Steering servo question

[James WingroveParticipant @jameswingrove29221]

I am currently building a tug (Brakengarth from MMM) and fitting running gear. I have got a servo (25KG High Torque Metal Geared Waterproof Digital Servo DS3225 ) with rotation 180degrees as couldn’t find any with a smaller rotation. How do I reduce the rotation for steering as I only need a rotation of around 70degrees.

[James WingroveParticipant @jameswingrove29221]

Adjusting servo rotation angle

[Ray Wood 3Participant @raywood3]

Hi James,

Are you sure the servo will work proportionally ? and its not an aeroplane retract servo doing 180 Deg ??

You don't need a servo as powerful as that for rudder, a standard servo would normally have a 90 Deg travel

If you have a computer radio you can reduce the travel

Regards Ray

[Richard SimpsonParticipant @richardsimpson88330]

James, there are three approaches. Firstly you can change the "gearing" of the linkages by adjusting the distances that you connect the linkages to on the servo arm and the tiller arm. To reduce rudder movement you should move the linkage connection closer to the centre on the servo arm and move the linkage away from the rudder stock on the tiller. In your case however 180 degrees may be very difficult, if not impossible to accommodate this way.

The second method is to check whether your radio allows a range adjustment. I have just put a new servo into a model which has very limited rudder movement so I had to reduce the range in the transmitter to 50%.

Finally, as Ray has already suggested, a standard servo is more than man enough for such a situation. You can get high torque, metal geared servos with the more normal arc of movement of 90 deg, which would be far easier to set up. Check out these guys and give them a ring for advice. They are very knowledgeable and very helpful:

https://www.servoshop.co.uk/

I must admit I'm a little confused by your comment that you couldn't find a servo with a smaller rotation. 180 deg is by far the more unusual with a 90 deg arc being the normal.

[ashley needhamParticipant @ashleyneedham69188]

James. Ditto. A bog standard, standard size servo more than man enough.

I can’t imagine how powerful a prop or how massive a rudder you would have on a model to need 25Kg of force to operate.

Ashley

[Trevor HollowayParticipant @trevorholloway99134]

I used a standard servo on my 7 foot corvette with a 100mm propeller.

Worked well, would not hesitate to use the same again.

[James WingroveParticipant @jameswingrove29221]

Thank you for all your responses, have learnt to ask questions and ask for advice before going and buying bits. All a learning experience though which is good.

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