Straw for Throttle push rod?
 

Do I have to run a straw? What will happen if I don't?

:eek:

RE: Straw for Throttle push rod?
 

Can you be more descriptive? Maybe a picture? A lot of models use a "push rod tube" with the metal rod running in it. What this does is limit the flex of the rod to maintain possitive control on the control surface or other item being controlled by the servo (ie. throttle). A "straw" would have to large of area inside for movement to be effective.

RE: Straw for Throttle push rod?
 

Gary
If the control rod does not bind or flex in movement you do not need the housing as long as it is just the throttle and is not to long.

RE: Straw for Throttle push rod?
 

Thanks. Yes, just a throttle, no binding, straight shot to the servo.

RE: Straw for Throttle push rod?
 

yes you should use a tube,not a straw, for the throttle pushrod.
like Mr67Stang put quite clearly, the tube prevents any flex or binding in the wire or rod.
example: the fuel tank moves in the tank compartment and rubs up against the pushrod causing servo to strain, and drain battery quicker than what you would normally expect,it's surprising how fast a typical battery drains down to nothing.
is it worth the risk, not on my planes
better be safe than sorry whats a little bit of pushrod tube ?

RE: Straw for Throttle push rod?
 

Sullivan makes rods with tubes that fit each other. Goldenrods, for instance, come in 2-56 and 4-40 sizes. The 2-56 size is just fine for the throttle.

They come in lengths of about three feet long, and you just cut them to length, feed the tubes through the hole in the firewall and any fuselage components to the servo. Leave some lenght (more than you actually need), rough up the tube so epoxy will adhere, and put the tube in place. After the epoxy sets up, then set the rod length, trim the tube so it does not intefere, and install it.

By the way, what you DO NOT want is a bind at either end of the servo throw, which will do two things.. flex (bend) the rod and the tube, and cause the servo to overwork, drawing additional current, and possibly stripping the internal gears. Adjust this out by either using a hole closer to the center of the servo for your clevis or z bend, or one further out on the carb end. If it sitll binds, and you have a computer radio, then adjust it with end point adjustments so that full throw works without binding the servo.

DS.