deardancer3
10 kW
Here is the site;
http://www.eng-tips.com/viewthread.cfm?qid=114051&page=1
part of the discussion:
btrueblood (Mechanical) 4 Feb 05 11:50
"The root cause failure mode is that the split washer is specified or installed by somebody who presumes it is an adequate thread locking or anti-rotation device. In its intended use, the split washer cannot prevent nut rotation when the joint is torqued down tight, since the cutting edge is acting parallel to the nut surface. Only after the nut has loosened (which is considered by most good engineers as a failure of the joint) can the edge of the washer "dig in" to the nut and the parent body."
second quotes:
http://www.eng-tips.com/faqs.cfm?fid=1257
Quote:
NASA Fastener Design Manual RP-1228:
"The lockwasher serves as a spring while the bolt is being tightened. However, the washer is normally flat by the time the bolt is fully torqued. At this time it is equivalent to a solid flat washer, and its locking ability is nonexistent. In summary, a lockwasher of this type is useless for locking."
Or the US Navy.
Quote:
Naval Ships' Technical Manual, Chapter 75:
"Although lockwashers may be encountered, using the flat washers with selflocking nuts, self-locking fasteners, self-locking inserts, or thread sealants such as MIL-S-22473 anaerobic compounds is preferable.
If loosening has been a problem, however, replace the lockwashers with self-locking fasteners.
The helical spring lockwasher (Figure 075-5-11) is flattened when the bolt is torqued down. Once compressed, it acts as a flat washer, contributing normal friction between the nut or bolt and the bearing surface during tightening."
any opinions fromthe M.E./ Scientist folks ?
I have some bolts that keep loosening up in a dirty environment down by the chain, (chainring to clutch attachment on cyclone crankset, 5 threaded holes in freewheel). Am wondering the best technique to stop this from happening, considering locktite, fingernail polish, lock washers and/or longer screws and boltign on the outside.
I am thinking that the bolts and mating freewhel threads have gotten munged from loosening, maybe get new longer bolts, clean everything up, and use threadlock AND nut on the back side, then use torque wrench to tighten to spec.
but what about usefullness of lock washers?
Thanks
D
http://www.eng-tips.com/viewthread.cfm?qid=114051&page=1
part of the discussion:
btrueblood (Mechanical) 4 Feb 05 11:50
"The root cause failure mode is that the split washer is specified or installed by somebody who presumes it is an adequate thread locking or anti-rotation device. In its intended use, the split washer cannot prevent nut rotation when the joint is torqued down tight, since the cutting edge is acting parallel to the nut surface. Only after the nut has loosened (which is considered by most good engineers as a failure of the joint) can the edge of the washer "dig in" to the nut and the parent body."
second quotes:
http://www.eng-tips.com/faqs.cfm?fid=1257
Quote:
NASA Fastener Design Manual RP-1228:
"The lockwasher serves as a spring while the bolt is being tightened. However, the washer is normally flat by the time the bolt is fully torqued. At this time it is equivalent to a solid flat washer, and its locking ability is nonexistent. In summary, a lockwasher of this type is useless for locking."
Or the US Navy.
Quote:
Naval Ships' Technical Manual, Chapter 75:
"Although lockwashers may be encountered, using the flat washers with selflocking nuts, self-locking fasteners, self-locking inserts, or thread sealants such as MIL-S-22473 anaerobic compounds is preferable.
If loosening has been a problem, however, replace the lockwashers with self-locking fasteners.
The helical spring lockwasher (Figure 075-5-11) is flattened when the bolt is torqued down. Once compressed, it acts as a flat washer, contributing normal friction between the nut or bolt and the bearing surface during tightening."
any opinions fromthe M.E./ Scientist folks ?
I have some bolts that keep loosening up in a dirty environment down by the chain, (chainring to clutch attachment on cyclone crankset, 5 threaded holes in freewheel). Am wondering the best technique to stop this from happening, considering locktite, fingernail polish, lock washers and/or longer screws and boltign on the outside.
I am thinking that the bolts and mating freewhel threads have gotten munged from loosening, maybe get new longer bolts, clean everything up, and use threadlock AND nut on the back side, then use torque wrench to tighten to spec.
but what about usefullness of lock washers?
Thanks
D