Adding Backhoe to Kubota R520 Compact Wheel Loader (CWL)

[sae8425]

I hope some forum members with experience of compact backhoe attachments will be able to provide me with some advice.

I have a Kubota R520, and I want to put a suitable size backhoe attachment on this CWL.

Examples of this combination are thin on the ground (backhoe equipped CWL's are like unicorns no matter where you look).

Last R520 with a backhoe AND canopy that I saw for sale was in Australia (and sold shortly before I inquired about shipping costs).

My girlfriend, being a VERY keen gardener, frequents every nursery within 50 miles – ALL have R520's – none with a backhoe!

Kubota offered sliding carriage backhoes on their older "seat over engine" R310/410/510/520 models.

But when Kubota changed their CWL design to a rear mounted engine with the R530 they quit offering a backhoe option.

Does any forum member actually own (or use) a Kubota R510/520 with the optional backhoe? If so, is it as handy as it seems?

Any forum member know of an R520 with a backhoe AND a canopy (I need to make the ROPS fold) for sale anywhere in the States?

Kubota R520 relevant specs –

Weight – 8,980 lbs (canopy)

Aux hydraulic flow – 15.4 gpm @ 2,988 psi

Rear Counterweight – 1,500 lbs (standard) / 2,020 lbs (optional)

Kubota CWL backhoe –

Reach from kingpin – 146"

Digging Depth (2 ft flat bottom) – 107"

Digging Force – Bucket – 4,100 lbs

Digging Force – Dipperstick – 2,755 lbs

Lift Capacity – Boom Cylinder – 1,005 lbs

Lift Capacity – Dipperstick – 896 lbs

Note: Kubota never listed the backhoe weight – I assume it's in the 1,500 lb range based on the performance figures

The OEM Kubota backhoe mounting system was a hook-on design secured to the frame with 2 pins (as pictured in manuals).

Whether I stay with the Kubota hook & pin design, or use a quick attach system (SSL or Telehandler type), remains to be seen.

From perusing photos, fabricating a mounting system that allows a backhoe to be removed or installed in minutes seems possible.

Regarding (assumed) installed weight and quoted performance, the Kubota R500/520 OEM backhoe seems most similar to the –

Bobcat 8709 (old) – 1,740 lbs / 9BH (new) – 1,487 lbs

Bradco 9 (old) – 1,425 lbs / 509B (new) – 1,425 lbs

John Deere Worksite Pro BH8 – 1,610 lbs

Woods Groundbreaker BH90-X (1,365 lbs + bucket + hydraulic thumb system)

Backhoes of these sizes are successfully used with sub-4,000 lb tractors, so they shouldn't overwhelm a 9,000 lb CWL. Right?

TractorByNet forum member "Industrial Toys" has, I believe, a Bradco 13MB (1,728 lbs) on an R510 with calcium loaded front tires, and he says the (assumed) 13MB "is just a bit much for this machine", but he raves about the reach it has!

I don't know if "Industrial Toys" comments are based on the backhoe weight, or center of gravity considerations, or both.

Currently there are a few Bobcat 811's (2,012 lbs) for sale within a day's drive. Likely these are a bit too heavy for an R520. Rats!

I don't want to compromise slope stability, and I want to do as much useful work with a compact backhoe on an R520 as possible.

I could always regain some cross slope stability by relocating the wheel rim center plates, or by fabricating say 6" wide spacers.

Or some version of "suitcase" type weights might well help to offset any loss of balance cause by a mounting a backhoe.

So; what size compact backhoe would forum members feel is prudent for use on "non-flat" terrain with a 9000 lb CWL?

What brands would forum members suggest, or what brands would forum members caution against? And why.

I'm ONLY looking at used backhoe attachments, although performance comparisons to current models should still be relevant.

Suggesting I "get a mini excavator" is NOT helpful – I have 3 excavators (6,500 lbs to 21,000 lbs) – but having a backhoe on my R520 would give me many more useful options for renovating the 2 (and soon to be 3) "farms" we have that date to the 1780's.

MANY thanks to any forum member who takes the time to share their knowledge about compact backhoe attachments and CWL's.

 

[paulsharvey]

Be careful, these small articulated front end loaders are more top heavy and side to side tippy then most machines.

 

[ptsg]

Can't help you finding a backhoe but last week, I was eyeing a Kubota R310 with the backhoe here in Portugal. Had some sort of issue in the rear axle and just don't have the budget for it at the moment.

The side shift backhoe they use is indeed a must.

Another option could be to adapt a backhoe from one of these compact tractors. Then again, those don't have side shift which means the backhoe sticks waaay out in the back and it's always in the way of the operator while in use.

