Abstract:
An adjustable apparatus for supporting an electronic device within a rack including a fixed rail, a sliding rail, and a latch. The sliding rail is adjustably receivable within the fixed rail. The latch maintains the relative positions of the sliding and fixed rails to define a length of the apparatus that accommodates a dimension of the rack. The fixed rail may be an L-shaped bracket including a plurality of locating points which interact with the latch to maintain the position of the fixed and sliding rails, a plurality of tabs suitable for receiving the sliding rail; and at least one mounting feature suitable for attaching to the rack. The sliding rail may include a mounting feature suitable for attaching to the rack, ribs that interact with the latch, and an attachment point. The latch typically includes a lever body and a tension member to which the attachment point attaches.

Description:
FIELD OF THE INVENTION 
   The present invention relates to the field of rack-mounted devices and, more particularly, the present invention provides an adjustable apparatus to support electronic devices within racks of differing depths. 
   BACKGROUND 
   Electronic devices, including data processing devices such as servers, may be housed in standardized equipment enclosures. Each such enclosure may have an outer, aesthetically pleasing housing that is supported by an inner rack. The rack is a substantially rectilinear metal frame including several vertical columns each provided with a plurality of mounting and alignment openings or holes that permit mounting various devices in the rack. 
   Rails that mount to the vertical members or columns of the rack support the devices or components. The rails are screwed, bolted, or otherwise attached to the rack and the devices are placed on a pair or set of rails. In order to be attached to the rack the length of the rails must conform to the depth of the rack. Commercially available rack systems vary in depth, typically from 18″ to 32″ in increments of 1 inch. Thus a consumer must obtain rails of the correct length or be supplied with rails that can adjust in length to accommodate installation in racks of differing depths. It would, therefore, be desirable to implement an apparatus and system in which the rails can adjust to the depth of the rack. 
   SUMMARY OF THE INVENTION 
   The problems identified above are addressed by an adjustable apparatus for supporting an electronic device within a rack including a fixed rail, a sliding rail, and a latch. The sliding rail is adjustably receivable within the fixed rail. The latch maintains the relative positions of the sliding and fixed rails to define a length of the apparatus that accommodates a dimension of the rack. The fixed rail may be an L-shaped bracket including a plurality of locating points which interact with the latch to maintain the position of the fixed and sliding rails, a plurality of tabs suitable for receiving the sliding rail; and at least one mounting feature suitable for attaching to the rack. The sliding rail may include a mounting feature suitable for attaching to the rack, ribs that interact with the latch, and an attachment point. The latch typically includes a lever body and a tension member to which the attachment point attaches. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the accompanying drawings in which like reference numerals indicate like elements. 
       FIG. 1A  depicts an embodiment of an adjustable support apparatus according to one embodiment of the present invention; 
       FIG. 1B  depicts the features of a fixed rail member of the apparatus of  FIG. 1A  in greater detail; 
       FIG. 2  is an isometric view of the apparatus of  FIG. 1A  as viewed from the inside (device side); 
       FIG. 3  is a top view of an embodiment of a latching mechanism and sliding rail of the apparatus; and 
       FIG. 4  illustrates greater detail of a latching mechanism of the apparatus of FIG.  1 A. 
   

   DETAILED DESCRIPTION OF EMBODIMENTS 
   The following is a detailed description of example embodiments of the invention depicted in the accompanying drawings. The example embodiments are in such detail as to clearly communicate the invention. However, the amount of detail offered is not intended to limit the anticipated variations or embodiments, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention as defined by the appended claims. The detailed descriptions below are designed to make such embodiments obvious to a person of ordinary skill in the art. 
