"Jon Elson" wrote in message ...
wrote:

On Saturday, March 18, 2017 at 12:51:08 AM UTC-4, wrote:
A friend of mine has a Bridgeport knee mill making a
loud clicking or
knocking sound in the head. I could not find any obvious
reason. So I
sorta just said sorry man I can't find anything. Well
about 2 weeks later
Karma I guess, I have a large Jet knee mill 3 phase
started doing the
exact same thing.So I am telling myself the same thing,
(sorry man can't
find anything ). Has anybody got info as to a guess what
it is ? I am not
a machinist just a hobbiest. Thanks for any input you
might offer.

On top is the lever arm that rotates a ring with two
grooves at an angle in which there are pins
attached to the part that engages the low range
gears. When the lever is moved to high range
these pins pull up on the engagement cogs for
low range. These pins can work loose enough that
the cogs are not fully disengaged in high. That's
the rattle you hear, the cogs hitting each other
ever so slightly.
phil k.