Importing and modifying a new mini excavator from China

[dfkrug]

I'm not super happy with the slop I already notice everywhere- guessing it's fairly common though. I took the slewing motor off to examine the house/swing slop and it's not the mesh with ring or the keyway /key, the slop is coming from inside the pump/gears itself, and of course just a little turns into quite a bit for the boom.

Interesting.

I looked closely at your vid and can see that the shaft is not loose on the gear, so the slop is internal. It looks like mechanical slop, rather than air inside the motor. If air was in there, I would think that the movement would not make the clicking noise I hear. Also, gear-rotor hyd motors do not turn very easily by hand, at least when new.

I think something is amiss internally. Now that you have come this far, open it up. The shaft may not be one piece.

 

[jaylast]

Yes sir it really seems like play between the gears inside the motor. I pulled bottom off confirming shaft goes thru the large bearing (which has no slop) further inside.

All back together - I didn't want to risk having the digger go down yet. I can't hack/fake machining work that well . .

If 2 to 3 degrees of slewing slop originating from motor itself is not normal for a fresh machine I will definitely go further. Likely when opening the hydro system for mods and with a backup/spare motor on hand.

 

[D'oh]

Well, no one said that you were afraid to Dive into a New Machine. Anyways, my JF12 (QH12) Yancheng Cross, both have some swing, worse when the Hydraulics have Bled Down after a shut down. While working them, neither seemed noticeable. Keeping them Greased, @ every 90 degrees position helps.

A Gear Pump/Motor has to have some play in them, adding a 6' lever to a 2" Diameter just makes it very noticable.

Thanks for the Swing Motor Pics!

 

[dfkrug]

A Gear Pump/Motor has to have some play in them, adding a 6' lever to a 2" Diameter just makes it very noticable.

There is no play in any of the gearoter motors or pumps I have here or ever bought. That is true down to the smallest motors on my hydraulic chainsaws, up to biggest one I bought new to convert my PTO PHD to hydraulic power.

In my mini-X spares collection, I have 2 new wheel motors and one new pump. You can not turn these at all by hand.

 

[MattB4]

After my problems with cold weather starting I was able to do a trenching job on Thursday for a neighbor about a mile up the road from me. He needed to bury an electrical line to a new metal garage building that he had had built about a month back. A few months previous I had leveled the pad for it with my skid steer for a concrete slab.

The approximately 150ft trench went good since there was no large rocks (just one about the size of a man hole cover) and I was able to get it done in 3 hours with the exception of filling back in. The neighbor was going to back fill with his tractor later so it made that task easier.

One comment about the mini operation however. I noticed that sometimes that I could get a hydraulic oscillation going where the boom/bucket would short cycle repeatedly without operator action. It took me operating the hydraulics again to stop the rapid cycling. Not sure what causes this. Not a good thing for safety.

In regards to the play in the the housing turntable. Mine has a small amount of play where you can push it about a few inches. These little Chinese machines are not something a professional excavating contractor would want to put up with. But for a land owner that needs some occasional digging work the low price for the machine makes it attractive. Just need to be careful with using and make sure people stay away from you when operating it . I had to watch the neighbor carefully as he wanted to walk right up next to things as I was digging away. Fine control to prevent injury takes real care.

 

[dfkrug]

...Cranked and Cranked, no go. Had Spark, turned out that the Carb was filled with a Vaseline type grease, that I guess doesn't just wash away @ 20F.

That grease-like substance that builds up in your carb bowl is what happens when your petcock is not securely closed and gas leaks slowly into the carb. The gasoline fraction evaporates, leaving the ethanol and water behind.

This may take days to happen. When the gas runs out, the "grease" dries out, too, often corroding the bowl and jet. I have had this happen with numerous engines where the petcock leaks (gravity-fed), or I forget and leave it on.

 

[dfkrug]

I suspected for the size of the filter it could limit flow (based on hose size). Turns out it's similar to some hydro cooler setups that only cool some of the oil at a time. . . the only thing it filters is just one single return from each joystick, 2 total. The other two returns from the other two joystick functions (each of 8 functions have returns right?) go directly to tank, whereas these two go thru filter, but then back to pump side of valve body right above the pressure tank thing on bottom (blue label closeup in pic). Figured they would also go to tank but surprisingly no.

Let me see if I understand your description of the connections to/from each servo valve in the arm rests.

Each valve has 2-spools (functions), so there are 4 hoses total for both work ports. These hoses each go to the top of the 8-spool main stack valve.

Then there is an IN hose that comes from the flow divider on the left side of the main valve stack to the servo valve block.

Then there is an OUT hose that exits the servo valve block and goes to an inline 15u filter, which then connects to the tank (or a port on the main stack valve)? Which one?

That would make a total of 6 hoses on each servo valve block. I doubt they would have a Power Beyond out connection (7th hose).

 

[pmsmechanic]

That grease-like substance that builds up in your carb bowl is what happens when your petcock is not securely closed and gas leaks slowly into the carb. The gasoline fraction evaporates, leaving the ethanol and water behind.

This may take days to happen. When the gas runs out, the "grease" dries out, too, often corroding the bowl and jet. I have had this happen with numerous engines where the petcock leaks (gravity-fed), or I forget and leave it on.

Honestly I've found the best thing to do is turn the gas off with the engine running and let it run out of gas.

 

[dfkrug]

Honestly I've found the best thing to do is turn the gas off with the engine running and let it rub out of gas.

I do that....when I remember.

 

[jaylast]

Let me see if I understand your description of the connections to/from each servo valve in the arm rests.

Each valve has 2-spools (functions), so there are 4 hoses total for both work ports. These hoses each go to the top of the 8-spool main stack valve.

Then there is an IN hose that comes from the flow divider on the left side of the main valve stack to the servo valve block.

Then there is an OUT hose that exits the servo valve block and goes to an inline 15u filter, which then connects to the tank (or a port on the main stack valve)? Which one?

That would make a total of 6 hoses on each servo valve block. I doubt they would have a Power Beyond out connection (7th hose).

Since one can buy a single spool control that has 3 hoses (two for control and one for return, yes?), I assumed these two spool controls were simply scaled up with two control and return for each spool. Except I didn't expect to see one of the 'returns' from each joystick go thru filter and back to main stack/body.

Yes each joystick (2 functions/ spools each) has a total of 6 small hoses. 1/4 I think. No 'power beyond' unfortunately.

Each spool/function has two hoses going to corresponding control portion of main body; to blocks top and bottom of the main body.
The 'pilot' blocks you can see on top have matches on the bottom also for each pilot function.

That leaves two more hoses for each joystick. I assumed that made for 1 return for each function, like a scaled up single spool remote.
One hose from each joystick does run to tank, but the other one from each goes thru filter and back to main stack near pump inlet.

I'm not 100% that I understand how these work- the two going back to main stack could be feeding pressure to each joystick? Making them fundamentally different than a scaled up single function 3-hose-one-spool-control

Thanks for the input on the turntable/slewing slop. D'oh did you see the video though? The slop in shaft has a distinct metal gear mesh sound I think. Like bad clearances.
I will measure exact slop at bucket full extend. A couple degrees at 1" dia makes all the difference at 15' dia. And when you're going hard the slop banging around has got to exaggerate wear.

Agree about either non ethanol or 2nd best a little stabil and run the gas out of carb when sitting for longer than 3 or so weeks.

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A little off topic but what kind of methods are people using to move alot of dirt (just the mini, no skidsteer or tractor loader available). My 4x8 trailer is full of shingles so I've been filling an IBC tub (just the plastic insert) and using blade and chain to move and dump about 100' away. About 1/2 full is about the limit.