 

[BlueKnife]

Currently there are a few Bobcat 811's (2,012 lbs) for sale within a day's drive. Likely these are a bit too heavy for an R520. Rats!

I can't imagine that'd be too heavy. The backhoe attachment on those machines were designed to replace the counter weight. On my R410 the counter weight weighs right around 1500 lbs. I would think that the counter weight on your bigger machine has to be very close to 2000.

That said, I seriously considered doing exactly what you're talking about. When it came down to it, I decided that the juice wasn't worth the squeeze. By the time I bought all of the stuff needed to build the backhoe, or buy and modify one, I could come close to buying an older used mini excavator, which is far more useful for that kind of digging anyway, plus it gives you two different machines that complement each other.

Be careful, these small articulated front end loaders are more top heavy and side to side tippy then most machines.

Mine is far more stable and capable on slopes and uneven ground than a comparable sized tractor. That's one of the reasons I love it. It'll operate and navigate places where a skid steer or tractor couldn't dream of going.

 

[dfkrug]

I will bet there are lots of ways to connect a fabricated subframe for that Kubota wheel loader. And there are many tractor backhoe attachments available now for reasonable prices. I have not seen an R520 up close, so I do not have suggestions, but a hoe attachment on a machine of that weight would work well IMO.

I still use my tractor's hoe attachment, even tho I have a mini-X now. I love the counterweight, and the reach and force is superior. And driving time is superior as well.

If the OP gets a hoe and makes a subframe, I want to see it.

 

[sae8425]

Thanks to all the forum members who have commented so far.

So; I bought a Kubota Workshop Manual (P/N: 9789960251) and a Parts Manual and studied them VERY closely.

Then, I went to the local Kubota dealer to verify that I wasn't "missing anything" of a remotely major importance.

Here are the ACTUAL Kubota details (note: these had to be calculated from various specifications listed in the manuals:

The R410/510 backhoe weighs 1,662 lbs

The R410/510 with a backhoe is 12.4" LONGER than a R410/510 with a counterweight

The R410/510 rear counterweights weighed: 1,102 lbs (standard) & 1,653 lbs (optional) –

Only the later R520's were fitted with 1,500 lb (standard) or 2,020 lb (optional) counterweights

Note: the Kubota dealer lists the R410 counterweight at 360 lbs (a VERY small counterweight is illustrated) - obviously Kubota got this wrong!

With a backhoe fitted the Tipping Load increases from 4,674 lbs to 5,445 lbs – a 771 lb increase

Regarding slope stability, Kubota believes these CWL's are DAMN stable –

Gradeability (in low) 30 degrees – in line with a slope (i.e. longitudinal)

Static stability (straight ahead) 40 degrees – across a slope (i.e. lateral)

So; I'm now having a hard time reconciling Kubota's published figures with the "all wheel loaders are unstable on slopes" mantra.

I was wrong about the Kubota backhoe attachment system – there are 4 hooks on the frame (1/14" wide) and 4 rods (1" diameter) on the counterweight or backhoe mounting frame – but 2 pins do prevent the hooks and rods from separating when coupled.

I've also been measuring and photographing EVERY potentially suitable backhoe attachment for sale within 200 miles of me.

I'm now crunching numbers and determining the availability of required components and steel in the right grades.

I will make another post about the intricacies of grafting a non-Kubota backhoe onto an R520 in the near future.

This is obviously going to turn into a somewhat (UNDERSTATEMENT) involved design and fabrication project.

Should I chronicle all of this in this thread, or start a new "project" post to document the actual endeavor?

If a new post is the better approach, where in the forum should I post it?

Again, many thanks to any forum members who take the time to contribute to this thread.

 

[Carl_NH]

Sounds like an interesting project!

You can just keep adding to this thread - the title is fine and if you want you can update the title description in the future.

 

[BlueKnife]

So; I'm now having a hard time reconciling Kubota's published figures with the "all wheel loaders are unstable on slopes" mantra.

I think it's a matter of folks having a limited sample size and assuming that all wheel loaders fit that generalization. I have operated wheel loaders that are pretty unstable on slopes. The Kubota's are not. I'm looking forward to seeing how this turns out for you. Should be a cool project.

Note: the Kubota dealer lists the R410 counterweight at 360 lbs (a VERY small counterweight is illustrated) - obviously Kubota got this wrong!

Yeah, indeed they did. I know for a fact that mine weighs at least 1500 lbs. I've had it off a couple times to work on various things.

 

[BlueKnife]

If a new post is the better approach, where in the forum should I post it?

Seems like it should be in the Build It Yourself section maybe?

 

[ptsg]

I mean, one of the selling points of those articulated loaders is exactly how stable they are on hills, just like this demonstration video: