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john-in-ga
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609 Posts
Discussion Starter #1
Thought some of you might enjoy seeing this. In doing disassembly to repair transmission on my 51 B John Deere, I found this example of safety wire on the bolts heads holding the crank shaft main bearing housing right side. Guess the last shade tree owner who had these bolts off couldn't remember the correct size wire. It should be the size that can be seen on the cam shaft quill. The correct size is 16 gauge.


Safety Wire

:cpu:
 

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EX Super Mod
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5,317 Posts
Definitely not the right wire as thin as it is the vibration would more then likely break it.:furious:
Jody
 

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Premium Member
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1,394 Posts
Looks like someone needs a lesson in saftey wire applications.

I wish I had a dollar for every safety wire I attached in all those years as an aircraft mech.

Personally I would not use the single strand continous loop method, even if the book shows it done that way. All it takes is for the wire to break, and all the fasteners security is jeopardized. Even that saftey on the upper right should be done with the double twist method.. The pulling tension of the wire should go up and over the bolt head, and it will provide better tension and reliability. Take the wire over the bolt head and twist the wire CW making 6 to 8 twists per inch, go into the next bolt head in the hole that makes the greatest angle, twist again but this time CCW and continue on to the next fastener, this time tewisting CW. When finishing up the pigtail twist until the wires just start to get snug, and then using wrist action, go in a circle without twisting, sort of like flipping your wrist. This will draw up the wire very snug into the fastener. Cut the pigtail about 5/8" or 3 to 5 twists long, and double it over and tuck out of the way. When applying safety wire you ned to keep from nicking or kinking the wire, as this makes it prone to breaking.

A wire twisted as that one in the upper right, with it being single strand and twisted between fasteners IMHO is just a matter of time until it breaks as its impossible to keep it taught that way.

See attached file for example of proper saftey wire application.
 

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Registered
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8,567 Posts
None of those safeties are any good but you would think the guy would have at least pulled them something resembling tight. army :nerd: :argh:
 

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Tractor Lover
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I look at it a little different. It was probably the only wire available to him at the time of repair. You have to give him credit for putting some kind of wire back on it.
 

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Tractor Lover
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If the bolts work loose it is there to ensure they won't turn all the way out. They will stay in place doing their intended job.
 

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Argee, if the safety is not tight, the bolt can work back and forth and eventually break. I have spent many years preflighting aircraft coming out of rebuilt. Sometimes a safety installed backwards can allow the flight contol rod to change enough to cause a problem in flight. They must be tight and wrapped by the book. Even on a tractor.
 

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Premium Member
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Safety wire to aircraft and race cars is like lock washers to most everything else. I have never seeen a lock washer used on aircraft at least not the typical split or serrated or toothed types. They all use self locking nuts or safety wire. Safety wire is applied correctly always maintains just a slight bit of tension on a fastener and prevents or at least helps in preventing it from loosing its torque setting. If it does loose its torque setting, the wire usually will still hold the fastener in its relative position and prevent it from falling out.........


I had an old Famall 200 with a home brew 3 point on it. After a bit of bush hogging and mowing and box scraper use it was not uncommon for the bolts that held the girdle on the final drive to get loose. Lock washers made no difference. Pulled all those bolts drilled the heads, reinstalled the bolts and installed .041" stainless safety wire and they never got loose again.
 

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Premium Member
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319 Posts
chipmaker. hasn't the use of safetywiring in military airframes[ or commercial for that matter ] been superceded in the last 34 years by using miltary grade loctite? wiring weighs a lot in bulk applications--
 

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Although locktite is used in some applications a wire safety, cotter key, lock tab, or some type of mechanical locking device is required is required. To speed the process up, safety guns are used in many applications that crimp a farrel end on the safety wire cable material instead of the wrap.
 
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