How To Specify an Equipment Chassis; Rackmount Computers

Rackmount Computer Types

The size and shape of an electronic equipment chassis is dictated by a number of factors. The type of card used within the chassis plays a large role, but many of the Board configurations result in the same size case.

Equipment enclosures can be sub-divided into three main categories; Rack-Mount, Tower, or table-top. Any of these types of chassis may be further categorized into either of these sub-categories; Commercial, Industrial, Rugged, or Military. Additional configurations include a Sub-rack which is not a complete electronic enclosure and may only include a metal frame and a card cage. A Card Cage has no enclosure at all and is just a frame [with card guides] to support the particular CCA form factor used.

Rack-Mount chassis are designed to fit inside a rack. The physical size of the rack sets the maximum width of the chassis. The most common rack width is 19", and there are a number of commonly used depths. Listing of Equipment Rack Manufacturers and related gear.

Table-top Industrial Chassis are designed to rest on a table. A table top chassis can be any size or shape, but will almost always have large rubber feet to support the chassis on the table. An Industrial chassis may also include a tilt-stand for raising front of case to some angle.
In many cases equipment chassis are convertible for rack or bench use, by either adding feet for table top use or 19 inch ears for rack mount use. Normally as a table top model is converted to rackmount the feet are removed and rack ears are added so the case will fit in the rack.

When designing a rack mount chassis remember to leave room for any cable bend radius within the rack. The larger the cable, the greater the bend radius.