shear pin breakage

greg_g · Jun 1, 2006

( The slip clutch is held on by the former shear pin. You use a strong bolt though so that it won't shear. )

Yeah, that aftermarket combination is kinda the worst of both worlds. You don't know if the bolt's gonna go before the friction plates lose lock, or vice versal. The splined slip clutches are much more effective. In this case, he might be better off buying an entire new PTO shaft - already equipped with a 50hp slip clutch (I think the Branson has <41 PTOhp). The OE shaft can be kept in reserve, or used for another implement that requires less torque.

//greg//

greg_g · Jun 1, 2006

( The slip clutch is held on by the former shear pin. You use a strong bolt though so that it won't shear. )

Yeah, that aftermarket combination is kinda the worst of both worlds. You don't know if the bolt's gonna go before the friction plates lose lock, or vice versal. The splined slip clutches are much more effective. In this case, he might be better off buying an entire new PTO shaft - already equipped with a 50hp slip clutch (I think the Branson has <41 PTOhp). The OE shaft can be kept in reserve, or used for another implement that requires less torque.

//greg//

Highbeam · Jun 1, 2006

"Yeah, that aftermarket combination is kinda the worst of both worlds. You don't know if the bolt's gonna go before the friction plates lose lock, or vice versal. The splined slip clutches are much more effective."

I call BS on what you say. The original shear pin is replaced with a stronger bolt. If anything causes the stronger bolt to break then that is actually good that it broke instead of something expensive. The slip clutches need to be adjusted properly on splined or smooth shaft models. I see no negatives to this upgrade, certainly not the worst of both worlds. Am I missing something?

Highbeam · Jun 1, 2006

"Yeah, that aftermarket combination is kinda the worst of both worlds. You don't know if the bolt's gonna go before the friction plates lose lock, or vice versal. The splined slip clutches are much more effective."

I call BS on what you say. The original shear pin is replaced with a stronger bolt. If anything causes the stronger bolt to break then that is actually good that it broke instead of something expensive. The slip clutches need to be adjusted properly on splined or smooth shaft models. I see no negatives to this upgrade, certainly not the worst of both worlds. Am I missing something?

greg_g · Jun 1, 2006

( Am I missing something? )

Yup. BS all you want, but you're missing the weekend warriors who don't have a clue how to adjust a slip clutch to match their PTO hp, how many ft-lbs of torque it takes to slip the clutch when properly adjusted, then factoring those numbers into selecting which grade bolt to use so the clutch slips before the bolt breaks.

Your way can work, IF you have answers to all of the above. None however, are jobs for the novice. Better (for them) to determine PTO horsepower, then match it with a purpose built PTO shaft with built-in (splined) clutch. Buying new also gives the advantage of an instruction manual, so that the slip clutch can then be adjusted for the PTO hp of the tractor with which it's going to be used.

//greg//

greg_g · Jun 1, 2006

( Am I missing something? )

Yup. BS all you want, but you're missing the weekend warriors who don't have a clue how to adjust a slip clutch to match their PTO hp, how many ft-lbs of torque it takes to slip the clutch when properly adjusted, then factoring those numbers into selecting which grade bolt to use so the clutch slips before the bolt breaks.

Your way can work, IF you have answers to all of the above. None however, are jobs for the novice. Better (for them) to determine PTO horsepower, then match it with a purpose built PTO shaft with built-in (splined) clutch. Buying new also gives the advantage of an instruction manual, so that the slip clutch can then be adjusted for the PTO hp of the tractor with which it's going to be used.

//greg//

Highbeam · Jun 1, 2006

Sure, if you assume we are all idiots and can't adjust or service a slip clutch according to the instructions then yes, the slip clutch won't work as well as a fail proof shear bolt.

Doesn't the splined version of a slip clutch also require adjustment and seasonal maintenance? How can my small brain adjust one type but not the other. Maybe I am only smart enough to use a briggs lawnmower. Oh, but then I might not be smart enough to read the instructions and check the oil. Sheesh.

Highbeam · Jun 1, 2006

Sure, if you assume we are all idiots and can't adjust or service a slip clutch according to the instructions then yes, the slip clutch won't work as well as a fail proof shear bolt.

