Heavy Duty Racks
A & J Manufacturing Company offers a heavy duty electronic equipment rack-cabinet, Series 159, with a large variety of equipment installation kits. These basic installation kits are shock and vibrations qualified and are also interchangeable among the light duty and medium duty rack-cabinets. The standard heavy duty rack-cabinet is 72 inches height, 24 inches wide, and 26 inches deep with a full top and bottom panel and is of modular bolted together construction. The bottom panel has four (4) cutouts, one near each corner, to facilitate bolting the cabinet to a foundation. The 159 Series rack-cabinet uses the A & J 9000 extrusion that has a heavy duty section modulus, approximately four times greater than the medium duty rack-cabinet.
The 159 Series section modulus enables the open frame rack to support a 560 pound payload successfully at 50Hz and at a transmissibility of 2.75 to 1. The heavy duty cabinet has been successfully qualified with a 900 pound payload at 33 Hz. Both enclosures have also been successfully shock qualified in accordance with MIL-S-901
The successful performance of the rack/cabinet with these payloads can best be achieved if the center of gravity (CG) can be maintained dimensionally at or below the middle of the rack and about the center axis.
The rack/cabinet has two (2) front RETMA Bars, which have the standard EIA panel mounting hole pattern and a vertical T-Nut slot. Two (2) backup bars containing the T-Nut slots are located in the rear. A rear EIA hole pattern is optional. A & J uses the four (4) T-Nut slots for the majority of the Kit mounting interface to the rack-cabinet. The T-Nut slot dimension from front to rear and side to side are maintained throughout the standard lines of light, medium, and heavy duty rack-cabinets to facilitate the interchangeability of kits (See Section V Alphabetical and VI Numerical for kit number and features). The use of the T-Nut slot provides infinite vertical adjustment without the necessity of drilling mounting holes in the rack/cabinet. The RETMA Bar EIA holes have stainless steel threaded inserts that may be removed and replaced when the insert becomes stripped or worn. A continuous integral EMI/RFI gasket groove is contained in all frame members, RETMA Bars, and backup bars, which enables the rack-cabinet to be configured at anytime to meet this requirement. The heavy duty design has been shock and vibration tested in the open rack and enclosed cabinet configurations.
When the rack is configured as an enclosed cabinet, the inner panel side to side dimensions are 19.12 inches and may be used as an equipment kit mounting surface. The inner wall may be used as a plenum wall for circulating air and may be configured with air supply cutouts as required.
An X-Brace is not required for the heavy duty 159 Series racks and cabinets and is not included. If the rack or cabinet payload distribution is maintained as suggested, a deck mounted and free standing configuration without sway bracing can be achieved. A clear area of three-tenths (.3) inch should be maintained all around the rack for free excursion under potential shock conditions. If there are racks or other cabinets adjacent, they should be fastened together at the top, using an A & J Joining Kit. Five eighths (.625) inch diameter CRES high strength bolts should be used when mounting or installing the rack on a foundation. If the weight distribution results in a higher center of gravity or excessive payload, a sway brace should be considered. When the fragility of the electronic components demand shock and vibration attenuation, the heavy duty rack may be configured for an isolation system.
The bolted-together construction provides the capability of disassembly of the rack/cabinet for passage through narrow openings and passageways and around tight corners. The rack-cabinet may be reassembled and still maintain its original structural integrity. When reassembling the rack-cabinet, the following type tools and torque values should be observed together with an application of component adhesive to the joining bolts.
|Bolt Size||APEX Tool Number||Torque Value(Inch Pound)||Adhesive Type (or Equivalent)|