dave_anderson

My Feedback: (47)

Hello Fellas,

I'm getting to the final stages of my TF P-51 1/5 scale and discovered an issue with my tailwheel retract. Forgive me if this is brought up somewhere else on RCU, but I couldn't find anything on it.

The tailwheel retracts just fine, but when trying to extend it, the mechanism 'sticks'... doesn't budge. If I apply a very slight manual pressure, helping it get moving, there’s a slight click then it extends with a vengeance. Is it possible the cylinder retracts too far and is over center? It seems like I manually get it off the stop and it works.

Would air tool oil work to give it some lubrication?

Have any of you experienced this?

The doors aren’t a factor as I have them taped out of the way and they aren’t touching the gear at all.

Thanks in advance.

Chad Veich

My Feedback: (60)

I have the same issue with my .60 size Robart mechanical tail wheel units and, as you suppose, they are getting too far over center. On the small units it is easy to add a stop to the retract unit to mechanically prevent the arm from going too far over center. Not sure if that is an option with your pneumatic retract but may be worth checking into. Good luck!

prop wash

Dave are your retracts new?
Tom

dave_anderson

My Feedback: (47)

Yes they are.

hydrolazer

mine was doing the same thing on the same mustang...it was hanging up a bit on the wooden frame inside...i got a small file and filed it down a hair and problem solved.

Lnewqban

Try contacting Robart:

http://www.robart.com/contact-us

dave_anderson

My Feedback: (47)

I called Robart and the gentleman there suggested I take the unit out and see if it works without being mounted (as if the frame was twisted). I did, and it did the same thing. I disconnected the cylinder and tried again, still stuck. When the cylinder is bottomed out in the 'up' position, the cylinder is sticking. maybe the seal is bad or scored in some way. I tried putting a little mystery oil in there and it didn't help. I have ordered a new cylinder from Robart. Hope this helps. I would send it in, but I don't want to wait and I probably voided the warranty anyway by taking it apart.

Ah, just had a thought. Going to swap the seals inside the actuator.

dave_anderson

My Feedback: (47)

Nope. Cylinder seals are different on each end.

When I retract the cylinder all the way, then try to extend it by gradually adding pressure. It doesn't budge until 60 psi. when in the plane I can shoot 100 psi out of the onboard tank and it wont move. There is an odd series where it will work, but only for a few cycles, then it sticks again.

Hope the new cylinder does the trick.

Lifer

My Feedback: (1)

My addition to an old thread: My tailwheel on a Tarheel Hal P-47 had the same problem with the tailwheel sticking in the "up" position. I cut a piece of 1/4x1/8th brass stock to span the area across the opening where the arm retracts into the tailwheel structure. I glued it in with JB Weld and this only allows the gear to retract about 3/4th of it's normal travel. On this plane it is enough to hide almost all of the tailwheel and no further sticking in the up position. My apologies for bad photography.

warbirdav8r

My Feedback: (11)

try adjusting the threaded rod out of the clevis and cylinder to make it longer. If it is longer it wont pull the wheel so far past center..and it should come down better. Dave.