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After reading the LML comments, and talking to Jim
Rogers yesterday, this is what I remember about these torsion
springs.
The design was not for appearance purposes, but to produce a
system to replace the tension springs which are folded and
crushed in the retracted position.
The first torsion springs were wound into to a coil to
small so that when loaded they gripped the over-center link boss on the
gear leg bending the spring.
Next, the wire material would loose tension and on some the
tang that connected to the gear leg would break off.
The current spring is 3.5 coils of .135" 17-7SS,
with a relaxed coil ID of .935".
Looking back through the manuals and Supplement we
showed a WS-6 washer on each side of the HF6 over-center link bearing
in the old manuals, and a AN970-6 washer on the aft side of the
bearing with a WS-6 forward, in newer manuals and the Supplement, either
arrangement is ok if there is sufficient clearance. A WS-6 is
nothing special, just a washer with a little larger OD than
a AN960 and smaller than a AN970.
One of the problems involved the length of the gear leg
boss. Some of the older gear had bosses were shorter than .610" in those
cases a washer aft of the bearing might bind the spring, if that is the case
don't use a washer, let the bearing retain the spring.
However you do it, make sure the spring is free to bend in the
coils, without binding, and it will apply about 19 lbs to the
link when pre-loaded 90 to 95 degrees.
Finally the spring can't force the gear down,
fortunately, gravity is pretty reliable, but, once down, the spring
will hold the link in the over-center position.
This is probably more than any one wanted to know about these
springs, but since it was March 1995 when we first worked with a spring
manufacturer, it's surprising to see this much interest 10 years
later.
Ross Connell
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