Backhoe Bobcat Backhoe on a Grand L series

design · Dec 24, 2006

I am considering adding a backhoe to the L2900 that I own. It is a want, not a need. I saw an add for a "3 pt hitch backhoe". Upon investigation, the Backhoe is a Bobcat 907. (Similar to the 607 in the link below)

http://bobcat.com/products/att/pdf/backhoe.0306.pdf

Someone converted the bobcat system quick attach to a 3 pt. attachment.
My number one concern: is this backhoe to big for this size tractor?
All of the main cylinders are 3" and the digging forces are 2x the BH90 series.
If the tractor can handle that size hoe, is there a way to attach this hoe to the tractor so as not to break the tractor? How do you find/modify/build a suitable subframe.

I really like the specs of this hoe, but breaking the tractor is not an option.

Are there any Engineers out there who have thought about the loads generated from a hoe and considered where to reinforce the frame to handle them?

Design.

john_bud · Dec 24, 2006

That is a lot of hoe for your size tractor. Minimum would be a tractor in the 40hp range. You can make a subframe with a long weekend of skilled fab work. (A couple weeks for a guy like me!). Use 1/4" thick material and tie into the loader frame and the rear axle. Probably rectangular tube in the 2x4 range. I could post pictures of the 4pt attach for my Ford hoe if that would help.

It's up to you. You would need to use front wheel weights, rear wheel weights, load the tires, move them to full width and probably keep a full FEL bucket. It will work, but will overpower the tractor if you don't use care. Does it have a PTO pump? If not, your tractor is no where near the hydraulic capacity to run it over a crawl with the engine screaming. You probably want to be in the 12-14 gpm range at 1800 rpm.

jb

dfkrug · Dec 24, 2006

That's a substantial hoe, at 1300#. Your tractor(4x4) weighs 2800# naked;
maybe another 900# w/ loader. This hoe could work, but you should build
a subframe and not use the 3-pt hitch. The budget L-series tractors use
a less robust 3-pt hitch than the Grand Ls, too.

A subframe will distribute the huge bending forces the hoe exerts on your
tractor to the loader subframe.

dfkrug · Dec 24, 2006

john_bud said:
That is a lot of hoe for your size tractor. Minimum would be a tractor in the 40hp range. You can make a subframe with a long weekend of skilled fab work. (A couple weeks for a guy like me!). Use 1/4" thick material and tie into the loader frame and the rear axle. Probably rectangular tube in the 2x4 range. I could post pictures of the 4pt attach for my Ford hoe if that would help.

It's up to you. You would need to use front wheel weights, rear wheel weights, load the tires, move them to full width and probably keep a full FEL bucket. It will work, but will overpower the tractor if you don't use care. Does it have a PTO pump? If not, your tractor is no where near the hydraulic capacity to run it over a crawl with the engine screaming. You probably want to be in the 12-14 gpm range at 1800 rpm.

jb

The L2900 has a 7GPM implement hyd pump. That will be plenty of flow
for a 3" cylinder.

Tractor hp has nothing to do with how well it handles a hoe. Weight is the
real issue. And at least 6GPM implement pump flow here.

My Deere weighs 800 lb less than an L2900 and the hoe on it weighs
1160#, and the custom subframe another 100# or so. Cylinder diameter
is 2.9". Works fine at only about 2000 RPM engine speed. Another 1000#
in weight and it would work even better. (I do not use weights or load
the loader bkt.)

I use mostly 1/2" plate and 1.5x3" channel for my subframes.

design · Dec 24, 2006

To all:
Two isues:
Hydraulic flow: A PTO pump could be purchased if I find the 7GPM insufficient.

Backhoe generated forces:
So I start thinking about the various loads going into the rear of the tractor: (By degree I am a metalurgical engineer, by profession, I am a mechanical engineer)

So: I want the load to go to the 4 wheels, (ideally the front wheels and the backhoe outriggers. Therefore the subframe would be in tension.

How do I ensure I have mounted to something strong enough in the rear of the tractor? Ideally I would want to make sure I can pick the rear end up to put the weight on the outrigger posts? Then what happens as I start digging? At some point I put enough moment through the frame that the front wheels get light. Do I worry about that? The hoe can generate 5000# of digging force with the dipperstick and bucket. The hoe will drag the tractor, hoe, any extra weight (including me, although my 200# does not add much) around like a toy. The hoe will also generate enough downward force at the rear of the tractor to potentially pick up the front end. Should I worry about this?

On several occasions I have had the entire tractor weight (incuding 600# of rear attachments) balanced on the front axle. (I am is the process of adding 900# to my balast box to solve that issue).

