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RE: multiple throttle servo failures - 9/27/2011 6:41 AM   
MetallicaJunkie



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ORIGINAL: BarracudaHockey

A device like the Hangar 9 Inline Amp meter makes quick work of this. Tick up the end points till you see the current start to bump up, back it off till its stable and voila perfect throw, no binding, no stalled servos.

aggreed... my brother has one and i was shocked to see how much i had a retract servo drawing... im amazed i didnt get a brown out.... im using a 645 as a retract servo, and was shocked that i was drawin 1.3 amps wit the retracts retracted... i dialed the endpoints a few clicks down and the draw went away

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RE: multiple throttle servo failures - 9/27/2011 7:11 PM   
scale only 4 me



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Status: offline 		You couldn't hear it buzzing??

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RE: multiple throttle servo failures - 9/29/2011 6:16 AM   
nitro wing


 

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Status: offline 		I find many people have binding rods to carb, and dont dial back the EPA from idle to flat out, Hardly ever will you get linear travel and need to adjust this mechanicly and on the radio.
I prefer Ny rods to avoid shocking the servo with engine pulses endlessly.
I have had one throttle servo fail in over 20years and over 50 aircraft... I find its the most trickiest linkage and radio adjustments needing channel in most aircraft.

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RE: multiple throttle servo failures - 9/29/2011 9:34 PM   
scale only 4 me



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Status: offline 		Remember doing in before radios with EPA,,, We are spoiled with technology these days

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RE: multiple throttle servo failures - 10/10/2011 5:25 AM   
nitro wing


 

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Status: offline 		OH yes, I have been around and my first radios had no dual rate or expo or EPA., it still was not that hard, but took some thought and placement and patience, thats why they put so many holes on the servo arms....

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RE: multiple throttle servo failures - 10/12/2011 1:05 PM   
MetallicaJunkie



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ORIGINAL: scale only 4 me

You couldn't hear it buzzing??



i forgot about this thread.... not that i can remember.... analogs are pretty quiet...im so used to hearing digitals

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RE: multiple throttle servo failures - 10/13/2011 3:24 AM   
3daerofly


 

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Status: offline 		Yep...believe it or not I used an amp meter between the throttle servo and receiver to make sure it wasn't pulling any current when installing the servo. I also made sure it didn't buzz like it was under load when I first put in the servo

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RE: multiple throttle servo failures - 10/13/2011 6:04 AM   
Tired Old Man


 

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ORIGINAL: 3daerofly

I have had two throttle servos fail on my 50cc Extra 260 (luckily they both happened on the ground). The first was a Hitec MG5245 servo. It was digital, had metal gears, and was a mini size servo. It had 76 oz. of torque. It just stopped working when I was throttling up the engine on the ground before a flight. After I took it out of the plane, I noticed that it's very hard to rotate the arm.
I replaced the broken servo with a standard JR ST47 servo that I had on hand. It has nylon gears. I just installed it in the same spot as the previous servo and flew. It worked for two flights. Before the third flight, it stopped working when I was testing the engine out on the ground. So I took the plane home and decided to try the servo again. When I turned the plane and radio on, the servo didn't move but instead became locked in one spot. (I couldn't move the arm with my fingers.) After turning the plane off, I was able to rotate the servo arm again.
I decided to turn everything off and on again. Weirdly enough, the throttle servo moved for a second when I moved the stick. It then stopped again and stuck.

I think vibration might have caused the servos to fail, but I'm not sure. Any help regarding why the servos failed would be great!




I'll lay odds you are over driving the servo and binding with the throttle linkage. I don't know why but I have seen a lot of that activity over the last year or so. If linkage geometry is wrong and end points not handled correctly you can burn out a servo, strip out the gears, or twist the servo output shaft in half. I have seen all three of those and a couple more of late in various planes. In a good many years I have never had any type ofgas engine throttle servo fail for a reason other than crash impact.

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RE: multiple throttle servo failures - 10/13/2011 2:13 PM   
nonstoprc



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quote:

ORIGINAL: 3daerofly

I use ball links on the servo arm and carb arm. They're nylon except for the metal ball bearing. The control rod between is metal, not nylon. Here a some pix of the setup.


Try the nylon pushrod with a sleeve. The metal rod passes the vibrations to the servo badly.

