Frequently Asked Questions

What is a Rack?

• Open frame racks are structures onto which equipment is mounted using screws, cage nuts, or other mounting hardware.
• Most rack-mounted electronic equipment have mounting widths of 19” (483 mm) or 23” (584 mm).
• Common uses include server, telecom, broadcast video, lighting, audio, and scientific lab equipment. 
• When equipment does not have the provision to be rack mounted, Hammond Mfg has many other options / accessories to help secure that equipment to the rack.  ie. shelves.

What is a Rack Unit (RU)?

• A rack unit is the unit of measure that the rack industry uses to define vertical space. Often referred to as the number of “U” or “RU” to describe the mounting height of a rack or cabinet.
• 1U = 1¾ inches (44.45 mm) in height. Example: A customer may ask for a 44U rack.
• Rack units are often indicated as a number and/or as a marking.
  
  

Mounting Types

• Equipment can be mounted to racks and cabinets in various ways. There can be;
  • tapped rails,
  • round hole and
  • square hole rails.
• It is important to confirm with your customer, what type of mounting rails they require.
• Typically, open racks come with tapped  holes, whereas larger cabinets meant for heavy servers come with square holes for cage nuts.

Mounting Hardware

• Rack screws are used to attach equipment directly to the tapped rack rails. There are several sizes of screws available, but 10-32, 12-24 and M6 are the most common. 
• Square (cage nut) or round (clip nut) holes on rack rails, require the nut plus a screw in order to secure equipment to the rail.   
• With square mounting holes, the screws connect to a removable cage nut placed in the required location on the rail.
• With round holes, the screws thread into a removable clip nut that is placed in the required location on the rail.