Rotary Wing Forum

Rotary Wing Forum (http://www.rotaryforum.com/forum/index.php)
-   General Discussion (http://www.rotaryforum.com/forum/forumdisplay.php?f=11)
-   -   Rotor Head...how do I know? (http://www.rotaryforum.com/forum/showthread.php?t=40686)

eddie 05-09-2014 12:11 PM

isn't the load being applied to the bottom of the bearing race,the rotor is pulling the race of the

bearing up and the load will be on the bottom side of the race and upper side of the inner cone.

best regards,eddie.....

Alan_Cheatham 05-09-2014 01:48 PM

Quote:

Originally Posted by madwinger (Post 571472)
Ok I read the thread and sorta understood but I am not technical in the least this way. I asked the same question to Mike and Chuck that I am going to ask here.

What bearing would you use in this application. Is the 3206 A-2RS1TN9 /MT33 the only one available for this application or is there something better?

Thanks again for your input.

Mark

The bearing is a dual row, angular contact (30 degree), and most typically with two rubber seals.

The old bearing number was 5206CZZ, this is the MRC designation, C being Conrad (normal bearing, a non max bearing), and two rubber seals. This bearing also used a steel bearing cage.

Note that while other manufacturers use 2RS to designate two rubber seals and ZZ for two metal shields MRC was different and used ZZ for two rubber seals.

SKF purchased MRC and replaced the 5206 with the 3206, although you might find some boxed bearings marked with both numbers. So, my recommendation based on this post: http://www.rotaryforum.com/forum/sho...06&postcount=8


would be 3206 A 2-RS1M MT33, the A being equivalent with the MRC C designation (Conrad), two rubber seals, and solid brass cage.

.

Alan_Cheatham 05-09-2014 01:58 PM

1 Attachment(s)
Quote:

Originally Posted by eddie (Post 571477)
isn't the load being applied to the bottom of the bearing race,the rotor is pulling the race of the

bearing up and the load will be on the bottom side of the race and upper side of the inner cone.

best regards,eddie.....

The bearing balls can only carry the axial load from rotor thrust by being in compression between the bearing races so only one row of balls, the top, is carrying the axial load. This is why, if a bearing with a loading slot is used, the slot should be at the bottom of the bearing block.

.

eddie 05-09-2014 02:08 PM

thanks for good the explanation.

best regards,eddie.....

madwinger 05-11-2014 02:08 PM

Quote:

Originally Posted by Alan_Cheatham (Post 571486)
The bearing is a dual row, angular contact (30 degree), and most typically with two rubber seals.

The old bearing number was 5206CZZ, this is the MRC designation, C being Conrad (normal bearing, a non max bearing), and two rubber seals. This bearing also used a steel bearing cage.

Note that while other manufacturers use 2RS to designate two rubber seals and ZZ for two metal shields MRC was different and used ZZ for two rubber seals.

SKF purchased MRC and replaced the 5206 with the 3206, although you might find some boxed bearings marked with both numbers. So, my recommendation based on this post: http://www.rotaryforum.com/forum/sho...06&postcount=8


would be 3206 A 2-RS1M MT33, the A being equivalent with the MRC C designation (Conrad), two rubber seals, and solid brass cage.

.

Alan, I did a Google on that bearing and the only thing that comes up is the reference to this forum. I did find lots of these 5206CZZ. Steel Cage. Is this the one I want?

Thanks

mark

Alan_Cheatham 05-11-2014 08:47 PM

Quote:

Originally Posted by madwinger (Post 571668)
Alan, I did a Google on that bearing and the only thing that comes up is the reference to this forum. I did find lots of these 5206CZZ. Steel Cage. Is this the one I want?

Thanks

mark

http://www.mscdirect.com/product/det...72292#features

http://www.mscdirect.com/FlyerView?p...alogs/big-book

There are I'm sure other suppliers but be prepared to pay a good price for a quality bearing. Bearings costing $15 or so are not what you want.

Also, while a brass cage may be more desirable, given the steel caged 5206's successful history in gyro use I wouldn't shy away from using one.

.

madwinger 05-12-2014 12:58 AM

Quote:

Originally Posted by Alan_Cheatham (Post 571715)
http://www.mscdirect.com/product/det...72292#features

http://www.mscdirect.com/FlyerView?p...alogs/big-book

There are I'm sure other suppliers but be prepared to pay a good price for a quality bearing. Bearings costing $15 or so are not what you want.

Also, while a brass cage may be more desirable, given the steel caged 5206's successful history in gyro use I wouldn't shy away from using one.