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RE: multiple throttle servo failures - 10/14/2011 12:10 AM   
MetallicaJunkie



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quote:

ORIGINAL: Tired Old Man


quote:

ORIGINAL: 3daerofly

I have had two throttle servos fail on my 50cc Extra 260 (luckily they both happened on the ground). The first was a Hitec MG5245 servo. It was digital, had metal gears, and was a mini size servo. It had 76 oz. of torque. It just stopped working when I was throttling up the engine on the ground before a flight. After I took it out of the plane, I noticed that it's very hard to rotate the arm.
I replaced the broken servo with a standard JR ST47 servo that I had on hand. It has nylon gears. I just installed it in the same spot as the previous servo and flew. It worked for two flights. Before the third flight, it stopped working when I was testing the engine out on the ground. So I took the plane home and decided to try the servo again. When I turned the plane and radio on, the servo didn't move but instead became locked in one spot. (I couldn't move the arm with my fingers.) After turning the plane off, I was able to rotate the servo arm again.
I decided to turn everything off and on again. Weirdly enough, the throttle servo moved for a second when I moved the stick. It then stopped again and stuck.

I think vibration might have caused the servos to fail, but I'm not sure. Any help regarding why the servos failed would be great!




I'll lay odds you are over driving the servo and binding with the throttle linkage. I don't know why but I have seen a lot of that activity over the last year or so. If linkage geometry is wrong and end points not handled correctly you can burn out a servo, strip out the gears, or twist the servo output shaft in half. I have seen all three of those and a couple more of late in various planes. In a good many years I have never had any type ofgas engine throttle servo fail for a reason other than crash impact.



im very curious to see how you do the throttle on you new plane

im not sold on nyrod... i hear it expands and contracts when its hot or cold

i still like my overkill 4-40 ballinks on both sides

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RE: multiple throttle servo failures - 10/15/2011 1:15 AM   
JoeAirPort



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Status: offline 		The carbon filled nyrod is the shiz. I use it.

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RE: multiple throttle servo failures - 10/17/2011 7:13 AM   
Tired Old Man


 

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quote:

ORIGINAL: MetallicaJunkie

quote:

ORIGINAL: Tired Old Man


quote:

ORIGINAL: 3daerofly

I have had two throttle servos fail on my 50cc Extra 260 (luckily they both happened on the ground). The first was a Hitec MG5245 servo. It was digital, had metal gears, and was a mini size servo. It had 76 oz. of torque. It just stopped working when I was throttling up the engine on the ground before a flight. After I took it out of the plane, I noticed that it's very hard to rotate the arm.
I replaced the broken servo with a standard JR ST47 servo that I had on hand. It has nylon gears. I just installed it in the same spot as the previous servo and flew. It worked for two flights. Before the third flight, it stopped working when I was testing the engine out on the ground. So I took the plane home and decided to try the servo again. When I turned the plane and radio on, the servo didn't move but instead became locked in one spot. (I couldn't move the arm with my fingers.) After turning the plane off, I was able to rotate the servo arm again.
I decided to turn everything off and on again. Weirdly enough, the throttle servo moved for a second when I moved the stick. It then stopped again and stuck.

I think vibration might have caused the servos to fail, but I'm not sure. Any help regarding why the servos failed would be great!




I'll lay odds you are over driving the servo and binding with the throttle linkage. I don't know why but I have seen a lot of that activity over the last year or so. If linkage geometry is wrong and end points not handled correctly you can burn out a servo, strip out the gears, or twist the servo output shaft in half. I have seen all three of those and a couple more of late in various planes. In a good many years I have never had any type ofgas engine throttle servo fail for a reason other than crash impact.



im very curious to see how you do the throttle on you new plane

im not sold on nyrod... i hear it expands and contracts when its hot or cold

i still like my overkill 4-40 ballinks on both sides



I never, ever use a flexible throttle linkage arrangement. Always rigid, usually carbon or fiberglass rod. I left nyrod/cable type linkage in the dirt with the glow engines a loooong time ago. I can understand that stuff in a multi engine plane but not many singles with any size.

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RE: multiple throttle servo failures - 10/17/2011 1:43 PM   
scale only 4 me



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quote:

ORIGINAL: MetallicaJunkie
im very curious to see how you do the throttle on you new plane

im not sold on nyrod... i hear it expands and contracts when its hot or cold

i still like my overkill 4-40 ballinks on both sides


I don't use it much anymore either,, only when it's the only way,,

Yes it expands, but not more than a click of trim,, They make a heavy duty version that has 4-40 wire thread ends

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RE: multiple throttle servo failures - 10/22/2011 4:08 PM   
garyr1


 

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Status: offline 		The guys here talked me into a good digital servo for throttle control on my first gasser...30CC Sbach.
I popped in the HiTech HS5485HB on 6V battery, well back in the fuse with good old Golden Rod plastic pushrod and sheath plus 2-56 ball end links. Working fine after one heavy summer of flying...maybe 300 flights?
The concensus here is use a longer linkage and make it vibration-absorbing.
Seems to be working really well for me, while others with more solid/shorter linkages are having their troubles.
I think there's something to this long and softer linkage idea. It's working for me.

Good luck.

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