720 with chain case trouble

Help Support SkidSteer Forum:

skidsteer.ca

Well-known member
Joined
Jan 20, 2006
Messages
3,853
My buddies 720 bobcat backs up fine but suddenly when he goes forward the one side binds ups and the front wheel jerks and jumps. Is anyone familar with the chain case layout on these or possibly has a service manual you could scan a few pages out of. He took it across the lake last spring on the ice to build a cabin. Now is broke down and he either has to fix it there or try to back it all the way out and hope it don't pile right up. He admitted he was kindof neglectful about tightening/checking the chains. He rebuilt the engine and just got it running in time to get to the cabin b4 the ice went out
Ken
 

Tazza

Administrator
Staff member
Admin
Joined
Dec 7, 2004
Messages
16,697
email me at work and I can possibly send you some info on it, I could also get with my service dept and get some info.
[email protected]
Mark Webb
I believe these are the same setup a 731 or a 743. Gear box with 2 sprockets in the middle. One joins via chain to the back, the other is the front. There is not much to it! There are 2 plastic guides along the top to keep the chain tracking straight. Thats about it.....
Hopefully it could just be a collapsed bearing or something making the axle twist and bind up.
 

wizard

Active member
Joined
May 15, 2005
Messages
38
I believe these are the same setup a 731 or a 743. Gear box with 2 sprockets in the middle. One joins via chain to the back, the other is the front. There is not much to it! There are 2 plastic guides along the top to keep the chain tracking straight. Thats about it.....
Hopefully it could just be a collapsed bearing or something making the axle twist and bind up.
I was wondering if there was a min. & max. for how much slack is allowed on the chains, before it would start to be a problem. I'm tearing my 731 down to the bone, and I noticed that my front chains have a lot of slack. I had lost all power on my steering, so I decided to tear it down. I'm just not sure if the chain slack had anything to do with me loosing power to my steering. This is not the only reason I'm tearing it apart, I also have a leak at the chain case which causes a big mess. It looks like it has a crack that was previously (some what welded, and a bad weld at that.) But this is the way I bought it, I just had not noticed it before. Thanks RUDY
 

Tazza

Administrator
Staff member
Admin
Joined
Dec 7, 2004
Messages
16,697
I was wondering if there was a min. & max. for how much slack is allowed on the chains, before it would start to be a problem. I'm tearing my 731 down to the bone, and I noticed that my front chains have a lot of slack. I had lost all power on my steering, so I decided to tear it down. I'm just not sure if the chain slack had anything to do with me loosing power to my steering. This is not the only reason I'm tearing it apart, I also have a leak at the chain case which causes a big mess. It looks like it has a crack that was previously (some what welded, and a bad weld at that.) But this is the way I bought it, I just had not noticed it before. Thanks RUDY
Chain slack will not cause power problems.
You can correct this when you have your machine pulled down. You will need to crack i think 6 bolts that hold the gear boxes to the chain case, these bolts are inside the chain case. You then can slide the gear box back wards or forwards to get the same amount of slack front and back. It takes a bit of guess work, but you will get there. Just watch how much the axle twists.
Are you removing the chain case from the chassis to replace the seals and weld up the crack? if so, i will tell you an easy way to re-install the axles and sprockets (assuming you will replace the seals and maybe bearings.
 

wizard

Active member
Joined
May 15, 2005
Messages
38
Chain slack will not cause power problems.
You can correct this when you have your machine pulled down. You will need to crack i think 6 bolts that hold the gear boxes to the chain case, these bolts are inside the chain case. You then can slide the gear box back wards or forwards to get the same amount of slack front and back. It takes a bit of guess work, but you will get there. Just watch how much the axle twists.
Are you removing the chain case from the chassis to replace the seals and weld up the crack? if so, i will tell you an easy way to re-install the axles and sprockets (assuming you will replace the seals and maybe bearings.
I realy was not planning to, since it is not leaking. But now that you've mentioned there's an easy way sure why not. It is torn down already, I suppose it will prevent me from having to do it later, when it becomes a problem.
 

Tazza

Administrator
Staff member
Admin
Joined
Dec 7, 2004
Messages
16,697
I realy was not planning to, since it is not leaking. But now that you've mentioned there's an easy way sure why not. It is torn down already, I suppose it will prevent me from having to do it later, when it becomes a problem.
Well if you are that far into it, you may as well i guess.
The only hard part is to crack the 1 1/8” bolts inside the chain case that hold the drive sprockets. I used a spanner on the inside and a piece of angle iron with a length of pipe welded to it bolted to the axle studs. Twist to crack the bolts and your set.
Now to remove the axles, number them so you know where they go back! you can remove the axles/sprockets and chains when on the ground by removing the bolt on the sprocket and using a hydraulic jack between the back of the axle hub and the chain case to pop the axle and seal out. The trick for re-installing is to hang the chain case up! let the chains and sprockets hang down when you push the axle back in. Trying to hold a length of chain PLUS a sprocket up in the air and aligning it is really really hard. Make sure you line the sprocket up WITH the chain attached as you push the axle back in. You will never get the chain or sprocket on the shaft when the axle seal is in place, trust me i tried!!!
Doing it this way was a 1 person job, very simple.
Do the same on the other end by hanging it up the other way and you are set! If you need more specific info just let me know.
 

skidsteer.ca

Well-known member
Joined
Jan 20, 2006
Messages
3,853
Well if you are that far into it, you may as well i guess.
The only hard part is to crack the 1 1/8” bolts inside the chain case that hold the drive sprockets. I used a spanner on the inside and a piece of angle iron with a length of pipe welded to it bolted to the axle studs. Twist to crack the bolts and your set.
Now to remove the axles, number them so you know where they go back! you can remove the axles/sprockets and chains when on the ground by removing the bolt on the sprocket and using a hydraulic jack between the back of the axle hub and the chain case to pop the axle and seal out. The trick for re-installing is to hang the chain case up! let the chains and sprockets hang down when you push the axle back in. Trying to hold a length of chain PLUS a sprocket up in the air and aligning it is really really hard. Make sure you line the sprocket up WITH the chain attached as you push the axle back in. You will never get the chain or sprocket on the shaft when the axle seal is in place, trust me i tried!!!
Doing it this way was a 1 person job, very simple.
Do the same on the other end by hanging it up the other way and you are set! If you need more specific info just let me know.
Mark
Thanks for the fax and your time.
Ken
 

WebbCo

Well-known member
Joined
Sep 19, 2006
Messages
177
Mark
Thanks for the fax and your time.
Ken
I hope the fax helped, that also may explain the crack....let me know if there is anything else I can do. PS the 720 is more like a 610 than a 743....
I also have Bobcat parts cataloging at home...wished it was emailable.

Mark
 

skidsteer.ca

Well-known member
Joined
Jan 20, 2006
Messages
3,853
I hope the fax helped, that also may explain the crack....let me know if there is anything else I can do. PS the 720 is more like a 610 than a 743....
I also have Bobcat parts cataloging at home...wished it was emailable.

Mark
I started scanning my 773g manual but i need to get back to it and finish it.
Then I could email Pages.
I have a 02 dorge ram manual in pdf, as well as kohler engine manuals (most models) and a 240 250 jd skidsteer manual and a 911 pro Jd backhoe manuals + 2 other models.if anyone needs something.
Deere has a great system where you can buy their manuals online and download them in a pdf instantly. More resonable then the books to.
Ken
 
Top