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LP10 piston assy assembly help

Posted: Fri Jul 03, 2015 9:25 am
by seamaster
My LP10 shooting pressure is very low.

Air cylinder is holding pressure well.

Pallet can't make it out of the barrel.

http://www.steyr-sport.com/images/flipb ... 0_c_en.pdf

Problem is the piston assy section 29 and valve assy section 18 on the diagram

Need help to put this humpty dumpty together after cleaning it.

Specific technical question:

I was very careful when I dissemble section 29. I did not see 29.13 and 29.7 in there.

Are those two parts essential?

What is the tightening pressure relationship between 29.5 and 29.4?

Too tight, no air goes in. Too loose, pressure destroys 29.9 seal.

Much obliged for your insight into the problem.

Re: LP10 piston assy assembly help

Posted: Mon Jul 06, 2015 10:55 pm
by seamaster
I took the regulator apart.

I can understand the basic function, the flow, how air pressure is progressively reduced by resistance.

But there is one part I don't understand. There are 8 washers stacked together on the outside of air flow tunnel.

What are those washers for? They don't seem to be in the direct way of air flow, so how are they involved in reducing pressure?

Re: LP10 piston assy assembly help

Posted: Mon Jul 06, 2015 11:18 pm
by j-team
seamaster wrote:I took the regulator apart.

But there is one part I don't understand. There are 8 washers stacked together on the outside of air flow tunnel.

What are those washers for? They don't seem to be in the direct way of air flow, so how are they involved in reducing pressure?
Those are Bellevue washers which are not flat and they are stacked in an alternating sequence and are in fact a spring. The strength of this spring along with the size difference of the high and low pressure pistons (each end of 29.1) is what determines the pressure reduction.

No offence, but if you don't understand this or how a regulator works, you should take it to someone that does so it can be reassembled properly.

Re: LP10 piston assy assembly help

Posted: Tue Jul 07, 2015 12:08 am
by seamaster
You are correct. I have no business taking the regulator apart not knowing the intricacy of those tiny things.

Your explanation of "Belleville washers" is excellent. I have looked at multiple diagrams of PCP air gun drawing. Those washers are drawn as a spring. I could not understand why washers would be drawn as a spring. Now I understand those are no ordinary flat washers that stack together. Why they are very slightly curved.

Someone must have explain those things to you as you took your first regulator apart.


https://www.youtube.com/watch?v=0isHchgWT8U Good explanation on those washers. Now I understand why those washers are used; to keep chamber volume identical as air cylinder bottle is screw on the regulator.

Re: LP10 piston assy assembly help

Posted: Tue Jul 07, 2015 3:04 am
by SamEEE
seamaster wrote:https://www.youtube.com/watch?v=0isHchgWT8U Good explanation on those washers. Now I understand why those washers are used; to keep chamber volume identical as air cylinder bottle is screw on the regulator.
Thanks for the link; nicely explained video. Mad for taking the regulator to bits, but I suppose this is how we learn!

Re: LP10 piston assy assembly help

Posted: Tue Jul 07, 2015 3:25 am
by scausi
You should not have disassembled 29 , all you had to do to remove that intact ,was leave the screws with the red paint alone .
And only unscrew the others, This would have allowed you to remove in one piece and get access to remove plunger 18 and replace .
Me, thinks you may need to send to Pilks to be put back together, the bevel washers need to go in a certain order.

Re: LP10 piston assy assembly help

Posted: Tue Jul 07, 2015 7:54 am
by dronning
The washers go together like this ()()()()()(), so they compress together.

- Dave

Re: LP10 piston assy assembly help

Posted: Tue Jul 07, 2015 8:50 am
by seamaster
Is it )()()()( or ()()()() ?

wide base or narrow base end ? Common sense says wide base.

Re: LP10 piston assy assembly help

Posted: Tue Jul 07, 2015 9:11 am
by dronning
seamaster wrote:Is it )()()()( or ()()()() ?

wide base or narrow base end ? Common sense says wide base.
It really wouldn't matter the tension would be the same. The large end out doesn't give any more stability. I would look for wear marks and put it back the same way.

- Dave

Re: LP10 piston assy assembly help

Posted: Tue Jul 07, 2015 10:44 am
by seamaster
http://www.steyr-sport.com/images/flipb ... 0_c_en.pdf

That Steyr diagram is excellent. Those washer drawings are not for show. Look at the edge width, they are alternating. Once you blow up the drawing to max. It actually showed the orientation of the washers. ()()()()

Those darn engineers. They are good.