Is the rear end of the tractor tough enough to take the loads of the hoe? Where do I attach the subframe to (front and rear)? Are the ROPS mounting points fair game to mount to?

The L2900 was one of the first Grand L's. I do not know how the L2900 compares to the current Grand L's or to the 2800/3400 series. Any ideas?

Design

dfkrug · Dec 26, 2006

design said:
So: I want the load to go to the 4 wheels, (ideally the front wheels and the backhoe outriggers. Therefore the subframe would be in tension.

How do I ensure I have mounted to something strong enough in the rear of the tractor?

The subframe is in compression in some places, tension in others, depending
on what you are doing. My suggestion is you look at some Good Subframes,
like you see on an industrial tractor, or ones that try to emulate that
design on a CUT. I think the so-called 4-point mounting schemes used
by the newer Woods subframes work well. Also the integrated subframes
you see on the Kubotas B21, L39, and even the BX24 with the BT601 hoe.

Most tractors have many "extra" tapped holes in the rear castings. Take
a look under the rear axle and differential. These make good mounting
points. It is often OK to use the same connections that your ROPS uses.
The idea of a 4-pt subframe is it totally bypasses the use of the toplink
bracket in favor of 2 mounting points above the rear axle, on the left and
right hand sides. This requires extra links in this area.

BTW, I was wrong....the L2900 is the first of the "Grand Ls", arriving in
1998. After that, Grand Ls were designated Lxx10 or Lxx30 or now Lxx40
and the "standard Ls" were Lxx00. The Grands are more robust and heavier
than equivalent hp Standards. I have had both.

design · Dec 27, 2006

A woods 9000 3pt BH became available for a good price <$3K. Would I be better off using the smaller BH9000 instead of the larger Bobcat?
Who has plans for the woods subframe? I have some welding and fab experience and a new Ranger 8 waiting for a project to be tested on.
I welcome any input....

Thanks for all your help. I do not want to break my tractor.

Design

dfkrug · Dec 28, 2006

design said:
A woods 9000 3pt BH became available for a good price <$3K. Would I be better off using the smaller BH9000 instead of the larger Bobcat?
Who has plans for the woods subframe? I have some welding and fab experience and a new Ranger 8 waiting for a project to be tested on.
I welcome any input....

Thanks for all your help. I do not want to break my tractor.

Design

The Woods 9000 is a similar weight to the Bobcat you mentioned, I will
bet. You can buy the subframe from Woods, probably. Go to their
website and download the PDF file to get a look at it. Otherwise you
will have to custom build one that will fit your tractor.

A Woods 9000 hoe in decent shape for <3K is a deal. Grab it. I have
never found any used backhoe attachments that were any good. They
often sit outside for years.

rtrent · Dec 28, 2006

Woods site doesn't list a 9000 sub-frame for the L2900
Backhoe Sub-Frame Mounting Kits Operator's Manuals
Only for BH6500 and BH7500. Not even the newer BH70X or BH80X. Seems strange. You could call Woods at (800) 319-6637 .

David_Kb7uns · Dec 28, 2006

Have a Bradco 408 backhoe that came off a Bobcat and is now mounted on a L3130. The Bradco backhoes are set up so that either a skidsteer bracket or a subframe bracket bolt to the hoe. Would check with Bradco to see if they have a subframe assembly that you could rework and bolt or weld to the Bobcat hoe, probably would have to cut off the skidsteer bracket to make it work.

David

design · Jan 2, 2007

I wish I could change the thread title to a Woods 9000 BH on a L series. At this point this appears to be the better deal. As for the frame, I spoke with our local Kubota/Woods dealer and there is no sub-frame that will fit.
My options are:
1. Modify the L3130/Woods9000 4 point frame to fit the 2900
2. Build my own
3. Use the L2900/Woods 7500 subframe and modify to fit the backhoe.

At this point I am leaning toward option 1. The dealers head of service made the following helpful suggestion:

"Make sure the load from the hoe goes to the loader frame and not to the tractor." ie. If you pick the tractor up with the bucket and the out riggers, (all four wheels off of the ground) and the backhoe subframe connects only to the loader mounts, you can not brake the tractor.

This seemed like good advice.

Any thoughts.
Design

Jay4200 · Jan 3, 2007

design said:
A woods 9000 3pt BH became available for a good price <$3K. Would I be better off using the smaller BH9000 instead of the larger Bobcat?
Who has plans for the woods subframe? I have some welding and fab experience and a new Ranger 8 waiting for a project to be tested on.
I welcome any input....

