8B Backhoe On A 4200?

[arrabil]

More of a rhetorical question cause there is soon going to be an 8B on my 4200. Picked it up Wednesday. And I removed all the brackets from the 970 tractor it came from too. The "leak" is from the fluid coming out of the connecting hoses. Too late to reposition them not to do that.

The 8B specs out in between the 47 and 48 weight and strength wise while utilizing the same hydraulic specs. This is unlike the 7 hoe which take less hydraulic pressure to operate and is much weaker than the equivalent digging depth 47.

I figure since the 42/43/4400 frame can handle the weight of the 48 hoe I can install a few hundred pound lighter hoe that still digs deeper than the 47 and costs a good bit less on the used market. And since I need to build a subframe for it anyway, I might as well have a hoe that came with half the subframe already there.

I'm probably gonna keep the brackets in case I need/want to sell the thing, but the plan is to copy the mounting design so that the hoe uses the same JDQA method as originally intended, and blend the design with dfkrug's subframe mount for his 4300.

You can also see how we pulled the UHaul trailer out from under the backhoe by strapping it to my offroader's bumper.

 

[kennyd]

Nice, that should fit your 4200 well:thumbsup:

 

[RoyJackson]

Dam right that's a nice backhoe! I stopped by Arrabil's place on Saturday (to check out the front axle venting) and saw that very nice backhoe setting in his drive. I was just thinking how nicely that would fit on the back of a 4400!!!!!!!

 

[arrabil]

Though if I had a waxed 4400 I'd have been looking at a curved boom 448!

I'll post the subframe progress as I go. I can start on it after the neighbor's stupid Suburban is fixed.

 

[Goosehunter]

Arrabil, that looks to be a very nice 8b! I just picked up a 8a and intend on hanging it on a JD 1070. Now the problem is that I don't have the frame strengtheners, which are the larger brackets. although you said you are hanging on to the brackets, if by chance you have changed your mind and would be willing to sell them, please pm me. Thanks

 

[arrabil]

So I had the hoe plugged in to position it for measuring the subframe build. When I operate the bucket or stabilizers at half power or more the tach would show the engine losing some RPMs. I couldn't quite make out the exact number from where I was standing but lets call it 100-200.

It was a constant drop. As in, at half power it lost that much and at full power it lost that much. It wouldn't lose more RPMs the longer I held the control though. But lightly feathering the controls didn't drop any RPMs.

The loader doesn't do this. But snowblowing up hill can. I usually avoid doing it by slowing down but now that I see the hoe does it, I'm wondering..... is this normal? Am I hurting the engine by making it lose some RPMs when it works hard? How much loss would constitute bogging it?

 

[mjncad]

I'm looking forward to seeing how this addition turns out.

 

[AKfish]

So I had the hoe plugged in to position it for measuring the subframe build. When I operate the bucket or stabilizers at half power or more the tach would show the engine losing some RPMs. I couldn't quite make out the exact number from where I was standing but lets call it 100-200.

It was a constant drop. As in, at half power it lost that much and at full power it lost that much. It wouldn't lose more RPMs the longer I held the control though. But lightly feathering the controls didn't drop any RPMs.

The loader doesn't do this. But snowblowing up hill can. I usually avoid doing it by slowing down but now that I see the hoe does it, I'm wondering..... is this normal? Am I hurting the engine by making it lose some RPMs when it works hard? How much loss would constitute bogging it?

Great idea! Looking forward to seeing your pics as you "design on the fly"!

First thought that comes to mind regarding the engine drop as you work the hoe cylinders - possible flow restriction due to the hose ID on the 8B.

Is it possible that the designed flow rate for the 8B valve body and the corresponding hyd hose is significantly less than the flow rate for your 4200 - making your main hyd pump labor against the restriction?

AKfish

 

[arrabil]

Is it possible that the designed flow rate for the 8B valve body and the corresponding hyd hose is significantly less than the flow rate for your 4200.

I hadn't thought of that when I evaluated the 8B specs. Here are some of the tractors spec'd for an 8B (and mine):

970: 8.7gpm
990: 8.5gpm
1070: 9.0gpm
4005: 8.5gpm
4200: 7.3gpm

You think 1.2gpm is enough to cause the problem? Would the solution then be to install a flow restrictor at the input of the hoe?

Looking forward to seeing your pics as you "design on the fly"!

I'll post some pics tonight. Already made a good deal of progress.

 

[arrabil]

Here is my progress on the subframe.......

First I had to line up the tractor to figure out how this was all going to work.

The top support of the current subframe prevented the tractor from backing up as close as I wanted. You can actually leave the 3pt hitch arms installed with the backhoe on when installed on a 970. I wanted it closer than that.

So out comes the top support. It needs to be cut out at the bottom. I cut off the top part too. I'm gonna reuse all three pieces but slightly differently.

 

[arrabil]

With the tractor only 3.5 inches off the ground the seat already clears. Thats great news as it means one less thing to worry about.

And although I didn't get exactly centered during my trial fit, you can see the tires and PTO cover clearances. The 8B has the pivot cylinders sticking out behind the operator platform. Probably because its so far away from the 970 anyway. But I can get it really close to the back of the 4200. More great news.

 

[arrabil]

I've also figured out by now that there is no way to reuse the original mounting design. The cam locks would be three inches off the ground if I did. The problem is that the subframe is too narrow to fit between the ROPS bracket and the rear housing. So it would have to go under the rear housing. And thats just unacceptable.

