Backhoe attachment

[rScotty]

Just found this in the manual. Is this where the BH lines would go ?

That's great! I'm impressed. It says all the right things & I'm not seeing any problems. It even uses the existing relief valve. The only question remaining is what type of thread is that port, and where you want to put the quick disconnects.... are they to becloser to the BH or to this remote outlet port. .

 

[John1550]

That's great! I'm impressed. It says all the right things & I'm not seeing any problems. It even uses the existing relief valve. The only question remaining is what type of thread is that port, and where you want to put the quick disconnects.... are they to becloser to the BH or to this remote outlet port. .

It also says maximum weight for Backhoe should be 600lbs....ugh

 

[rScotty]

It also says maximum weight for Backhoe should be 600lbs....ugh

Maybe you had better look into it a little more. Find out why 600 lbs is the limit. It might be that Kubota rated that 825 lb 3pt spec you mentioned at the ends of the 3pt arms instead of a foot or two back from that point.

Certainly backhoes can put a lot of downforce on the tractor when they are digging. To the tractor, the vertical component of the digging force is no different than weight.

\It is common even with a big BH to get the bucket hooked under a root or something that won't give. Then instead of the bucket scooping soil, the tractor bounces around. That's why hoes can be hard on tractors. They don't have to be, but operators find it hard to resis throwing the tractor around with the hoe.

Are you having second thoughts about overstressing your tractor?

 

[Vigo327]

Nice job posting helpful pics, nothing much left to guesswork now.

On your loader valve you have a port marked PB. That will now lead to the inlet of your backhoe valve. Whatever hole that PB hose is currently hooked to, is what your backhoe return line will plumb into.

I seriously doubt you will have trouble with the backhoe weight.

Consider this: A B6100 tractor is much smaller than yours, ~1000lbs bare weight. Its 3pt can only lift 500lbs. Yet, they put a B670 backhoe on it which weighs 750lbs, and it's fine. I should know, ive been fixing up my buddy's 6100&670 for too long, a year this month, and ive put some hours on it and its JUST FINE.

Now could you get away with the backhoe without already having the front loader? No, not really. But you do! So, carry on.

As far as putting stress on the tractor, sure some is more than none, but the factory backhoe subframes ive been around are hooked up in such a way that they protect the tractor very well from anything other than you picking it up and dropping it hard repeatedly (user error). The top link is really only needed (if at all) because the backhoe/subframe assembly is, aside from the digging arm, a giant L with the long end sticking under the tractor and the short end sticking up behind the tractor. The top link is mostly there to keep you from changing that 90 degree angle in the L, to some other angle. But you can set the top link in a way where for it to put tension on the top link bracket, it would have to bend the subframe mounts first. But i wouldn't even worry about it!

 

[John1550]

Maybe you had better look into it a little more. Find out why 600 lbs is the limit. It might be that Kubota rated that 825 lb 3pt spec you mentioned at the ends of the 3pt arms instead of a foot or two back from that point.

Certainly backhoes can put a lot of downforce on the tractor when they are digging. To the tractor, the vertical component of the digging force is no different than weight.

\It is common even with a big BH to get the bucket hooked under a root or something that won't give. Then instead of the bucket scooping soil, the tractor bounces around. That's why hoes can be hard on tractors. They don't have to be, but operators find it hard to resis throwing the tractor around with the hoe.

Are you having second thoughts about overstressing your tractor?

I've been operating excavators most of my life so no worries about stressing the tractor being my fault and it has a pretty heavy sub frame. More concerns with transport weight and doing wheelies. I may have to put some ballast in front bucket

 

[John1550]

Nice job posting helpful pics, nothing much left to guesswork now.

On your loader valve you have a port marked PB. That will now lead to the inlet of your backhoe valve. Whatever hole that PB hose is currently hooked to, is what your backhoe return line will plumb into.

I seriously doubt you will have trouble with the backhoe weight.

Consider this: A B6100 tractor is much smaller than yours, ~1000lbs bare weight. Its 3pt can only lift 500lbs. Yet, they put a B670 backhoe on it which weighs 750lbs, and it's fine. I should know, ive been fixing up my buddy's 6100&670 for too long, a year this month, and ive put some hours on it and its JUST FINE.

Now could you get away with the backhoe without already having the front loader? No, not really. But you do! So, carry on.

As far as putting stress on the tractor, sure some is more than none, but the factory backhoe subframes ive been around are hooked up in such a way that they protect the tractor very well from anything other than you picking it up and dropping it hard repeatedly (user error). The top link is really only needed (if at all) because the backhoe/subframe assembly is, aside from the digging arm, a giant L with the long end sticking under the tractor and the short end sticking up behind the tractor. The top link is mostly there to keep you from changing that 90 degree angle in the L, to some other angle. But you can set the top link in a way where for it to put tension on the top link bracket, it would have to bend the subframe mounts first. But i wouldn't even worry about it!

Don't I lose my loader function by doing that ?

 

[John1550]

That's great! I'm impressed. It says all the right things & I'm not seeing any problems. It even uses the existing relief valve. The only question remaining is what type of thread is that port, and where you want to put the quick disconnects.... are they to becloser to the BH or to this remote outlet port. .

Dang my loader is attached to those ports

 

[John1550]

This is my current setup. On the loader valve the PB port (red arrow) goes to one side of hydraulic block (red arrow)
The other port (yellow arrow) goes to other side of block (yellow arrow) return to sump is the other port. There is also another port marked "in"

 

[rScotty]

This is my current setup. On the loader valve the PB port (red arrow) goes to one side of hydraulic block (red arrow)
The other port (yellow arrow) goes to other side of block (yellow arrow) return to sump is the other port. There is also another port marked "in"

OK, I didn't realize it was plumbed that way. We also didn't know before that the FEL was already using the ports. So now we do. Ignore what I wrote before in #38 then.... I'll just delete that message to avoid confusion. t.

So... now I am wondering what the best way to go is. Frankly I'm not sure. What is needed here is a hydraulic schematic.

1.First things first. I don't understand why the OEM manual diverter output to the FEL goes into an unmarked port on the side of the loader control valve instead of to the port marked "IN". It could be as simple as it being an alternate "IN" port. I see a tag on the top of the loader control valve. Will that lead us to some more info on that valve?

2. And then there is the question of how to hook up the backhoe. It depends on if the BH control valve assembly also has a PB port. If so, then my thought would be to disconnect the hose (red arrow) currently running between the PB on the FEL loader valve and the hydraulic block. Disconnect the red arrow hose at the hydraulic block and run it to the "IN" on the Backhoe valve stack. Then run a hose from the PB port on the Backhoe valve stack back to the hydraulic block. Add a separate low resistance return line from the OUT port on the BH valve stack that goes to the sump.

When the backhoe is not mounted, either reconnect the hoses or have a jumper hose to replace the back hoe. In fact, something I hadn't realized until just now is that type of plumbing explains why those jumper hoses are so commonly used when swapping backhoes into an existing system. I learn something everyday.

3. What I don't like about that plan above is it relies on a PB on the BH control valve stack, and also we are sure putting a lot of obstacles that use up flow strength and all in the path of a small hydraulic pump to start with.

So... we need some hydralic schematic diagrams of these parts: FEL loader valve & the hydraulic block and probably the valve stack on the BH as well.

A PTO pump with reservoir is beginning to look better all the time.

rScotty

 

[John1550]

Well here it is. Picked it up today. He claims no top link used with this sub frame and he didn't have one hooked up ?