Thrust bearings the wrong way in manual? L700X

Hi!

I'm looking at the picture of the bladegrips in the manual, and to me it looks like the thrust bearing is mounted the wrong way with the open side out? Shouldnt the open side face in to keep the grease from beeing pressed out?

Logo 700 Xxtreme Vbar 5.3 Pro
T-Rex 700N LE Vbar 5.3 Pro
Velocity 50 N2 Vbar 5.3 Pro

Hmmm ... good point, never thought about that.

So, i would do it your way, both sides of course.

regards (EN) / Gruss (DE)

Rainer Vetter

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Thanks for the reply, Rainer

Logo 700 Xxtreme Vbar 5.3 Pro
T-Rex 700N LE Vbar 5.3 Pro
Velocity 50 N2 Vbar 5.3 Pro

Hi.

Imo the grease finds it's way out anyway. It's just wishful thinking that the direction matters there.

Kind regards

Eddi

Born to fly ...
forced to work.

Was a long discussion on Helifreak regards to this.
The grease stay in was an old thing from Finless bob as I remember it.

With it, I always have had issues with balls falling out of the thrust bearing after XXX number of flights, from now on I mount them as described in the Logo 700 manual, I suspect it will make the ball-race hold longer.

Any official statement on this matter would be greatly appreciated.

Hi,

just had a discussion with our R&D... guess what he says?

"I don't care, I'll go flying now."


So technically it is absolutely no difference.

One says:...but the grease will stay longer

Another one:...but mounting it like the manual say will prevent the ball cage from beeing crushed by the balls with heavy load on it!


So my opinion: Both of them are right.
For some time I personally have one side mounted like the manual and the other one mounted 'to keep the grease'.
Well: I can see no difference in wear and tear or keeping the grease.

Jörg

Surely the manufacturer of the thrust bearings would have the definitive answer.

Logo 700/800 Xxtreme, Silverline , Kosmik 200A, Pyro 850-40L, 157 and 256 HV BLS's,

Logo 400SE ,Silverline , Pyro 600-09, Jive 80+HV , MKS 9660A+, 8900G,

While I have gone along with the OP's point, too...I will also ask this:

Another thing I noticed is that on my 600SX, the main grip bearing
is on the inside of the thrust bearing assembly....no problems.

On the 700XXtreme, the manual shows that the main grip bearing
is also located on the inside of the thrust bearing assembly....it's on the way...lol

Haven't checked the 800XXtreme manual....

Here's what seems odd....

Align 700's have the thrust bearing assembly on the inside of the main grip,
with the grip bearing towards the outside....exactly opposite, according to their manual.

The Blade 700X is the same way.

And so do many other manufacturers....

It would seem to me that the centrifugal force of the rotating main blades
cause the main grip to be "pulled" outwards....and with the thrust bearing
assembly on the outside of the main grip bearing....the thrust bearing
assembly is handling the forces on it by the spindle washer and then the
spindle bolt......rather than on the race/races of the grip bearing....

With the grip bearing on the outside, it seems that the when the grips
try to move under aerodynamic loads, the bearing could undergo excessive
wear from the side loads imposed on that bearing....

I thought that was the purpose of the thrust bearing assembly...with the
larger ID towards the inside and the smaller ID on the outside....
Given spindle damping effects.

I am wondering what the engineering reasoning is for the others to locate
these components "backwards"?

My thoughts are the the Mikado way is the proper way...but who am I?...lol

I spoke with Gregor McGrath at Amain, and he had no definitive reason,
other than he hasn't had any problems.

IMHO, the Mikado way is the correct way....or am I missing something?

Any thoughts on this?....Hadn't thought about it until the OP pointed out
his note with regards to the manual....so "hat tip" to the OP....

Thanks for any input....

Hi,

no problem with the forces so far. If set up proberly, the centrifugal forces are directed over shims and the inner or outer rings of the ball bearing, so no centrifugal loads here for the ball bearing.

The reason to set the thrust bearing in middle and the ball bearings to the outside is quite simple: just to get as much distance between the two ball bearings as possible. To direct the 'flapping' forces of the blades more efficiently through the spindle / yoke to the main shaft.

The real funny things is (I will not call any names of brands):
most of these 'constructions' do not use any kind of dampening at all. Or even something that You can call dampening. So it's completely useless imho.
One could say: they have no idea what they are doing. Just to be different maybe?

The only, in my opinion, really working setup can be found at the Diabolo / Joker. It uses steel sleeves that take the centrifugal forces from the blade grip directly to the thrust bearing (in between the ball bearings) and has a dampening), and the TDR without those sleeves, also working properly.


The reason for putting the thrust bearing to the outside is logical: just giving the thrust bearing some 'space' to work properly when the blades is flapping (this is why the two rings have a smaller and larger inner diameter).

Jörg

Thanks for the info, Jorg

Am amazed things work so well, as long as one properly assembles
the components.

Building mistakes are unacceptable...lol

To follow up on the thrust bearing orientation...

The technically correct way is to have the open portion of the cage facing away from the center shaft- main shaft in our case. On the larger thrust bearings, they WILL bind if you turn them the other way around (keeping the grease in the 'cup' of the cage). This is a fact and it will lock up your mechanism if installed incorrectly.

Fortunately for the r/c helicopters, almost all of our thrust bearings are small enough that it doesn't matter. The dimensions don't really allow for much binding. The Logo Xxtreme models, having some of the largest thrust bearings in r/c models, are approaching the size where you can get binding.

I would play it safe and assemble per the photo in the manual.

BTW- the other machine that specifies the thrust bearing must be installed in this manner is the Vibe 90 SG- designed by Scott Gray. We have both worked on large UAVs (think rotor span over 10m) and this is a REAL issue on these machines- hence passing this knowledge to the r/c enthusiasts.



Edited 1 time(s). Last edit at 01/13/2015 04:29PM by RyanW.