Attaching a 709 backhoe to a 843 Bobcat

[HanSolo]

I just bought my first hoe! Yuk, yuk! Anyway, I know the correct backhoe attachment for the 843 is the 909 but I got a good deal on this 709 and it's in good shape. So if you've been using a 709 on 843, I'd really like to see the attachment brackets that you've fabricated.

 

[[email protected]]

i think you just need the brackets bobcat sells. should fit.

 

[HanSolo]

i think you just need the brackets bobcat sells. should fit.

The brackets for the 709 are the hook type that attach to the side of the chassis, under the 753 "fender" with bolts. The 843 accepted the 909 backhoe attachment that used the 2" balls mounted to the front of the chassis on a plate above the peddles. The 909 had attaching members that passed in between the boom arms verses the 709 attaching members passing to the outside of the boom arms. It's going to require some creative fabrication. My current thought is make an attaching bracket to the boom arms. There doesn't appear to be enough room for a bracket above the front wheel and below the boom arm. The boom arms on a 843 are actually curved to fit quite close to the front wheel.

 

[[email protected]]

The brackets for the 709 are the hook type that attach to the side of the chassis, under the 753 "fender" with bolts. The 843 accepted the 909 backhoe attachment that used the 2" balls mounted to the front of the chassis on a plate above the peddles. The 909 had attaching members that passed in between the boom arms verses the 709 attaching members passing to the outside of the boom arms. It's going to require some creative fabrication. My current thought is make an attaching bracket to the boom arms. There doesn't appear to be enough room for a bracket above the front wheel and below the boom arm. The boom arms on a 843 are actually curved to fit quite close to the front wheel.

right but im pretty sure they the hooks for the 843. a member in this post says he has the combo of the 2. http://www.skidsteerforum.com/DesktopDefault.aspx?tabid=54&frmView=ShowPost&PostID=27916

 

[mogman]

I see a 853 bracket kit on ebay

 

[HanSolo]

I see a 853 bracket kit on ebay

There's two sets. What's really interesting is the first set is just with the hooks http://www.ebay.com/itm/BOBCAT-853-863-to-709-backhoe-mounting-kit-6587606-skidsteer-loader-backhoe-/261223539276?pt=BI_Heavy_Equipment_Parts&hash=item3cd222e24c and the second set has both hooks and 2" balls http://www.ebay.com/itm/Bobcat-backhoe-brackets-off-of-743-skidsteer-bracket-loader-/271213928585?pt=BI_Heavy_Equipment_Parts&hash=item3f259c2089. It appears that second set would allow you to attach either a 709 or 909. Unfortunately I don't think either of those will fit under the lift arms of a 843. I'll take some photos tonight so you guys can see what I'm looking at.

 

[HanSolo]

There's two sets. What's really interesting is the first set is just with the hooks http://www.ebay.com/itm/BOBCAT-853-863-to-709-backhoe-mounting-kit-6587606-skidsteer-loader-backhoe-/261223539276?pt=BI_Heavy_Equipment_Parts&hash=item3cd222e24c and the second set has both hooks and 2" balls http://www.ebay.com/itm/Bobcat-backhoe-brackets-off-of-743-skidsteer-bracket-loader-/271213928585?pt=BI_Heavy_Equipment_Parts&hash=item3f259c2089. It appears that second set would allow you to attach either a 709 or 909. Unfortunately I don't think either of those will fit under the lift arms of a 843. I'll take some photos tonight so you guys can see what I'm looking at.

Here's how the 709 mounts line up with my 843.

So the hook type brackets won't fit under the arms and over the front tires. In the last shoot which is a top view you can see the holes for the 2" ball (for the 909 attachment). I assume the smaller hole is for the ball bolt and the larger so you can get a crows foot wrench in there. I'm thinking the best way to secure this attachment without welding something to the lift arms is to utilize those OEM attachment points. I'm not keen on securing to the lift arms anyway. I think that should be the chassis. I'm thinking of getting a couple of 2" ball replacement trailer tongues and welding them to the attachment (just like it was a 909). You can see the foot rest would be the correct spot for that weld but that steel is not so thick. Perhaps add a thick gusset plate under that for a more robust support.

 

[HanSolo]

Here's how the 709 mounts line up with my 843.



So the hook type brackets won't fit under the arms and over the front tires. In the last shoot which is a top view you can see the holes for the 2" ball (for the 909 attachment). I assume the smaller hole is for the ball bolt and the larger so you can get a crows foot wrench in there. I'm thinking the best way to secure this attachment without welding something to the lift arms is to utilize those OEM attachment points. I'm not keen on securing to the lift arms anyway. I think that should be the chassis. I'm thinking of getting a couple of 2" ball replacement trailer tongues and welding them to the attachment (just like it was a 909). You can see the foot rest would be the correct spot for that weld but that steel is not so thick. Perhaps add a thick gusset plate under that for a more robust support.

