Bellville Lock Washer
Bellville Lock Washer
(OP)
I'm designing an oil filter head for a six cylinder motor. The head will be made in two pieces, I'll be fastening them using low grade steel bolts. I'm thinking of adding a bellville under the bolt head to compensate for thermal expansion and contraction of the parts. I don't think locktite works for this particular joint, because it will need to be broken down from time to time.





RE: Bellville Lock Washer
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RE: Bellville Lock Washer
I take it your filter head is aluminum and you're worried about the difference in thermal expansion rates from the bolts. I've seen plenty of aluminum oil and coolant outlets that worked fine with standard bolts and no thread-locker. I would hazard a guess that there's a gasket in between these pieces as well which, being the least rigid part of the joint, will account for any change in the joint preload by deforming.
Use as long a bolt as you can to increase the joint's tolerance to thermal expansion.
RE: Bellville Lock Washer
RE: Bellville Lock Washer
The filter head componentes are aluminum, which is why I have a concern about thermal effects. The filter will be screwed into the outer half of the unit, which will mount horizontally. I need the bolt to hold snugly to maintain even compression on the o-ring, rather than the o-ring expanding to maintain sufficient tension on the bolt.
I'm not comfortable with using threadlockers, because this is being designed as a field replacement. Not sure I trust a mechanic of unknown reliability to apply the right threadlocker.
RE: Bellville Lock Washer
As far as the threadlocker goes, you could supply a bolt with pre-applied threadlocker. Of course this doesn't get around your reuse issue though.
ISZ
RE: Bellville Lock Washer
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RE: Bellville Lock Washer
RE: Bellville Lock Washer
As noted above, a belleville is a spring. It can be used to maintain relatively constant tension to compensate for thermal expansion. It isn't a locking device.
You might consider a pellet or strip bolt, or a stud and elastic stop nut.
RE: Bellville Lock Washer
RE: Bellville Lock Washer
What is the application? Meaning aftermarket performance, industrial etc.
Saftey wire it if your so concerned about it loosening. That is what is done in the aircraft world.
RE: Bellville Lock Washer
Never had any issues with unscrewing with thermal expansion, as long as the filter has been torqued up correctly.