They are serrated on the outer faces of the pair Martin, so grip the bolt head and whatever you're bolting too very effectively. When you try to undo a bolt like this, the cam action of the inner faces forces them apart, making them grip even tighter. Nord-Locks are great, but overkill for battery terminals I would have thought.
IMO the concern for our application is relative movement between cells causing the rigid straps to "turn" fractionally, with a low frequency. With a plain washer alone, I could imagine that eventually slackening off the bolt. Maybe the spring washer is doing something useful, as it will have a sort of ratchet action, preferring to tighten the bolt rather than loosen it. On Thu, Jan 9, 2014 at 4:49 PM, Martin WINLOW <[email protected]> wrote: > I have a concern over Nord-Lock (NL) washers. It is simply that there is > - as I understand it - a plain metal to metal interface between the top of > the NL washer and the underside of the bolt head. Then there is another > plain interface between the bottom of the NL washer and the article that > the bolt is securing. Whilst I can see that there is an interesting and no > doubt effective mechanism to resist movement between the 2 halves of the NL > washer, what is stopping the bolt head moving relative to the top half of > the NL washer or the bottom half of the NL washer relative to the 'secured > article'? > > They just seem to be moving the slipping point, or rather they are not > because these two regions is where slipping would occur with just a > standard washer in there instead of a NL one. So I'm not convinced. MW > > > On 8 Jan 2014, at 04:24, David Nelson wrote: > > > How was the Nord lock video rigged? Have you used nord-lock washers? > > > > "The vibration that a dozer undergoes traversing rock, day in and night > > out, is incredible." > > > > There is no doubt about that. However, the tension in the bolts in one is > > also significantly higher than what an M8 bolt is under when in an > aluminum > > post. Scale does affect how things behave. > > > > What is your experience with prismatic batteries like the TS or CALB > cells > > that many of us are using? Is your pack put together with no terminal > prep > > and no washers? What is your climate like? > > > > On Tue, Jan 7, 2014 at 6:55 PM, Michael Ross <[email protected] > >wrote: > > > >> I guess I am old school. I did mechanical design at Caterpillar for 4 > >> years and have a copy of their tome on bolted joint design. I have seen > >> their labs and proving grounds. They build front shovels that weigh 1.5 > >> MILLION lbs, seriously. The down time on these things is incredible and > >> they spare nothing to be convinced of the components and procedures they > >> use. The vibration that a dozer undergoes traversing rock, day in and > >> night out, is incredible. > >> > >> I think Nordlock is snake oil in comparison. But that is me. YMMV, but > I > >> bet less. > >> > >> > >> On Tue, Jan 7, 2014 at 8:21 PM, David Nelson <[email protected]> wrote: > >> > >>> On Tue, Jan 7, 2014 at 3:55 PM, Michael Ross <[email protected] > > > >>> wrote: > >>>> Hi Jukka, > >>>> > >>>> Is that "tight enough" ± a smidge? I am going with the torque wrench. > >>>> > >>>> I watched a class once where people tried to control applied torque by > >>> feel > >>>> with the max hold set, but hidden, then check the max after to see how > >>> well > >>>> that worked. It was just terrible. A person might get it right once, > >>> but > >>>> they were unable to do very well repeatedly. > >>>> > >>>> Then a set of seemingly identical joints were torqued, and the > >>> un-torquing > >>>> checked. Again, no correlation to the applied torque. > >>> > >>> I'm wondering if they did a controlled test to see how well a "machine" > >>> did. > >>> > >>>> My contention is this loosening is not because the joints are prone to > >>>> loosening, but that they were not torqued correctly to begin with, and > >>>> maybe sometimes not enough. If you torque them right, they won't > >> loosen > >>> - > >>>> ever. > >>>> > >>>> Mike > >>> > >>> I'm not quite buying your last line there. With no movement then yes > >>> but with vibrations in all directions, no. I've seen this test in > >>> other videos but couldn't find them but here is one to show what > >>> happens with a bolt/nut and a vibrating machine with strain gauge: > >>> http://www.nord-lock.com/wp-content/uploads/2012/06/nl_us.wmv > >>> _______________________________________________ > >>> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > >>> http://lists.evdl.org/listinfo.cgi/ev-evdl.org > >>> For EV drag racing discussion, please use NEDRA ( > >>> http://groups.yahoo.com/group/NEDRA) > >>> > >>> > >> > >> > >> -- > >> Put this question to yourself: should I use everyone else to attain > >> happiness, or should I help others gain happiness? > >> *Dalai Lama * > >> > >> Tell me what it is you plan to do > >> With your one wild and precious life? > >> Mary Oliver, "The summer day." > >> > >> To invent, you need a good imagination and a pile of junk. > >> Thomas A. Edison< > >> http://www.brainyquote.com/quotes/quotes/t/thomasaed125362.html> > >> > >> A public-opinion poll is no substitute for thought. > >> *Warren Buffet* > >> > >> Michael E. Ross > >> (919) 550-2430 Land > >> (919) 576-0824 <https://www.google.com/voice/b/0?pli=1#phones> Google > >> Phone > >> (919) 631-1451 Cell > >> (919) 513-0418 Desk > >> > >> [email protected] > >> <[email protected]> > >> -------------- next part -------------- > >> An HTML attachment was scrubbed... > >> URL: < > >> > http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20140107/6514640c/attachment.htm > >>> > >> _______________________________________________ > >> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > >> http://lists.evdl.org/listinfo.cgi/ev-evdl.org > >> For EV drag racing discussion, please use NEDRA ( > >> http://groups.yahoo.com/group/NEDRA) > >> > >> > > > > > > -- > > David D. Nelson > > http://evalbum.com/1328 > > http://www.levforum.com > > -------------- next part -------------- > > An HTML attachment was scrubbed... > > URL: < > http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20140107/6d7f829e/attachment.htm > > > > _______________________________________________ > > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > > http://lists.evdl.org/listinfo.cgi/ev-evdl.org > > For EV drag racing discussion, please use NEDRA ( > http://groups.yahoo.com/group/NEDRA) > > > > _______________________________________________ > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > http://lists.evdl.org/listinfo.cgi/ev-evdl.org > For EV drag racing discussion, please use NEDRA ( > http://groups.yahoo.com/group/NEDRA) > > -------------- next part -------------- An HTML attachment was scrubbed... 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