Backhoe Design Ideas

[Iplayfarmer]

The 3 things I wish my BH had more of are;

1) reach
2) reach
3) reach

And my bh's both have 17'9" reach from the swing post and are rated to do a 22' 11" trench 4' deep (by digging under the machine).

I was wondering if that would be the case. I've noticed that all of the name brand hoe attachments are straight boom (i.e. Massey Ferguson, New Holland, etc.). The only curved hoes I'm seeing are on construction vehicles and P.F. Engineering's homemade plans.

I also wonder if there is some kind of transport advantage to the curved boom. Maybe the bucket tucks up closer to the boom or something like that.

 

[Iplayfarmer]

Okay, Next design question...

Is it worth it to get a PTO pump? My onboard pump is rated at 4.8 GPM, but some of that is taken by the power steering priority valve. I can get various pumps from Surplus Center in varying GPM ratings that I could run off my 2000 RPM midmout PTO. I can get a pump for under $100, but I'd have to get a tank, filter, etc. to set up the system. If I run it off the tractor it only costs me a little more hose and a QD fitting.

Thoughts?

 

[David Devuono]

Perhaps someone can elaborate on Airic's comment on not being able to reposition the tractor with the backhoe, if using a 3PH mount? I have already made up my mind that I am going to use a 3PTH mount on my project which should make the intitial hook up easier. I am thinking that on a 3PTH mount the lower link arms will only position the BH fore and aft and you would still need a couple of stought support brackets to triangulize the mount and lock it to allow lifting the weight off the wheels onto the stabilizers. Why would I then not be able to drop the tractor back down and push it forward with the bucket? (Perhaps I miss-interpeted the comment) thanks Dave

 

[hbaird]

The 3PTH has lift power but no down force at all. If you lift the Hoe with the bucket the tractor stays in place. I can get a little lift due to binding on the toplink but not enough to lift the tractor. I am in the process of frame mounting the Hoe for that very reason.
Harold

 

[MJPetersen]

I've noticed that all of the name brand hoe attachments are straight boom. The only curved hoes I'm seeing are on construction vehicles and P.F. Engineering's homemade plans.

That is not really true. Woods' back hoes have curved main booms and it is an option on the CAD Plans bh's. I would say that MOST of the current production machines have curved booms. That includes the name manufacturers like NH, Kubota, Woods and JD.

The curved boom is now the standard. Its advantages include digging deeper and closer to the machine, more compact, stronger, and better aesthetics.

Mike

 

[David Devuono]

Thats interesting because I looked at several comercial 3PTH backhoes and they have hydraulic stabilizers, how do they work if there are not some extra parts to keep the 3PTH backhoe locked in a specific position. My plan was use the 3PTH and then I could easily hook up the BH and raise it to a static position and then attach some brackets to maintain that static position. In the case of my MF135, there are a series of holes cast into the rearend housing that I would use for these brackets.

 

[john_bud]

Okay, Next design question...

Is it worth it to get a PTO pump? My onboard pump is rated at 4.8 GPM, but some of that is taken by the power steering priority valve. I can get various pumps from Surplus Center in varying GPM ratings that I could run off my 2000 RPM midmout PTO. I can get a pump for under $100, but I'd have to get a tank, filter, etc. to set up the system. If I run it off the tractor it only costs me a little more hose and a QD fitting.

Thoughts?

If you go to a hydraulic site with calculators for cylinder speed like;
Hydraulic Cylinder  Speed Calculator

you will find out how slow 4.8 gpm is. (think frozen molasses in January).

Typical operations will have you using the boom cylinder, the dipper stick cylinder and the bucket cylinder at the same time. That's how you dig a flat bottom by raising the boom, crowding the dipperstick and un-curling the bucket all at the same time. Then when you lift, you are using the boom, dipperstick, bucket and swing cylinders all at once. You can probably put postion locks on the controls and get off and brew a cup of coffee while it does that! My hoe has 22 gpm and it is too slow.

I would advise against the mid-pto option. You will loose clearance and you WILL rip it off when using the FEL. Find a used 540 pto pump for $100 and encorporate the hydraulic tank into the box of the hoe. 5-10 gal will be plenty. Naturally, more is better, but the practical improvement from 5 to 20 gal on a hoe the size you are making is very very small.

jb

 

[David Devuono]

That calculator is a neat thing. So my bucket cylinder using 24 inch stroke will only take 3.9 seconds to extend and 2.4 seconds retract. Thats with a 2" cylinder and 5GPM pump. For my needs that will be pretty fast. We are talking homemade backhoes. Note the one on the Harbor Freight site has a 2.5GPM pump. With the same pump a 6inch cylinder would take 34 seconds to extend so yes that would be slow.

 

[Iplayfarmer]

If you go to a hydraulic site with calculators for cylinder speed like;
Hydraulic Cylinder* Speed Calculator

you will find out how slow 4.8 gpm is. (think frozen molasses in January).

Typical operations will have you using the boom cylinder, the dipper stick cylinder and the bucket cylinder at the same time. That's how you dig a flat bottom by raising the boom, crowding the dipperstick and un-curling the bucket all at the same time. Then when you lift, you are using the boom, dipperstick, bucket and swing cylinders all at once. You can probably put postion locks on the controls and get off and brew a cup of coffee while it does that! My hoe has 22 gpm and it is too slow.

I would advise against the mid-pto option. You will loose clearance and you WILL rip it off when using the FEL. Find a used 540 pto pump for $100 and encorporate the hydraulic tank into the box of the hoe. 5-10 gal will be plenty. Naturally, more is better, but the practical improvement from 5 to 20 gal on a hoe the size you are making is very very small.

jb

Where are you finding used PTO pumps for $100? If I could find that kind of a deal, I might just go with it.

One of the reasons I'm thinking of going with the mid PTO is that I may convert the loader to run off it too. I have nothing else that I'm running off the mid PTO, and I'd probably just disable the seat safety and leave it hooked up permanently. Then I could use the rear PTO for the tiller or bush-hog without needing to remove the loader.

As far as clearance goes, I'll have to measure. I'm already pretty low due to mounting the Loader subframe under the front wheel drive shaft. The surplus center pumps are about 5 inches, and I think I'd have the clearance. The only thing I'm still unsure of is how to adapt from the splined shaft of the mid PTO to the Pump.

I suppose I could figure my onboard pump output by timing my loader arms. What's a typical time for a backhoe boom cylinder to fully extend or retract?

 

[denmansoft]

My 3pt Backhoe mount is braced to an oversized 2 pin toplink. Once the pins are in the 3PT cannot move up or down. It is not as rigid twisting as a frame mount would be, but I can move the tractor around with it.