Throtle Spring
08-29-2012 | 01:43 PM
#1
Thread Starter
Senior Member
Joined: Jan 2007
Posts: 1,550
Likes: 0
Received 0 Likes
on
0 Posts
From: Lancaster,
NY
Throtle Spring
In Bob P's sticky on gas engines he says not to remove the throtle spring (item #7). But in the sentence prior he says to unhook it so the the servo is not under constant tension. What does he mean?
08-29-2012 | 01:54 PM
#3
Thread Starter
Senior Member
Joined: Jan 2007
Posts: 1,550
Likes: 0
Received 0 Likes
on
0 Posts
From: Lancaster,
NY
RE: Throtle Spring
Pe, Just took a look at my engine and see what you mean - to leave it on the shaft. Stupid for me to ask without looking at the engine. Thanks
08-29-2012 | 02:23 PM
#4
Joined: Nov 2002
Posts: 507
Likes: 0
Received 0 Likes
on
0 Posts
From: Rapid City,
SD
RE: Throtle Spring
I have been flying gas engines for over 20 years, and have never unhooked any of the throttle springs and have never lost a servo. I have Owned atleast one of almost every gas engine on the market. IMHO there is no reason to unhook the throttle spring on any gas engine, it is all in your set up. Use a medium torque servo with a heavy duty linkage 4:40 rod, titaniumpro link or carbon fiber rod. Never use a 2:56 rodor nyrod or golden rod tomuch flex and the vibration will kill your servo. that is my 2 cents worth take it from there.here is one example of a good linkage set up the spring is hooked up on the opposite side of the carb. With the spring unhooked and left on the engine over time the butterfly will still bounce back and forth due to vibrationwearing grooves in the throttle body of the carb the small pieces of aluminum go right into the engine causing eventual engine failure. I have seen this many times over the years." the spring is on the shaft for more than one reason" but do what you want
08-29-2012 | 04:07 PM
#6
My Feedback: (66)
RE: Throtle Spring
I clip my springs. measure the load the servo is pulling from the battery with a watt meter and you will see how much of a load is applied to it. Why do it. its just like flying with stiff control surfaces. yes you can do it for 20+ years but why. a lot of guys think it adds safety in that if the push rods comes off it will go to idle. lol that just comes down to better instalation of your push rod. Also the large gas singles will vibrate more than smaller glow engines. if you use a really cheap servo you need to isolate it from those vibrations also or the pot in the servo will burn out. there is also talks of using anything other than metal to metal for hook ups. i have yet to have a problem with it on the ones i have used them on. You can make your own throttle servo savers with wire push rods. use a quick conneck on servo control horn. use a wheel collor and a light spring on to the wire push rod. then insert it in to the quick connect on the servo with no set secrew. let it slide in and out freely. then use another spring and wheel collor on the other side. adjust so the minium amount of sprning pressure is reguired to move the throttle.
I also remove the throttle idle stop screw. i do this for two reasons. one its extra weight (althought very little) and i want to have a back up to the opto kill by closing the throttle all the way with the servo.
i know a lot of guys will come on here a refute all this but thats way i do my stuff.
Also i forgot i removed the spring to test the thoughts of the butterfly moving around and wearing out the carb. mine didnt move very much at all if any.
I also remove the throttle idle stop screw. i do this for two reasons. one its extra weight (althought very little) and i want to have a back up to the opto kill by closing the throttle all the way with the servo.
i know a lot of guys will come on here a refute all this but thats way i do my stuff.
Also i forgot i removed the spring to test the thoughts of the butterfly moving around and wearing out the carb. mine didnt move very much at all if any.
08-29-2012 | 05:32 PM
#8
Senior Member
Joined: Jan 2009
Posts: 841
Likes: 0
Received 0 Likes
on
0 Posts
From: Salinas,
CA
RE: Throtle Spring
If you set up the linkage properly servo torque of a standard servo is more than adequate with the spring as issued. Leaving the spring in place puts a small load on the linkage and removes all play. The spring closes the throttle in the event of a linkage failure. I can not think of any good reason to remove or alter the spring.
