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Throttle Cables sticking

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TheSchultzFamily(at)comca
Guest

Posted: Mon Jan 28, 2008 9:22 pm Post subject: Throttle Cables sticking

I am looking to see what others have done to prevent throttle cable bowing

of the twisted wire used in most throttle cables. I have a 914 installed on

a Europa and am having problems with one of the cables wanting to bow in the

throttle box and not allowing me to get full power. The throttle springs are

not strong enough to pull the cable and keep it in tension all the time. On

the Europa form others have talked about going to a solid cable .055 or .078

SS piano wire. I have some concerns about the carburetor attachment point

producing a stress crack and failing under the vibration. I am interested to

hear what others have done?

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jack.kuehn(at)gmail.com
Guest

Posted: Tue Jan 29, 2008 8:10 am Post subject: Throttle Cables sticking

Not sure if I am using the same type of twisted cable as you are, but

when the cables were new I took the cable out of the housing and

sprayed it down with a silicone lubricant and made sure it was clean.

I inspect them now every 50 hours and no problems.  Could your bowing

cable just be sticky?



Jack



On Jan 28, 2008 9:53 PM, Rich & Sandy Schultz

<TheSchultzFamily(at)comcast.net> wrote:

 	  Quote: 	
		   

 I am looking to see what others have done to prevent throttle cable bowing

 of the twisted wire used in most throttle cables. I have a 914 installed on

 a Europa and am having problems with one of the cables wanting to bow in the

 throttle box and not allowing me to get full power. The throttle springs are

 not strong enough to pull the cable and keep it in tension all the time. On

 the Europa form others have talked about going to a solid cable .055 or .078

 SS piano wire. I have some concerns about the carburetor attachment point

 producing a stress crack and failing under the vibration. I am interested to

 hear what others have done?

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Roger Lee

Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.

Posted: Tue Jan 29, 2008 9:13 am Post subject: Re: Throttle Cables sticking

Here are a couple of things to do. 



1. Use cable housing that has the plastic lining in it and not just plain steel lining. It allows the cable to move within the sheath smoothly and doesn't rust or develop rough spots.

2. Do like Jack said and remove the cable and use some cable lube

3. Step down a cable size to allow more room in the cable housing to move and not bind. On many planes trying to use 1/16" cable size is too big depending on the routing and turns that are made with the throttle cable. My cable in my CT is only 3/64" or 1.2mm. This is because it goes around a 1 1/4" size pulley and needs to be able to make the bend and be very flexible. Using the smaller size cable will allow your carb springs to work better and do their job. Use 7x7 or 7x19 cable. 7x19 is a little more flexible than 7x7.

4. Lube the throttle quadrant if you have one and make sure it moves freely.



If it were me I would do all the above and then the throttle should be very smooth in its operation.

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_________________
Roger Lee
Tucson, Az.
Rotax Instructor & Rotax IRC
Light Sport Repairman
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056

daberti(at)sbcglobal.net
Guest

Posted: Tue Jan 29, 2008 7:16 pm Post subject: Throttle Cables sticking

Keep the cables as short as possible too, just long enough to make smooth a

radius if they have to change direction in your installation.



--

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Gilles.Thesee(at)ac-greno
Guest

Posted: Wed Jan 30, 2008 5:39 am Post subject: Throttle Cables sticking

Rich & Sandy Schultz a écrit :

 	  Quote: 	
		    others have talked about going to a solid cable .055 or .078

 SS piano wire. 


	


Relieving only on the carb throttle springs to overcome the cable 

friction may prove troublesome. There have been cases of flexible cables 

binding between trhottles and cable outer case, leaving the pilot with 

no option when additional power is needed, despite a perfectly running 

engine.

One needs a positive actuation of the carb throttle arms towards the 

full throttle position.



This is why our project has piano wires, works great. To date 400+ MCR 

kitplanes are flying with piano wires in place of stranded cables making 

them a real push-pull device, with no reported problem whatsoever.

Some of them have logged more than 1000 flight hours to date.

 	  Quote: 	
		   I have some concerns about the carburetor attachment point

 producing a stress crack and failing under the vibration. I am interested to

 hear what others have done? 

   


	


Not sure what you fear. The throttle arm cable attachment is of the 

swivel type. No bending there.



Best regards,

-- 

Gilles

http://contrails.free.fr

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hagargs(at)earthlink.net
Guest

Posted: Wed Jan 30, 2008 6:10 pm Post subject: Throttle Cables sticking

I have installed a Cessna Push pull vernier type throttle single cable up

into the engine compartment.  Once there, it is split into two where the 

normal motorcycle type cable that comes with the  plane is used. Each

length of these is  18 inches  or less long and is easily overcome by the

carberator springs.



Steve Hagar

A143

Mesa, AZ

 	  Quote: 	
		   [Original Message]

 From: Rich & Sandy Schultz <TheSchultzFamily(at)comcast.net>

 To: <rotaxengines-list(at)matronics.com>

 Date: 1/28/2008 10:49:46 PM

 Subject: Throttle Cables sticking



 

<TheSchultzFamily(at)comcast.net>
	


 	  Quote: 	
		  



 I am looking to see what others have done to prevent throttle cable bowing

 of the twisted wire used in most throttle cables. I have a 914 installed

on
	


 	  Quote: 	
		   a Europa and am having problems with one of the cables wanting to bow in

the
	


 	  Quote: 	
		   throttle box and not allowing me to get full power. The throttle springs

are
	


 	  Quote: 	
		   not strong enough to pull the cable and keep it in tension all the time.

On
	


 	  Quote: 	
		   the Europa form others have talked about going to a solid cable .055 or

.078
	


 	  Quote: 	
		   SS piano wire. I have some concerns about the carburetor attachment point

 producing a stress crack and failing under the vibration. I am interested

to
	


 	  Quote: 	
		   hear what others have done?

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ami(at)MCFADYEAN.FREESERV
Guest

Posted: Thu Jan 31, 2008 3:49 am Post subject: Throttle Cables sticking

I did something similar, but had the two Bowden cables connected directly to 

the vernier via a slider arrangement.

This worked OK with two fuel injection throttle bodies, which are extremely 

difficult to balance accurately (far more difficult than carbs, even without 

a balance tube).



For the ROtax, I have teflon lined stainless Bowden cable which works OK, 

and at reduced tension on carb springs. Has to be stainless with teflon, for 

best effect. And same length of cable for each carb, irrespective of actual 

requirement.



For nylon/acetyl lined cables, the possibility of the liner softening and 

welding the throttle open on a long cruise (if the cable is routed near to 

under-cowl hotspots such as exhausts) needs to be considered.



Duncan McF.



---

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