need help Throttle - through firewall

[Marty_d]

Hi all,

 

I'd actually put this question in my build log but didn't get a response - probably because it was tucked down the bottom of a post.

 

What I want to know is - where your push/pull throttle goes through the firewall, what holds it in position?

 

Do I need to get a spherical grommet like this or is there some other option? And does the grommet actually clamp the outer sheath of the cable or is it just a swivelling hole?

 

My cable has a groove about 100mm back from where it will go through the firewall (see picture below). I'm guessing the groove could be a mounting point too - would I create a box structure inside the firewall?

 

 

Any information, including pictures of your setup, would be fantastic.

 

Thanks!

 

Marty

[Guest Machtuk]

I have several of these passing they my firewall, very high quality and professional? They are not anchored at the eyeball.

[Thruster88]

Any information, including pictures of your setup, would be fantastic.

 

Thanks!

 

Marty

 

Not an aircraft but my tractor has a similar throttle cable. It is anchored at the groove with a clamp like this

[facthunter]

However you do it make sure it can't slip. ALL throttle cable etc fittings are critical and should be fail safe .Duplicated attachment s are the go. If your throttle linkage becomes detached you have problems you can do without. The usual 912 set up is spring loaded to OPEN and you have to tug the thing hard to get to idle position and have enough friction for it to stay there. I much prefer a throttle that just stays where you left it with an easy adjusted friction set up .Nev

[kasper]

However you do it make sure it can't slip. ALL throttle cable etc fittings are critical and should be fail safe .Duplicated attachment s are the go. If your throttle linkage becomes detached you have problems you can do without. The usual 912 set up is spring loaded to OPEN and you have to tug the thing hard to get to idle position and have enough friction for it to stay there. I much prefer a throttle that just stays where you left it with an easy adjusted friction set up .Nev

Hmmmm. Not on the 912 80hp fitted to my trike it doesnt ... it moves that carb to idle.

For me if a cable breaks the outcomes will depend on where the break occurs:

1. cable break between foot throttle and hand throttle - single cable run so both carbs go to idle but I have hand throttle with friction lock available

2. cable break between hand throttle and cable splitter - single cable run so both carbs go to idle and I am landing fairly soon

3. cable break after the cable splitter - one carb goes to idle and I have foot/hand control over the remaining carb ... its going to be a very unhappy engine and I will probably still be landing very soon.

 

I do not mind this set up (its the same as on the two stroke engines I have flown and still fly) and for me my landing run once i get the mains on the ground is under 100m even when at MTOW so I am comfy.

[Blueadventures]

Hi all,

 

I'd actually put this question in my build log but didn't get a response - probably because it was tucked down the bottom of a post.

 

What I want to know is - where your push/pull throttle goes through the firewall, what holds it in position?

 

Do I need to get a spherical grommet like this [ATTACH alt=1585223412055.png]51676[/ATTACH]or is there some other option? And does the grommet actually clamp the outer sheath of the cable or is it just a swivelling hole?

 

My cable has a groove about 100mm back from where it will go through the firewall (see picture below). I'm guessing the groove could be a mounting point too - would I create a box structure inside the firewall?

 

[ATTACH type=full" alt="20200322_204449.jpg]51678[/ATTACH]

 

Any information, including pictures of your setup, would be fantastic.

 

Thanks!

 

Marty

That groove anchors the outer against movement, like 88 mentions in post #3. Teleflex morse are a supplier of these types of control cable and a look on thier fitout instructions will show the method.

[Geoff_H]

I found this article. It is general and not specifically for your device. Do the download on installing.

[kgwilson]

Hi Marty,

 

I used cable glands which are designed to protect and grip cables that pass through a wall. They come in many sizes. I used 2 small ones for the choke & throttle cables & bigger ones for fuel line and electrical cables. They are water & dust proof made of ABS or nylon & quite cheap $5-$10. You can get them from Jaycar or AU-RS-online.com. There is a nut either side of the firewall and an iris type end on the engine side that you tighten up on the cable & it locks it in place. You can see the throttle & choke glands in the picture before I inserted the cables. The back end is shown in the other picture from the Jaycar catalogue

 

 

 

 

 

[facthunter]

I was not thinking of Throttle Cables themselves, breaking. It's almost unknown with quality cables that are generously dimensioned and serviced at correct Intervals. It's how they are anchored I'm concerned about.. Don't rely on just one clip or nut that may unwind and then NO POWER. .Going through the firewall is not the problem It's the security of the knob and the dash face and the carburetter linkage end and of course any splitter devices you might have Duplicated throttle can be an issue in many ways and best avoided if possible. Nev

Edited March 27, 2020 by facthunter

[kgwilson]

Correct the cable should terminate at a bracket of some description on the engine as in the lower left of this photo.

[Marty_d]

I was not thinking of Throttle Cables themselves, breaking. It's almost unknown with quality cables that are generously dimensioned and serviced at correct Intervals. It's how they are anchored I'm concerned about.. Don't rely on just one clip or nut that may unwind and then NO POWER. .Going through the firewall is not the problem It's the security of the knob and the dash face and the carburetter linkage end and of course any splitter devices you might have Duplicated throttle can be an issue in many ways and best avoided if possible. Nev

 

As you mentioned before it's spring loaded to open, pull throttle to idle.

 

I have an A-800 friction nut throttle which I'm installing on the pilot side, the passenger's side will have a direct rod link to the torque tube (I'll put a knob on it so it looks like the pilot's side). If the pilots side throttle comes loose the passenger's side will be the backup, luckily the cabin is not that wide so it'll be possible to lean over for a while and operate it. (Either that or jump over and fly from the right seat if solo!)

 

Ok so it seems that I will be making a box to capture the cable at that groove. Thanks all! (Still want to see your setups if you're happy to post a picture).

 

Cheers, Marty