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[R1sahoot]

apologies if this is a dumb question but I just cannot find any information on this subject.


My question is, is there any reason why I cannot use gears to operate rudder ? Has anyone any experience of this? I am building a hefty 1/12 scale Watson class and I am trying to find a neat solution to the servo / rudder connection.

[malcolmfrary]

If you can fit one to the servo, and line it up with the one on the rudder shaft, no problem.  Its probably the alignment/meshing problem that causes most of us to use arms and pushrods.  Some have successfully used a pulley on the shaft and a pair of pull lines to the servo arm.

[R1sahoot]

I found this...


https://www.servocity.com/html/32p_futaba_metal_gear.html#.VH4EE0eQGrU

[Bob K]

I have used a series of gears, driven by a servo mounted toothed belt, to operate a pair of bow rudders mounted close together where hull space was very limited.  If room had not been so tight I would have used standard arms and linkage. Getting the gears to mesh closely enough can be a problem.

[radiojoe]

Is there a reason you are trying to use gears, when the tried and tested tiller and rod is simple and effective and widely use on full size boats albeit hydraulic push rods. 

[derekwarner]

Hullo Joe...here is the answer to answer your question  but first you need to.....

1. shrink yourself to 1:48 scale 
2. wade thru the bilges of a semi submersible pre turn of the century warship 
3. by the time you get up FWD.....it would be lunch time...so take a few Vegemite sangas & a small drink just in case you get thirsty
4. after lunch you will find the bow mounted rudder all in a very squeesyily watery compartment

This is why Bob installed the servo mounted gear drive mechanism as such  ..... & IP600065 rated to boot......  Derek

[radiojoe]

Yes I understand that but my question was for the author of this thread who said he was building a 1:12 so should have plenty of room, perhaps I could have made that clearer,
: 

[derekwarner]

No Joe........your question was quite clear  ...I was just having a little fun with Bob K's famous infamous  FWD rudder drive...... Derek

[tigertiger]

In answer to the original question.
Why not gears? To keep things simple is a good reason.


A servo with push rod will work well.
One with push and pull rods will work very well, and take some of the strain off of the servo.

There are lots of big servos, some listed for 1/4 scale aircraft undercarriage. They have between 7-11 kg/cm of torque. I think the HitecHS75BB was one. They cost under 30 pounds. They are about 50% bigger all round than a standard servo.

[Bob K]

No Joe........your question was quite clear  ...I was just having a little fun with Bob K's famous infamous  FWD rudder drive...... Derek

Derek:   "Infamy, infamy . . .  They've all got it in for me !" 

For those not understanding Derek's joke (tee hee!), this is the mechanism referred to



My point is why use gears unless other factors dictate.  Servo arms are more adjustable, better positional tolerance, and less torque stress on the servo.

(Since then I have seen another build of this ship in which the bow rudders retract too.)

[radiojoe]

OK Derek
I missed that one   but I did enjoy the toast and wine but please take that vegemite away agghhh.

Nicely done Bob 

[derekwarner]

  Joe....just raisin toast & a cup of tea in future OK......

Seriously ...the reason I mentioned the FWD rudder build by Bob K was just that   ...it was a complex solution to a very problematical design criteria

Bob has never confirmed the results but an ACTion P96 servo morph controller would perfect in this application  ...... Derek

[Bob K]

Seriously ...the reason I mentioned the FWD rudder build by Bob K was just that   ...it was a complex solution to a very problematical design criteria

Bob has never confirmed the results ..... Derek

It works very well.  +/- 40 degrees rudder movement, with rudders close together in a really tight volume of hull.  Used a reversing Y lead so when the rear rudder turns to port so do the forward rudders.  Intended use was for manoeuvring inside enemy harbours, long before bow thrusters were invented.  Actual additional turning effect is fairly minimal though, just like the real ship.

Bob K

[radiojoe]

Hi Bob the important thing is, you found a solution to a problem installed it and made it work, hats off to you sir 
Joe.

[missyd]

Works even with chain/sprockets .... much easier to build!