Rack Shelf Description
A rack shelf is normally used when slide rails are not used. The chassis or gear is supported in the equipment rack by the shelf and not by any slide rails. A rack shelf runs the entire width of the rack. However the depth may be selected based on requirements. |  Rack Slide Shelf |
Instead of installing a rack shelf two 'L' brackets may be used which support the chassis on either side of the rack. The 'L' brackets allow air flow up the center of the rack into the chassis while the rack shelf does not, it blocks all air flow up the center of the rack forcing air to the sides of the rack.
Equipment shelf's may either be fixed Shelf or movable, in which case it would use a Ball Bearing style shelf with Slide Rails, as shown in the drawing. The sliding shelf may have a recess to hold a keyboard or laptop computer screen. Regardless of actual final shape, a fixed shelf or sliding shelf will be another option when order an equipment rack. An L bracket is a partial shelf.
The important aspect of rack design besides adding a shelf is that a shelf will block air flow to any equipment above the shelf. To over come the air flow issue the shelf can be made perforated and not a solid metal plate. In addition the shelf could be half depth and not block the entire internal area of the rack. Otherwise the only air flow will be up the side of the rack, bypassing the equipment entirely. Normally a shelf will be placed 2/3 or half way up the rack, blocking any air flow to the equipment above.
Shelf Manufacturers
General Devices {Rack Shelf, L Bracket, Chassis Support}
Index page; How To Write an Equipment Chassis Specification
