How to Design an Equipment Chassis

I produced a section of pages back in 2005 relating to Electronic Equipment Chassis Design.

The attached pic shows total page hits for that section from the middle of 2006 on, and the top 10 producing pages. Although it says 86 URL's, there really are only 42 pages. Looks like the section get about 50 to 150 page views a week. With about 16,000 page views in 2007.

Any way I'm out up-dating the search bar on those pages and notice [again] that a number of pages have no page rank any longer. I posted a related entry in the main blog "pages losing ranking". Looks like about 10 pages no longer have a page ranking from Google. Here are those page links:
Equipment Racks Shelfs.
Equipment Rack Casters.
Panel Meter Manufacturers.
Equipment Chassis Slot Keying.
Chassis Connector Types.
Elapsed Time Indicates.
Rack Mount Environmental Alarm Manufacturers.
Chassis Cable Assemblies.
Electronic Terms for Equipment Chassis.
Page two of Chassis Terms.

The only thing I can figure is that because these pages get so few page hits, that they lost their page rank. Internal Pages point to them, and via the sitemap, external pages point to them. And now this blog points to them.

These pages help to round out the How-to section, so I don't really mind that they my be getting just a few page views. I would rather have the page there for someone than not have it...