murphy tail wheel

[Phil Stubley]

There has been some discussion lately on the murphy tailwheel survival
or lack of.

I live on a grass strip and have spent a lot of time taxiing (learning?)
for few hours on the Hobbs'.

I overhauled mine at about 40 hrs., and have now rebuilt it at 120 hrs.

There are 2 issues with it in my opinion.

first, the connection from the top of the shaft to the detente collar is
not adequate. Two little rollpins dont survive if you have any rough
use. And that is making sure the bolt is tight, as per bobp. My fix for
that is a 3/32 key horizontally across the top of the shaft and in the
collar. A woodruff key would work but I can't cut one here. After
fitting I just drilled for the bolt, and the pin halves are trapped but
the bolt and the shaft bore.

second is the pin/detent combination. The pin (brass) does not survuve.
My immediate fix is to remove the auto breakout function by removing
the cam follower from the (new) pin, and putting a rollpin further
outboard to manually retract the pin for ground handling.
A possible fix (if I get tired of the manual thing, or the turning
radius is too small) is to make a new collar, with a larger diameter
(2") giving the pin/detent combo a lower load and thus less scuffing
wear.

I have tried it and so far it seems to be not too hard to get it around
on our field. Sure is nice to have positive steering again.

Phil




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