630 Bobcat

[discountufoparts]

I have a 630 Bobcat that all of a sudden lost drive on the left side. I have removed the front transmission cover last night and noticed that both chains are still attached and there is a slight jerking motion to the chain going forward or backward but no overall movement. It lost drive randomly with no load on it just going forward to backward at a low speed. Any ideas? I had only the time to pull off the front cover last night and remove the pump front mount bolts to get at the rear cover as well and it was getting dark. The previous owner had disconnected all of the parking break apparatus and as I look in the transmission case I notice one of the discs for the break is hanging at a very odd angle. Is it possible something fell off of this and is jamming the drive now? Thanks for your input. David

 

[chuckcnm]

I would take a look at the nut that holds the chain gear and special washer that keeps the disk from coming off the chain gear. The disk are very loose and have 3 teeth that the special washs hold it on with.

 

[discountufoparts]

I would take a look at the nut that holds the chain gear and special washer that keeps the disk from coming off the chain gear. The disk are very loose and have 3 teeth that the special washs hold it on with.

Thanks for the input chucknm. I did take that rear cover off the transmission so I could see what was going on but I haven't been able to figure it out yet. I see the shaft and nut spinning on the end of it but the sprockets and chains won't turn. I have removed the whole brake assembly from the system other than the discs. I don't see any special washers. The discs are right off the sprocket. However that isn't the problem. Does anyone know what engages the gears? Is there a keyway or is it splined? I fear that something connecting the gears to the motor output shaft has stripped. Thanks.

 

[chuckcnm]

Thanks for the input chucknm. I did take that rear cover off the transmission so I could see what was going on but I haven't been able to figure it out yet. I see the shaft and nut spinning on the end of it but the sprockets and chains won't turn. I have removed the whole brake assembly from the system other than the discs. I don't see any special washers. The discs are right off the sprocket. However that isn't the problem. Does anyone know what engages the gears? Is there a keyway or is it splined? I fear that something connecting the gears to the motor output shaft has stripped. Thanks.

Item 11 is the special washer, i posted this in the media center in BOBCAT 630. You should be able to open an see much better. i have not figure out how to post a pdf yet.
Hyd fluid drive the motor which turns the chain sprocket. you say the nut is spinning, it is a tapered/key shaft. once you get it out you should be able to tell more.
I can sen you a drawing of the drive moto as well if you need it.

 

[discountufoparts]

Item 11 is the special washer, i posted this in the media center in BOBCAT 630. You should be able to open an see much better. i have not figure out how to post a pdf yet.
Hyd fluid drive the motor which turns the chain sprocket. you say the nut is spinning, it is a tapered/key shaft. once you get it out you should be able to tell more.
I can sen you a drawing of the drive moto as well if you need it.

So that would make item number 2 the nut then that holds everything together then?

 

[chuckcnm]

So that would make item number 2 the nut then that holds everything together then?

yes sir, when I pull mine I jam a 1x1x4 block of oak wood in the chain and gear to break the torque, it worked surprising will for both sides, now when you reinstall you have to re torque to 300 ft-lb I think it was, double check that. What I did here was to get a piece of flat steel 1 X .25 X 2 feet. I laid the flat steel on top of the of the chain gear and rested the other end on the transmission opening, drew me a line with a sharpie on the disk. pull everything out and laid the flat steel on the disk till it just covered the line, drill 2 holes about 4 inches apart, the tap the holes in the disks and install 2 bolts on the outside attaching the bar to the disk. Installed the disk, special washer and nut. Then torque it down, I also laid a block of would for the bar to rest on when I torque it. Watch the washer cause it will move on you, it has to be lined up so it stops the disk from coming off the gear. I know cause after getting my 1st one tongue the disk came off on me, what the ___. I reversed the bar to break the torque.

I wish I took a picture

 

[discountufoparts]

yes sir, when I pull mine I jam a 1x1x4 block of oak wood in the chain and gear to break the torque, it worked surprising will for both sides, now when you reinstall you have to re torque to 300 ft-lb I think it was, double check that. What I did here was to get a piece of flat steel 1 X .25 X 2 feet. I laid the flat steel on top of the of the chain gear and rested the other end on the transmission opening, drew me a line with a sharpie on the disk. pull everything out and laid the flat steel on the disk till it just covered the line, drill 2 holes about 4 inches apart, the tap the holes in the disks and install 2 bolts on the outside attaching the bar to the disk. Installed the disk, special washer and nut. Then torque it down, I also laid a block of would for the bar to rest on when I torque it. Watch the washer cause it will move on you, it has to be lined up so it stops the disk from coming off the gear. I know cause after getting my 1st one tongue the disk came off on me, what the ___. I reversed the bar to break the torque.

I wish I took a picture

I don't plan on putting the brake discs back in it. It was missing all the parts when we got it.

