Hey guys I have a 941B serial:80H5655 The problem I’m having is the machine will only move about 10ft in forward and reverse. I jacked the tracks off the ground put it in gear and the tracks will almost make a full revolution. If I depress the left pedal the left track stops and the right track started to move but if I press the right pedal the left track disengages after moving about 10 ft. I’m thinking there’s something going on with left final drive but I’m a newbie to these machines. Any help would be greatly appreciated.
Have you removed the drain plug on each final drive to inspect the oil for metal particles.?
Planning to do that this weekend. I have an endoscope I can send in there as well. Will report back as soon as I’ve inspected it. Thank you for the reply
Well I figured out what was causing the issue, the rail for the tracks rubbed a hole through the final drive casing. What would cause this?
I don't see how the tracks can rub on that but also don't know else that could happen
It might be interesting to see what the track links and bushes look like on that side.
I'm wondering if you might have a bent track pad that went un-noticed because it was thought to be broken off? Conveniently taking a scrape off the final housing each round of the track? It looks like the pad might have had to be bent almost at 90 degrees to do that. How far is that scrape mark from where the centerline of the track chain would ride on the sprocket? It looks like it is a good 6" or so. I thought track pads were hardened up the yinyang so that they didn't bend-they broke. But maybe not this time!! Jon.
I’ll double check this weekend when I’m out at my property but I inspected the rails, bushings and track pads and nothing is bent, the bushings are in great shape. The only thing I can think is that the sprocket is wore out causing the track rail to ride lower but I’m not sure what the sprocket is supposed to look like. Mine looks okay from the naked eye. Is there a measurement I can take to reference to a new sprocket?
Post a photo.? Maybe post photos of the sprockets on both sides.
I will this weekend when I get back out to the property
Make sure to take at least one photo on each side from directly side-on to the machine. Also see if you can get a photo from the opposite side to the damaged one showing how close the track links run to the final drive case.
Left side (problem side)
Right side
In your earlier photo showing the LH case worn through, was that taken from above.? Both sprockets have had a replacement rims installed but for some reason I can't see at the moment the RH sprocket teeth appear to be sitting higher than the other side. The two sprockets don't appear to be the same. Time to break out the measuring tape I think. EDIT: Maybe it’s the fact that one track is off and the other one is still installed but a tape measure and/or counting the number of teeth should tell you the answer.
Nige, I think you are on the right "track". Another way to check this out is to count the # of sprocket teeth on each side. There was some comment earlier that some machines had "hunting tooth" sprockets and others did not have "hunting tooth". The difference of one tooth could be the difference between dragging the chain on the final housing or riding clear of it. Jon.
Yes it was taken from above, that’s the route I’m leaning towards. The sprockets are definitely not the same. Time to drop the tracks and count the teeth and get some precise measurements.
That sounds like a winner, the clearance between the final housing and chain on the RH side has about 1”-1.5”. Looks like I’ll be having some fun this weekend.
On the 951B the Track chain was 6.75" pitch from new, but there was a conversion to adopt the later 951C Track Group that was 6.91" this made the sprocket a Non Hunting Tooth rim, if you look at the sprockets on this 941 they look in a queer shape and should be hunting tooth.
Based on the part numbers in my book they should have 29 teeth so I’m gonna count them tomorrow
What does it mean to be a hunting tooth sprocket?
They should have an odd number of teeth on them. Look at your photo of the RH side, the track pin bushes contact the sprocket every 2nd tooth. If the sprocket has an odd number of teeth it means the bushes sit in a different tooth for every rotation of the sprocket if that makes sense.
Well guys the left side sprocket has 28 teeth and the right side has 29 so I think I found our problem. Any good tips for getting these things jacked up high enough to pull the bottom rail?
Check the track pitch on both sides. Measure between 5 pins (4 links) and then divide by 4. Post back with your results.
Nige the track pitch is 6.25 if I did it correctly
Both sides.? That would be strange if there was a 1 tooth difference in the sprockets. One side should track faster than the other. I need to check the undercarriage guide or maybe tctractors knows.? EDIT: 941 track link pitch is supposed to be 6.75". 931 tracks are nearer at 6.125", which with a bit of internal wear could easily stretch to 6.25". Measured as per the illustration below. You can do it across the grousers or from centre to centre of the pins.
I just RE measured, track pitch is 6.75
I just RE measured, track pitch is 6.75
The Track Assembly or the sprocket needs to have an odd number of either links or teeth to establish a Hunting Tooth action, when you cut a link out of near any Track Chain you end up with a Non Hunting Tooth, there has been loads of talk on many Construction Machinery Sites about 1 track being longer or shorter and driving off left or right and not straight ahead, all I will say is if no steering controls are touched both sprockets turn as 1 at the same rate as the drive via the Cross Shaft is solid, just because 1 Track might be 3 feet longer it still has to pass under the sprockets at the same rate it's just moving floor the fixed drive sets the pace unless a clutch is eased, anyhow back to the little 941 well it looks like someone has managed to rig up something weird as its clear to see that something metal has dragged off the top of the outer case, these cases are near always showing wear on the top pinion area from Dirt drag with patches welded over to improve things, but now you have 2 ways of fixing this Shovel, the first 1 is cut it up for parts and Scrap Iron, or you need to drop out the frame and burst down the Final Drive, this is a simple job for me as I have all the CAT tooling and have done at least a 100 of them, but it can prove a Task for the non experienced Hand, if you go to tackle it we will give you any support and help we can right here, a few years ago I restored a 951B to strong shape but bought 3 others just for bits (it was 2 1/2 really as 1 had been robbed of the engine) I sold near all of the good bits left over with the leftovers going in the pot.
