tailwheel steering spring problem

low-n-slow · Post by **low-n-slow** » Wed May 09, 2007 23:13

I have an Maule 8 inch pnuematic tailwheel on an L-16 and am looking for input on the proper steering spring setup. When the older 6 inch hard rubber assembly was removed and the new 8 inch Pnuematic assembly was installed, a new set of compression springs and linkages was also installed. Since then, the right steering spring linkage, and chain have snapped twice on hardsurface landings. I then put the old stretch springs back on hoping this would help. Today, the right spring chain linkage broke again. In 30 plus years of flying with the older small hard rubber tailwheel with regular springs (stretch style) never had an issue. Looking for advice on where to go with this problem. The larger tailwheel is nice becuase the home strip is fairly sandy and the smaller wheel sinks in... If someone has pictures they could send or post of an 8" maule tailwheel set up that would be great! Any and all input welcome!!!

MikeB · Post by **MikeB** » Thu May 10, 2007 08:43

Jon,
I wonder if it isn't the 'elcheapo' chain set up that comes with the Maule TW. I have the same set up (8 inch Maule) and when I installed the chains I thought they were awfully light and easy to cut. Never had one break, but I guess it could happen. As far as the Maule wheel goes, it seems to work fine on both soft and hard surface.

I hesitate to mention it, but chain from a hardward store might be made of better stuff

. (just a thought).

Mike Berg

Post by **joea** » Thu May 10, 2007 10:28

Agree with Mike and as well I always use .040 safety wire to provide a backup between the tailwheel and spring, then the spring and the rudder horn in case the last link breaks.

Ron Babos · Post by **Ron Babos** » Thu May 10, 2007 17:26

low and slow: What I did was make up two stainless strips. 5/8 inch wide at the bolt hole in the horn, and tapered down to 5/16 inch for the hole for the spring. Thickness is .062. Set the wheel straight with the rudder to determine the lengths. One may be longer than the other when rudder and wheel are aligned. Bolt one end under the horn with castle nuts and cotter pin and disassemble the spring to run it through the hole in the small end.
The slack in the spring will be taken up and at most 1/8 inch compression if you got the lengths on the links correct.
If you have the Maule springs with one heavy and one light, the heavy goes on the starboard side. Better to have a heavy on both as that spring anti shimmy setup is total crap anyway. It sounds like you are having tailwheel shimmy in order to break the chains. Trust me, the last kind of a spring you want on the plane is a tension spring. Both could depart the aircraft in a bad shimmy.
Maules pneumatics are prone to shimmy. I have finally solved the mystery as to why. Make sure the fork geometry is correct for starters. The culprit believe it or not is wheel ballance. The valve stem area combined with wheel design causes a serious out of ballance. The out of ballance is offset with centerline of wheel. When the wheel spins, it automatically wobbles side to side, even when holding it by hand on the pivot when removed and spinning it. One bolt opposite the stem needs to be lengthend with a piece of drilled bar stock attached at this point. It is a substantial amount. Mine is about 3/4 od x 5/8 inch long in conjuntion with the longer bolt. Also run the tire at 40 psi for best results.
Ron

low-n-slow · Post by **low-n-slow** » Thu May 10, 2007 20:35

Thanks for the great tips.

Ron, would it be possible to post a picture of your set showing the stainless strips and the counterweight. Sometimes a picture is worth a thousand words. Hopefully this weekend I will have a chance to dig into this and go to plan B

Ron Babos · Post by **Ron Babos** » Thu May 10, 2007 21:12

low and slow: Sure, I' see if I can swing by the airport after work tomorrow. 4130 is also good to use, but will rust in time. Should have it posted in a couple of days.
Ron

Nathan K. Hammond · Post by **Nathan K. Hammond** » Sun May 13, 2007 01:48

Here's the picture of Ron's counter-weight.

nkh

low-n-slow · Post by **low-n-slow** » Sun May 13, 2007 15:31

thanks for the picture. I found that the tire has a large flat spot that is causing a severe vibration and out of balance situation. Will be putting a new tire on with new compression springs to see if the problem goes away.

Mnflyer · Post by **Mnflyer** » Sun May 13, 2007 16:44

Hi Jon, you may have this site but here is a good PDF site for the Maule tailwheel
http://www.bowersflybaby.com/tech/Maule_Tailwheel.pdf
Personal I prefer the tension springs to help keep a Maule from shiming you need to differnet springs a heavery duty spring attaches to the fork side and the lighter strength on the other side or the left side.

low-n-slow · Post by **low-n-slow** » Mon May 14, 2007 22:06

Also found that the vertical straightness of the wheel was out wack due to the main leaf spring being twisted. I am currently making a tapered shim to fit on top of the leaf spring to bring in into plumb. I am thinking this was contributing to the problem also. We shall see...

low-n-slow · Post by **low-n-slow** » Tue May 15, 2007 21:49

Ron,

curious about the counterweight that you added to bring your wheel into balance... How did you determine that this was the problem? How did you know when you had added enough weight? did you actually have way to spin balance test it? (Other then going out and trying it)

Thanks
Jon

Ron Babos · Post by **Ron Babos** » Wed May 16, 2007 18:29

low and slow: Take the fork off the spring bracket so you can hold onto the fork area where the bushing normally rides with your hand. Wash grease out of bearings and do not over tighten. Static ballance and then find a way to spin it. I think I stacked washers up until it came into ballance, then made a weight . Don't forget to account for the longer bolt you will use. The length may change a few times until you have everything the way it should be. You will see dramatic before and after results.
Ron