Pull-Pull servos

[Dean Pappas]

Hi Eric,
I'm too cheap to buy that many ball bearings!
later,

Dean Pappas
Sr. Design Engineer
Kodeos Communications
111 Corporate Blvd.
South Plainfield, N.J. 07080
(908) 222-7817 phone
(908) 222-2392 fax
d.pappas at kodeos.com


-----Original Message-----
From: discussion-request at nsrca.org
[mailto:discussion-request at nsrca.org]On Behalf Of Grow Pattern
Sent: Wednesday, December 01, 2004 10:09 AM
To: discussion at nsrca.org
Subject: Re: Pull-Pull servos


Dean,
           It works even better of you use an MK ball-bearing servo-arm 
clevis on top of the servo output-shaft. I swap in a 3-mm ball bearing and 
use a 3-mm allen-bolt and spacer to hold the arm in place.

Also, although it may seem like over-kill, using ball-bearing clevises on 
all four pull-pull attachment points greatly improves the centering of the 
rudder and shuts-up those groaning digitals :-)

Regards,

Eric.


----- Original Message ----- 
From: "Dean Pappas" <d.pappas at kodeos.com>
To: <discussion at nsrca.org>
Sent: Wednesday, December 01, 2004 10:02 AM
Subject: RE: Pull-Pull servos


Hi Jim,
The JR top post brace is neat, but I've taken to putting a ball-link on top 
of the servo arm or wheel,
using a long screw in the servo, and then running a short link to the 
airframe.
Usually it's a short link in compression, attached to the bulkhead behind 
the servo tray.
That takes the bending load off the servo output shaft. Rudder servo life 
doubled, instantly.
Sometimes a spacer is needed between the servo arm and the ball link ...
You know those tapered aluminum nuts that come with the DuBro #867 horns?
I turn them down in the lathe to make spacers for this purpose.
Regards,


Dean Pappas
Sr. Design Engineer
Kodeos Communications
111 Corporate Blvd.
South Plainfield, N.J. 07080
(908) 222-7817 phone
(908) 222-2392 fax
d.pappas at kodeos.com


-----Original Message-----
From: discussion-request at nsrca.org
[mailto:discussion-request at nsrca.org]On Behalf Of Jim Ivey
Sent: Tuesday, November 30, 2004 6:44 PM
To: discussion at nsrca.org
Subject: Pull-Pull servos


Guys
 Another discussion about pull-pull systems. I use pull-pull on the rudder 
and compared to the elevator servo the rudder servo gets worn and loose at 
the top bearing much quicker than the elevator servo.The cables are not too 
tight and are setup correctly so far as ackerman is concerned.The rudder 
being much bigger than the elevators may cause some of this problem. More 
momentum...
 I have used the JR top post brace before, but it can't be used with the 
8411's without some mods.
 Any input or solutions?

TIA

Jim Ivey

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