08-29-2012 | 05:55 PM
#9
Thread Starter
Senior Member
Joined: Jan 2007
Posts: 1,550
Likes: 0
Received 0 Likes
on
0 Posts
From: Lancaster,
NY
RE: Throtle Spring
Hmmmm - I see there are pros and cons to the spring situation. I have a strong servo so I think I will leave it hooked up. Thanks for the informative discussion.
08-29-2012 | 06:32 PM
#10
RE: Throtle Spring
Current think seems to not unhook the spring, but to let the spring return the throttle to the closed position in case of servo or linkage failure as a safety measure. Think is that the load on the servo of the spring was negligible.
08-29-2012 | 07:15 PM
#11
RE: Throtle Spring
ORIGINAL: pe reivers
Unhook, but do not remove.
The spring puts a side load on the throttle valve plate that keeps it from vibrating to death.
Unhook, but do not remove.
The spring puts a side load on the throttle valve plate that keeps it from vibrating to death.
yup i found out the hardway... the valve got so worn ...it couldnt shut the motor down
08-29-2012 | 08:16 PM
#12
My Feedback: (66)
RE: Throtle Spring
on the carbs i have seen there isnt any movement side to side in the carb butterfly. If the spring provides side tension then wouldnt it wear on the side it pulled against.
Also on the servo thing. yes most servos will have the power to pull the throttle open and hold it there but do you fly with springs on the control surface's so they will center if the control rod breaks lol.
If you have problems with your throttle to carb set up then you have other issues lol. its a hobby and fly how you want.
To be leaving the carb spring hooked up is just wasting battery power trying to hold it open all the time.
Cut the spring!!
Also on the servo thing. yes most servos will have the power to pull the throttle open and hold it there but do you fly with springs on the control surface's so they will center if the control rod breaks lol.
If you have problems with your throttle to carb set up then you have other issues lol. its a hobby and fly how you want.
To be leaving the carb spring hooked up is just wasting battery power trying to hold it open all the time.
Cut the spring!!
08-29-2012 | 08:23 PM
#13
Joined: Nov 2002
Posts: 507
Likes: 0
Received 0 Likes
on
0 Posts
From: Rapid City,
SD
RE: Throtle Spring
ORIGINAL: airraptor
I clip my springs. measure the load the servo is pulling from the battery with a watt meter and you will see how much of a load is applied to it. Why do it. its just like flying with stiff control surfaces. yes you can do it for 20+ years but why. a lot of guys think it adds safety in that if the push rods comes off it will go to idle. lol that just comes down to better instalation of your push rod. Also the large gas singles will vibrate more than smaller glow engines. if you use a really cheap servo you need to isolate it from those vibrations also or the pot in the servo will burn out. there is also talks of using anything other than metal to metal for hook ups. i have yet to have a problem with it on the ones i have used them on. You can make your own throttle servo savers with wire push rods. use a quick conneck on servo control horn. use a wheel collor and a light spring on to the wire push rod. then insert it in to the quick connect on the servo with no set secrew. let it slide in and out freely. then use another spring and wheel collor on the other side. adjust so the minium amount of sprning pressure is reguired to move the throttle.
I also remove the throttle idle stop screw. i do this for two reasons. one its extra weight (althought very little) and i want to have a back up to the opto kill by closing the throttle all the way with the servo.
i know a lot of guys will come on here a refute all this but thats way i do my stuff.
Also i forgot i removed the spring to test the thoughts of the butterfly moving around and wearing out the carb. mine didnt move very much at all if any.
I clip my springs. measure the load the servo is pulling from the battery with a watt meter and you will see how much of a load is applied to it. Why do it. its just like flying with stiff control surfaces. yes you can do it for 20+ years but why. a lot of guys think it adds safety in that if the push rods comes off it will go to idle. lol that just comes down to better instalation of your push rod. Also the large gas singles will vibrate more than smaller glow engines. if you use a really cheap servo you need to isolate it from those vibrations also or the pot in the servo will burn out. there is also talks of using anything other than metal to metal for hook ups. i have yet to have a problem with it on the ones i have used them on. You can make your own throttle servo savers with wire push rods. use a quick conneck on servo control horn. use a wheel collor and a light spring on to the wire push rod. then insert it in to the quick connect on the servo with no set secrew. let it slide in and out freely. then use another spring and wheel collor on the other side. adjust so the minium amount of sprning pressure is reguired to move the throttle.
