RK55 with 8.5 backhoe -- very weak

   / RK55 with 8.5 backhoe -- very weak #1  

SMiller13

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Mar 20, 2023
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8
Tractor
RK55
Hello,

Got an RK55/8.5 backhoe with about 5 hours on it. Went out to use the backhoe for the first time today. The dipper arm is really anemic on digging. I'm guessing a hydraulic problem.

RK says I should see 9 gpm and 2000 psi. I've found cheap pressure gauges but does anyone know where I can find a cheap pressure/flow combo? It cost $300 one-way to have the tractor taken to my nearest RK so I'm motivated to spend a little to troubleshoot this. Or is the pressure gauge good enough?

RK also says that I might try changing hydraulic filter and cleaning the hydraulic screen. But if those were the problem, shouldn't my front bucket be having problems too?

Sure would appreciate any suggestions.
 
   / RK55 with 8.5 backhoe -- very weak #2  
Pressure gauge will work. To test flow rate take a hose off a cylinder and put it in a clean 5 gal bucket marked for a gallon. Then time how long it takes to fill to the line and do the math.
 
   / RK55 with 8.5 backhoe -- very weak #3  
How many remotes do you have on the rear of the tractor? Check they are in the neutral position.

Mine are touchy and rear lift/bh act as you describe on my 55 when one of the remotes is accidentally in detent position.
 
   / RK55 with 8.5 backhoe -- very weak
  • Thread Starter
#4  
How many remotes do you have on the rear of the tractor? Check they are in the neutral position.

Mine are touchy and rear lift/bh act as you describe on my 55 when one of the remotes is accidentally in detent position.

There are two. Active remote powering backhoe is in detent. Unused is in neutral. I understand this is normal?


Had a mechanic out today. It appears that we hit the trifecta of gotchas:

1) heavy clay soil
2) 18" bucket
3) lightweight hydraulics


RIght now, we are getting a price on a 12" bucket.

Mechanic also said that after warranty, I may want to consider pto power for the backhoe. That would allow going from 2000 PSI to 3000 PSI.
 
   / RK55 with 8.5 backhoe -- very weak #5  
Absolutely normal, just didn't want you tripped up on something simple but hard to see.

I think you'll be happier with the smaller bucket. The one that came with the bh is, let's say ambitious for my soil too. Swapped to a smaller bucket, it's a competent digger and truck loader. We use a v Ditch bucket on it and a 13" one and it digs well. No excavator, but a decent tractor bh.

psi is raw power, but perhaps power the bh is not engineered for. It's also additional power to bend a tractor.
 
   / RK55 with 8.5 backhoe -- very weak
  • Thread Starter
#6  
Absolutely normal, just didn't want you tripped up on something simple but hard to see.

I think you'll be happier with the smaller bucket. The one that came with the bh is, let's say ambitious for my soil too. Swapped to a smaller bucket, it's a competent digger and truck loader. We use a v Ditch bucket on it and a 13" one and it digs well. No excavator, but a decent tractor bh.

psi is raw power, but perhaps power the bh is not engineered for. It's also additional power to bend a tractor.


Thanks -- I appreciate all the info I can get.

With the current bucket, I can extend the hoe to approximately mid reach and set the bucket down with the teeth and an inch or two of bucket below the clay surface. I can pull the hydraulic stick back all the way and the bucket will not move. It's stalled. To get the bucket moving, I have to "saw" the bucket up and down. That's how poor it is. I went to a part of the farm with a dark loam soil and the backhoe worked ok.

If I keep the tractor, I'll definitely be going to PTO power for the backhoe after the warranty. Either that or finding an old used beatup commercial backhoe.
 
   / RK55 with 8.5 backhoe -- very weak #7  
I'm sure that's frustrating. Tractor has been great.

Good luck .
 
   / RK55 with 8.5 backhoe -- very weak #8  
I have a 3000 psi hydraulic pto powerpack on my front snowblower. There very powerful units, but require a 25 gallon reservoir of oil. How can you do this with backhoe installed? I have run hoes and excavators for years, i cant believe you cant pull thru a few inches of clay. I dug alot in hard clay, never had any issues. But these were real contractor grade units and at least a 3 ton mini excavator.
 
   / RK55 with 8.5 backhoe -- very weak
  • Thread Starter
#9  
I have a 3000 psi hydraulic pto powerpack on my front snowblower. There very powerful units, but require a 25 gallon reservoir of oil. How can you do this with backhoe installed? I have run hoes and excavators for years, i cant believe you cant pull thru a few inches of clay. I dug alot in hard clay, never had any issues. But these were real contractor grade units and at least a 3 ton mini excavator.

The mechanic said a reservoir would have to be installed but we did not go into details. His conversational tone seemed to indicate it was not a big deal.

I went thru heavy equipment school 30 years ago and have run a number of commercial backhoes and excavators and never encountered a problem. This is the second tractor mounted backhoe I've tried. The first was actually a John Deere 25 hp unit and I do believe it outperforms this unit in the same soil. Of course, it had a smaller bucket. As I mentioned, performance in dark loam was acceptable.

The mechanic pointed out that the stock hydraulic pump was very tiny in the scheme of things. Having said that, I do enjoy the tractor. Just majorly disappointed in the backhoe performance.
 
   / RK55 with 8.5 backhoe -- very weak #10  
Can you post a video of the backhoe working? 9 gpm isn’t a lot and that’s only at full throttle. Slowing the rpm would significantly reduce that volume. Tractor backhoes are slow and not excessively powerful even when working correctly.
 
 
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