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Old 05-08-2014, 12:32 PM
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Default Rotor Head...how do I know?

Is there a way to look at my Air Command Rotor head and by looking at it know it is put together correctly? I mean NOT UPSIDE DOWN. This concerns me since Steve Weir's accident last year and especially since I have encountered so may issues with my gyro since I purchased it.

I would appreciate any and all advise. I just want to make sure.

The bearing seems to be quite, smooth and tight but that is all know.

Thanks

Mark
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Old 05-08-2014, 12:56 PM
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In my opinion an important thing is make certain that the main rotor bearing is retained from slipping out of the bore on both sides. Generally there is a step in the block on one side and a plate on the other. Sometimes it can be done with two plates. Either way the outer bearing race should be retained in both directions.

From your pictures I cannot see if there is a step in the block to retain the bearing.

I feel this is important enough to disassemble the rotor head to see how the bearing is retained and make certain it cannot escape out of either side of the bore when everything is assembled.

Regards, Vance
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Old 05-08-2014, 01:06 PM
Alan_Cheatham Alan_Cheatham is offline
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The rotor head appears to be assembled correctly, at least as far as the bearing block/ teeter tower orientation.

On that Aircommand head the holes in the bearing block are not drilled on the blocks centerline but offset toward the top of the block. When bolted together, if the block were up-side-down the bottom of the towers would project below the bottom of the block and there would be a gap between ring gear and block instead of gap between ring gear and towers.

In this way you can't install the block wrong side up as you would not be able to properly bolt the ring gear in place without it being obviously wrong.
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Old 05-08-2014, 06:18 PM
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Default Thank you.

Thank you Vance. I always value your knowledge and input. If I had more experience I would take it apart and put it back together. I feel I need to wait for a time with hands on with some one who knows.

After reading Alan's reply I believe this gives me everything I need to know for now. I went and took a look at my rotor head it is exactly as he described it should be.

Thank you Alan. I feel confident that my rotor head is in proper working order and will have the guys and ROTR verify that.

So nice to have this access to so much help.

Mark
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Old 05-09-2014, 05:42 AM
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MadMuz,

When Steve died I first thought he had the bearing in upside down, like you mention...bit instead he had the bearing block upside down, as we all now know.

The slots for the resessed bolts sure seem to reduce the cross-section. What's left about 1/8" thickness?
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Old 05-09-2014, 06:00 AM
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Mark, your pictures are showing the top of the rotor head, you need to look at the bottom. It is very easy to see if it is installed properly, when you look at the bottom the block, make sure the hole in the block is smaller than the bearing.
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Old 05-09-2014, 06:55 AM
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You can read about it here, also has a report with pictures.

http://www.gyrosaway.com/newsletters/2013-12-LSRC.pdf
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Old 05-09-2014, 07:29 AM
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Quote:
Originally Posted by MadMuz View Post
cburg, hi there, I am not familiar with Steve's accident as I am from Australia, but am a keen gyro flyer and asra member. Condolences to Steves family and friends from your Aussie bretherin.

I just noticed this thread and thought I would put my 2 cents worth in, as in the past I have had some bearings which have to be put in a certain way up due to the bearings design, and others that can go either way up. I just felt compelled to mention that to the op Mark. These critical components are so important to get right, it is good he is asking for advice rather than just assuming all is well because it 'looks right'. On looking at Marks photos, I am wondering why there are uneven gaps between the alloy prerotator ring and the bottom of the teeter towers? One side there appears to be a small maybe 1/16" gap (pic 3) all the way across, at the other end there is a gap on one side and contact on the other (pic 2)? It appears the prerotater disk is not running true? I would be happier if Mark could find someone near him to have a quick look at it for him, just to be sure it is correct. It apears to me to be one of the heads that the bearing housing is open ended (the bearing can go in from the top and out the bottom.... the pre rotater ring on the bottom and the top plate sandwich the bearing in place? I see there are no teeter stops? Does that mean that the hub bar when teetering rests on the edge of the top plate? If this is the case, the hub bar would be getting a mark across it where it contacts the plate with no teeter stops? Marking of the hub bar would create a stress riser? Some nylon or rubber teeter stops/cushions might be a good idea there?

I will look for a thread on Steves accident, you say it was caused by the bearing block being assembled upside down? That is terrible, but a simple and easily made mistake to make. Again, my thoughts go out to his family and friends. When disassembling critical parts it is a good idea to take pics for reference and engrave or punch tiny marks (avoiding creating stress risers) so reassembly is correct.
Hi Mad Muz, Thank you for your input and advise. I really do appreciate it. Believe me when I say I will have some one that is an authority on Air Command rotor heads look at it live and in person before I fly with this.

It must be shadows in the picture as I looked at the head again after reading your last post. The towers are an even distance from the ring gear on both sides front and back and according to Alan's post the bearing block is in the correct position.

As far as the teeter stops go, I have spacers placed there to hold the teeter in a neutral position to do a hang test. Doug from Air Command told me that to get a correct angle it has to be held in the neutral position. I thought this would make it easier so so I don't have to manually try and hold it neutral. These will come out after the hang test.

I am not assuming that this rotor head is perfect and airworthy, I just wanted to know if some one could tell me how to tell if the bearing block is upside down or not. Now I know.

Thanks to all for the input. You guys Rock!

Mark
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Last edited by madwinger; 05-09-2014 at 08:37 AM.
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  #9  
Old 05-09-2014, 07:36 AM
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Quote:
Originally Posted by MadMuz View Post
The only thing I can see that I would do differently, is put both bolt heads on the same side (and nuts on the other) of the side plates. I do this for 2 reasons, so I know which side of the rotor head is which.

