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  1. #21

    Join Date
    Apr 2001
    Posts
    26
    Location
    Newburgh Maine
    Tractor
    John Deere 990

    Default Re: PTO shear pin advice.

    My experience is quite different than the rest I guess....

    I continually sheared the bolts on my snowblower for about a year. I changed to the hardened bolts about 10 years ago and have had no problems (other than shearing those bolts under hard conditions) since then. No instructions with the blower so I dont know if I am doing right or wrong.

    One interesting note, I guess, is that I took the drive chain to the shop to have a link removed ( the chain was loose) and I was told that since the chain had stretched that there was something wrong with the unit, no chain should stretch to require removal of a link. Well I come from the motorcycle age when everything was driven by chain ( no driveshaft) and you always had an adjustment to tighten the chain and you also had a splicing link to alow the removal of chain links.

    Anyway I am not sure that my use of the hardened bolts is correct, but I know regular bolts would not work in my case.


  2. #22

    Join Date
    Jul 2001
    Posts
    1,806
    Location
    Houston, TX.
    Tractor
    2001 TN65, 1951 8N Ford

    Default Re: PTO shear pin advice.

    On industrial chains you can also do a half link. Sounds like they are trying to sell chain.


  3. #23
    Epic Contributor Bird's Avatar
    Join Date
    Mar 2000
    Posts
    38,082
    Location
    Texas

    Default Re: PTO shear pin advice.

    BrianC, I noticed a long time ago that my Bush Hog tiller manual, in telling about maintenance on the chain drive, says "If chain has one link or more of slack, have an authorized Bush Hog dealer resize the chain." So I guess that may not be too unusual; however, in over 6 years of hard use, I've not had to do that.

    Bird

  4. #24
    Platinum Member
    Join Date
    Apr 2000
    Posts
    658
    Location
    Central Wisconsin
    Tractor
    1986 Ford 1910 with 770B (FORD) loader, 4 MFWD; 1986 Bolens G214,back hoe,loader,MFWD (Iseki) 21 hp)

    Default Re: PTO shear pin advice.

    <font color=blue>I continually sheared the bolts on my snowblower for about a year.</font color=blue>
    I had this problem with a Lucknow rear snowblower. The shear pin was located on the front u-joint of the PTO shaft. I consisted of 2 lobes intergrated into the casting of the u-joint that were bolted together with a 1/4" bolt. The hole through these lobes had been drilled as far away from the center of the shaft as possible- even at the point where the casting started to round off.There was too much leverage out there- I redrilled the same sized hole closer to the center of the PTO shaft, about a 1/2", and that solved the problem. Changing that shear bolt up under the PTO guard of the tractor, in the dark at 10-20 degrees F was my definition of a royal pain in the @ss

    RCH

  5. #25

    Join Date
    Aug 2000
    Posts
    239
    Location
    Texas
    Tractor
    my 18 horse Sears doesn't even count as a tractor

    Default Re: PTO shear pin advice.

    The grade 2 bolt issue is a real can of worms. There are various material specifications that could be sold as a grade 2 bolt but are not. The problem is there is no head marking requirement for a grade 2 bolt. The head is plain and may not even have a manufacturers symbol on it. The grade marking designations came from the automotive industry with Specification J429. The J429 grade 2 has a tensile strength of 74,000 psi for bolts between 1/4 and 3/4 in diameter and 60,000 psi for bolts between 3/4 and 1 1/2 diameter. An J429 grade 1 also has no head marking but it only has a tensile strength of 60,000 psi and the diameters run from 1/4 to 1 1/2. Then there is the ASTM A307 specification that alot of people try to pass off as a grade 2 bolt but comes in grades of A and B, it only has a minimum specified tensile strength of 60,000 psi. The long and short of it, you as a purchaser have no way to really identify what is being sold to you. This is why when you go to the hardware store and buy an unmarked bolt, some of them can be almost as strong as a grade 5 depending on how the bolt was manufactured. I have noticed that in the last few years the ASTM A307 designation has started showing up on the head of the bolt. I would not buy the A307 and try to use it as a grade 2. There are no proof load requirements for an A307 bolt and this is why you can have a real soft bolt that does not shear readily but just stretches.
    Sorry for the long post but it something as an OEM manufacturer that we face everyday and sometimes have to take a bolt sample to the lab just to see if we received what we ordered. Good luck.

    Randy


  6. #26
    Veteran Member hayden's Avatar
    Join Date
    Sep 2000
    Posts
    1,709
    Location
    MA/VT
    Tractor
    Kubota L5740 cab + FEL, Cat D5G dozer, Kubota KX121 excavtor

    Default Re: PTO shear pin advice.

    I used a grade 5 bolt in my snow blower in place of the grade 2 and the next time I picked up a rock I blew out the drive chain. I've been using grade 2 bolts ever since. I view a clutch as a self-repairing, adjustable grade sheer bolt. That's why I'm getting one.


  7. #27

    Join Date
    Jul 2001
    Posts
    1,807
    Location
    Sharpsburg, Md
    Tractor
    John Deere 4100 HST

    Default Re: PTO shear pin advice.

    Randy,

    I think that you have explained why the JD guys suggested that I use a Grade 5. He stated that the Grade 2 didn't shear but bent or stretched.

    I'm going out early tomorrow to drop of the youngest daughter to get certifiied as a baby sitter (yep, nice to do that now...) and hit the Home Depot and another JD dealer. Lost a pin for my FEL latch and need to pick one up.

    Let's see how much more I can add to this saga. [img]/w3tcompact/icons/smile.gif[/img]

    Terry


  8. #28
    Silver Member
    Join Date
    Jan 2001
    Posts
    147
    Location
    Rockingham County, Va.
    Tractor
    NH TC35 bought 5/01

    Default Re: PTO shear pin advice.

    Terry,

    I use a #2 1/2"X3 1/2" shear bolt on my Land Pride 60" rotary cutter and they shear just fine. No bending, no stretching, just "zing" and I'm reaching into my spares.

    The cutter came from the manufacturer without instruction on this point, (they presume all were ordered with a slip clutch - an option I was unalert to and which my dealer did not mention). But dealer and previous posts on this board led to me use #2's, and as I suggest above, they do a fine job protecting the gear assembly etc.

    Since I have gotten better at using the cutter, and since I've gotten the very tall stuff cut so I can see where I am going, I hardly ever break a bolt, so the idea of retrofitting a slip clutch seems less necessary...esp if it involves cutting the PTO shaft to accomdate. Though if I had slip clutch, I might not need the New Holland toolbox where I keep spares and some wrenches. Could store a thermos of coffee or something.

    Good luck,

    Chas



  9. #29

    Join Date
    Jan 2001
    Posts
    2,518
    Location
    Capital District, Upstate New York
    Tractor
    Satoh S650G, MF135, MF165, JD5205

    Default Re: PTO shear pin advice.

    Shear Bolt Strength
    Shear Bolt Strength Chart


    "You are what you eat, drink, think, say and do..."
    Attached Files Attached Files

  10. #30

    Join Date
    Aug 2000
    Posts
    3,371
    Location
    California - S.F. East Bay & Sierra foothills
    Tractor
    Kubota L2500DT Standard Transmission

    Default Re: PTO shear pin advice.

    Same chart modified for Mac users (attached). [img]/w3tcompact/icons/wink.gif[/img]

    Attached Files Attached Files

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