   Generally speaking, the present invention contemplates a mounting rail apparatus that may be adjusted to fit into racks of differing depths. The apparatus typically comprises a fixed rail member with a plurality of locating points and a sliding rail member with a latching mechanism affixed to it. In use, the latching mechanism is unlatched from one of the plurality of locating points, allowing the sliding rail member to move relative to the fixed rail member. When the combined length of the sliding rail and the fixed rail members is appropriate for the rack, the latching mechanism is again latched into one of the locating points, thereby setting and maintaining the rail apparatus at the appropriate length for installation into the rack. The increments of length adjustment possible for the apparatus are determined by the incremental spacing of the locating points. As a result of the design of the apparatus, the adjustment operation may be accomplished by a single operator without the use of tools using only one hand to make the adjustment. Once both mounting rails of a pair or set are adjusted to the length required by the depth of the rack and installed in the rack, the electronic device, which may be a data processing device such as a server, can be set on them within the rack. 
   Turning now to the drawings,  FIG. 1A ,  FIG. 1B , and  FIG. 2  depict an embodiment of an apparatus  100  according to the present invention suitable for creating adjustable rails for mounting an electronic device in a rack.  FIG. 1A  shows apparatus  100  as viewed from the “outside” relative to the rack.  FIG. 1B  also shows apparatus  100  as viewed from the “outside” relative to the rack, but is an enlarged view of the features in the longitudinal center of apparatus  100 .  FIG. 2  shows the apparatus as viewed from “inside” or device side. 
   In the depicted embodiment, apparatus  100  comprises a fixed rail member  102 , a sliding rail member  104 , and an “inch-worm” latching mechanism  106 . Fixed rail member  102  receives sliding rail member  104  while latching mechanism  106  sets and maintains the relative position of fixed rail member  102  and sliding rail member  104 . In this manner the length of apparatus  100  is adjusted to that required to fit into a given rack. 
   In the depicted embodiment, fixed rail member  102  is in the form of an L-shaped beam, comprising a vertical section  103  and a horizontal shelf  114  (which is visible in FIG.  2 ), both of which extend for the length of the member. The preferred embodiment envisions the vertical section  103  and horizontal shelf  114  as formed from the same piece of metal. In another embodiment the two sections  103  and  114  could be produced separately and attached to each other by a fabrication method such as welding. In an alternative embodiment, fixed rail member  102  could have a drawer slide attached to vertical section  103  in place of horizontal shelf  114 . Such an embodiment would advantageously enable the electronic device to be easily pulled out of the rack for service or use. 
   Examining  FIG. 2 , horizontal shelf  114  extends substantially the entire length of fixed rail member  102 . In an alternative embodiment, horizontal shelf  114  could be produced as discrete tabs also formed from fixed rail member  102 . In another alternative, shelf  114  may be produced as a plurality of separate pieces and affixed to fixed rail member  102  by a process such as welding. 
   The depicted embodiment of fixed rail member  102  includes a set of mounting features  108  suitable for mounting fixed rail member  102  to one corner of a rack. Fixed rail member  102  also comprises a plurality of locating points  110  that inter-act with latching mechanism  106  to set and maintain the overall length of the apparatus  100 . Several locating points  110  are visible in  FIG. 1A  where sliding rail member  104  does not conceal them. Fixed rail member  102  also includes a plurality of tabs  112  that receive sliding rail member  104 . 
   Continuing with the depicted embodiment of fixed rail member  102 , it will be appreciated by one skilled in the art that member  102  is implemented as a cantilever beam. In this implementation, the fixed end of the beam is connected to the rack via the set of mounting features  108 . The weight of the electronic device, which may be a data processing device such as a server, rests on shelf  114  (shown in  FIG. 2 ) and is supported by fixed rail member  102  and its attachment to the rack through mounting features  108 . 
   The stiffness of fixed rail member  102 , which determines the amount of weight it can support without excessive deflection, is a function of the height of vertical section  103 . Another factor that influences the stiffness of fixed rail member  102  is the thickness of the material from which fixed rail member  102  is made. In addition, the width of shelf  114  and the modulus of elasticity of the material selected for the member influence the stiffness. 
   In one embodiment, it is envisioned that fixed rail member  102  is made from cold rolled, low carbon steel of a temper capable of being formed as required to produce the design. Other materials, such as aluminum alloys, may be used, but low carbon, cold rolled steel provides advantages of cost, formability, and stiffness (modulus of elasticity) that one skilled in the art will appreciate. The height of vertical section  103  may be established during the design process such that fixed rail member  102  will have sufficient stiffness to support the weight of an electronic device such as a server. 
