Clutch problem

Had a bit of problem with my Trex 600 today.
The clutch is in three sections now ! What causes something like this ? And how do you go about preventing it from happening again in the future.

Thanks

Was that related to the 'orrible noise we heard yesterday when you started her up?
I guess ( although I am no heli expert ) that a clutch is a clutch no matter what it is fitted to, and the friction material will eventually wear out and become frictionless, springs can weaken /break, oil on the plates will cause slip, overheating will cause disintegration, and excessive strain /overloading will have similar effect.

HAHA, very funny Tim. Maybe I should have add something about about mowing the strip and photo editing just to get one up on you

Not so sure about the noise as we all know that most helis are noisy (not mine) but the last few flights the clutch been almost engaging at tick over speed, which I have been told its an early indication.

I do understand what you are saying and I did get a year out of it.

Thanks

I wasnt being funny Zaidy - I am genuinely enquiring whether the noise may have been early signs of clutch problems. I would think that if the clutch was starting to engage early, that would be sign of weak springs, allowing the centrifuagal action to kick in too soon?

Tim wrote:I wasnt being funny Zaidy - I am genuinely enquiring whether the noise may have been early signs of clutch problems. I would think that if the clutch was starting to engage early, that would be sign of weak springs, allowing the centrifuagal action to kick in too soon?

Opppsssssssss SORRY Tim, us guys with helis get a bit of stick about them being soooo noisy all the time, I should have know that you are better than this (grovel grovel)

Not too sure or can remember the noise Tim, I remember hearing something that stood out, which made me look and give it a quick once over it looked all in order. One thing for sure is that the heli was not very happy..

That looks like material fatigue to me......

Andy

Yeh...its goosed

Yep, those little holes drilled through the clutch are sized to allow the big chunks (that have now broken off) to move outwards and engage with the friction material inside the clutch bell. Whoever has designed that parts has obviously forgotten about doing any fatigue life calculations on the amount of movement and stress/strain going though the little bit of material left. So whilst it may give the clutch engagement characteristics required (i.e. at just the right motor RPM), the material can't handle the number of cycles that the friction material is designed to last for.

Align design engineers = Amateurs.....

Andy

In a perfect setup
Once up to full speed, the shoes are under no other forces. They simply remain pressed hard against the lining and should return to be clear of lining when engine returns to tickover.
This cycle occurs once each flight.

Fatigue cracking takes many thousand of cycles to develop. Particularly bad in some high tensile alloys, notably Magalloy and Dural. Also common in high tensile hardened machined parts like clutch disks in heli's. These also suffer from cracking from being hardened after machining. Maybe, some actually have cracks already in them as new from overer zealous machining followed by violent heat treatment.

Agree it could be fatigue at waisting bridge to weight part of the one piece shoe part.
Fatigue would take well over 80,000 (rough guess) starts and stops to clock up fatigue cracking damage

Or it could be the shoes were free to travel too far to make full contact with the bell lining.
For this, the lining had become thin or was too thin to start with and the shoes had too far to travel to make contact the lining each time the engine ran up to full speed. The waisting part was repeatedly "overbent" and failed early not by fatigue but simply by being bent too far too many times.

Or there was axial misalignment between engine and clutch bell shaftt
There would then be a regular cyclic rocking of the contact between shoe segments and the bell lining
This is the one that could soon clock up the 80,000 or more cycles to wreck the clutch shoe disk

Whatever.........
You need to replace !

I wonder if the manufactures ever crack test them before sale !!!

PQ

He's an animal

Brian Colclough wrote:He's an animal

LOL
hehehe

Don't worry Zaide,this isn't an isollated (I know I spelt that wrong) incident with the 600 clutch.Mine did the same but didn't quite break up,just cracked.
There are loads of them fracturing like this,because the Align standard clutches aren't machined all the same.Some are slightly larger than others,therefore the larger ones catch the liner at lower revs and the others take more revs to engage.
I have 2 here that are very different with one taking about a quarter throttle and the other bites at tickover.
The ones that bite at higher revs are bending outwards more and as such will fracture earlier than others.
The other week you might remember my 600 LE was needing huge revs to engage so I fitted the Quick uk upgrade because I know it would have failed soon.
I would do what Dave said with the new liner and the Quick uk clutch and all your problems will go away.
Danny.

Gosh I must get me one of these - all my troubles will disappear eh

Here you go Zaide I did a little search on Helifreak and this is just one of many discutions on the same subject.
http://www.helifreak.com/showthread.php?t=100224&highlight=trex+600+clutch+problems

Danny.