Question about Bob-Tach

[lesgawlik]

I have a number of attachments, and it seems like with every one I have to do some grinding to get the pins to engage. I thought that the Bob-Tach might be bowed out, put I've put a straight edge on it and it appears to be flat in all dimensions. Is this a standard problem? Do most attachments need grinding to fit properly? Today I hooked up a used Rockhound and spend more than an hour grinding the of the attachment so it would drop down far enough to allow the pins to engage at the bottom of the mounting plate.

 

[Tazza]

If it was new it shouldn't need anything done to the attachment plate. I guess on used gear, people can modify it slightly to make it fit their machine properly from extra welds or bent pieces.
Is it just the holes the wedges go through that you need to mess with?

 

[lesgawlik]

If it was new it shouldn't need anything done to the attachment plate. I guess on used gear, people can modify it slightly to make it fit their machine properly from extra welds or bent pieces.
Is it just the holes the wedges go through that you need to mess with?

On the Rockhound, the bottom edge of the attach plate was 1/2" away from Bob-Tach on the machine. The top of the attach plate was riding too high on the Bob-Tach near the levers. I had to grind down the upside down "V's" on the attach plate to allow the plate to sit lower on the Bob-Tach. This diminished the gap between the bottom edge of the attach plate and the bottom of the Bob-Tach. The easiest way to do it was to grind the "V's" with relatively sharp edges. Then I would put the plate on and tap it with a mallet. Then I would remove the plate and look for witness marks, which I would grind off. I still had to open up the slots which capture the pins, though. It isn't a big deal, I was just surprised that every attachment seems to need some grinding to fit well enough that the levers push down easily and don't pop up.

 

[skidsteer.ca]

On the Rockhound, the bottom edge of the attach plate was 1/2" away from Bob-Tach on the machine. The top of the attach plate was riding too high on the Bob-Tach near the levers. I had to grind down the upside down "V's" on the attach plate to allow the plate to sit lower on the Bob-Tach. This diminished the gap between the bottom edge of the attach plate and the bottom of the Bob-Tach. The easiest way to do it was to grind the "V's" with relatively sharp edges. Then I would put the plate on and tap it with a mallet. Then I would remove the plate and look for witness marks, which I would grind off. I still had to open up the slots which capture the pins, though. It isn't a big deal, I was just surprised that every attachment seems to need some grinding to fit well enough that the levers push down easily and don't pop up.

That is a bit unusual imo. I have had to tune up the odd one, but not every one.
Do you have a buddy with a loader you could try them on?
What is your make and model?
Ken

 

[lesgawlik]

That is a bit unusual imo. I have had to tune up the odd one, but not every one.
Do you have a buddy with a loader you could try them on?
What is your make and model?
Ken

There's nothing else nearby. I have a Bobcat T-200. It was a rental, and I rescued it from an abusive relationship. I bought it to finish off some landscaping on my property. Since we're doing a lot of different things, I have a number of attachments- a trencher/backhoe, a landplane, a stump bucket/grapple, snow pusher and rockhound. I thought that the Bob-tach might be bowed out in the center, and that would account for the difficulty I had in getting the pins down and locked. But visually and with a straightedge it appears to be perfectly flat. I lightly scuffed the Bob-tach front with a wheel just in case there was a slight bow I couldn't see. With just about all of the attachments, I find myself trying to figure out why the attachment won't mount.

 

[SkidRoe]

There's nothing else nearby. I have a Bobcat T-200. It was a rental, and I rescued it from an abusive relationship. I bought it to finish off some landscaping on my property. Since we're doing a lot of different things, I have a number of attachments- a trencher/backhoe, a landplane, a stump bucket/grapple, snow pusher and rockhound. I thought that the Bob-tach might be bowed out in the center, and that would account for the difficulty I had in getting the pins down and locked. But visually and with a straightedge it appears to be perfectly flat. I lightly scuffed the Bob-tach front with a wheel just in case there was a slight bow I couldn't see. With just about all of the attachments, I find myself trying to figure out why the attachment won't mount.