And here's a photo I found of a 909. So I'd be fabricating the attaching arms shown in this photo. That's actually an attactive proposition because that modification would make the attachment compatible with the 843 and 753.

 

[[email protected]]

And here's a photo I found of a 909. So I'd be fabricating the attaching arms shown in this photo. That's actually an attactive proposition because that modification would make the attachment compatible with the 843 and 753.

i think the 911 is for the 8 series.

 

[[email protected]]

i think the 911 is for the 8 series.

i know i have seen hooks on an 843. either way i think i would made brackets to mount to the machine rather than alter the backhoe. the backhoe is done, leave it be. maybe you can buy a set of hooks and modify them to work.

 

[[email protected]]

i know i have seen hooks on an 843. either way i think i would made brackets to mount to the machine rather than alter the backhoe. the backhoe is done, leave it be. maybe you can buy a set of hooks and modify them to work.

ps do you like the solideal lifemaster tires? any drawbacks?

 

[HanSolo]

ps do you like the solideal lifemaster tires? any drawbacks?

I'm moving forward on the 2' ball arms. I got two couplers, two 36" lengths of 2" x 2" square steel tube (1/4" wall) and I just happened to have two 2" balls. The plan is to cut a wedge out of the 36" lengths at the middle. Leaving just one wall un-cut, heat and bend to form the right angle arm. I'll weld the joints and weld in the wedge as a stiffener. Then trim the ends for an exact fit on the hoe and coupler. I thought about bolting the fabricated arms to the hoe but I think welding will be much stronger than bolts in tapped holes. I don't think there's any access to the inside of the structure for nuts. Regarding the Lifemaster tires... I like the grip and tread pattern but oddly they turned out to be 1" larger OD than the rears (even being the same 16.5 x 12). The rears are Sampsons that came with the machine, they have a heavier lug pattern and priced out more expensive than the Solideal. Lesson learned... always check the specifications on tires before mixing fronts and rears.

 

[HanSolo]

I'm moving forward on the 2' ball arms. I got two couplers, two 36" lengths of 2" x 2" square steel tube (1/4" wall) and I just happened to have two 2" balls. The plan is to cut a wedge out of the 36" lengths at the middle. Leaving just one wall un-cut, heat and bend to form the right angle arm. I'll weld the joints and weld in the wedge as a stiffener. Then trim the ends for an exact fit on the hoe and coupler. I thought about bolting the fabricated arms to the hoe but I think welding will be much stronger than bolts in tapped holes. I don't think there's any access to the inside of the structure for nuts. Regarding the Lifemaster tires... I like the grip and tread pattern but oddly they turned out to be 1" larger OD than the rears (even being the same 16.5 x 12). The rears are Sampsons that came with the machine, they have a heavier lug pattern and priced out more expensive than the Solideal. Lesson learned... always check the specifications on tires before mixing fronts and rears.

First, I'm a novice welder and much of what your about to see will appear to be quite ugly (especially to expert welders). However, I learn quickly from my mistakes and appreciate helpful advise. So I started Thursday evening cutting the 2" square tube.

Then taking that to the bench, heating and bending.

That bend fractured and was only useful to keep the two segments aligned for welding. The next piece I actually just cut in half.
I proceded to weld those pieces and used the wedge as a stiffener.

The position where these arms needed to be welded on the Backhoe attachment is obstructed by the operators footrest so using a mini-grinder (sorry, no cutting torch), I made notches.

My first attempt at welding the arms was not so good. I wasn't using the correct rod at the right amperage and I didn't have a large enough clamp. I will show how the positioning turned out. It took several attempts to determine the exact placement using tack welds. To compound the difficulty, the boom and tilt cylinders leak down slowly as your aligning and measuring. Also, getting the 2" balls tightened requires some real gymnastics with a large socket wrench.

So Saturday mornings's welding lasted about two bites with the hoe when the welds busted. Again, novice welder making mistakes. So, with renewed interest and vigor, I got up Sunday morning, purchased heavier rods and big clamps. This time I'm getting good penetration and much fatter beads. Everything lined up well and here's what I ended up with.

And here's how it attaches.

I was able to work the hoe along a fence line for a half hour or so and the welds are holding. I do think I'm going to reinforce the footrest area with some angle iron though. I think that will greatly increase the strenght. When your swinging the boom there's a lot of force pitching the attachment. I'll probably also add some gusset plates on the right angles of the arms too.

