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What is the cylinder torque value for the nuts at the base.

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yakman285(at)gmail.com
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Posted: Wed Jun 19, 2019 2:43 am Post subject: What is the cylinder torque value for the nuts at the base.

Be sure and check that the reason why the nuts became loose was not related to loosening and/or backing out of the cylinder studs. I have found this to be more common. Double nut each stud and check tightness first before proceeding.

Craig Payne



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wlannon(at)shaw.ca
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Posted: Sun Jun 23, 2019 12:07 pm Post subject: What is the cylinder torque value for the nuts at the base.

Hi;



Very interesting comments particularly in the area of "multi step, angular 

or stretch based" torque.  Multi step (1/3 or 1/2 torque value per step) is 

standard practice and stretched based is a given.  That left me with 

"angular" which I thought may be in reference to the application in 

sequences of 180 deg. separation. This is also standard practice.

But I looked that up and found a very interesting article (Warren & Brown - 

Australia) that equated "angular" with "torque to yield" technology which 

applies only to special bolts on which a portion of the head fails when the 

correct torque (and stretch), within the elastic limit, is reached.  A neat 

idea, also used in aviation in a product called "Hi- Lock" fasteners, though 

in this case part of the special nut fails at the correct torque.  In any 

event not applicable to cylinder hold down.



The one and only specification we have for the torque value is 304 lb/in. 

This comes from the M14P documentation.  We have absolutely nothing from 

China.  This is not a major concern as the hardware is identical, though an 

English language overhaul manual would be appreciated.  Just realized I have 

not checked the Polish overhaul manual!  Will do that.



As noted previously I have made some comparison of these cylinder stud 

specs. with those of Pratt & Whitney and found them to be very similar in 

strength related characteristics which strongly co-relate with the given 

torque values.  P&W specify 300 lb/in, LUBED.  Our engines use 8 studs per 

cylinder.  The R985 uses 12 (450 hp/t.o.) and the R1340 16 studs. (600/t.o.)

We have been assured by some on this list that the Russian specification 

applies only to"clean and dry" threads yet the only reference page that has 

been provided made no mention of the  subject.   If this is in fact stated 

in the manual I would hope they would provide it.

If that is correct information it would likely be the only aircraft engine 

manufacturer in existence to not specify lubricated in this case.



I am one of those LAME guys but in Canada we drop the L.



Walt



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Vic

Joined: 12 Aug 2008
Posts: 115
Location: Southern Bavaria

Posted: Sun Jun 23, 2019 12:34 pm Post subject: Re: What is the cylinder torque value for the nuts at the ba

No matter, how much you mess around with all sorts of torque settings, your real root of the mess is the paper gasket. I bet, nobody with a M 14 has had any troubles there, no gasket , just an o-ring for seal. So there is metal-to metal contact at the cylinder base, no creeping paper due to loads and vibration. Any preload from base studs will vanish with time so instead get a Loctite low strength sealant, anaerobic like thread locks, no silicone or thinner based sealants. There are rubber like or soft plastic type  Loctite sealants and I have not used paper gaskets for decades on cylinder bases, they just lead to distorted base flanges and creep under load. 



     Vic

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dsavarese0812(at)bellsout
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Posted: Mon Jun 24, 2019 3:43 pm Post subject: What is the cylinder torque value for the nuts at the base.

Loose cylinder base nuts are Much more common on the Huosai than the M14.  M14 manual specifies dry thread torque too. 

Dennis



Sent from my iPhone



 	  Quote: 	
		   On Jun 24, 2019, at 6:52 PM, woodja51 <mwuillemin(at)mac.com> wrote:

 

 

 

 Following on from what a poster sent about nut torque/ wet or dry.

 

 It would appear that failure to lubricate / oil nuts when applying torque can lead to about half the torque simply being used to break thread / friction etc?

 

 28 foot lbs on a dry nut might result in only half that value actually being applied to create clamping forces. I know these nuts are only acting in tensionso might not be 100% applicable ( as the YouTube video concerned plates in building steel  etc.. but worth consideration and might be why M14P?nuts torqued this way might come loose ? Just a thought.  M

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=489814#489814

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wlannon(at)shaw.ca
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Posted: Mon Jun 24, 2019 6:32 pm Post subject: What is the cylinder torque value for the nuts at the base.

Hi Dennis;



Can you supply a copy of that manual page?



Thanks;

Walt



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