I have a Woods BH9000 on my L4200 with a subframe mount. The L2900 is the same basic design, just a little smaller everywhere. <$3k is a great price for a BH9000, incidentally - typically decent used ones are ~$5k.

A backhoe generates some really violent forces - not so much when its doing normal stuff, but when you make a mistake, things get ugly fast. My BH can (and does) toss my L4200 around like it's made of tissue paper. I think that a 9' backhoe will rip your 3pt hitch off like its made of sticks. The Bobcat 'hoe will work too - it's of similar weight to the Woods. I wouldn't worry too much about hydraulic volume, but the backhoe might move a little slow. Personally, I wish my BH9000 was bigger (I have excavator envy).

The real problem is weight - the backhoes sit pretty far behind the tractor. You could find yourself riding wheelies everytime you hit the gas. You could load down the front, but then you have to worry about axle loading.

The L2900 is only rated for a 7.5' backhoe, but I think it could carry a BH9000 no problem -BUT- you definately need a subframe mount. They are little more than a couple of pieces of square stock, so if you can't find one, make one. If you can get a subframe mount for another backhoe, you could probably modify it for whichever 'hoe you end up with fairly easily. Even if you have to use a 7.5' mount for a 9' backhoe, it'll work.

JayC

dfkrug · Jan 3, 2007

design said:
My options are:
1. Modify the L3130/Woods9000 4 point frame to fit the 2900
2. Build my own
3. Use the L2900/Woods 7500 subframe and modify to fit the backhoe.

At this point I am leaning toward option 1. The dealers head of service made the following helpful suggestion:

"Make sure the load from the hoe goes to the loader frame and not to the tractor." ie. If you pick the tractor up with the bucket and the out riggers, (all four wheels off of the ground) and the backhoe subframe connects only to the loader mounts, you can not brake the tractor.

Sorry you can not a get a ready-made subframe for that hoe.

My first choice would be to build my own. You can mount the hoe
closer in to the tractor than pre-built subframes allow. This reduces
the bad effects of having such a heavy weight hanging out so far. Go
look at how close the hoes are mounted on an L35/L39, or even a
BX24 with the BT600 hoe.

2nd choice is modify a subframe built for the L2900. The harder part
is done, which is your tractor-specific mounts on your rear axle
casting. When you pay your $1000 for the Woods L3130 4-pt subframe,
you might have wished you went to build-your-own.

Backhoe subframes are supported by the loader subframe AND stout
connections to the rear axle housing, usually bolted to factory-provided
threaded holes.

design · Jan 3, 2007

Thank you for all the encouragement. If all goes well I hope to pick up the Woods 9000 this weekend.
The frame may take till spring, but that seems like a good winter project anyway.

Jay4200: As you are just down the road and I work in Hollis, live near Concord I would love to see how the 9000 is attached. I am sending you a PM to that effect.

dfkrug: I agree: A custom sub-frame is the way to go. I just need to think about the design. The bottom of the rear axle where the ROPS mounts plus the loader frame should be sound mounting points. My concern is the following three situations:
1. driving with the hoe on the back over rough terrain.
2. working to the side of the tractor and putting large torsion moments through the frame/sub-frame.
3. Is the 480 loader capable of taking the loads from having a large backhoe pick the tractor up? It is possible that the tractor could end up supported by only the backhoe arm and the bucket

It seems the 3130 has a little more width at the rear axle then the 2900. Can I squeeze a .25 wall 2”x4” box beam between the rear wheel and the frame/ROPS? Should I try to go inside the ROPS? What about spacing the rear wheels off 1 inch each side( Custom adapters) I know this will increase the bending moment through the rear axle. Can the tractor take that?

Design.

dfkrug · Jan 3, 2007

design said:
I agree: A custom sub-frame is the way to go. I just need to think about the design. The bottom of the rear axle where the ROPS mounts plus the loader frame should be sound mounting points. My concern is the following three situations:
1. driving with the hoe on the back over rough terrain.
2. working to the side of the tractor and putting large torsion moments through the frame/sub-frame.
3. Is the 480 loader capable of taking the loads from having a large backhoe pick the tractor up? It is possible that the tractor could end up supported by only the backhoe arm and the bucket

It seems the 3130 has a little more width at the rear axle then the 2900. Can I squeeze a .25 wall 2”x4” box beam between the rear wheel and the frame/ROPS? Should I try to go inside the ROPS? What about spacing the rear wheels off 1 inch each side( Custom adapters) I know this will increase the bending moment through the rear axle. Can the tractor take that?