How is tis important? Well, 2 reasons. I like to know the orientation of the head to the blades (hub bar) so I always have the blades in the same orientation every time they are fitted. Some people have complained sometimes thier machine shakes more than other times and they dont know why. I ask them if they have the blades on the machine in the same direction as last time. Often they don't know. When I try new rotors, I fly them one way, then remove the teeter bolt, lift out rotors, turn the head 180 degrees and fit the rotors and fly them that way. I pick which gave the smoothest stick and always mount the rotors that direction. IE, heads of the bolts on the rotor head towards me, the red tipped blade to my right. How you have the bolts in the side plates of the head now, even if you rotate the head half a turn, it looks the same, bolt head on the right, nut on the left.

The other reason, is I always put bolt heads on the right hand side of the frame and nuts all on the left of the machine. That way starting a walk around starting at the left wheel, I can see all nuts are there and accountable and thier paint blob isnt cracked (indicates moved nut) Also, if the machine has been trailered any distance on rough roads, or had any hardish landings, by standing on the right hand side of the machine with a wrench, i can gently try to turn any bolt heads which are all on the same side..... if any turn, they must have grown/stretched for some reason, so I can remove the bolt, check the whole area and fit a new bolt. If you try to turn the nut end, if it was loose, you might tighten it. You are looking for a bolt that can now turn, when it was tight last time.

I know it is a bit pedantic, but I find it works for me.

On the bearing, if the bearing has a thrust direction (it can pull thru one way, but not the other) it is important the bearing is 'right way up' if the bearing doesnt have any certain thrust direction, it can go either way up.... if your bearing is the latter, the head appears to be assembled correctly. I see you have washers under the prerotator disk, I cant see if you have washers on the through bolts of the side plates. I would like to see an washers under nut and head of bolts on head, just so when you torque them up, they are more likely to keep thier tension, rather than sinking into the side plates.
MadMuz, Yes there are washers on both ends of every bolt.

Tell me more about the paint on the end of the bolt and nut. I believe I seen this in pictures but I guess I just though it was "loctite" bolt lock. Its it actually paint and if so how is it applied and what kind of paint?

Thank

Mark
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Old 05-09-2014, 09:07 AM
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Pictures to clearify my earlier post.

To know if the bearing block has a through hole or flange is simple, if it has the through hole the block will be the same thickness as the bearing, if it has a flange the block will be thicker by about 1/4".

The head block pictured has a flange.

I do agree that the head should be dissembled and the components inspected before flight. One to make sure you have a quality bearing, and two, if by chance the bearing is a max bearing (more balls) that the loading slot is in the down direction.

.
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Old 05-09-2014, 09:20 AM
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Quote:
Originally Posted by Alan_Cheatham View Post
Pictures to clearify my earlier post.

To know if the bearing block has a through hole or flange is simple, if it has the through hole the block will be the same thickness as the bearing, if it has a flange the block will be thicker by about 1/4".

The head block pictured has a flange.

I do agree that the head should be dissembled and the components inspected before flight. One to make sure you have a quality bearing, and two, if by chance the bearing is a max bearing (more balls) that the loading slot is in the down direction.

.
Friggin Awesome Alan....as the saying goes a picture is worth a thousand words. I have no idea what a MAX bearing is but I will have someone help me with a tear down and inspection. Might just as well put a new bearing in while its torn down.

What bearing does this take?. Where can I get it. What would you recommend? It is a single seat CLT

Thank you for taking the time to do this. This will be of great benefit to many here with the same kind of rotor head.

Mark
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Old 05-09-2014, 09:51 AM
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Quote:
Originally Posted by madwinger View Post
I have no idea what a MAX bearing is ...........

Mark
Read this thread about head bearings.
http://www.rotaryforum.com/forum/sho...d.php?p=566351


A MAX bearing is a bearing that has additional balls for some added axial load capacity. The extra balls makes it impossible to assemble the bearing normally so a loading slot is cut into the race for ball loading. For gyro use you don't want flight loads applied against the loading slot so the slot needs to face DOWN in the bearing block.

As the added load capacity is not needed for gyro use the trend in the community has been to get away from the MAX bearings but if you have an old rotor head there is a possibility you might have one.

You can read more here in this document:
http://www.skf.com/binary/30-97834/519959-.pdf

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Old 05-09-2014, 10:01 AM
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http://www.vxb.com/page/bearings/PRO...ONTACT/Kit8357
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Old 05-09-2014, 10:26 AM
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I feel the need to chime in here and say a big "Thank You" to Alan for posting those detailed pics..... really helps a newbie like me take what is written and truly understand based on the pictures.

Thanks again!!!
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Old 05-09-2014, 11:43 AM
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Default So which Bearing?

Quote:
Originally Posted by Alan_Cheatham View Post
Read this thread about head bearings.
http://www.rotaryforum.com/forum/sho...d.php?p=566351


A MAX bearing is a bearing that has additional balls for some added axial load capacity. The extra balls makes it impossible to assemble the bearing normally so a loading slot is cut into the race for ball loading. For gyro use you don't want flight loads applied against the loading slot so the slot needs to face DOWN in the bearing block.

As the added load capacity is not needed for gyro use the trend in the community has been to get away from the MAX bearings but if you have an old rotor head there is a possibility you might have one.

You can read more here in this document:
http://www.skf.com/binary/30-97834/519959-.pdf

.
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
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