cat 225 sn 51u725 sprocket came off

[Vernon Lowe]

bolt broke and sprocket came off. My question is to replace the drive shaft that the sprocket splines on what do i have to do to replace the shaft? Can the shaft be replaced without removing the final drive from the machine?

 

[fastline]

bolt broke and sprocket came off. My question is to replace the drive shaft that the sprocket splines on what do i have to do to replace the shaft? Can the shaft be replaced without removing the final drive from the machine?

You don't 'remove the final' on those, their are an integral part of the machine. You pull the cover which will display all the reduction guts.

My suggestion is explore all other methods, including welding the sprocket if practical, especially if the sprocket is mostly toast. You would want to split the track and ensure you don't have serious runout when welding.

i can't recall if that sprocket is cast iron or cast steel, but there are ways, including a really good preheat of the sprocket.

if you want to split, you just take all the cover bolts off and remove cover. Be very prepared for heavy gears trying to drop. Get wood in there to catch/protect stuff. Nothing complicated in there, just heavy.

 

[Vernon Lowe]

You don't 'remove the final' on those, their are an integral part of the machine. You pull the cover which will display all the reduction guts.

My suggestion is explore all other methods, including welding the sprocket if practical, especially if the sprocket is mostly toast. You would want to split the track and ensure you don't have serious runout when welding.

i can't recall if that sprocket is cast iron or cast steel, but there are ways, including a really good preheat of the sprocket.

if you want to split, you just take all the cover bolts off and remove cover. Be very prepared for heavy gears trying to drop. Get wood in there to catch/protect stuff. Nothing complicated in there, just heavy.

have you welded the sprocket to the shaft before on these,Is the weld strong enough to handle the torque?

 

[fastline]

have you welded the sprocket to the shaft before on these,Is the weld strong enough to handle the torque?

No I have not, and I only offer that as a bandaid solution since that machine would certainly have some age to it. It seems to be how some people "fix" stuff. The engineer in me would highly question the likelihood of that holding long term, especially if the splines are toast or super sloppy.

The application of torsion through that weld would be in shear and though I could probably spec a weld that could hold that level of shear, there are other factors at play such as off center axial forces from turning and with that big sprocket, it would be a lot.

If you are truly looking for a "fix" and putting the bolt back on is not practical, a tear down is needed. I don't know the situation or condition of the goods to make any call here. Could post pics for further thoughts. If the bolt broke in the hole, there are techniques to attempt extraction of that bolt but skill is needed because once you start screwing up threads, walking the bolt out becomes that much harder.

I have successfully removed countless broke off undercarriage bolts that were flush with the rail. But it only takes one wrong zap with a MIG to consider yourself F'd.

 

[Nige]

Already asked and answered. See the pdf attachment in Post #10 that gives complete instructions on how to disassemble the final drive and also contains a Parts List.

https://www.heavyequipmentforums.co...erial-number-drive-sprocket-bolt-loose.96981/

 

[Vernon Lowe]

thanks

 

[Nige]

And FWIW I would not recommend attempting a welding repair to try to glue the sprocket to the shaft.

If you are looking for parts try contacting Offroad Equipment in Alcoa.

 

[Vernon Lowe]

And FWIW I would not recommend attempting a welding repair to try to glue the sprocket to the shaft.

If you are looking for parts try contacting Offroad Equipment in Alcoa.

I’m not having any luck locating the original type sprocket. Everyone is offering a rim style sprocket as a replacement but they can’t tell me what I need to convert my current style to a rim style sprocket. Can you help with that?

 

[Nige]

I’m not having any luck locating the original type sprocket. Everyone is offering a rim style sprocket as a replacement but they can’t tell me what I need to convert my current style to a rim style sprocket.

A rim-style sprocket is going to be of no use to you because that type of sprocket is designed to be used to repair a sprocket that has worn/damaged teeth on the outer rim - the teeth that drive the track chains in other words.
Installing the rim involves cutting off the outside ring of the existing sprocket containing the teeth and welding the new rim on to the existing sprocket centre hub. In your case because the splines are torn out of the hub of the existing sprocket it is not suitable as a "donor" to have a new rim welded on to it. See below.

 

[Nige]

Seems as though complete sprockets are available out there........... both these two appear to be complete sprockets. 3V-1727 is also apparently available from Cat dealers.
Did you speak to Offroad Equipment.? 1-888-299-8413. They are local to you.

 

[Vernon Lowe]

Seems as though complete sprockets are available out there........... both these two appear to be complete sprockets. 3V-1727 is also apparently available from Cat dealers.
Did you speak to Offroad Equipment.? 1-888-299-8413. They are local to you.

View attachment 269983
View attachment 269984

yes but they had to order one from Miami Fla and the one they offer is a rim style

 

[Jonas302]

I wonder how hard that driveshaft is if you or a machinist could say drill and tap maybe three 1/2 inch bolts in to replace the splines maybe taper pins would be better anything that could transfer the torque and and keep it from wiggling a real machinist may have a better solution if you showed them

 

[Nige]

You are aware that the sprocket hub is supposed to be a light-to-moderate press fit on the shaft I assume..?
If it's loose now I would suggest that the splines on both the hub and the shaft are worn.
The details of the sprocket R&I were included in the attachment posted on the thread I linked in Post #5 above.