Importing and modifying a new mini excavator from China

[dfkrug]

It seems to me that the only way to test the shock-RV settings accurately is to TEE in a gauge at the IN port on the valve stack (or pump OUT) and operate the house motor to relief. This needs to be done after adjusting the main RV up to or above the target setting of the cushion valves.

My target setting would be 2500psi for both shock-RVs, so I would start with the system RV bumped up to 2600, then operate the house motor to see what I get. Should be about 1300psi, if I use the Summit valve above. Then adjust and repeat until I get 2500psi. Same for the reverse rotation.

Then reset the system RV to 2400psi.

 

[JamesTheNextDoor]

Hi, I'm new to here. I bought the Leking KV128 last year, so it's been almost a year now. Please bear with me if my English isn't perfect. I'm Korean, BTW. The model I purchased seems to have been discontinued due to too many issues. The swing pinion and boom swing bracket broke, and I had to replace the travel motor. I also installed a crossover relief valve. Now, I'm using it well.

 

[Rich B1]

Maybe, but if you set the shock-RVs to lower than system pressure, you will not be able to utilize full system pressure when the valve is actuated.

That is the downside of a simple system.

IME, swing tends to run at a lower pressure than system. And the cushion runs even lower. But the valving involved is far more complex than is easily available to us.

since the primary purpose is to protect the swing motor and gears, my guess is about 150 PSI below system would be a good start

 

[jodieadair]

Hi, I'm new to here. I bought the Leking KV128 last year, so it's been almost a year now. Please bear with me if my English isn't perfect. I'm Korean, BTW. The model I purchased seems to have been discontinued due to too many issues. The swing pinion and boom swing bracket broke, and I had to replace the travel motor. I also installed a crossover relief valve. Now, I'm using it well.
View attachment 852029

Hello and welcome. Your English is much better than our Korean. I have watched all of your videos , you have been responsive and helpful. I installed a crossport relief valve on my machine after watching your video and am very pleased with the result. I made a short tutorial and posted on another forum, I gave you credit in the file. That has incouraged many others to install a relief valve on their machines to protect the moving parts. Keep up the good work.

 

[Carl_NH]

I plan on posting how the DDP goes. Tracking , carrier service , transport time, paperwork , the full catastrophe.

Hi Fredrik,

Did you get your machine yet, or is it still in transit? Or maybe you are having fun with the new tool!

 

[dfkrug]

Hi, I'm new to here. I bought the Leking KV128 last year, so it's been almost a year now. Please bear with me if my English isn't perfect. I'm Korean, BTW. The model I purchased seems to have been discontinued due to too many issues. The swing pinion and boom swing bracket broke, and I had to replace the travel motor. I also installed a crossover relief valve. Now, I'm using it well.

Thanks for posting, JAMES, and welcome to TBN.

Before the pinion gear broke, was there noticeable slop between it and the ring gear? How many hours on your mini?

Since your machine came with the boom-swing option, it sure seems that that circuit needs some cushioning, too. The boom-up/boom-down could use shock RVs, too, but I do not think the jerkiness in that circuit will break anything.

 

[drawthree]

I installed a crossport relief valve on my machine after watching your video and am very pleased with the result. I made a short tutorial and posted on another forum, I gave you credit in the file.

Can you post a link or direct us to where you posted the tutorial?

 

[jodieadair]

Can you post a link or direct us to where you posted the tutorial?

Sure thing. Join the Facebook group here. It's in the " Files" section under "Cushion Valve" If you don't have or like Facebook let me know and I'll get it to you. facebook.com/groups/5508502585925303

 

[JamesTheNextDoor]

Hello and welcome. Your English is much better than our Korean. I have watched all of your videos , you have been responsive and helpful. I installed a crossport relief valve on my machine after watching your video and am very pleased with the result. I made a short tutorial and posted on another forum, I gave you credit in the file. That has incouraged many others to install a relief valve on their machines to protect the moving parts. Keep up the good work.

Thank you. I'm glad I could help you.
I recommend that you also perform the attached tests for your safety.

 

[TimberFarm]

Thank you. I'm glad I could help you.
I recommend that you also perform the attached tests for your safety.

What manual did you get that info from?

 

[JamesTheNextDoor]

Thanks for posting, JAMES, and welcome to TBN.

Before the pinion gear broke, was there noticeable slop between it and the ring gear? How many hours on your mini?

Since your machine came with the boom-swing option, it sure seems that that circuit needs some cushioning, too. The boom-up/boom-down could use shock RVs, too, but I do not think the jerkiness in that circuit will break anything.

Thank you. I'm glad I found this forum. I didn't have anyone to discuss things with in my country, so it's nice to have this platform.

Before hitting 60 hours of operation, the pinion broke. Although backlash was a concern, most of the play stemmed from a damaged shaft key, consistently impacted by swing shocks.

In larger equipment, overcenter valves are often installed on booms. However, the 1-ton Kubota U10 only features an anti-cavitation valve(check valve).

