I am working with some 20 year old HP 19 inch equipment racks (HP
29402 B/C) into which I will be installing some test equipment.
Would like to find a source for the special spring-loaded nuts used
to attach the horizontal angle brackets which support the equipment.

These nuts are designed to fit into one of four channels (or slots)
which run vertically the entire height of the rack (one channel in
each corner of the rack). Haven't used these types of nuts in years
but recall they used to be quite common.

Will attempt to describe them. Draw a rhombus approximately 0.7 by
0.4 inches. This rhombus is made of metal and extends into the paper
about 0.15 inches. Next draw a hole in the center of the rhombus
which is tapped to fit a 1/4x20 screw. Lastly draw a coil spring
slightly larger in diameter than the hole and which has one end
welded to the face of the rhombus and extends vertically out from the
paper about 0.5 inch. This spring is centerd on the hole.

The channel opening is only slightly larger than 0.4 inches but its
interior widens to about 0.7 inches. These nuts are inserted into the
slots along their narrow dimension (0.4 inch) and then twisted 90
degrees so the lip of the channel prevents then from being pulled out.
The sping holds them in place while the bracket screws are being
screwed into them.

Lyman