Need help identifying these parts

[aczlan]

Hello and good evening,

I had a young mechanic come over, and he replaced the top link. We bought a new one from TSC. It was about $~50, CAT 2.

He also hammered the bolt out of the shaft, and we bought a new battery, which may have been in haste, oh well.

Now, the issue is that we bought several Grade 5 shear bolts, 3/8 inch I think, 3 inches, but they kept breaking soon after turning the PTO ON

We even put a nylon locknut on each bolt

Do I need to get grade 8 shear bolts?

What is the make and model of your mower? The manual should specify what size and grade bolt to use.

How fast was the engine going when you turned the PTO on? It should be just above idle (around 1500RPMs), if you are much faster than that, the shock load from turning the PTO on can break the shear bolts.

Aaron Z

 

[jimmysisson]

And if the bolt is too small diameter the slop will help shear it upon engagement. Got a manual?
Jim

 

[Tangoddess]

Hello and good afternoon,

The model of the mower/brush hog is JOHN DEERE 513.

I could not find a manual online unfortunately, unless one of you has one?

I tried a 7/16th size bolt, that fit...about 3 inches, but I am not sure if I need grade 5, grade 8, or grade 2?

Do I need it to specifically say shear bolt, or can I get any bolt?

I really want to get this mower going

thank you!!

 

[Tangoddess]

Hello and good evening,

I found a reference to a similar issue here on TBN and found the following solution:

"Doc ID: WX53287

Solution Summary: Shear Bolt Fails Easily on 413/513 and LX4/LX5 Rotary Cutters

Publication Date: Jul 12 2002



Complaint or Symptom:

Shear bolt fails easily.

Problem or Situation:

Tractor PTO engages too aggressively, PTO cannot be modulated, or material being cut is too dense and heavy. This may too much stress to be placed on shear bolt causing failure. The 19M7329 repair bolt may not be strong enough when any of these conditions exist.

Solution:

Install 19M7479 Grade 8.8 bolt that has a longer shank. If application is still too heavy, a 19M8081 Grade 10.9 may be tried but care should be taken. Increasing shear strength of bolt may result in other damage to the driveline if due care is not practiced. The best solution is to install a clutch protected driveline. "

Is this 19M7479 Grade 8.8 bolt something I can only get from JD? It seems like it is $8 a bolt!

Or can I get an equivalent somewhere?

Thank you!!

 

[aczlan]

Hello and good evening,

I found a reference to a similar issue here on TBN and found the following solution:

"Doc ID: WX53287

Solution Summary: Shear Bolt Fails Easily on 413/513 and LX4/LX5 Rotary Cutters

Publication Date: Jul 12 2002



Complaint or Symptom:

Shear bolt fails easily.

Problem or Situation:

Tractor PTO engages too aggressively, PTO cannot be modulated, or material being cut is too dense and heavy. This may too much stress to be placed on shear bolt causing failure. The 19M7329 repair bolt may not be strong enough when any of these conditions exist.

Solution:

Install 19M7479 Grade 8.8 bolt that has a longer shank. If application is still too heavy, a 19M8081 Grade 10.9 may be tried but care should be taken. Increasing shear strength of bolt may result in other damage to the driveline if due care is not practiced. The best solution is to install a clutch protected driveline. "

Is this 19M7479 Grade 8.8 bolt something I can only get from JD? It seems like it is $8 a bolt!

Or can I get an equivalent somewhere?

Thank you!!

Grade 8.8 is a metric bolt, roughly equivalent to a Grade 5 bolt. Grade 10.9 is roughly equivalent to a Grade 8 bolt.
Hit your local hardware store and find one, it should be a snug fit and the unthreaded "shoulder" should stop just before the bolt comes out the other side of the shaft. That was it has to shear through the "shoulder" on both sides and not the "shoulder" on one side and the threads on the other.

Aaron Z

 

[Tangoddess]

hello @aczlan

Thank you!!

So can you or someone else explain which is the unthreaded shoulder?

Maybe this image below helps?

Thank you

 

[tcreeley]

hello @aczlan

Thank you!!

So can you or someone else explain which is the unthreaded shoulder?

Maybe this image below helps?

Thank you

HU and TU is designed to shear (undercut). The shoulder center of the bold remains in place when either end shears. The threads are just to hold the bolt tight with the use of the nut. They are not part of the shearing mechanism.



Shear bolts are designed with specific lengths in mind. I would think twice before substituting regular bolts that are not designed to shear, even of the same grade. - But then we all take shortcuts, and sometimes it works, or doesn't.

Research slip clutches - might consider working one of those in, more costly than just a shear bolt.

This bolt has an un-threaded shoulder and the a threaded portion for the nut.
This is a shear bolt with the undercuts in the unthreaded shoulder for shearing.