I also remove the throttle idle stop screw. i do this for two reasons. one its extra weight (althought very little) and i want to have a back up to the opto kill by closing the throttle all the way with the servo.
i know a lot of guys will come on here a refute all this but thats way i do my stuff.
Also i forgot i removed the spring to test the thoughts of the butterfly moving around and wearing out the carb. mine didnt move very much at all if any.
08-30-2012 | 02:45 PM
#14
My Feedback: (66)
RE: Throtle Spring
and you may should have any problems. what i am saying is that why do do it. none of the glow engines have a spring. also again would have return springs on your elevator, rudder or ailerons??????? its like running with a stiff control surface.
i just like to make my connections very secure, light and ease of movement.
Old habits are hard to let go even if a newer and better way to do something is presented. how many threads have been started where the guys complain of throttle servo issues on gas motors. a common theme is they have the spring still hooked up. do you really need a 100 oz torque servo just to hold the throttle open. no remove the spring, use a lighter, faster servo. This will save weight with a lighter servo, lighter battery requirement, lighter control set up and faster throttle response.
keep the spring if you want as you have done in the last 20 years or more. your hobby do as you wish. but there are better ways to do things.
i just like to make my connections very secure, light and ease of movement.
Old habits are hard to let go even if a newer and better way to do something is presented. how many threads have been started where the guys complain of throttle servo issues on gas motors. a common theme is they have the spring still hooked up. do you really need a 100 oz torque servo just to hold the throttle open. no remove the spring, use a lighter, faster servo. This will save weight with a lighter servo, lighter battery requirement, lighter control set up and faster throttle response.
keep the spring if you want as you have done in the last 20 years or more. your hobby do as you wish. but there are better ways to do things.
08-30-2012 | 03:26 PM
#15
My Feedback: (19)
RE: Throtle Spring
ORIGINAL: airraptor
keep the spring if you want as you have done in the last 20 years or more. your hobby do as you wish. but there are better ways to do things.
keep the spring if you want as you have done in the last 20 years or more. your hobby do as you wish. but there are better ways to do things.
The extra power required (both servo torque and electrical) to hold the throttle in place against the spring tension is very minimal.
08-30-2012 | 04:01 PM
#17
My Feedback: (19)
RE: Throtle Spring
Disconnecting the spring.
Seriously though, I have no issue with anybody doing whatever they prefer with their throttle return springs. I just don't see the need to modify the carb as provided other than installing a longer throttle and choke arm.
Seriously though, I have no issue with anybody doing whatever they prefer with their throttle return springs. I just don't see the need to modify the carb as provided other than installing a longer throttle and choke arm.
08-30-2012 | 04:58 PM
#18
Joined: Sep 2006
Posts: 8,131
Likes: 0
Received 5 Likes
on
5 Posts
From: The Sunshine state, when it's not raining!
RE: Throtle Spring
On the spring issue. Leaving it on is compareable to deflection to a control surface. When you pull up elevator your applying load to the servo, can't disconnect that. Pull full aileronron left, can't disconnect that. Are those senario's too much load for the servo?, NO!!!
Disconnect the spring and it will wear the carb body, when, depend's on how much you fly but it will. Many small engine repairmen will agree, and have.
One can get as nasty as one want's regarding how he does thing's, and that's fine. Each to his own. One thing is for certain, fact's are fact's, some know them and some pretend to. Those that know them -know those that don't. Those that don't should listen!
That's all I have to say.
Disconnect the spring and it will wear the carb body, when, depend's on how much you fly but it will. Many small engine repairmen will agree, and have.
One can get as nasty as one want's regarding how he does thing's, and that's fine. Each to his own. One thing is for certain, fact's are fact's, some know them and some pretend to. Those that know them -know those that don't. Those that don't should listen!
That's all I have to say.
