Just moved these two posts that were posted further down my blog by mistake as they are significant to the discussion and bring back the subject as I think its important as I would like to know if any others have a view. the photo is Johns
Response by JOHN on the 6th Mar 2019 Modify โ Like This Post ( 2 )
hi there
With regard the servo
rudder
linkages - I was advised that it is always best to use the 'push/pull method' of linkage - as this has two strong points in its favour.
The first problem it alleviates is - sometimes if on a single connection between
rudder
and servo and it is not set up quite right - a servo movement can force the
rudder
tiller arm to come back on itself under certain circumstances - i.e. when the distance from the centre of the servo to the outer hole on the servo arm isn't equal to the centre of the
rudder
post - to the centre of the linkage arm on the
rudder
.
The second problem - you can get an odd strain on the gearing in the servo, because on some models there is a fair bit of force on the
rudder
blade - whilst the model is in motion & turning to port or starboard. The way to think of this, you are riding a pushbike and holding the handlebars with one hand and you are trying to turn a sharp corner - think of how much strain and effort you have to put in. Now, if you have a double linkage to either side of the tiller arm from your servo - that strain now is balanced and is evening out the strain in the servo. Admittedly, this problem where you wear the servo out only happens on very rare occasions - but - as the old saying goes 'belts and braces/better be safe than sorry'.
John
Response by RNinMunich on the 6th Mar 2019 Modify โ Like This Post ( 1 )
In the wrong post but sensible stuff John.๐
Hadn't considered it before but it certainly makes sense to me that a dual linkage will help cancel the backlash from the
rudder
. And hence stop the servo motor having to fight it. That would reduce potential 'hunting' of the servo and also take the strain off the gearing.
Probably not a noticeable problem for short term
rudder
commands or in small, light models.
But could be in the heavyweights with big
rudder
s I suppose. like Mike said (sort of); makes yer think!!
More power to yer servos Gents.
Cheers, Doug ๐
PS Dual linkage not possible in some situations, see pic of cramped space in my Sea Scout. Had to lay the servo on it's side.๐ฒ