Snowblower chain adjustment

[Toyboy]

I've got a BX5450 that threw the chain this morning. I purchased it new in '14 and just never paid attention to the chain slack until today. It's a bugger to try and check the 1/16" slack that is called for so I just screwed up and never thought about it.
I will now !!
How do you guys with the same blower keep track of the chain tension. ??.

 

[DustyRusty]

Make sure that you keep the chain lubricated, and check it at the end of the season. From memory, there is an upper and lower bolt that retains the cover. Remove the lower bolt and then loosen the upper bolt to get a visual of the chain. If it just came loose, then you can loosen the bottom adjustment bolts and raise it up to put the chain back on without removing the master link. If the chain has damage to it, then replace it. If you are not familiar with cutting chains, then take it to a local lawnmower shop and have them make up a chain for you. Bring the old one so they can count the number of links. Without knowing your mechanical skills, it is difficult to go into too much detail because the job might be more than you can handle. I am not trying to be cruel, but being honest.

 

[davidsmartin]

I've got a BX5450 that threw the chain this morning. I purchased it new in '14 and just never paid attention to the chain slack until today. It's a bugger to try and check the 1/16" slack that is called for so I just screwed up and never thought about it.
I will now !!
How do you guys with the same blower keep track of the chain tension. ??.

How did you get the cover off the gear box? I don't see any bolts holding it on, but I can't pry it off. Thanks for any advice.

 

[DustyRusty]

There are 2 very long 1/4" bolts that go horizontally across the back side of the chain cover. Loosen the top one, remove the bottom one, and using the hole in the top cover, lift it off. If necessary remove them both to gain access. It is easier to remove the service link to separate the chain, and then feed it up from the bottom and onto the top sprocket and then reinsert the service link and lock than it is to try to get it onto both sprockets with the chain whole. Once it is on the sprockets, the adjustment is at the lower sprocket by loosening the bolts and pushing down on the assembly.

 

[davidsmartin]

There are 2 very long 1/4" bolts that go horizontally across the back side of the chain cover. Loosen the top one, remove the bottom one, and using the hole in the top cover, lift it off. If necessary remove them both to gain access. It is easier to remove the service link to separate the chain, and then feed it up from the bottom and onto the top sprocket and then reinsert the service link and lock than it is to try to get it onto both sprockets with the chain whole. Once it is on the sprockets, the adjustment is at the lower sprocket by loosening the bolts and pushing down on the assembly.

Thanks. As usual, I was confused. I thought those two bolts were used to adjust the chain. Now that the cover is off I can see that the chain must have broken and is lost in the snow. So tomorrow I that I can get a new chain from my dealer.

 

[NoJacketRequired]

Just be aware that Kubota uses O-ring-sealed chains on these speed reduction units. Those chains are brutally expensive. My dealer suggested that I switch to generic roller chain, stating it would not last nearly as long as the Kubota part, but would cost 1/10th the price of the Kubota part.

So far this plan is working out. I tear everything apart in the spring and check for wear and any other items which need attention so I'll be giving the chain a good once over and, if necessary I'll replace it.

 

[DustyRusty]

You can buy a box of chain at Tractor Supply. I believe it is 10' of #40 chain for under $25. Also buy some spare links.

 

[nbryan]

I've got a BX5450 that threw the chain this morning. I purchased it new in '14 and just never paid attention to the chain slack until today. It's a bugger to try and check the 1/16" slack that is called for so I just screwed up and never thought about it.
I will now !!
How do you guys with the same blower keep track of the chain tension. ??.

I check my blower reduction box play before every job. There's the chain tension which now after 5 years has settled in and rarely needs tightening anymore, but beware that the 2 sprockets it's on are not perfectly round or concentric and the chain free play adjustment needs to be measured at all points in its rotation. If not, from experience, if you adjust it to 1/16" play at only one position in rotation it will likely be tight at some point as you rotate it to other positions because of slight out-of-roundness of the assembly.
It takes a couple of slow hand cranked revolutions of the big gear while watching the chain to find the cahin's tightest position of rotation. Then with the 2 set bolts snugged up just tight enough that the adjuster can still pull the assemby tighter, adjust the tension bolt to set the 1/16" chain play. Make sure you're TIGHTENING the adjust bolt to set the play, so I loosen the adjustment before the reset so the final tightenng adjustment is always tightening the chain. With the set bolts just snug enough to allow the adjustment then fully tighten them and CHECK THE TENSION AGAIN through severl large gear rotations. The TIGHTEST spot for the chain should remain close to 1/16" and it will have looser positions through the rest of the rotations.
I did my first adjustment after new on my B2782B and set the chain play at the LOOSEST position and after engaging the pto to test it out the chainnoise of the overtightening was dreadful.
So set it to 1/16" at the tightest point and haven't had a problem with chain tension since.

BEWARE that there's a couple of set screws pinning the input shaft to the small gear shaft that have come loose every year on my blower. So now I put the tractor's pto into rear only mode so the mid pto shafts can spin freely and while watching the small gear carefully, jog the shaft back and forth clockwise and couterclockwise firmly and watch for ANY OTHER PLAY in the input shaft/gear assembly. There should be ZERO rocking of that shaft relative to the small gear. The 4 shaft lock set screws that hold it all together, as well as the pin bolt through the female PTO shaft connector, have all come loose on my unit, the first time to the point that the 1/4x1/4 key fell out!

So I check for play every time I mount the blower now.

So, tighten well the hex set screw and pin bolt of the EXTERIOR portion of the PTO input shaft, and as well, IMPORTANTLY, the 2 hex set screws just INSIDE the reduction gearbox that pin the small gear to the spline key and input shaft.

My unit has a small window on the left (facing front) side of the reduction box that the small gear is visible through so I can watch it while twisting the pto back and forth to check for play. It has needed tightening every season start, so I added an extra bit of tightening torque with a socket wrench hex bit this winter and so far has held, but still don't trust them.

 

[DustyRusty]

If your sprockets are out of round, then the teeth are most likely worn. The other reason might be that the manufacturer bought parts that are not true on day one. Whenever I need a new sprocket, I head to the local bearing house that shocks quality parts for industrial use and pay more for quality than buying a made-in-China cheap sprocket. Same with bearings, the cost difference is negligible when you look at the time factor of doing the job correctly once vs. doing it over when something breaks during a snow storm.

 

[nbryan]

If your sprockets are out of round, then the teeth are most likely worn. The other reason might be that the manufacturer bought parts that are not true on day one. Whenever I need a new sprocket, I head to the local bearing house that shocks quality parts for industrial use and pay more for quality than buying a made-in-China cheap sprocket. Same with bearings, the cost difference is negligible when you look at the time factor of doing the job correctly once vs. doing it over when something breaks during a snow storm.

The sprockets were slightly out of round the first year since new, when I delved into the maintenance schedule and attempted my first chain tension adjustment. That was after a about a half a winter snow blowing season.
It's fine, as long as it isn't wearing out the chain and needing increasing frequency of tightening. Right now after 5 1/2 winters and adjusted last in fall 2021 winter it hasn't needed adjustment since.
But the reduction box high speed shaft seems quite fond of shedding its set screws in the bushing lock collars and the pto input joint.
The first time it messed me up was the pto spline key disappearing with the set screw loosening, and the through bolt had vanished. I added an extra locking nut for the replacement bolt, as the lockwasher supplied obv doesn't hold.
But when it happened, I was standing there wondering why with that horrid sinking feeling WHY the pto shaft was spinning away but the entire snow blower had stopped? Thought I'd REALLY bust something bad.

 

[Toyboy]

Thanks guys

 

[Eagle]

I check my blower reduction box play before every job. There's the chain tension which now after 5 years has settled in and rarely needs tightening anymore, but beware that the 2 sprockets it's on are not perfectly round or concentric and the chain free play adjustment needs to be measured at all points in its rotation. If not, from experience, if you adjust it to 1/16" play at only one position in rotation it will likely be tight at some point as you rotate it to other positions because of slight out-of-roundness of the assembly.
It takes a couple of slow hand cranked revolutions of the big gear while watching the chain to find the cahin's tightest position of rotation. Then with the 2 set bolts snugged up just tight enough that the adjuster can still pull the assemby tighter, adjust the tension bolt to set the 1/16" chain play. Make sure you're TIGHTENING the adjust bolt to set the play, so I loosen the adjustment before the reset so the final tightenng adjustment is always tightening the chain. With the set bolts just snug enough to allow the adjustment then fully tighten them and CHECK THE TENSION AGAIN through severl large gear rotations. The TIGHTEST spot for the chain should remain close to 1/16" and it will have looser positions through the rest of the rotations.
I did my first adjustment after new on my B2782B and set the chain play at the LOOSEST position and after engaging the pto to test it out the chainnoise of the overtightening was dreadful.
So set it to 1/16" at the tightest point and haven't had a problem with chain tension since.

BEWARE that there's a couple of set screws pinning the input shaft to the small gear shaft that have come loose every year on my blower. So now I put the tractor's pto into rear only mode so the mid pto shafts can spin freely and while watching the small gear carefully, jog the shaft back and forth clockwise and couterclockwise firmly and watch for ANY OTHER PLAY in the input shaft/gear assembly. There should be ZERO rocking of that shaft relative to the small gear. The 4 shaft lock set screws that hold it all together, as well as the pin bolt through the female PTO shaft connector, have all come loose on my unit, the first time to the point that the 1/4x1/4 key fell out!

So I check for play every time I mount the blower now.

So, tighten well the hex set screw and pin bolt of the EXTERIOR portion of the PTO input shaft, and as well, IMPORTANTLY, the 2 hex set screws just INSIDE the reduction gearbox that pin the small gear to the spline key and input shaft.

My unit has a small window on the left (facing front) side of the reduction box that the small gear is visible through so I can watch it while twisting the pto back and forth to check for play. It has needed tightening every season start, so I added an extra bit of tightening torque with a socket wrench hex bit this winter and so far has held, but still don't trust them.

Did you ever find out why the chain tension changes as you rotate the drive?

I have exactly the same problem with my B2782B. I only have 285 hours on it. I disconnected the drive shaft to isolate it from being the problem somehow. I removed the chain so I could easily rotate the large sprocket to check to see if the shaft was possibly bent and thereby causing the sprocket to be out of round. I used a set square placed a few millimeters from the outside of the teeth and then rotated the sprocket to see if there was any sign of wobble. There was none. The smaller sprocket was harder to reach but I did place a straight edge ruler close to its teeth and could see no wobble there either.

I checked the chain and it did have a little bit of lengthways play at some sections so I bought a new chain. The new chain did not, however, solve the problem. I still had variable play as I rotated the sprockets.

I took the chain off again and actually removed the entire Reduction Box from the blower to check the bearings and look for other possible problems.

The bearings seem just fine. There is no play in them. You mention in your post that there are set screws for the bearings, but I didn’t see any and there are none shown in my parts diagram. I did notice that both the set screws were missing on the high rpm input shaft #40 and the small chain sprocket #60. My parts diagram only shows one set screw so I put in a new set screw for the key position. The next day I put a second set screw in the other position but I still had variable play as I rotated the sprockets.

The Reduction Box was a real hassle to put back in. The two 3/8 Carraige Bolts Part #240 that go in the bottom of the Reduction Box Part #110 are really hard to get the nuts back on as there is no room for your fingers to get them started. I first tried just putting some electrical tape on the bottom of an open end 9/16 box wrench to hold the nut, but you can’t get enough swing on the wrench to get the nut started.

I finally figured it out. I put the furthest bolt in first, then placed a heavy pry bar on top of it to hold it from being pushed up as I tried to put the nut on from the bottom. If I place the second closer bolt in as well it prevents the pry bar from resting on the further bolt. I then placed the lock washer over the bolt with needle nose plyers and stuck it to the bottom of the reduction box by using a good dab of grease. I then used a piece of tin about 8 inches long by a few inches wide as a kind of spatula to slide the nut into place under the bolt. I then pushed up on the tin to get the nut to touch the bolt, and then while gently pushing up on the tin I was able to gently turn the nut enough times with a 9/16 wrench to get it started. Repeat for bolt number two.

By the way, the Kubota price for a new chain was over $200.00 Canadian. I bought an industrial 10 foot length of #50 chain at a heavy equipment dealership for $90.00 and just disconnected the length I needed. Now I have many years’ worth of spare chain.

 

[nbryan]

But still the chain sags & tightens, the play varies!
Did you try watching for play using your straight edge at the root diameter of the large sprocket?
Meaning the bottom of the space between the teeth instead of the teeth themselves.

 

[Eagle]

No I didn't, but that's a really good idea. I'll see if I can do the same at the small sprocket. Might have to pull the reduction box off altogether do do that one. I'll try to check that out in few days and will let you know. Hopefully won't be needing the blower again this year. I see you are in Southern Manitoba, not far from me. I'm in Eagle River, about 30 km west of Dryden, Ontario.

 

[nbryan]

No I didn't, but that's a really good idea. I'll see if I can do the same at the small sprocket. Might have to pull the reduction box off altogether do do that one. I'll try to check that out in few days and will let you know. Hopefully won't be needing the blower again this year. I see you are in Southern Manitoba, not far from me. I'm in Eagle River, about 30 km west of Dryden, Ontario.

Hey there, CA member! You get same-ish winter weather as us.
I've just adjusted that chain at its tightest pass to be within play spec, with just a litle play there, and I've not had an issue for about 4 years with it either getting sloppy or the shaft lock screws needing re-tightening, and wear and tear seem to be minimal or nominal for the reduction box.
My old abused wrists need settling down from some major arthritis flare-ups before I'll go remove and service the blower for next year.
That will be a good time to pop the chain cover and go over everything, along with all the greasing and auger reduction gear drain and fill gear oil.

 

[Eagle]

Sounds like we have not only have the same snowblower but also the same arthritis problems. I'll remove my blower as well in the next week or so and will check everything over then.

 

[Eagle]

I finally got around to checking over my snowblower chain adjustment again. It’s amazing how other jobs can take priority once the snow is all gone. At least it was nice and warm to work on.

I removed the entire Reduction Gear Box so that I could check the small gear to see if it was somehow out of round. I tried as best as I could to measure both the teeth and the valleys between the teeth while rotating it but could not tell if there was anything wrong. If there was it was a very minimal amount. I did notice that there was rotational play in the small gear on the shaft. As I turned the shaft the small gear had some rotational play and was able to rotate maybe a ¼ inch on the shaft. There were 2 places on the small gear where set screws could be put that were devoid of the actual set screws. I’m positive that I had put new set screws in those places earlier this spring, but they were both gone. I don’t think I even used the blower to blow snow since I put in the two set screws. I may have run the blower for a few minutes to see if it ran OK. Those set screws could not have worked their way out in such a short period of time. I had used an Allen key socket and socket wrench to tighten them in place. I wonder if they got eaten into the center of the small gear and shaft? Very strange. I put in two new 5/16 NC x 5/16 set screws to secure the small gear to the shaft. I’ll check them after I use the blower for the first time this fall.

I reinstalled the Reduction Box, put the chain back on and adjusted the chain tension but still had the same problem. The chain was tight at certain rotation spots and loose at other spots. I had inserted a roughly ¾ x ¾ inch by 1 foot long piece of wood in the end of the Driveline female half, (part # 16) so I could rotate the drive assembly by hand by rotating the piece of wood. When I came to a tight spot on the chain I marked an X on the top side of the wooden shaft. I then kept rotating and noticed that the chain would be tight every time the X mark would be in the same place. This indicated that the chain would be tight only when the small gear was a specific point in its rotation. So somehow the small gear is the reason for the change in chain tension, but I can’t figure out how. It must be out of round, but I can’t measure it with my crude method of using a straight edge ruler and judging it by eye.

I adjusted the chain tension to the required 1/16 inch play at the tight spot of the rotation.
As others have mentioned on this site, you just have to live with the anomaly of the various tension of the chain. The only other option is to replace both bearings #20, the small sprocket #50, and the shaft #40 and see it that fixes the problem. I have my doubts as it seems that even when new, these blowers have this problem. If my outfit was the only one with this problem then I would just bite the bullet and replace those parts.

I wonder if the small sprocket has a slightly larger inside diameter than the shaft, and after tightening the sets screws the sprocket is forced off center on the shaft, causing it to wobble slightly as it rotates? Would have to completely disassemble the parts to check that. If that is the cause, then even new parts would not help as it is a manufacturers specification tolerance problem.

 

[nbryan]

I wonder if the small sprocket has a slightly larger inside diameter than the shaft, and after tightening the sets screws the sprocket is forced off center on the shaft, causing it to wobble slightly as it rotates? Would have to completely disassemble the parts to check that. If that is the cause, then even new parts would not help as it is a manufacturers specification tolerance problem.

Well I can say that once set as you describe with 1/16 play at tightest point of rotation the blower has performed just fine for me for 9 winters, and chain still seems fine.
I regularly check for pto-input-shaft-to-sprocket looseness by twisting the shaft back and forth while holding the sprocket still, and it's not moved fora couple winters now. That last torque I applied to the setscrews seems to be holding nice.

So it's just grease it up, and change the gear oil in the auger reduction box. The warm/hot weather sure makes draining and filling that unit easier!

 

[Eagle]

Well I can say that once set as you describe with 1/16 play at tightest point of rotation the blower has performed just fine for me for 9 winters, and chain still seems fine.
I regularly check for pto-input-shaft-to-sprocket looseness by twisting the shaft back and forth while holding the sprocket still, and it's not moved fora couple winters now. That last torque I applied to the setscrews seems to be holding nice.

So it's just grease it up, and change the gear oil in the auger reduction box. The warm/hot weather sure makes draining and filling that unit easier!

My tractor is a 2014 and I bought it used in 2019 and it's been running with the chain tension anomaly all that time so I guess I'll do as you say and just keep checking things, keep up the maintenance, and keep using it.