Doesn't the splined version of a slip clutch also require adjustment and seasonal maintenance? How can my small brain adjust one type but not the other. Maybe I am only smart enough to use a briggs lawnmower. Oh, but then I might not be smart enough to read the instructions and check the oil. Sheesh.

greg_g · Jun 1, 2006

Not quite sure what's got you all bent outa shape, but the idea of a smooth bore or splined slip clutch is academic anyway - since neither of us knows what kind of transmission input shaft is on Toby's rotary cutter. How bout lettin' the fella back in here for a few words of his own?

//greg//

greg_g · Jun 1, 2006

Not quite sure what's got you all bent outa shape, but the idea of a smooth bore or splined slip clutch is academic anyway - since neither of us knows what kind of transmission input shaft is on Toby's rotary cutter. How bout lettin' the fella back in here for a few words of his own?

//greg//

Soundguy · Jun 2, 2006

( Sure, if you assume we are all idiots and can't adjust or service a slip clutch according to the instructions )

I agree... IMHO.. owning a tractor does, or should convey having, or learning a few maintenance skills that the average homeowner may not need.

Things like how to adjust the tractors clutch adjustment, brakes, and change simple bolt on and belte run parts.. this would include knowing how to use a torque wrench... once you know that.. everything else you find in a manual can be done by 'cook-book' method...

I do realize there will be a few city slickers that move tot he country, buy tractors, and don't know how to check oil, let alone change oil.. but then.. those are the kind that need to pay the tractor mechanic to come out and do yearly services, and that could include things like slipping the clutch ont he mower.

Reminds me... when i get to feeling better.. I need to go service my 10' mower's clutch...

Soundguy

Soundguy · Jun 2, 2006

( Sure, if you assume we are all idiots and can't adjust or service a slip clutch according to the instructions )

I agree... IMHO.. owning a tractor does, or should convey having, or learning a few maintenance skills that the average homeowner may not need.

Things like how to adjust the tractors clutch adjustment, brakes, and change simple bolt on and belte run parts.. this would include knowing how to use a torque wrench... once you know that.. everything else you find in a manual can be done by 'cook-book' method...

I do realize there will be a few city slickers that move tot he country, buy tractors, and don't know how to check oil, let alone change oil.. but then.. those are the kind that need to pay the tractor mechanic to come out and do yearly services, and that could include things like slipping the clutch ont he mower.

Reminds me... when i get to feeling better.. I need to go service my 10' mower's clutch...

Soundguy

Toby873 · Jun 2, 2006

greg g/highbeam,
Thank you for comments. Both have excellant points regarding buying new vs clutch. I am a suburban slicker trying to make in the country. I contacted Howse and they believe that the shear pin yoke has been worn out and allows to much movement. My opinion is how could that be if I am only putting in pins that I got from them??? They also said that the yoke is made of cast iron and would certainly be destroyed way before I could hurt the hardened steel shaft. Well that aint true cuz my gear box shaft looks like a dried up friggin burned up BBQ hotdog. Now my problem is I cant get the whole friggin thing off of the gear box shaft. I know there has to be some piece of chewed up pin keeping it on. I have knocked the old out. Cut a belt sander pad in half and polished that shaft to a hue but the yoke wont come off? I can slide it all the way to the box and all the way to the front of the shaft but it wont come off. The safety clip on the front of the shaft has been removed. #$%^&*&^*$%#

Toby873 · Jun 2, 2006

greg g/highbeam,
Thank you for comments. Both have excellant points regarding buying new vs clutch. I am a suburban slicker trying to make in the country. I contacted Howse and they believe that the shear pin yoke has been worn out and allows to much movement. My opinion is how could that be if I am only putting in pins that I got from them??? They also said that the yoke is made of cast iron and would certainly be destroyed way before I could hurt the hardened steel shaft. Well that aint true cuz my gear box shaft looks like a dried up friggin burned up BBQ hotdog. Now my problem is I cant get the whole friggin thing off of the gear box shaft. I know there has to be some piece of chewed up pin keeping it on. I have knocked the old out. Cut a belt sander pad in half and polished that shaft to a hue but the yoke wont come off? I can slide it all the way to the box and all the way to the front of the shaft but it wont come off. The safety clip on the front of the shaft has been removed. #$%^&*&^*$%#

greg_g · Jun 2, 2006

( greg g/highbeam,
Thank you for comments. Both have excellant points regarding buying new vs clutch. )