Below is the table of relief valve settings for Kubota 008 and U10. Shock RVs pressure is quite low. Shock RVs also serve as overload valves, so when you actually use them, you may feel power is weaker than before and it's true.

However, it's not recommended to exert too much strain on the rotary actuator operated by gears anyway, so even if the power is weak, it doesn't seem to be a problem in practical use.

 

[JamesTheNextDoor]

What manual did you get that info from?

It's Workshop manual for kubota u10 and k008.

 

[jodieadair]

It's Workshop manual for kubota u10 and k008.

It's Workshop manual for kubota u10 and k008.

You should also join the Chinese excavator Facebook groups. They are not quite as technical but there are some very intelligent people there. facebook.com/groups/5508502585925303/ and
facebook.com/groups/1398622933920944/

 

[dfkrug]

I recommend that you also perform the attached tests for your safety.

Looks like a Kubota mini-X manual.

"Safety lock"? What is that?
On a 15-degree slope (27%), my house will rotate faster than those specs.

 

[dfkrug]

Before hitting 60 hours of operation, the pinion broke. Although backlash was a concern, most of the play stemmed from a damaged shaft key, consistently impacted by swing shocks.

In larger equipment, overcenter valves are often installed on booms. However, the 1-ton Kubota U10 only features an anti-cavitation valve(check valve).

Below is the table of relief valve settings for Kubota 008 and U10. Shock RVs pressure is quite low. Shock RVs also serve as overload valves, so when you actually use them, you may feel power is weaker than before and it's true.

Thanks for posting. I had no idea that the Kub had such a low cushion valve relief pressure. IDK if I want to go that low, but I may be on borrowed time with 150 hours on my Xiniu. It does seem that my machine is assembled better than many out there.

What are the "overcenter" valves you refer to, and how do they work?

 

[JamesTheNextDoor]

Thanks for posting. I had no idea that the Kub had such a low cushion valve relief pressure. IDK if I want to go that low, but I may be on borrowed time with 150 hours on my Xiniu. It does seem that my machine is assembled better than many out there.

What are the "overcenter" valves you refer to, and how do they work?

I don't think you need to follow these pressure values. It's more appropriate to find the suitable pressure through actual testing. I haven't even measured the pressure of the shock RVs.

Testing on a slope is to ensure that the cushion valve is properly set. Since this document is about Kubota equipment, you don't need to pay attention to the numbers. If the cushion valve pressure setting is too low, it may not hold and rotate freely at neutral valve position. For instance, during actual work, when carrying heavy objects or when affected by gravity on a slope, unintended results may occur when starting or stopping the swing.

You can think of the overcenter valve as a counterbalance with an external pilot line. When attached to the boom or travel motor, it prevents freewheeling.
I bought one. I’ll post it one day

Overcenter Valves are Key to Hydraulic Control | Armadillo Group

 

[dfkrug]

You can think of the overcenter valve as a counterbalance with an external pilot line. When attached to the boom or travel motor, it prevents freewheeling.
I bought one. I’ll post it one day

Interesting link. Thanks for posting. Different names for some of the same kinds of valves

Of even more concern should be the wheel motors. You should look into adding cross-port RVs (counter-balance valves, or wheel braking valves) to the wheel motors. This was done by request to the maker by local importer Jason. It helps a lot with keeping the mini-X from going downhill too fast. A Big Problem.

Note that ports already exist on the motors, but there is no info on how they are connected. Have you looked into this? Photo shows a wheel motor with attached valve block with 2 RVs.

 

[jodieadair]

Hey guys. It seems like we just talked about this. The pics are from a Facebook group user. He rented his machine out and the customer bent the motor mount. I feel bad for him and he mostly got criticism instead of help. I figured I would ask you smart guys about any possible straightening solutions. I believe the machine is still in the field. It is a 1.8 ton AGT 18.

 

[oldrustysteel]

Hey guys. It seems like we just talked about this. The pics are from a Facebook group user. He rented his machine out and the customer bent the motor mount. I feel bad for him and he mostly got criticism instead of help. I figured I would ask you smart guys about any possible straightening solutions. I believe the machine is still in the field. It is a 1.8 ton AGT 18.

I know what I would try first. I would spin the house around so the bucket is in front of the wheel motors.
I would extend the bucket out and push it into the ground as far as possible. An anchor point is what I am trying to achieve. attach a 4 ton come-along to the bucket and then around the outboard side of the wheel motor. Be sure the bucket is positioned so the cable is pulling forward and slightly toward the opposite wheel motor. Heat can be applied if necessary. I think with possible fine-tuning this may work.

 

[jodieadair]

I know what I would try first. I would spin the house around so the bucket is in front of the wheel motors.
I would extend the bucket out and push it into the ground as far as possible. An anchor point is what I am trying to achieve. attach a 4 ton come-along to the bucket and then around the outboard side of the wheel motor. Be sure the bucket is positioned so the cable is pulling forward and slightly toward the opposite wheel motor. Heat can be applied if necessary. I think with possible fine-tuning this may work.

Great suggestion, I'll pass it along.