SparrowHawk Tail Bearings

Greg Lockhart

Member
Joined
Oct 31, 2003
Messages
149
Location
West Virginia / USA
Total Flight Time
125
I'm in the process of building the tail of my SH and I'm wondering if the supplied type of bearings are the best way to go. The spherical bearings that were supplied with my kit have been on a shelf for the past 4 - 5 years and were totally froze up... the inner ball would not move at all. So I bought exact replacements. The new ones move a little but not very freely like I would expect a bearing to move. These bearings are what the rudder/tail pivots on. I feel that if I use these bearings their tightness will prevent the rudder from operating smoothly and freely. Is this type of bearing suppose to move freely like a ball bearing? Will they loosen up with use? Is this the best type of bearing for this application or would another type be better?
I'll be using the original "cable in sheath" rudder cables instead of the newer design that uses exposed cables on pulleys so I know that will add some resistance to the rudder system. I don't want to add even more resistance with stiff bearings.
Any advice would be appreciated.

Thanks,
Greg Lockhart
 

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Steve McGowan

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Joined
Jul 12, 2004
Messages
2,517
Location
Macon Ga.
Call Groen Broes if you want to replace them with new or,,place the brngs in a cup of diesal fuel for a few day's.

If that doesn't free them up.. or GBA doesn't have them in stock call bearings and drives or aircraft spruce with the number and replace them.

They're not really bearings.. but ball sockets..

Steve
 

Mayfield

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Oct 30, 2003
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887
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Avondale, Arizona
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Hatz Classic Bi-plane, AAI modified RAF, Tractor gyro project
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>14K hours
Greg,

The bearings you describe are used to allow the tail booms to flex without damaging/bending the tail pivot bolts. They can be quite stiff and still do the job.

Jim
 

willisbr

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Joined
Sep 23, 2009
Messages
1,371
Location
Pace, Florida
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Maule MT7-235; RAF 2000 (sold)
I found that Motion Industries Online is a very useful source for hardware, especially bearings. So far, price can't be beat and they have just about all the brands you want. Get them to ship to a business/office and your shipping is cut in half. UPS is stupid that way. Motion has good phone support. Will walk you through whatever. They seem to actually know what they are selling you. Ordered two redrive bearings and had them in two days for like 3-4 bucks shipping.
 

Greg Lockhart

Member
Joined
Oct 31, 2003
Messages
149
Location
West Virginia / USA
Total Flight Time
125
Thanks Steve, Jim and Brian.

Steve and Jim I know you both have lots of experience with the SH so I value your opinion. I knew there was probably a technical reason for using this type of bearing instead of another type (tail boom flexing). They just seemed too stiff for something that is intended to move freely. I can hardly move them by hand.
I soaked the original (frozen) bearings in several different oils and penetrants but they never loosened up. I'll try the diesel fuel. Is this type of bearing supposed to be lubricated? If so, with what? I think they are Teflon lined.
Should they loosen up a little with use?
Since these are pressed into the spar end caps they would not be easy to remove if necessary. I just didn't want to end up with a rudder that is hard to move (and maybe wouldn't center itself with your feet off the pedals??).

Thanks,
Greg
 

Colin Gibson

Member
Joined
Jun 27, 2004
Messages
192
Location
Nelson New Zealand
Aircraft
Sparrow Hawk ZK RCU
Total Flight Time
142.6
I'm in the process of building the tail of my SH and I'm wondering if the supplied type of bearings are the best way to go. The spherical bearings that were supplied with my kit have been on a shelf for the past 4 - 5 years and were totally froze up... the inner ball would not move at all. So I bought exact replacements. The new ones move a little but not very freely like I would expect a bearing to move. These bearings are what the rudder/tail pivots on. I feel that if I use these bearings their tightness will prevent the rudder from operating smoothly and freely. Is this type of bearing suppose to move freely like a ball bearing? Will they loosen up with use? Is this the best type of bearing for this application or would another type be better?
I'll be using the original "cable in sheath" rudder cables instead of the newer design that uses exposed cables on pulleys so I know that will add some resistance to the rudder system. I don't want to add even more resistance with stiff bearings.
Any advice would be appreciated.
Thanks,
Greg Lockhart
I suggest you don't use the conduit supplied but purchase a Teflon lined conduit and fit your cables in that if you are assembling without the pully system.
Thats what I did and its a lot more free than using the supplied conduit.
Colin
 

Greg Lockhart

Member
Joined
Oct 31, 2003
Messages
149
Location
West Virginia / USA
Total Flight Time
125
Thanks Colin,
I didn't know they made teflon lined cable conduit. I'll check into that. I'm sure it would be better. I want my rudder pedals to be as friction free as possible.

Greg Lockhart
 

Colin Gibson

Member
Joined
Jun 27, 2004
Messages
192
Location
Nelson New Zealand
Aircraft
Sparrow Hawk ZK RCU
Total Flight Time
142.6
Got mine from a motor bike shop. They use them with their brake cables.
Also cycle shops can get various sizes of the same stuff. They run cables a lot smoother than the spiral conduit that came with my kit.
Colin
 
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