Topic: 2 push rods from 1 servo

What are the possibilities of driving 2 push rods from 1 servo, for driving elevators without a wire joiner?

I was thinking maybe put ball-links on the servo end then bolt through both ball links into the servo arm.

Anybody tried this before.

Reason I ask is I'm not happy with attaching 2 x 2mm wire rods, cranked to get out of the fuse from the same pushrod.

Are there any other alternatives without using 2 servos. Pictures would help.

Andy,

Number of ways of doing this, Sorry no diagrams, at work at the moment so havn`t got time to draw!

1, use collets to join two wire pushrods, then just go to the servo with one wire

                    --------------
servo----c--c/--------------

2, if using snakes. Use a large servo horn  or something similar and screw into the two snakes through two of the outer servo holes,  then use a rod and two nuts in the middle whole to run a rod to the servo, something like below

                     |--------- ======
servo--------n|n
                     |----------======

hope that makes sense!!

This was the same set up on my Black Horse Sukhoi. Two separate push rods, one for each elevator half, joining together at the servo. Must admit I changed mine for snakes, (yeah I know about snakes before you all jump in), but the set up is probably better shown in a pic rather than try to describe it. So here's a gash up I just did for you to show how it all works

Obviusly the two rods on the right of the pic go off to the elevators and the short rod on the left connects to the servo. Dunno where you buy the connector though. Maybe any model shop selling BH kits would sell 'em? If you're stuck for getting hold of one, I've got a couple spare and will pop one in the post for if you want it.  

[ Attachment Invalid Or Does Not Exist ]

Come to think of it my Black Horse extra was the same,

Could you not use some large electrical connector block to achieve the same results??

Thanks guys, I now have a few ideas. The Servo horn method sounds promising.
BTW have you used 5mm carbon tube for push rods before?


Andy

Have used rod/dowel before, not tube.

I find it much better than wooden dowel as it has very little flex in it

Andy ,
If you use carbon rods make sure the Rx aerial does not run close to it or it can effect range apparently.

Rob

Not a great image but you can see the collet method here on my Tucano

You could try a closed loop system.

Andy,

The F3A boys are using "dual elevator bellcranks" when installing 2 servos isn't an option.  There are two sources - MK and Protech.  The MK item is available from Probuild in the UK, for a picture see

http://www.probuild-uk.co.uk/products/product.php?id=592&keyword=&cat_id=7&man_id=

The bellcranks look the same from both manufacturers and the spec is the same, i.e. ballraced.  Over here though the MK unit is about £24 and the Protech one is 21 Euros.  I have just ordered 3 of the Protech ones from my local Protech stockist.  For your local stockist, see

http://www.protech.be/html/dealers.html

The Protech web-site dosen't list the MA695 item, but they were very helpfull when I contacted them by email.  They did send me the following images that show you what it is that I have been wittering on about.  The MK item looks identicle and works the same way.  One aerobatic pilot who has used one said it was brilliant and eliminated all slop from his elvator setup.  In my mind that makes it worth the price of a servo for a high performance model.




Hope this helps!

Bish.  8)

Yike!  I didn't expect those pictures to come out that big!  Sorry Wiz.

BTW - the Protech unit is designed to fit between fus. sides that are a minimum width of 3.1cm and a maximum width of 4.2cm

Bish.  8)

Having examined the fuse when I got home from work, I dont think the dual push rod is a go-er, as the fuse is very narrow towards the rear end.

I'm still thinking of using a single carbon rod tho' in lieu of the spruce supplied.

I'll have to sort out the Y shaped rods that link the elevators.

Andy,

If you do use a Y, then mount the elevator servo on its side if accurate control is important.  This will preclude any errors (asymmetric travel) resulting from lateral movement of the Y at the servo end.

Leon

Andy,

If you do use a Y, then mount the elevator servo on its side if accurate control is important.  This will preclude any errors (asymmetric travel) resulting from lateral movement of the Y at the servo end.

Leon

Leon  -  Thanks!  That is one of those little tips that is blindingly obvious when you read it, but which never occurs to you when you are building.

Brian.    :-[

Leon  -  Thanks!  That is one of those little tips that is blindingly obvious when you read it, but which never occurs to you when you are building.

Brian.    

Brian,

You're welcome!  I only wish I knew more of them.

Leon.