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.