08-30-2012 | 06:41 PM
#19
My Feedback: (6)
RE: Throtle Spring
Well, my thoughts, for whatever they are worth are as such:
The spring is there to retard the throttle after a simple very flexible pull only cable pulls the throttle open. We don't set our throttle setups that way. Your throttle linkage should be push/pull and have virtually no slop in it if you expect to have a reliable idle setting. As such, it shouldn't be letting the throttle butterfly vibrate much if at all. Further, the spring is made to work in torque. By disconnecting it and leaving it in place, you are expecting it to operate in compression, which it wasn't designed to do and won't do a very good job. Even if it does, the pressure would push the butterfly against one side of the carb throat causing more wear, not less. Also, many of the better carbs have a "C" clip on the throttle butterfly shaft that holds the throttle shaft and butterfly in position.
In any case, I think it is all a rather moot point and silly to argue about. If you want to leave the spring on, hoping that if you ever have a throttle disconnect that it will close the throttle for you, go for it. If not, don't. In either case just go fly and have fun....
It would take a very long time to wear out the butterfly/carb throat interface even if you have some slop in your throttle linkage. By that time, you surely will have crashed the airplane anyway!!
AV8TOR
The spring is there to retard the throttle after a simple very flexible pull only cable pulls the throttle open. We don't set our throttle setups that way. Your throttle linkage should be push/pull and have virtually no slop in it if you expect to have a reliable idle setting. As such, it shouldn't be letting the throttle butterfly vibrate much if at all. Further, the spring is made to work in torque. By disconnecting it and leaving it in place, you are expecting it to operate in compression, which it wasn't designed to do and won't do a very good job. Even if it does, the pressure would push the butterfly against one side of the carb throat causing more wear, not less. Also, many of the better carbs have a "C" clip on the throttle butterfly shaft that holds the throttle shaft and butterfly in position.
In any case, I think it is all a rather moot point and silly to argue about. If you want to leave the spring on, hoping that if you ever have a throttle disconnect that it will close the throttle for you, go for it. If not, don't. In either case just go fly and have fun....
It would take a very long time to wear out the butterfly/carb throat interface even if you have some slop in your throttle linkage. By that time, you surely will have crashed the airplane anyway!!
AV8TOR
08-31-2012 | 02:52 AM
#20
Senior Member
RE: Throtle Spring
In most cases I leave the spring in function. I then have a ball link on the throttle arm and use a pull wire with looped ends to actuate the throttle with spring return. Very easy to set up, Very easy to disconnect, very stable idle, very reliable.
08-31-2012 | 07:58 AM
#21
My Feedback: (2)
Joined: Jan 2003
Posts: 737
Likes: 0
Received 0 Likes
on
0 Posts
From: Billingsley, AL
RE: Throtle Spring
Since I usally make a longer throttle arm to match the servo arm, I leave the spring on. The extra leverage of the longer arm minimizes the backpressure of the spring. Not a big deal with the spring since the throttle is moving all the time anyway.
10-25-2012 | 11:17 PM
#23
My Feedback: (13)
RE: Throtle Spring
I'm new to gas engines myself, with my first gas model with 50+ flights on it. I unhooked the spring to the throttle and left the spring on the carb. I tossed the idle set screw and my RCG 20 cc engine is running great. I use a Airtronics 94322 standard ball bearing servo on the throttle...and no problems. I'm using a 440 wire on ball links to both servo and choke. Works like a charm so far. I'm also running two five cell nickle 2000 ma. batteries. One for the enigne and one for the receiver, mounted as far aft as I could mount them, had CG issues with the model.
What is so cool, is that so many folks have found good ways to do stuff...and a lot of it works quite well. Being new to gas engines, I just followed the advice of folks that chimed into my questions and pointed the way. The rest is trial and error...ie, experience.
It took longer to learn how to tune the carb then everything else. Lots of dead sticks until I got it down...thank the gods...I had a floater for a first gas model. My first gas model was a .60~.90 size Big Stick (Ugly Stick).
Soft Landings always,
Bobby of Maui
What is so cool, is that so many folks have found good ways to do stuff...and a lot of it works quite well. Being new to gas engines, I just followed the advice of folks that chimed into my questions and pointed the way. The rest is trial and error...ie, experience.
It took longer to learn how to tune the carb then everything else. Lots of dead sticks until I got it down...thank the gods...I had a floater for a first gas model. My first gas model was a .60~.90 size Big Stick (Ugly Stick).
Soft Landings always,
Bobby of Maui