 

[chuckcnm]

I don't plan on putting the brake discs back in it. It was missing all the parts when we got it.

if that is the case you can use the disk to torque the nut, same of drilling a tapping or just weld the flat steel to the disk, there is a procedure in the MM if you need it.
I just went thru all this 2 weeks ago and it was my 1st time so i am learning as i go and with the help from the guys in this forum. I hope to have mine out digging holes in about 2 weeks if all my parts show up.

 

[discountufoparts]

if that is the case you can use the disk to torque the nut, same of drilling a tapping or just weld the flat steel to the disk, there is a procedure in the MM if you need it.
I just went thru all this 2 weeks ago and it was my 1st time so i am learning as i go and with the help from the guys in this forum. I hope to have mine out digging holes in about 2 weeks if all my parts show up.

Yah i saw that in the manual. Thanks though. I wonder which part is broken or stripped out. I don't think I will be able to get to taking the rest of it apart till next week. Driving me nuts. haha

 

[discountufoparts]

Yah i saw that in the manual. Thanks though. I wonder which part is broken or stripped out. I don't think I will be able to get to taking the rest of it apart till next week. Driving me nuts. haha

Do you happen to know what size the large nut is that holds that assembly together? And is that just a compression type assembly that keeps everything together or are there splines or a keyway???? Thanks.

 

[discountufoparts]

Do you happen to know what size the large nut is that holds that assembly together? And is that just a compression type assembly that keeps everything together or are there splines or a keyway???? Thanks.

Sorry I didn't read the part above that said tapered key shaft. I got it now.

 

[chuckcnm]

Sorry I didn't read the part above that said tapered key shaft. I got it now.

I had to take mine to the John Deere shop to get the sprocket press off I did not have anything big enough to get it off with.
Now when you remove the 9 bolts to take the motor a part this is not going to be easy either. I use a brass rod and tap around the edge and soaked it in penetrating oil. It took a long time because I did not what to damage anything. When I was able to get a screwdriver in to pry it, it came right off. At this point you can take all the insides out, even the shaft. I took an exacto knife and ran it around the inside edge of the case and cut the o ring and the case came right off you might have to make couple of trips around it but is what worked for me.
A friend of my suggested a big vise and a strap wrench might have worked better but I did not have access to one at the time.
Now the expensive part. The o ring and seal kit for the motor is $140 at bobcat. (MAE 24024 MOTOR). You only get 2 large O ring, bonded seal, oil seal, wiper seal, snap ring, spacer and washer. I was able to find everything at a local seal and packing company here for around 35, the biggest cost was the oil seal.
Now with that being said I am not tested the motors yet. I am still waiting on a couple of parts to show up before I can try it out.
It does however sound like you are going to need a new motor however.

 

[discountufoparts]

I had to take mine to the John Deere shop to get the sprocket press off I did not have anything big enough to get it off with.
Now when you remove the 9 bolts to take the motor a part this is not going to be easy either. I use a brass rod and tap around the edge and soaked it in penetrating oil. It took a long time because I did not what to damage anything. When I was able to get a screwdriver in to pry it, it came right off. At this point you can take all the insides out, even the shaft. I took an exacto knife and ran it around the inside edge of the case and cut the o ring and the case came right off you might have to make couple of trips around it but is what worked for me.
A friend of my suggested a big vise and a strap wrench might have worked better but I did not have access to one at the time.
Now the expensive part. The o ring and seal kit for the motor is $140 at bobcat. (MAE 24024 MOTOR). You only get 2 large O ring, bonded seal, oil seal, wiper seal, snap ring, spacer and washer. I was able to find everything at a local seal and packing company here for around 35, the biggest cost was the oil seal.
Now with that being said I am not tested the motors yet. I am still waiting on a couple of parts to show up before I can try it out.
It does however sound like you are going to need a new motor however.

Oh my motor is working fine. The nut and shaft are spinning, just the sprockets the chains are on are slipping on the shaft. The side that's slipping looks set off compared to the side that's working though. It looks like somehow the sprockets have slide towards the center of the machine as well. I may just try tightening the nut up if I can purchase a good big wrench and grind it down some and then weld it and strengthen it up with some careful welding. That's why I wanted to know the size of the nut so I can buy the right wrench. But if it has a key way that popped out that wont work by itself. I would need to get the motor out and put a new keyway in and then put it back together.

 

[chuckcnm]

Oh my motor is working fine. The nut and shaft are spinning, just the sprockets the chains are on are slipping on the shaft. The side that's slipping looks set off compared to the side that's working though. It looks like somehow the sprockets have slide towards the center of the machine as well. I may just try tightening the nut up if I can purchase a good big wrench and grind it down some and then weld it and strengthen it up with some careful welding. That's why I wanted to know the size of the nut so I can buy the right wrench. But if it has a key way that popped out that wont work by itself. I would need to get the motor out and put a new keyway in and then put it back together.

I think it was 1.75 inch, a big nut. If that is all it is you have save a ton of cash and work.

 

[discountufoparts]

I think it was 1.75 inch, a big nut. If that is all it is you have save a ton of cash and work.

Yep you are right. It is 1 3/4" nut. I hope i get lucky with it. Thanks for the help.