   In an embodiment wherein fixed rail member  102  is made of steel, it may be plated with a material such as nickel to provide a measure of protection against atmospheric corrosion. Alternatively, fixed rail member  102  may be plated with a lower cost plating such as zinc if a lower measure of corrosion prevention is required. If cost is of primary concern, fixed rail member  102  may be made from preplated steel such as electrogalvanized steel. While this alternative leaves the cut edges of the part unprotected, this may be acceptable in certain commercial applications and provides a significant advantage in terms of cost. The discussion of possible materials and platings of fixed rail member  102  is not intended to limit the anticipated variations or embodiments, but to make clear the advantages of the current invention. 
   In the depicted embodiment, mounting features  108  of fixed rail member  102  are formed as an integral portion of the member. The set of mounting features  108  comprises a plate  109  and two wings  111  and  113 . Plate  109  is at a right angle to the long axis of fixed rail member  102 . Wing  111  is parallel to shelf  114  and extends rearwards (relative to the direction of the rack) at the top distal end  119  of fixed rail member  102 . Wing  113  is parallel to fixed rail member  102  and is offset from it in the lateral dimension outward from fixed rail  102  by plate  109 . Plate  109  includes a circular aperture  144 . In this embodiment, apparatus  100  may be attached to the rack by a fastener inserted through aperture  144 . 
   Mounting features  108  may be formed as integral sections of fixed rail member  102 . In another embodiment, mounting features  108  may comprise a separate set of parts to be attached to fixed rail member  102 . In this manner, different types of mounting hardware may be accommodated by the present invention. 
   Continuing with  FIGS. 1A ,  1 B, and  2 , fixed rail member  102  includes a plurality of locating points  110  which interact with latching mechanism  106  to set and maintain the length of apparatus  100 . As shown in the depicted embodiment, locating points  110  comprise pierced holes, located at regularly spaced intervals along the horizontal centerline of vertical section  103 . This is seen most clearly in  FIG. 2  where locating points  110  are viewed from the device side of apparatus  100 . In  FIG. 1 , several of locating points  110  may be seen where they are not covered by sliding rail member  104 . In other embodiments, locating points  110  may comprise embossed dimples in vertical section  103  of fixed rail member  102 . The precise arrangement of locating points  110  is not crucial to the current invention as long as they match with the geometry of latching mechanism  106 . In one embodiment, locating points  110  are implemented as pierced holes with the protrusion produced by piercing toward the outer side of vertical section  103 . Raised section  133  on sliding rail member  104  clears the protrusions, allowing relative motion of sliding rail member  104  and fixed rail member  102 , while simultaneously providing increased engagement with the latch point  124  of latch lever  116 . Details of latch lever  116  are shown in FIG.  3  and will be discussed later. In an alternative embodiment, locating points  110  may be implemented as simple apertures in vertical section  103  of fixed rail member  102 . Raised section  133  of the sliding rail  104  would not then be required to allow relative motion. 
   The spacing of locating points  110  in the longitudinal dimension determines the gross granularity of adjustment of apparatus  100 . In one embodiment, a spacing of one inch between locating points  110  is envisioned. In other embodiments, other incremental distances could be used, such as spacings which conform to a metric dimension to accommodate rack depths in metric standard measurements. 
   Fixed rail member  102  also includes a plurality of tabs  112 , which receive sliding rail member  104 . In the depicted embodiment, tabs  112  are formed as an integral part of fixed rail member  102  and comprise a horizontal section  115  and a vertical lip  117 . The configuration of tabs  112  is more clearly seen in FIG.  1 B. The height of lip  117  is sufficient to restrain any lateral movement of sliding rail member  104  relative to fixed rail member  102 . In another embodiment, tabs  112  could be produced as separate pieces of material and attached to fixed rail member  102  by a fabrication method such as welding. 
