Brian Wilson 2 Posted February 3, 2015 Share Posted February 3, 2015 I have never used a pull pull system but need one for a future project for tail wheel steering and was thinking of running this through a tube , ie both wires converge into the tube at the servo end and diverge at the rear. The reason I considered this was for accessibility reasons. Is this a practical solution? Quote Link to comment Share on other sites More sharing options...
Dave Bran Posted February 3, 2015 Share Posted February 3, 2015 Pull Pull runs ideally should be straight from horn to horn. How are you going to route the wires into and out of the tube to avoid snagging/rubbing/wear/friction/metal to metal static/noise? Will this be linked to rudder or only operate on ground (minimising wear, etc)? Quote Link to comment Share on other sites More sharing options...
Brian Wilson 2 Posted February 3, 2015 Author Share Posted February 3, 2015 I was considering it in the manner of a loose fitting bowden cable arrangement....it would only be tight when the wheel was in the down position. I thought that passing through a tube would not really be any different from a control wire which runs around a pulley to change direction. I know this is not the norm but I am always looking at new ways of doing things. Edited By Brian Wilson 2 on 03/02/2015 05:29:37 Quote Link to comment Share on other sites More sharing options...
cymaz Posted February 3, 2015 Share Posted February 3, 2015 Thought this picture might help.. The tail wheel and rudder run off the same arm. The tail wheel pull pull has springs on it to absorb the ground shock. It has proved to be quite a reliable system. This article may also help you Edited By cymaz on 03/02/2015 06:54:39 Quote Link to comment Share on other sites More sharing options...
Brian Wilson 2 Posted February 3, 2015 Author Share Posted February 3, 2015 Thank you for the comments Quote Link to comment Share on other sites More sharing options...
stu knowles Posted February 3, 2015 Share Posted February 3, 2015 I have used pull pull cable routed via tubes to operate a tailwheel in the manner you describe,it works fine. There is a bit of friction / double centering but for a tailwheel it is not important. The first effort I used full length tubes - on a later one I just used 1/4 inch tube 'bearings' in the fus formers (to change direction) rather than a full length tube and I though that this worked better, probably because there was less cable/tube friction. I put the t/w retract unit in so it retracted the 'wrong' way to be scale but it made it possible to have the pull cable tight with the wheel down and slack with the wheel up, which neatly disconnects the servo. I didn't have any springs or shock absorbing in the cables. hope that this helps stu k Quote Link to comment Share on other sites More sharing options...
Brian Wilson 2 Posted February 3, 2015 Author Share Posted February 3, 2015 Hi Stu, that is essentially what I had in mind, thank you for the comment. Quote Link to comment Share on other sites More sharing options...
Jimbo565 Posted February 3, 2015 Share Posted February 3, 2015 Works a treat, very little friction, both wires running inside a yellow snake inner tube. Quote Link to comment Share on other sites More sharing options...
Jimbo565 Posted February 3, 2015 Share Posted February 3, 2015 Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted February 3, 2015 Share Posted February 3, 2015 The chaps have already shown that this approach is a perfectly sound approach. Putting springs in the tailwheel pull-pull is an excellent way to reduce the shock load and should always be considered. Reduce the angles as much as you can to ease the strain. The only thing I can add is that you may want to use the nylon coated steel trace I find it slides more easily. Cheers Danny Quote Link to comment Share on other sites More sharing options...
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