New AGT Midget Excavator: 6 Questions Including Jerky Control Stuff

[Suburban Plowboy]

Yesterday I picked up a new QR16K AGT 15-horse gas excavator. For $5K, there was no way to resist. I should be able to get rid of it with a minimal loss if I don't like it.

I have questions, of course.

1. People are saying I should change the hydraulic fluid because the Chinese put everything from Crisco to Vitalis in there. Okay, I bought fluid from Tractor Supply. But they also say I should wash out the tank with detergent and/or use a magnet to get rid of metal particles. My question: what do I care about metal particles if I have a filter between the tank and the pump? How are particles going to pass the filter?

2. Does anyone know if this machine has a second filter hiding in the back somewhere? I haven't found one yet.

3. The machine was making kind of a roaring noise yesterday when I did certain things and gave it a lot of juice. Anyone else have this issue? Wondering if the sheet metal just likes to vibrate at certain frequencies.

4. The jerkiness issue is real. It only applies to the tracks. Some dude on the web claims the Chinese don't make much effort to set the hydraulic pressure, and this causes the jerking. Apparently, the pump likes a slow diesel, and gas engines turn too fast. Has anyone here checked and adjusted their pressure? It looks easy on the web, but I can't tell exactly which gauge and fitting to buy.

5. It seems to me that I could reduce the jerking a lot by making two longer track levers. The longer the lever is, the farther you have to push it to get the same response. Has anyone here tried this?

6. Some people say there is no need to run the excavator at top RPM, and that slowing the engine down reduces the jerking. Plausible? Can anyone suggest a target RPM? I would guess low RPM's wouldn't cause overheating in an air-cooled engine, but then I don't know anything.

The hydraulic fluid was a little low when I got the machine, and I could swear topping it off reduced the jerking a little, but I don't know how that could be possible.

 

[Jrasband]

Is your machine a pilot control hydraulic? If so this helps for the jerkiness, www.PilotSpringMod.com.

 

[tacticalturnip]

$5k? That may be the cheapest I've seen a Chinese excavator go for new.

 

[oldnslo]

Yesterday I picked up a new QR16K AGT 15-horse gas excavator. For $5K, there was no way to resist. I should be able to get rid of it with a minimal loss if I don't like it.

I have questions, of course.

1. People are saying I should change the hydraulic fluid because the Chinese put everything from Crisco to Vitalis in there. Okay, I bought fluid from Tractor Supply. But they also say I should wash out the tank with detergent and/or use a magnet to get rid of metal particles. My question: what do I care about metal particles if I have a filter between the tank and the pump? How are particles going to pass the filter?

I would hesitate to use any type of detergent unless you are 100% certain that you remove all of it from the reservoir or it may dilute the new oil.

A typical inlet filter is 20 micron or coarser so the finer particles will pass on thru. If it is a screen potentially even coarser.

2. Does anyone know if this machine has a second filter hiding in the back somewhere? I haven't found one yet.

3. The machine was making kind of a roaring noise yesterday when I did certain things and gave it a lot of juice. Anyone else have this issue? Wondering if the sheet metal just likes to vibrate at certain frequencies.

Was roaring potentially the pump cavitating? This can sound like a rock crusher.

4. The jerkiness issue is real. It only applies to the tracks. Some dude on the web claims the Chinese don't make much effort to set the hydraulic pressure, and this causes the jerking. Apparently, the pump likes a slow diesel, and gas engines turn too fast. Has anyone here checked and adjusted their pressure? It looks easy on the web, but I can't tell exactly which gauge and fitting to buy.

Pressure shouldn’t make the system jerky. Poor metering valves or air in system can and will cause jerkiness.
If the track drive motors have counterbalance or overrunning load control valves these can cause jerkiness if set incorrectly

5. It seems to me that I could reduce the jerking a lot by making two longer track levers. The longer the lever is, the farther you have to push it to get the same response. Has anyone here tried this?

6. Some people say there is no need to run the excavator at top RPM, and that slowing the engine down reduces the jerking. Plausible? Can anyone suggest a target RPM? I would guess low RPM's wouldn't cause overheating in an air-cooled engine, but then I don't know anything.

The hydraulic fluid was a little low when I got the machine, and I could swear topping it off reduced the jerking a little, but I don't know how that could be possible.

If pump was cavitating if would potentially cause jerky movement

View attachment 3581157

 

[RandyT]

$5k? That may be the cheapest I've seen a Chinese excavator go for new.

Had 2 Qk16R's go for $4300 and $4525 at auction near me on Tuesday.

 

[HawkinsHollow]

I WANT ONE!

Yeah I see them for mid $4k plenty.

 

[Suburban Plowboy]

I believe they are piling up at places like Ritchie Brothers.

