Configurations Ī typical full size rack is 42U, which means it holds just over 6 feet (180 cm) of equipment, and a typical "half-height" rack is 18–22U, which is around 3 feet (91 cm) high. The 19-inch rack format with rack-units of 1.75 inches (44.45 mm) was established as a standard by AT&T around 1922 in order to reduce the space required for repeater and termination equipment in a telephone company central office. Although it is called a 19-inch rack unit, the actual mounting dimensions of a 19-inch rack unit are 18 5⁄ 16 inches (18.3125 in or 465.1 mm) wide, center to center. The mounting-hole distance (as shown to the right) differs for 19-inch racks and 23-inch racks: The 19-inch racks uses uneven spacings (as shown to the right) while the 23-inch racks uses evenly spaced mounting holes. Manufacturing allows for dimensions with less precision. If n is number of rack units, the ideal formula for panel height is h = (1.75 n − 0.031) for calculating in inches, and h = (44.45 n − 0.794) for calculating in millimetres. To allow space between adjacent rack-mounted components, a panel is 1⁄ 32 inch (0.03125 in or 0.794 mm) less in height than the full number of rack units would imply. While a rack unit is defined as 1 + 3⁄ 4 inches (44.45 mm), a front panel or filler panel in a rack is not an exact multiple of this height. The standard was adopted worldwide as IEC 60297 Mechanical structures for electronic equipment – Dimensions of mechanical structures of the 482.6 mm (19 in) series, and defines the sizes for rack, subrack (a shelf-like chassis in which cards can be inserted), and the pitch of printed circuit boards/cards providing physical compatibility of technological equipment, typically in telecommunications. The Eurocard specifies a standard rack unit as the unit of height it also defines a similar unit, horizontal pitch (HP), used to measure the width of rack-mounted equipment. The rack unit size is based on a standard rack specification as defined in EIA-310. For example, a typical full-size rack cage is 42U high, while equipment is typically 1U, 2U, 3U, or 4U high. It is most frequently used as a measurement of the overall height of 19-inch and 23-inch rack frames, as well as the height of equipment that mounts in these frames, whereby the height of the frame or equipment is expressed as multiples of rack units. Use unit connectors (PART H) to fasten two shelving units together.A typical section of rack rail, showing rack unit distributionĪ rack unit (abbreviated U or RU) is a unit of measure defined as 1 + 3⁄ 4 inches (44.45 mm). STEP 11 Insert MDF boards (PART E) on to each level, sitting comfortably on the front, back and side beams, and beam ties. Ensure that the tabs are fully bent back, and securely slotted into the front and back beams, and are used on each level of shelf. STEP 10 Slot the beam ties (PART D) into the loops on the inside of the front and back beams (PART C). STEP 9 Repeat steps 7 and 8 to add the rest of the front and back beams (PART C) connecting both sides of the two side frames together, at the same heights as the side beams you have already attached. STEP 8 Slot other end of side beam (PART C) into second side frame at the same height. Knock into place with a rubber mallet if required. STEP 7 Add a long front and back beam (PART C) to upright (PART A) at the same height as the lowest side beam (PART B). To ensure you get it right, use your first frame as a template to get the correct spacing. STEP 6 Repeat steps 1 to 5 to create the second side frame. STEP 5 Continue to add side beams (PART B) to the uprights (PART A) at the preferred shelf heights to create the side frame. For convenience, ask another person to hold the frames in place while you secure them by tapping with a rubber mallet. STEP 4 Join other end of side beam (PART B) into the other upright (PART A) at the same height. STEP 3 Insert a short side beam (PART B) into upright (PART A) at the required level for the lowest shelf. STEP 2 Add second half upright (PART A) to the upright connector (PART F) using mallet. Attach plastic feet (PART G) on to the bases, and upright connectors (PART F) into the tops. STEP 1 Select two half uprights (PART A).
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