 

[discountufoparts]

First, I'm a novice welder and much of what your about to see will appear to be quite ugly (especially to expert welders). However, I learn quickly from my mistakes and appreciate helpful advise. So I started Thursday evening cutting the 2" square tube.

Then taking that to the bench, heating and bending.

That bend fractured and was only useful to keep the two segments aligned for welding. The next piece I actually just cut in half.
I proceded to weld those pieces and used the wedge as a stiffener.

The position where these arms needed to be welded on the Backhoe attachment is obstructed by the operators footrest so using a mini-grinder (sorry, no cutting torch), I made notches.

My first attempt at welding the arms was not so good. I wasn't using the correct rod at the right amperage and I didn't have a large enough clamp. I will show how the positioning turned out. It took several attempts to determine the exact placement using tack welds. To compound the difficulty, the boom and tilt cylinders leak down slowly as your aligning and measuring. Also, getting the 2" balls tightened requires some real gymnastics with a large socket wrench.

So Saturday mornings's welding lasted about two bites with the hoe when the welds busted. Again, novice welder making mistakes. So, with renewed interest and vigor, I got up Sunday morning, purchased heavier rods and big clamps. This time I'm getting good penetration and much fatter beads. Everything lined up well and here's what I ended up with.

And here's how it attaches.

I was able to work the hoe along a fence line for a half hour or so and the welds are holding. I do think I'm going to reinforce the footrest area with some angle iron though. I think that will greatly increase the strenght. When your swinging the boom there's a lot of force pitching the attachment. I'll probably also add some gusset plates on the right angles of the arms too.

Thats some excellent looking work

 

[[email protected]]

Thats some excellent looking work

looks good, i still think i would not have altered the backhoe, i would have made something for the machine.......now it will only ever work with that. But that's just me.

 

[HanSolo]

looks good, i still think i would not have altered the backhoe, i would have made something for the machine.......now it will only ever work with that. But that's just me.

I think it wouldn't be too hard to strip the added attachment arms to get the attachment back to original configuration. Especially with my crappy welds The cut outs in the foot rest could be doctored up and it's pretty much like before. I added some angle iron around the cut outs and some gusset plates on the arms to strengthen. Everything is holding for now! Now I've got a bad flat face connector on the Bobcat that leaking. It's always something!

 

[HanSolo]

I think it wouldn't be too hard to strip the added attachment arms to get the attachment back to original configuration. Especially with my crappy welds The cut outs in the foot rest could be doctored up and it's pretty much like before. I added some angle iron around the cut outs and some gusset plates on the arms to strengthen. Everything is holding for now! Now I've got a bad flat face connector on the Bobcat that leaking. It's always something!

Here's the additional support I added on the foot rest. I also added gusset plates on the right angles. Warning! These welds can damage the viewers eyes! Seriously, everything is holding fast and I'm going to start in on 600' of trench this weekend. Wish me luck gentlemen!

 

[skidsteer.ca]

Here's the additional support I added on the foot rest. I also added gusset plates on the right angles. Warning! These welds can damage the viewers eyes! Seriously, everything is holding fast and I'm going to start in on 600' of trench this weekend. Wish me luck gentlemen!

Not trying to be a troll, but I think the vertical pieces and the length they stick above the where they weld to the backhoe is going to be your weak point. These hoes will skid the machine around while digging, you might want to keep an eye on that area for awhile to see if it flexes, bends or cracks.
Most of the old 909 had trouble pulling the balls through the back (normally the front in a trailer application) of the couplers,
Jmho
Ken

 

[HanSolo]

Not trying to be a troll, but I think the vertical pieces and the length they stick above the where they weld to the backhoe is going to be your weak point. These hoes will skid the machine around while digging, you might want to keep an eye on that area for awhile to see if it flexes, bends or cracks.
Most of the old 909 had trouble pulling the balls through the back (normally the front in a trailer application) of the couplers,
Jmho
Ken

No worries Ken. I started the thread for discussion and I'm glad you joined. Indeed, the area from the foot rest up to the right angle seems to take the most forces. And I did already experience two failures before re-welding the square tube and adding gusset plates. Aligning the couplers with the trailer balls is difficult with slowly leaking hydraulics while attaching. But I dug 300' of trench yesterday and everything is still together! I can see why there were issues with the couplers in the past. I get the most creaking and groaning from that area. And I've had to tighten the balls up already (which is a real PITA). I'm babying the hoe by not putting the outriggers down too hard and dancing the machine with the boom is not an option at this point. Clearly, it was a poor engineering design and Bobcat had to come up with better attachment structure in subsequent models.

 

[musclesbenz]