I have tried a number of different strategies with the subframes I have
made. Some used a ladder-style subframe that always stayed attached
to the hoe when it came off. My latest uses a system like the Woods
4-pt subframes that leave a substantial part of the subframe on the
tractor all the time. I would not do this if the tractor used a mid-mnt mower
at any time. This kind of subframe connects at 4 pts above and below the
rear axle.

Every tractor is different and I think you should view examples to see how
hefty you need to build things. I looked at, measured, and photo-ed many
before I attempted my first custom job. There are many ways to do a
custom subframe that will be strong enough. It is OK to use rect tubing,
channel, or plate.

It is OK to use the same connection that the ROPS uses on the rear
axle casting. This photo I am posting is of the Woods 9000 on an L4830.
You can see that there are not a lot of extra holes provided on the
axle casting. Kubota has been kind enough to provide an "ear" on the
ROPS bracket with holes for the subframe to mount. You can also
remove your ROPS bracket and weld an ear on it. I did that for an
L2500 and it worked great.

All the tractors I have mounted subframe hoes on are capable of
lifting themselves off the ground with hoe and loader. Not a "good"
regular practice, but doing that should not damage the tractor.

My current Kioti CK30 project is totally different....I plan to post pix
soon.

dfkrug · Jan 3, 2007

...here is the Woods 9000/L4830 subframe shot....

john_bud · Jan 3, 2007

design said:
Thank you for all the encouragement. If all goes well I hope to pick up the Woods 9000 this weekend.
The frame may take till spring, but that seems like a good winter project anyway.

dfkrug: I agree: A custom sub-frame is the way to go. I just need to think about the design. The bottom of the rear axle where the ROPS mounts plus the loader frame should be sound mounting points. My concern is the following three situations:
1. driving with the hoe on the back over rough terrain.
2. working to the side of the tractor and putting large torsion moments through the frame/sub-frame.
3. Is the 480 loader capable of taking the loads from having a large backhoe pick the tractor up? It is possible that the tractor could end up supported by only the backhoe arm and the bucket

It seems the 3130 has a little more width at the rear axle then the 2900. Can I squeeze a .25 wall 2”x4” box beam between the rear wheel and the frame/ROPS? Should I try to go inside the ROPS? What about spacing the rear wheels off 1 inch each side( Custom adapters) I know this will increase the bending moment through the rear axle. Can the tractor take that?

Design.

You have to design the mounting stout enough to hold the tractor rigid. If you don't - bad things can happen. (See the attached pictures) Those castings are 3/4" thick on the differential and 1/2" for the transmission. Both were replaced as that was more economical than repair. The factory sub-frame is 3/8" x 2" x 6" C channel. But the hoe is a 14' dig and about 3000# weight. The tractor is an industrial Ford (basically an 841).

Don't mean to scare you off of this project, if you can get 1/2x2x4 tube, it should be fine.

jb

Jw5875 · Jan 3, 2007

Here are pics of my "Kubota certified re-enforced bracket part" to beef up the top link bracket on the rear end housing recommended for heavy box blade and backhoe attachment. Also they have a heavy duty top link pin that goes in to this bracket. Previously ??? yr or so, a post was made with pics showing a rear end housing that had broken because this bracket was not installed along with a 3 pt hoe attachment and no subframe

More inquirement found that this part is needed for heavy/stress making rear attacments. along with the subframe.

Pics are on my L3400.

Of course it is a piece of $3.00 steel from the scrap yard that you could make, but to keep my warrantee, I paid $xx.xx for this "Kubota" part.

I welded the original two piece bracket to this, the design seemed to me that the bolts coming through the new bracket, only made a "washer" part with the original brackets bolted to it. (Bolts could still be pulled through along with housing piece)

Hope that future backhoe attachers research more for all the parts that are needed, and the salesman can also advise.

"Just Trying to save my rearend" (punn intended)

jw5875

dfkrug · Jan 4, 2007

The better subframes (like the Woods 4-pt and Kubota BT
series) make no use of the toplink bracket at all.

Also, don't forget, this is a 1300# hoe, not a 3000# hoe.

design · Jan 4, 2007

The more I think about the design, the more I want to copy the B21 (B26)/L39 sub-frame. Having the hoe close to the tractor offers several advangtages:
1. There is a greater departure angle
2. The hoe can be closer to the ground (with out effecting departure angle as much) meaning the outriggers will be able to lift the tractor higher off the ground. Helpful for working on a side slope or uneven/soft ground.
3. The load is better shared between the two axles (not by much..) when the hoe is not in use and is ridding about as a counter weight.

Again, thank you for all of the suggestions. God willing, I am picking the 9000 up tomorrow.

Design.