Jumping Mechanism close-up
A carriage bolt is secured to the bottom end of the spring. The bolt
passes through an over-sized hole in the upper steel arm. The upper portion
(the end with the locking nut) of the carriage bolt slides
in and out as the spring compresses an decompresses.
The rounded head of the carriage lands perfectly on the square
block (attached to the lower steel arm. ) Using a different length Carriage
bolt will determine how far the arm will travel.
This spring was part of a latching mechanism from the
hood of an old pick up truck. It's a fairly stout spring.
Update July 30, 2002
The spring was a good idea, but has been replaced with a bolt.
Since adding the new Bimba pneumatic cylinder I've noticed
great improvement in this mechanism's power.
(The spring was taking a beating and couldn't be trusted.)
The photos above show the new "limiter" bolt.
At left is the linkage at rest. At right is the linkage at full extension.
The bolt passes through the double 1" steel angle bars without any interference.
Adding this bolt will allow me to limit the distance this mechanism
will extend. If allowed to extend fully, the skeleton prop would whip downward
during the last half-inch of the cylinder's stroke.
This is a 1/2" grade 5 hex bolt. I chose 1/2" mainly for strength.
Grade 2 is "soft" and grade 8 is "hard". I chose grade 5 for a few reasons:
Grade 2 may not handle the impact well.
Grade 8 bolts generally have a smooth shank (in this length - 5")
There is a possibility that the Grade 8 bolt may be too brittle
for use with this impact-type arrangement.
This is not to say that I intent to bash this mechanism to pieces.
The nature of this limiter is impact, even at slow speeds and lower p.s.i..