Importing and modifying a new mini excavator from China

D'oh · Jun 7, 2023

Ok, why does 1 Pump have a Double Stack?

Ok, I get that it would have twice the Flow up to 13.5hp. But what would it drive? The Track Motors separately? Track Motors and Aux Bank? Why only 1 line?

Rich B1 · Jun 7, 2023

I don’t think that is a double pump but rather an unloading pump, like a log splitter. A crude form of variable flow hydraulics.

ArlyA · Jun 7, 2023

I'd guess it is a pump per track. Pisten Bullys have a pump for each track plus more. The last bully I operated had 5.

ptsg · Jun 7, 2023

D'oh said:
Ok, why does 1 Pump have a Double Stack?

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Ok, I get that it would have twice the Flow up to 13.5hp. But what would it drive? The Track Motors separately? Track Motors and Aux Bank? Why only 1 line?

The bottom picture is a tandem pump. They share the suction side, hence why you only see 3 lines.

Having a tandem pump allows them to use two separate control valves and split all the functions between the two pumps. With one pump, everything is ran off a single pump, which makes it difficult to run various functions at the same time.

D'oh · Jun 7, 2023

ptsg said:
The bottom picture is a tandem pump. They share the suction side, hence why you only see 3 lines.

Having a tandem pump allows them to use two separate control valves and split all the functions between the two pumps. With one pump, everything is ran off a single pump, which makes it difficult to run various functions at the same time.

I could see the SUction being a part of the Housing, that make sense. The Control Valve bank is where I was confused. thinking the Track Motors and Aux have the little control sticks, but I thought they were still tied into the main Valve Bank Like Fredrick's previous picture

ptsg · Jun 7, 2023

D'oh said:
I could see the SUction being a part of the Housing, that make sense. The Control Valve bank is where I was confused. thinking the Track Motors and Aux have the little control sticks, but I thought they were still tied into the main Valve Bank Like Fredrick's previous picture

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On some excavators they use a single sectional valve bank. However they can configure it to have two inputs (one from each pump) which then combine flows and return through a common section in the middle of the valve bank.

Fredrik · Jun 7, 2023

As far as i can tell on my mini everything goes through the valve block .

Is there a way to increase the RV pressure on these mini's ? I've looked and can't find it. I know I should know this but.........

D'oh · Jun 7, 2023

Fredrik said:
As far as i can tell on my mini everything goes through the valve block .

Is there away to increase the RV pressure on these mini's ? I've looked and can't find it.

I doubt that the extra pump will add pressure, just flow. However the only time I find mine laking is traveling. If I try to swing while moving, it's priority is the travel motors.

dfkrug · Jun 7, 2023

Fredrik said:
As far as i can tell on my mini everything goes through the valve block .

Is there a way to increase the RV pressure on these mini's ? I've looked and can't find it. I know I should know this but.........

Interesting pump. i was gonna ask, but you beat me to it.

Follow the two small outlet hoses to see where they connect. If BOTH go to the valve stack, then they must be joined first. As to why, I do not know...maybe your factory ran out of the right pumps? If it IS a log splitter pump like Rich describes (2 chambers with RV between), then some
performance tests are in order.

I do have an extra new 8-spool valve stack, and I have taken it apart to see how it is built. I also made the AUX control spring-centered, rather than detented, since I use a hyd thumb. Auger users may prefer detented.

As for the relief valve, I linked a Utube vid on how to test and adjust that. My XN08 was nuts-on, but the ones from Ouke were way low. Here it is again for those who don't want to wade back thru the whole thread: