B2789 snowblower problem

[GEPM64]

Hi guys,

We got our first snow of the year the other day and I made a total of 4 passes before the PTO shaft came off the gear box end on the blower. The dealer did come out quickly and fix it. I'm out of town now and was not there whe he fixed it, but when I asked what the problem was he said a shear bolt broke. I don't buy that as I'm pretty sure the shear pin is on the other side of the gear box. To me it looks like the yoke was not bolted to the gear box shaft properly. The shaft has a key way in it, but I never noticed if there are threads in the shaft itself for a bolt. Does anybody know how the yoke is supposed to attach? What would cause this to fail? Was it poor assembly or something I could have done?

Thanks in advance for your comments,

Regards,
Glenn

 

[KeithG]

I have no idea if this is going to help you, but I created a .jpg of the B2789 with parts explosion for you to look at.

 

[MikeyA]

From the looks of your picture, the keyway sheared. If Kubota uses the key as a shear point, then dealer was on the up n up.

 

[OldeEnglish]

I'm not familiar with your blower but I would assume whatever goes onto that keyed shaft would be held in place with a set screw or two. Probably never tightened from the get go

 

[North Idaho Wolfman]

That connection does not have a shear bolt!

#1 Any shear bolt location would allow the bolt to shear without the connection being able to come apart.
#2 They would not put a shear bolt in with a key way! What good would the shear bolt do? The key way would still keep it from braking loose!

When you get home I would look at it real close, I would even dissemble and reassemble it to make sure it's right!

 

[GEPM64]

Would a set screw be enough to hold the yoke on the shaft? The blower did come with a spare key and set screw so I assume that's what it would be for. I am going to take it apart when I get home tomorrow and have a better look. I took that picture as I was leaving and I was too pissed off to look at it closer at the time.

Thanks,

 

[RCW]

My bet is the set screw loosened or came out, then the key jiggled out and let whole thing slide off.

Bet that's why they included a spare key and set screw - that arrangement is prone to loosen.

I would tighten the set screw good with some blue Loctite so it won't back away from the key.

Another option, if there is room, is a small Grade 8 hex-head bolt with extra nut to lock to yoke, but still blue Loctite on bolt and extra nut.

Seems like the impellor (fan) on my old JD snowblower had a similar deal, but without the key to avoid damage to the shaft or impellor. That was a pain at first, but no problem once I figured it out.

Like Wolfman said, still want to check it over real good first.

Good Luck!

 

[NoJacketRequired]

I was looking at buying one of these blowers recently to put behind my recently-acquired B7200. Now that I see how the PTO shaft connects I'm very glad I didn't make this purchase. The Meteor blower I purchased uses the same spline on its input as the tractor's PTO output shaft. This makes it really easy to disconnect the complete PTO shaft to service it, and makes for a very positive connection to the blower. The PTO shaft itself contains a sheer bolt that's exceedingly easy to access and service while providing a fail-safe sheer point which does not result in the shaft falling off the blower and potentially flailing around to maim any and all who may be nearby.

The design of this Kubota blower clearly leaves much to be desired.

Oh as an aside, when I was pricing blowers I discovered a local dealer who would sell me a B2789 for $1800 + tax on the pallet, unassembled. That was the best price I was able to find on a new snowblower, period.

 

[mpham]

My 54 inch Rad blower uses a keyway yoke like that pictured, but also has a bolt that goes thru the yoke and shaft. No set screws. It is a pain in the butt to remove and install the shaft at seasons change.

 

[SLIMSHADIE]

My front mounted version snowblower BX2750 is held on with the key and set screws, read about them backing out so before I used it, I blue loctited them down. Also on the mid shaft had a couple of set screws. Borrowed my daughters white nail polish and put a dot on the shaft on both sides of the collar just to see if they are moving. On my 3rd season with no problems.

 

[GEPM64]

That connection does not have a shear bolt!

#1 Any shear bolt location would allow the bolt to shear without the connection being able to come apart.
#2 They would not put a shear bolt in with a key way! What good would the shear bolt do? The key way would still keep it from braking loose!

When you get home I would look at it real close, I would even dissemble and reassemble it to make sure it's right!

Well, they sent a service tech to the house while I was gone and he fixed it.......or so I thought. I got home today, did one pass with the blower and "BANG" it broke again. I checked my manual and it shows a keyway and key, a regular bolt and a set screw - NO SHEAR BOLT

Called the dealer again and told him what happened. With hesitating, he said he's going to load a new blower up in the morning and bring it out and swap this one. The salesman is pretty pissed off at the service tech.


Regards,

 

[North Idaho Wolfman]

Called the dealer again and told him what happened. With hesitating, he said he's going to load a new blower up in the morning and bring it out and swap this one. The salesman is pretty pissed off at the service tech.

I got to hand it to the Salesman, good job on his part.
When you get it, if the bolt in there is a silver bolt with no markings,or 3 dashes on the head, pull it out and go get a #8 bolt with a nylock nut, that will save you any damage in the future from that joint coming apart!

 

[GEPM64]

I got to hand it to the Salesman, good job on his part.
When you get it, if the bolt in there is a silver bolt with no markings,or 3 dashes on the head, pull it out and go get a #8 bolt with a nylock nut, that will save you any damage in the future from that joint coming apart!

I took it apart and sure enough, no key, no set screw, just the center part of a shear bolt. How can you tell a shear bolt from a regular bolt? Are there marking on a shear bolt?

Yep, pretty impressed with the salesman.

Regards,

 

[GEPM64]

The dealer was out this morning with the new blower. He made sure this one was assembled right the first time. He even cleaned some of my driveway after he installed it to make sure it's right. I just came in after cleaning the rest of the yard and no issues. All looks to be good now. He's been really good and I'm very pleased with the service he has provided.

Am I allowed to mention his name on here? I think good reviews are as important as bad ones.

Regards,

 

[KeithG]

I took it apart and sure enough, no key, no set screw, just the center part of a shear bolt. How can you tell a shear bolt from a regular bolt? Are there marking on a shear bolt?

Yep, pretty impressed with the salesman.

Regards,

There is no such thing as a "shear bolt". There are "shear pins" but not "shear bolts". Rather than post a lengthy reply here, I did a lot of research on this when I got my snowblower and all that information can be found here:

http://www.orangetractortalks.com/forums/showthread.php?p=167597#post167597

I would strongly recommend reading this since many/most people do not know the specifics of what is needed in certain applications. I have even asked some tractor dealers questions and got completely wrong and misleading information...

-Keith

 

[North Idaho Wolfman]

Replacing a grade 5 shear bolt with a grade 8 could lead to disaster.

Why would it lead to disaster???

It's a connection that not ever supposed to come apart, especially under load!

Not having a good bolt in there will lead to "disaster" from a flying driveshaft!

 

[North Idaho Wolfman]

There is no such thing as a "shear bolt". There are "shear pins" but not "shear bolts".

While I applad your efforts, your info is a little off.

Yes there is shear bolts, they just get mixed up with shear pins.

Shear bolts (or snap-off bolts) are a premium 1-way permanent security solution, ideal where maintenance is not required. The hexagonal shaped section on top of the bolt snaps off when fully tightened, leaving a tamper-proof dome, countersunk or cap head.

Shear pin is a mechanical detail designed to allow a specific outcome to occur once a predetermined force is applied. It can either function as a safeguard designed to break to protect other parts, or as a conditional operator that will not allow a mechanical device to operate until the correct force is applied.

And yes Shear pins can be bolts!

For those that are confused, I'm not saying to put a "grade 8 shear bolt" in it, quite the contrary, I'm saying put a grade 8 bolt in it because that connection is not ever supposed to come apart especially when loaded.
That is not a safety bolt, pin, whatever you want to call it connection!

 

[North Idaho Wolfman]

I took it apart and sure enough, no key, no set screw, just the center part of a shear bolt. How can you tell a shear bolt from a regular bolt? Are there marking on a shear bolt?

Yep, pretty impressed with the salesman.

Regards,

You would have to see the head of the bolt, often they use a grade 2 bolt as a shear bolt.

In this case it it should have a hardened key in the key way, if bolted should have a strong bolt, or set screws, to keep it in place to prevent the pto shaft from coming off of the blower input!

 

[KeithG]

While I applad your efforts, your info is a little off.

Yes there is shear bolts, they just get mixed up with shear pins.

Shear bolts (or snap-off bolts) are a premium 1-way permanent security solution, ideal where maintenance is not required. The hexagonal shaped section on top of the bolt snaps off when fully tightened, leaving a tamper-proof dome, countersunk or cap head.

Shear pin is a mechanical detail designed to allow a specific outcome to occur once a predetermined force is applied. It can either function as a safeguard designed to break to protect other parts, or as a conditional operator that will not allow a mechanical device to operate until the correct force is applied.

And yes Shear pins can be bolts!

For those that are confused, I'm not saying to put a "grade 8 shear bolt" in it, quite the contrary, I'm saying put a grade 8 bolt in it because that connection is not ever supposed to come apart especially when loaded.
That is not a safety bolt, pin, whatever you want to call it connection!

This is exactly why I created the post I did. A "bolt" is a "bolt" and a "pin" is a "pin". A "shear pin" is a non-threaded pin that has relief grooves cut into it to allow for shear force to break the pin in a perpendicular plane when a certain amount of force is reached.

A "bolt" is not defined to be a "shear bolt"! A "bolt" is defined to be a fully, or partially, threaded bolt of certain grades that meet specific tensile strength values from which shear strength is calculated. Your definition above is simply a bolt that is torqued so much as to force the hex head off the bolt. Your example has no value in an application that is supposed to allow for failure AND REPLACEMENT once a certain force is reached.

For all intensive purposes your example could be solved by taking a steel rod and welding it in place also. Again not the intent of a bolt that is designed to fail and then be replaced.

If you find any factual evidence in my post that is incorrect then please identify that and correct it and I would request that you do not mislead anyone about what is needed for tractor implements. By the way, I also posted all my reference material so if my "info" is a little off I would be greatly surprised.

 

[KeithG]

Why would it lead to disaster???

It's a connection that not ever supposed to come apart, especially under load!

Not having a good bolt in there will lead to "disaster" from a flying driveshaft!

Here is an example for you. My neighbor was mowing a field with a 3pt mower and when he broke the grade 5 bolt that was being used to guard against the condition of the blade being caught he put in a grade 8 bolt because he could not be bothered with changing bolts.

A week later doing another field he ran over a property pin that was sticking up out of the ground but not visible do to the high grass. When the blade hit the pin it stopped. Since the grade 5 bolt was now a grade 8 bolt it did not fail. Result, the PTO drive shave for the 3pt attachments broke INTERNALLY and the tractor was in the shop for 4 weeks because the part had to be specially ordered and the had to tear down the back end. I think the cost was around $5,000.

If he had used the grade 5 bolt cost would have been about $2.50.