That is a wierd one.
The one difference that I have experienced is that somewhere between the 20 series (eg. 722) and the 40 series (eg. 743), the locking pin width changed. Earlier machines were ~3"-4" narrower than the modern interface.
The width vaiation is still allowable under the SAE attachment spec, and most factory built attachments can handle this variation, but this may not be the case with homemade attachments.
I ran into this when I tried to mount our wood splitter on my nieghbour's 610. The splitter attachment pin width (34" centre to centre) was based on our 773. I noticed that my neighbour's 722 was the same config as the 610.
I doubt this is the case with your T200, but FWIW....
Cheers,
SR

 

[TriHonu]

That is a wierd one.
The one difference that I have experienced is that somewhere between the 20 series (eg. 722) and the 40 series (eg. 743), the locking pin width changed. Earlier machines were ~3"-4" narrower than the modern interface.
The width vaiation is still allowable under the SAE attachment spec, and most factory built attachments can handle this variation, but this may not be the case with homemade attachments.
I ran into this when I tried to mount our wood splitter on my nieghbour's 610. The splitter attachment pin width (34" centre to centre) was based on our 773. I noticed that my neighbour's 722 was the same config as the 610.
I doubt this is the case with your T200, but FWIW....
Cheers,
SR

I own a pile of a attachments from various manufacturers. When I bought my Tilt-Tach from Bobcat I found that my Virnig Forks would not fit.
After a little inspection, I found that the Top Strap on the forks that hooks over the top of the Bobtach was too wide and was hitting the Tilt-Tach. This prevents the lower flange with the holes to sit low enough to get all the way under the Bobtach so the pins could engage the holes.
I checked all my attachments and found a couple with the wider top strap. I contacted Bobcat thinking that my Tilt-Tach was not built properly. I was contacted by a Bobcat design engineer who told me that it was designed that way. Bobcat added their own addition to the SAE Standard. The Tilt-Tach is not designed to pull attachments at full power. It is only designed to push attachments. Bobcat attachments that will put considerable force on the Bobtach when you pull them have the wide top strap to keep you from attaching them to the Tilt-Tach.
This is the only difference I have found on the Bobtach system since it was standardized and used by other manufacturers. All my attachments fit the Bobtach on my 1995 763 with no modification at all.
It appears that your Bobtach was either damaged and not repaired properly or is bent. The other possibility is your attachment mounts are not built to the SAE Standard.

 

[USN Retired]

There's nothing else nearby. I have a Bobcat T-200. It was a rental, and I rescued it from an abusive relationship. I bought it to finish off some landscaping on my property. Since we're doing a lot of different things, I have a number of attachments- a trencher/backhoe, a landplane, a stump bucket/grapple, snow pusher and rockhound. I thought that the Bob-tach might be bowed out in the center, and that would account for the difficulty I had in getting the pins down and locked. But visually and with a straightedge it appears to be perfectly flat. I lightly scuffed the Bob-tach front with a wheel just in case there was a slight bow I couldn't see. With just about all of the attachments, I find myself trying to figure out why the attachment won't mount.

I have a 1995 753 which, as the majority of the people on this forum, I purchased from a previous owner. One of the tasks I had to perform was to replace the Bob-Tac pins. This was accomplished with a lot of muscle power, torch and a 16 lb. sledge hammer. Once the pin replacement was accomplished I was able to put the bucket on and off with no problem. I purchased a rock bucket from the dealer and found that engaging and disengaging the pins was very difficult. I had to use the torch to give me enough clearance to be able to engage/disengage the bucket easly by hand. I know this does not answer your question as to why but there are those of us who have experienced the same problem. As an additional note the dealer told me he had the bucket in the yard for quite some time. Maybe it was one of those manufactured items that just did not come out right and he found a fish.