An idea from left field. I wonder if the replacement sprocket ring that has been welded on the LH side is from a smaller machine of some sort.? Maybe a 931 or even something non-Cat.? That might explain why it only has 28 teeth and also a smaller diameter than what it should be.
So the sprockets measure out the same diameter on both sides but the tooth count is different and the width is different
I had it all apart in about 2 hours ready to pull the frame rail, I just have to take my skid steer up to my property to move it. Everything is unbolted and ready to go. I plan on pressing the old sprocket off and new one on and replacing the inner and outer bearings. While it’s apart I’m going to weld up the skuff mark in the top of the drive casing. The top pinion gear in the drive looks like it has some wear and a partially chipped tooth and the inner cone bearing is completely gone. Waiting for the skid steer to get it completely removed so I can do a thorough inspection of the drive.
Is there anything else in this drive casing that I should inspect or just replace while I have it apart?
Until you have the Rim pressed off and the damaged case removed you need to ease down on the RPM a bit, any damage to the pinion changes the game going forward, plus the Dead Shaft and back Hub bearing will need to be inspected, the outer bearing looks scrap so lets hope the hub is viable it mounts on, at first I could not understand your photos but its possibly due to you not having the track frame out of the way, I am thinking this is the Top Pinion with a great chunk missing, also a back bearing all fell to bits, how come the case has not been wrenched off, by the way unbolting the drive as a lump like this is a crap way of doing things as they are easier to pull to bits mounted, any welding to the top pinion area of the outer case can cause massive distortion to the bearing location, plus the outer race is pegged in location.
I don’t have the puller to get the sprocket off the hub that’s why I’m pulling it as one
Is there another way to get it off without it? My book says it’s pressed on with 20-25 tons of force
You better revoved the bearing first and loosed the nut to make sure the sprocket is still press on
You can pull the whole housing and take it to CAT and have it pressed off but you will still have to have it pressed on tightening the nut will not put it on tight enough. Maybe you can find a independent shop with the right equipment to do it. Georga is to far for me to come out
I have a local machine shop with a 100 ton press they’re going to let me use. I’m taking my skid steer down to my property on Saturday to remove the bottom roller assembly and once it’s out of the way the drive assembly is ready to be loaded up. I’m just hoping there’s not a ton more damage to the gears than what I see.
Just a Heads Up the 941B has if I recall right the same Bull and Pinion gears as the 951C and D4E, so you will be able to find them easy enough, then you need to look at the Track groups.
i got the track roller assembly removed and was able to pull the final drive. The final drive pinion is pretty ate up and the bearing behind it is gone. I was hoping not to have to get into the bevel gear case but it’s looking like that’s the route I’m gonna have to take. Any tips on getting the final pinion removed. My book is pretty vague.
pull the bevel gear shaft out remove the clutch flange then unbolt bearing cage and remove pinion from the inside
Well here is another 2 hours job ahead and it will keep you entertained, as it's Tank off, floor plates off, seat frame off, control rods off, batteries off, any extra left hand panel work off, case top off, actuator frame off, be warned that the pins on the linkage have a bolt in underneath them, cross shaft out and then you need to press off the drum flange from the top pinion to remove the pinion and housing, plus you might find it a good idea to split the other track to free off the sprocket to turn, plus always check the area on the main case for cracks around the top pinion, they are easy enough to tackle I always like doing them, best of Luck chap. just thought I would say mark everything so you know where its from and take a photo of the bevel gear location as often they can be fitted 180 out.
a little bit of fab work and I got the case fixed up like new. I have my new to me sprocket and bearings and will be putting the final drive assembly back together soon. My next step will be pulling the bevel gear and final drive pinion. Not bad for a heating and air guy.
possibly I might have warned you that any welding or even heat will distort that pinion bearing location in the case from a round to an oval shape, you need to have a blank machined to fit in the bearing location before any welding is done, even the old bearing with the pinion still fitted placed in the cover will stop a lot of distortion, if you can still get the outer bearing in the cover the chances of getting the pinion and bearing also in will be close to Zero, you might be able to sort things by heating the cover as needed with a cutting torch and beat the old pinion back in to it, things have got to spin free and welding that cover is easy to do but hard to do correctly.
I’ve welded cast steel quite a bit, I left the bearing in while welding it and I made sure not to get it to hot. The bearing slides in and out nicely. Thank you for the info
I suppose you are talking about the outer race of the bearing that is dowel pegged in position, you might struggle to fit the other part of the bearing in, its best to have the pinion in the bearing so you can assess the lateral movement on all points of the compass when fitted in the outer case, I have welded these casings for 50 years chap so I am not talking crap.
Thanks for the info, hopefully it goes back together okay. Can you tell me if there is supposed to be a lip type seal on the outside of the drive casing or is it just the o-ring and plate that seals it
See the attached which is the complete parts listing for the final drive.