So at this point I'm copying dfkrug's design very closely. First the extension needs to be added to the bottom ROPS bracket. Mine came out embarrassingly crooked. I swear I measured it and thought it looked straight in the vice! It'll still work though.

 

[arrabil]

On to the front frame reinforcement..... this was very fortuitous.... the original frame reinforcement brackets from the 970 have the same hole spacing as the holes in the front of the tractor. So a 1985 design has made it all the way to 2003 without even being used!

The bracket is a little short but we'll figure that out. First I cut off the cam lock and the rear mounting plate. You can see how it looked originally in the last picture of the first post.

 

[arrabil]

While engineering the extension to the ROPS bracket I figured out I needed a flat spot at the back of the front bracket to have a good spot to weld on. Out comes the grinder. The neighbor offered his band saw but it would have taken longer to get it than it was to grind it.

You can see how the extension will attach. And you can see where I'm reusing the metal from the top support I cut apart earlier. I could make this joint much stronger with extra plate welded in. And I will add some triangular reinforcement brackets. But......

.....I decided to make this the engineered weak point in the subframe. If so much force gets transferred this far that something is going to break, I'd rather it was my subframe than the tractor's transmission tunnel.

Whether I will reconsider the designed strength of this joint at some point is still up for debate.

 

[arrabil]

And some more pictures of the the brackets and how they'll look. The end of the extension will have the backhoe mounted to it. I'm going to weld the bar to the original subframe after some careful measurement. I haven't fully engineered everything here yet but I do know I will have to cross brace a good bit to handle any twisting forces.

You can also see where I'm going to use the drawbar as a support. The drawbar can handle 1500lbs of weight. So it might as well be part of the weight distribution design. I think it will make it easier to mount and dismount the subframe too because it won't just drop when you unbolt it from the ROPS bracket.

I've currently tack welded all that together. Its at the neighbor's shop so I can drill two holes. As soon as thats done I'm putting it all back together and repeating all this on the other side. Then onto the back part. If it isn't raining tomorrow I'll make some good progress on it.

 

[arrabil]

As for my hydraulic issues, I guess I will get to them later. AKFish, I was thinking more about it, and dfkrug gave me some ideas, and I don't think the valve works quite like we were saying. If I'm providing less gpms, it'll just move slower. The valve doesn't care about its fill rate. It'll send fluid to the work ports at the same rate as it receives it. Its not cavitating because of a lack of fluid. Know what I mean? So something else is the problem. If I have to rebuild the valve or something.... thats going to happen after the subframe is built.

 

[arrabil]

AKfish, I have to apologize. I totally misread your post. I just read it again (for the fourth time) and realized I read the opposite of what you said. So yes, there has to be some kind of restriction. Going about finding it is going to be a pain.

 

[mjncad]

Looking good, please keep the pix coming.

 

[dfkrug]

First the extension needs to be added to the bottom ROPS bracket. Mine came out embarrassingly crooked. I swear I measured it and thought it looked straight in the vice!

When I first saw your photo, I thought you were trying to weld this up
on the tractor. You are using some pretty thick steel there....looks like
maybe 3/4"?

I used a welded-on brace to keep this weldment perpendicular. I guess
you did not. I knew that heat distortion was going to have to be
managed.

Question: do the turf wheels have a different spacing if you flip them
around? Glad to see you can get the hoe in really close.

As for the hyd issue, that can be explored when you get a pressure
guage setup so you can dynamically monitor what is happening.

There is certainly nothing wrong with providing connections to your
draw bar bracket, as long as that does not decrease your ground
clearance. Note that if you have a cross brace here, you will not have
the tiny bit of flex that you may need to bolt up to the above weldments.
Clearance will have to be about 0. Something to consider.

 

[arrabil]

Yes, that piece welded to the ROPS bracket is 3/4". I'm just using what I have. No point in spending yet more money and having this piece lay around for another four years.

I used a welded-on brace to keep this weldment perpendicular. I guess you did not. I knew that heat distortion was going to have to be managed.

Just learned something.... weld-on brace. I did manage heat distortion. I did think of that. If you take a square to each part of the new bracket, each face is perfectly flat. So I got that right. Its my lame redneck-engineered jig that failed me. I'm gonna fix it on the backend. I got some really good penetrating welds into it and I didn't want to redo it and possibly weaken it.

Question: do the turf wheels have a different spacing if you flip them around? Glad to see you can get the hoe in really close

Yes, 1.5" per side. Just figured that out the other week while I had the wheels off to air them up. The turfs on a 43/4400 are taller but narrower. I don't remember what Roy and I gained when we flipped his. I believe it was more than 3 total inches but I'm not sure. Roy?

And yeah, I was surprised how close the hoe came in. I could take off the bottom corner of the PTO shield and the hoe's lower steps and come in another 1-2 inches. But then the stabilizers would 1/2" or less from touching the tires. Thats probably too close, yes?

Note that if you have a cross brace here, you will not have the tiny bit of flex that you may need to bolt up to the above weldments. Clearance will have to be about 0. Something to consider.

I think I have this covered. But you maybe right. We'll see when I get it together. I may change it to a bolt together design if necessary. I'd really like to distribute the weight here though. I don't like how all the weight is on the ROPS welds otherwise.

What do you think of adding a cross brace at the front of the frame that gets screwed to the bottom of the tunnel? There are two tapped holes there too. My initial concern is that it will be near impossible to remove this thing but my major concern is weight distribution.