SnowRidge
Elite Member
zzvyb6 said:
OK, Mrs. Slocum.
bolts that back out...why?
- Thread starter jimg
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OK, Mrs. Slocum.
Danno1
Veteran Member
RobJ
Elite Member
SnowRidge said:Nobody mentioned the "dash of weld" method of locking the bolt or nut to whatever it is holding.
I use this as a security method on my home made multi-mount winch for my truck. Just a dab will do ya.
k54frog
Bronze Member
- Joined
- Aug 25, 2006
- Messages
- 51
- Location
- Northern California
- Tractor
- Mahindra 2015hst w/hydraulic top&tilt
OK, gotta join in,
jimg said "Interesting...thanx Robj. Do you understand the mechanism(s) ov movement? I can sort of understand vibration but even in that case what causes a bolt to loosen vs tighten?"
In response to the question of WHY the bolt backs OUT (instead of in)...
Like zzvyb6 mentioned, a threaded bolt or nut is like an inclined plane.
When you tighten a bolt, you are pushing it UP the plane of the receptacle threads.
The force that holds it in place has a large vertical component along the long axis of the bolt (perpendicular to the threads) but also has a small horizontal component which is oriented mostly along (with/down) the incline of the threads.
When a force (vibration, etc.)overcomes the large vertical component and causes the bolt to loosen, it will travel DOWN the threaded incline of the receptacle along the direction of the small horizontal component . [ie: it will back out.]
And that folks, is a very simplistic rendition of vector physics (of which I know very little)
As to the question of why the bolt starts to loosen in the first place.... see the other posts.
jimg said "Interesting...thanx Robj. Do you understand the mechanism(s) ov movement? I can sort of understand vibration but even in that case what causes a bolt to loosen vs tighten?"
In response to the question of WHY the bolt backs OUT (instead of in)...
Like zzvyb6 mentioned, a threaded bolt or nut is like an inclined plane.
When you tighten a bolt, you are pushing it UP the plane of the receptacle threads.
The force that holds it in place has a large vertical component along the long axis of the bolt (perpendicular to the threads) but also has a small horizontal component which is oriented mostly along (with/down) the incline of the threads.
When a force (vibration, etc.)overcomes the large vertical component and causes the bolt to loosen, it will travel DOWN the threaded incline of the receptacle along the direction of the small horizontal component . [ie: it will back out.]
And that folks, is a very simplistic rendition of vector physics (of which I know very little)
As to the question of why the bolt starts to loosen in the first place.... see the other posts.
Last edited:
k54frog
Bronze Member
- Joined
- Aug 25, 2006
- Messages
- 51
- Location
- Northern California
- Tractor
- Mahindra 2015hst w/hydraulic top&tilt
tallyho8 said:Why is it that when I am changing a tire at my shop and have all my tools handy, the lug nuts seem like they are almost too loose. But when I have a flat on the road, with a stupid manufacturer supplied lug wrench, the lug nuts seemed to have tightened to the point of nearly breaking?
Hi Dudley,
The reason is probably due to the heat buildup in the studs that comes from the brakes when you are driving. The studs will expand slightly and cause the nuts to get tighter and, of course, harder to get off.
We generally work on our vehicles in the shop after they have had a chance to cool off a little.