I agree it sounds like you've got a burr under there to overcome. I think I'd start by aligning the holes and look for obviously displaced metal. You might be able to get it with a drill bit. If not, you might consider using a wooden block to stop the blades from turning. Then put a cheater bar through the two yoke holes and try to turn the burr off. But again, this won't work if your tranny shaft is splined. I'm still waiting to hear if yours is splined or smooth.

But I don't think you got the right impression of my comments above. I absolutely positively am not suggesting that a shear pin type PTO shaft - new or otherwise - is better than a clutch type shaft. In fact, a slip clutch type for your application is superior in all regards - smooth or splined. I have several PTO shafts; some with slip clutch, some with sear bolt, some smoothbore, some splined. My point was that a splined clutch attachment is superior to a smooth type, in that the splined type completely removes shear bolt from the equation. The splines are the clutch stop. On a smoothbore type, one single bolt is the clutch stop, brining us back to the shear pin concept. Unless properly matched and adjusted, that retaining bolt may itself become a shear pin - breaking before the clutch slips.

//greg//

greg_g · Jun 2, 2006

( greg g/highbeam,
Thank you for comments. Both have excellant points regarding buying new vs clutch. )

I agree it sounds like you've got a burr under there to overcome. I think I'd start by aligning the holes and look for obviously displaced metal. You might be able to get it with a drill bit. If not, you might consider using a wooden block to stop the blades from turning. Then put a cheater bar through the two yoke holes and try to turn the burr off. But again, this won't work if your tranny shaft is splined. I'm still waiting to hear if yours is splined or smooth.

But I don't think you got the right impression of my comments above. I absolutely positively am not suggesting that a shear pin type PTO shaft - new or otherwise - is better than a clutch type shaft. In fact, a slip clutch type for your application is superior in all regards - smooth or splined. I have several PTO shafts; some with slip clutch, some with sear bolt, some smoothbore, some splined. My point was that a splined clutch attachment is superior to a smooth type, in that the splined type completely removes shear bolt from the equation. The splines are the clutch stop. On a smoothbore type, one single bolt is the clutch stop, brining us back to the shear pin concept. Unless properly matched and adjusted, that retaining bolt may itself become a shear pin - breaking before the clutch slips.

//greg//

Toby873 · Jun 2, 2006

Im sorry. I dont understand what you mean by tranny shaft. If you mean the shaft that comes out of the cutter gearbox, that is smooth. If you are talking about the shaft of my drive train, that is a rectangle, I know most are square. If you are talking about the pto shaft from the tractor that is splined.
Toby

Toby873 · Jun 2, 2006

Im sorry. I dont understand what you mean by tranny shaft. If you mean the shaft that comes out of the cutter gearbox, that is smooth. If you are talking about the shaft of my drive train, that is a rectangle, I know most are square. If you are talking about the pto shaft from the tractor that is splined.
Toby

greg_g · Jun 2, 2006

The box that sits on top of your rotary cutter is its transmission. Sorry for the colloquialism, but that's the "tranny" to which I referred. Now I know that - if you decide to go with a slip clutch PTO shaft - that it will have to be smoothbore on the implement end. That in turn means you'll secure the slip clutch to the "tranny shaft" with a bolt, which - if the wrong grade is selected - will once again put you back in shear bolt territory.

//greg//

greg_g · Jun 2, 2006

The box that sits on top of your rotary cutter is its transmission. Sorry for the colloquialism, but that's the "tranny" to which I referred. Now I know that - if you decide to go with a slip clutch PTO shaft - that it will have to be smoothbore on the implement end. That in turn means you'll secure the slip clutch to the "tranny shaft" with a bolt, which - if the wrong grade is selected - will once again put you back in shear bolt territory.

//greg//