 

[2manyrocks]

Auction sales are one way to sell a bunch of machines without creating an extensive dealer network to sell and service.

You need to look into adding a hydraulic filter.

The guy who runs central digger supply has a youtube channel where he talks about adding filters and other tips. Imported Mini Excavator Accessories

 

[Suburban Plowboy]

I don't know what it sounds like when a hydraulic pump cavitates. I would say the system was something like a quart and a half low. I will see if it makes noise tomorrow.

I don't know how to put a second filter on the system. I'll have to find out and see if it's practical. I haven't even found the engine oil filter yet. It was boiling hot when I was fooling with the excavator today, and I didn't feel like spending a lot of time with it.

It is normal for these cheap machines to be jerky, but the impression I get from reading up is that various things can make it worse.

I don't know much of anything about pilot controls, but I don't think this machine has them.

Just for the heck of it, I'm going to put long PVC pipes over the track levers to lengthen them, and I'll see if it improves my control.

 

[RandyT]

No engine oil filter on the Rato engine. And the QK16R doesn't have pilot controls which are the digging controls next to the seat.

The main boom is the only this that is jerky on my LS15R, It will start out jerky when cold going up and down, and then seems to smooth out until about the 3-3.5 hour mark and then it will about throw you out of the seat. Just gets really touchy. The rest of the controls are actually rather smooth considering.

 

[Sidwuffler]

This owner goes through changing the fluids in his new mini and provides some good tips that might assist you..

Here is another video on how this owner smoothed out his jerky controls.

 

[Suburban Plowboy]

That is truly strange, because I have no problems with my boom.

Thanks for the info about the filter and controls.

No engine oil filter on the Rato engine. And the QK16R doesn't have pilot controls which are the digging controls next to the seat.

The main boom is the only this that is jerky on my LS15R, It will start out jerky when cold going up and down, and then seems to smooth out until about the 3-3.5 hour mark and then it will about throw you out of the seat. Just gets really touchy. The rest of the controls are actually rather smooth considering.

 

[HawkinsHollow]

I believe they are piling up at places like Ritchie Brothers

That's what I am hoping for! Market Saturation and a better used market then I will scoop one up.

 

[Suburban Plowboy]

I have not changed my hydraulic fluid yet. I was putting it off until I got a new drain plug with a valve and filter on it, but now I think that's a dumb idea.

If I change the fluid, I have to keep the old plug until the next fluid change, unless I want to change the fluid and then try to install the new plug later. That would be a mess, because fluid would be running out as I tried to install the plug. The alternative is to wait for a new plug.

I checked the change interval in the manual, and it's 2000 hours. That means the excavator will never survive until the next fluid change, so it doesn't matter what kind of drain plug I have.

Should I change the filter now? An earlier post says the old filter will let 20-micron stuff go through, which is apparently a problem. The machine has run a couple of hours now, so I suppose a certain amount of stuff is already in the lines.

Finding a filter that matches the threads, O-ring, and flow rate may be difficult.

 

[Suburban Plowboy]

I was using this thing today, and the treads got stuck. I would have expected a tracked machine to turn the tracks even if it couldn't go anywhere, but I was sitting in dirty sand, and I couldn't get it to go forward or back. I had to turn it until I found a way it was willing to go.

 

[dfkrug]

Here is another video on how this owner smoothed out his jerky controls.

If you go to 12:15 in this video, you will see why a flow restrictor is not a good way to cut down on the jerkiness. Heat.

These machines get really hot, even if you are fortunate enough to have a hydraulic radiator. Flow restrictors make this problem worse. I have adjustable flow restrictors here, but they are problematic for high duty-cycle circuits that already run hot.

I have posted about jerkiness numerous times in many threads on TBN. The best approach to making things smoother is a smaller-displacement hydraulic pump. Feathering the sticks and operating the bucket or dipper at the same time as the boom also helps a lot.

Note that feathering is lot harder if you do not hold the joysticks at the top.

 

[WI-citizen]

That's what I am hoping for! Market Saturation and a better used market then I will scoop one up.

In December they were going for about $2500 after fee for models like the MX12R and QH12R. Now they're back up to $4000. Hard to find used ones because any price discount and they sell quick as they're posted.

 

[Suburban Plowboy]

The official price direct from AGT through their website or Ebay is about $8500 right now. This is for the 15-horsepower models. For the extra $3500, I would have gotten a warranty.

I don't have any idea how I would find a slower pump that would fit this machine.

 

[WI-citizen]

The official price direct from AGT through their website or Ebay is about $8500 right now. This is for the 15-horsepower models. For the extra $3500, I would have gotten a warranty.

I don't have any idea how I would find a slower pump that would fit this machine.

I was referring to auction prices.

 

[Suburban Plowboy]

Of course.