 gallon two stage with similar total pressure and similar rv setting capability
If I had a single pump I might wanna try an amazon two stage for < 200$ also. My travel controls aren't pilot and they do fine with the dual flow/speed.

I think a pressure gauge and adapter(s) is prob a good investment for adjustments and eventual troubleshooting

 

[dfkrug]

CBL-ES06/FS03 two-stage pump technical parameters
1. Displacement: front pump 6ml/r, rear pump displacement 3.2ml/r.
2. The opening pressure of the relief valve is 13MPa. When the system pressure is lower than 13MPa, the front pump and the rear pump supply oil at the same time, and the displacement at this time is 9.2ml/r. When the system pressure is greater than 13MPa, the relief valve opens and the 3.2ml/r rear pump supplies oil. 6ml/r front pump circulation.
3. The rated pressure of the rear pump is 20MPa, and the maximum pressure is 25MPa.

OK, I see. The 20 and 25MPa specs are just the ratings of the pump. RV for the system will still be about 2400-2500psi. And the 1900psi for the 2nd stage cutoff makes sense, too.

You should not do anything until you get a gauge and adapter to test and adjust the system RV. I suspect it is set low, and possibly close to the 1900psi setting, which is not what you want.

 

[Rich B1]

I added hinges to the rear cover yesterday to make engine access vastly better. Also a pic of the hydraulic filter I had previously added. With the rear cover hinged, I can move the filter further to the rear.

 

[dfkrug]

I added hinges to the rear cover yesterday to make engine access vastly better. Also a pic of the hydraulic filter I had previously added. With the rear cover hinged, I can move the filter further to the rear.

Good mods, Rich. Have you checked RV pressure yet?

 

[Rich B1]

No I haven’t checked the RV yet. The pump has a 90° elbow on it, need to get thread size and order another one to see if I can thread it for a test port or get a T and adapters for a test port at the pump.

I am making a bracket to install a cylinder on the grapple. Going to add quick connects to the boom so may use a test port there as an alternate.

It isn’t hurting for power, so checking the RV hasn’t been a priority.

 

[dfkrug]

I am making a bracket to install a cylinder on the grapple. Going to add quick connects to the boom so may use a test port there as an alternate.

You should get some metric O-ring plugs and adapters anyway.

Just attach gauge at AUX hose on dipper. remove the plugs to determine what size it is. I have seen 2 sizes, both metric O-ring, used there.

If you saw my vids, you saw the grapple in action. It is junk, IMO, cuz the pivots are not greaseable. It also operates off a mechanical linkage, not hydraulic. Not completely useless, but hydraulic would be way better, and the plumbing is already there.

 

[Rich B1]

I do need to get some metric caps and plugs. My first foray into getting metric fittings did not go smoothly. So ended up getting only what I needed. Next order will have a bit more on it.

The lack of grease fittings on the grapple is a concern. Have an idea to try, but not sure it will work yet. The actual grapple on the machine I got is fairly robust, but the available positions with the supplied link are limited at best.

 

[jaylast]

DIN 2353 mostly on mine so far. Has the o-ring and steeper interior chamfer. (compared to din 7631)
2353 m16-1.5 dia/thread (L10) at boom - converting to m14 (L08) for attachments.

Will also have to get adapters to sae for future mods and something to attach pressure gauge.

VEVOR 60MPa Hydraulic Pressure Test Kit Diagnostic 3 Gauge 6 Couplings Excavator | eBay

Why Choose VEVOR?. VEVOR Hydraulic Pressure Test Kit 5 Hoses 5 Gauges 13 Couplings 14 Connectors. VEVOR 60 Ton Hydraulic Cylinder Ram Hollow Jack Single Acting 2" 50mm Stroke. Our straight hydraulic pressure testing set includes three pressure gauges, and three connect tubes, six couplings.

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I don't think a single fitting will work haha.

Discount hydraulic (as mentioned) has been a great source. And possibly more expensive Brennan Brennan Hydraulic Fittings and Adapters Is a great resource they spell out the threads/fittings well.