.

Cant thank you enough Alan. I am now educated and armed with the info I need to make and informed decision.

This thread will be an invaluable resource for those who are in the same floundering boat as I am. Especially with the bearing block pictures that explains the proper positioning.

Mark

cbonnerup 06-27-2014 10:56 AM

General RotoHead Re-Work
 
Group,
I have recently purchased a Barnett Rotorhead from a fellow member.
NICE piece of work! Mr. Barnett was a talented craftsman and machinist. I am bringing it back from long sleep and have ordered a new bearing (Nachi 5304ZZ). Original? was a ND5304(ZZ type), which was made in the USA by New Dimensions Bearings, now kaput. Looked and felt good and was well lubed, but caution abounds.

Question: Quite a few fasteners on the head, most under load stress rather than shear. I need to decide to go ahead and replace all or? The 'Jesus' bolt will be replaced, just wondering about the rest? Magnafluxed the spindle and looks great; I would hope so being 4130 steel!

Slight surface corrosion but overall they look good when given a bath`. Will use new locknuts (MIL spec expanding nuts rather than nylock.

Comments please.
Thanks,
Chris

madwinger 08-22-2014 09:29 AM

Quote:

Originally Posted by MadMuz (Post 582575)
Hi Chris, I am a bit of a 'scaredycat' when it comes to things like rotor heads which I don't know the complete, true history of, so my advice would be disassemble, good clean of parts.... extra good inspection of parts (magnifying glass, magnet and wet iron filings).... I would replace every bolt and the bearing. If you know and trust the member you bought it from.... and he actually knows the complete true history... different story perhaps.... but I would still replace all bolts.... especially since you mention that four letter word 'corrosion' (ok, 9 letter word)

Madwinger, the bolts all one way thru the rotorhead, is so you know which direction the head is in relation to the rotors. When you put new rotors on a machine and test fly it, it is a good practice to note smoothness.... land lift out rotors, turn head 180 degrees, replace rotors.... fly to see if they are smoother, the same smoothness or rougher. Then you note which way was smoothest, lets say blade B to the right when the heads of the 2 bolts in your rotor head are facing you (threads away). With your head with one bolt each way, if you turn the head 180 degrees it still looks identical. If you don't want to pull a bolt and put it in from the other side, you can just put a little paint on each side of the head teeter fork... so when the red side faces you, blade B goes to the right.... this way the rotors are in the head so they run the smoothest each time. Oh, and don't forget to turn your cotton reals (teeter bolt bushes) whenever you remove or refit the rotors, so teeter bolt doesn't always bear the weight and wear the cotton reels in exactly the same place, forever:cool:

MadMuz, That is good advise. Thank you, I appreciate it.

mark

cbonnerup 08-22-2014 12:40 PM

Scared-y-Cat
 
Thanks,
I too am a scaredycat.
Had a not-so-good landing due to things mechanical in a Quicksilver on my first introductory flight; a WHILE back. I tend to question everything re: aircraft since; sometimes to my detriment I suppose.

Appreciate your comments,
Chris


Quote:

Originally Posted by MadMuz (Post 582575)
Hi Chris, I am a bit of a 'scaredycat' when it comes to things like rotor heads which I don't know the complete, true history of,...
:cool:


LDay 09-03-2014 08:46 AM

Nobody has mentioned the type of bearing, I one of my machines I used twin tapered roller bearings. Both outer tracks,fit in recessed bores so it is impossible for them two move.With no central spacer. Another type of bearing is angular contact, but they can fail, if worn or out of adjustment. IE early VW front wheel bearing. They are improved, with a central spacer. It must be an exact fit however.

LDay 09-29-2014 02:36 AM

Why don't you use tapered roller bearings, that way you can adjust the preload.

LDay 09-29-2014 02:38 AM

Does any one know if, contra rotating rotors will auto rotate.

XXavier 09-29-2014 01:56 PM

Quote:

Originally Posted by LDay (Post 586359)
Does any one know if, contra rotating rotors will auto rotate.

Yes, they will. Cierva's first autogiro, the C1, was fitted with superimposed, contra-rotating rotors. The autogiro did not flew, but the rotors worked...

HH60FE 11-30-2014 06:51 AM

HI im sorry for unmatched reply but im looking for FE of HH60 Black hawk
and i have no idea where can i find them!
Im ROKAF segeant, Black hawk FE!


All times are GMT -8. The time now is 11:43 PM.

Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Ad Management plugin by RedTyger