shear bolt size for landing gear?

[sreigle]

One of the shear bolts in the cross-locker shaft of the landing gear mechanism did it's job and sheared off, recently. I found a bolt in my supply that would work but have doubts it has the strength to last long.

Anyone know the specs for the proper shear bolt? Besides strength, it has to be long enough to get the nut threaded in place but short enough not to hit the motor housing as it turns. The one sheared is on the motor end. I suppose the one on the other end of the shaft could be longer.

[H. John Kohl]

Steve from another post.

quote:Originally posted by dandt

John...We would love the info.....don't feel safe taking it off truck.
Dick...How long has it been since you replaced the bolt with 1/4 20 stainless and have you had any problems
Jay...To answer your question only one stabilizer jack on front went down. other one stayed up because rod would not spin.
Thanks EVERYONE...this forum has saved our butts many times over. Teresa

I got these from my local Hardware True Value Hardware store.

The bolt or shear pin I use is a 1/4 x 3/4 Socket Shoulder Screw with 10-24 threads. The bolt has a 1/8" Hex wrench socket on the end. I use 10-24 Nylon insert lock nuts.
This is what it looks like

FYI, the threads are not part of the 3/4 length, just the shinny part.
Sorry I was slow posting this information.
NOTE: make sure it clears the Motor on the motor side. That side has the closets clearance.

[sreigle]

Thanks, John. Good info!

I guess there's no need to worry about the strength rating like there is for the shear bolts for the slides, huh?

[H. John Kohl]

I just replaced with what was in there. The one I broke looked just like this one.

My personal opinion is they are bolts, not shear bolts. But I have been wrong before. (Well at least once.)

[sreigle]

"Shear" bolt is just the function, isn't it? Not a specific type of bolt? I thought the bolt is intended to be strong enough to handle normal duty but also be the weak point so if there is a serious problem it is the shear bolt that breaks rather than something expensive breaking. Right?

I will get some bolts of the size specified above to keep around for spares. I have the spares for the slide. Those are the spec MIMF gave us some time ago. Those required a particular strength rating to be strong enough to hold up under normal use and weak enough to be the weak point. But those bolts are too long for the landing gear application.

Thanks again. I'll get some spares next time I am in a hardware store. Soon. I'm not real confident about the bolt I'm using as a temporary measure.

[H. John Kohl]

Steve,
You said it better than I did. I feel the threads on this style bolt make it a shear type bolt that will do as you said.

My farming experience point to the soft bolts on the PTO that were shear bolts.

[sreigle]

quote:Originally posted by H. John Kohl

I just replaced with what was in there. The one I broke looked just like this one.

Mine had a hex head rather than the head on the bolt shown. But I wouldn't think the head matters so long as I have the right tools to remove and install.

[H. John Kohl]

The one I purchased has a hex head hole for an Allan wrench.

[Ozz]

I have it somewhere in my stuff, but it is a cap screw, allen head, it needs to be close to the original to shear when too much torque on the shaft.

[Ozz]

http://tinyurl.com/28g4jtn

http://tinyurl.com/29cqtz5

[drsmart]

If there is a pattern on the HEX head of the broken bolt, or if it's gone check the remaining bolt at the other end of the shaft. That indicates the grade of bolt and reflects the sheer strength.

[The Oldguard]

quote:Originally posted by sreigle

"Shear" bolt is just the function, isn't it? Not a specific type of bolt? I thought the bolt is intended to be strong enough to handle normal duty but also be the weak point so if there is a serious problem it is the shear bolt that breaks rather than something expensive breaking. Right?

I will get some bolts of the size specified above to keep around for spares. I have the spares for the slide. Those are the spec MIMF gave us some time ago. Those required a particular strength rating to be strong enough to hold up under normal use and weak enough to be the weak point. But those bolts are too long for the landing gear application.

Thanks again. I'll get some spares next time I am in a hardware store. Soon. I'm not real confident about the bolt I'm using as a temporary measure.

Steve, this is the bolt Spec. Dale gave for the slide bolts

[sreigle]

Thanks, all. Mine must have had that same head. It was gone from having sheared and dropped out. The one I put in has the hex head but I'll get some of the right ones soon as I can.

Dale's specs in that thread are for the slide mechanism shear bolts but what I need are for the landing gear. They're shorter. They may still be grade 8, but that's what I need to know. I have emailed Dale. Hopefully he'll see it before I need another bolt!