   It will be appreciated by one skilled in the art that fixed rail member  102  may be manufactured from low carbon, cold rolled steel in strip or coil form by stamping and forming. In this process, the outside perimeter of the member is defined by action of stamping stations in what is known as a progressive die set. Forming stations in the same progressive die set form the various features of fixed rail member  102 , such as tabs  112 , shelf  114 , and set of mounting features  108 . While other processes may be used, such as fabricating the individual features and then assembling them by a process such as welding, stamping and forming is an advantageous process in that it is typically a lower cost process than assembling fixed rail member  102  from discrete pieces. 
   In the depicted embodiment, sliding rail member  104  is seen in its position relative to fixed rail member  102 . Sliding rail member  104  is received within the plurality of horizontal tabs  112  on the outside (relative to the electronic device to be mounted in the rack) of vertical surface  103  of fixed rail member  102 . As seen in  FIG. 2  sliding rail member  104  comprises a set of mounting features  135 . In  FIG. 1A , sliding rail member  104  also comprises an attachment point  130  for a tension member  118  of a latching member  106  (discussed in greater detail below), a plurality of ribs  128 , and a raised center section  133 . 
   Mounting features  135  of sliding rail member  104  are visible at the proximal end and outside of apparatus  100  (relative to the position of the electronic device in the rack). Mounting features  135  act in combination with mounting features  108  of fixed rail member  102  (at the distal end of apparatus  100 ) to attach apparatus  100  to the rack. In this embodiment, mounting features of the sliding rail member  102  are typically similar to and compatible mounting features  108  of fixed rail member  102 . 
   In the depicted embodiment, mounting features  135  of sliding rail member  104  are formed as an integral portion of member  104 , and similarly for mounting features  108  of fixed rail  102 . Mounting features  135  comprise a plate  137  that is at a right angle to the long axis of fixed rail  104  and two wings  140  and  142 . Wing  140  is parallel to shelf  114  of fixed rail member  102  and extends forward (relative to the direction of the rack) at the bottom surface of sliding rail member  104 . Wing  142  is parallel to vertical section  103  of fixed rail member  102  and is off set from the body of sliding rail member  104  in the lateral dimension outward from fixed rail member  102  by plate  137 . In an alternative embodiment, wings  140  and  142  may be implemented as cylinders affixed to plate  137 . Said cylinders could be pins, stepped pins, or compression pins which mate with racks having differing mounting hole sizes. Plate  137  includes a circular aperture  144 . Other embodiments of mounting features  135  may be used, dependent upon the requirements of the rack to be used. As an example, circular aperture  144  may take a geometric form other than a circle and need not be the same as aperture  109  of mounting features  108  of the fixed rail member  102  as required by the rack in use. Typically, apparatus  100  is attached to the rack by a fastener inserted through aperture  144  in mounting features  135 . 
   In the depicted embodiment, mounting features  135  are formed as integral sections of fixed rail member  104 . In another embodiment, mounting features  135  may be implemented as a separate set of parts to be attached to sliding rail member  104 . In such a manner, different types of mounting hardware may be accommodated by the present invention. 
   Turning to  FIG. 3 , a top down view of sliding rail member  104  with latching mechanism  106  affixed to it is depicted. Particularly evident in  FIG. 3  is attachment point  130  for tension member  118 . In the depicted embodiment, attachment point  130  is a tab that is fixedly attached to and formed at a right angle to sliding rail member  104 . Attachment point  130  includes an aperture (not evident in the drawings) to which tension member  118  is attached. In another embodiment, the attachment point could be produced as a hook structure which is subsequently attached to sliding rail member  104 . 
   Continuing with  FIG. 3 , ribs  128  are shown in profile in the top down view. Ribs  128  serve to constrain latching mechanism  106  to sliding rail member  104 . In the depicted embodiment, ribs  128  are formed from sliding rail member  104  as a pair of arch shaped structures, which are cut from sliding rail member  104  and formed outward from it. In one embodiment, ribs  128  comprise a pair of structures as described above which contact and constrain opposing pivot arms  122  of latch lever  116 , which will subsequently be described in greater detail. 
   Further continuing with  FIG. 3 , sliding rail member  104  also includes a raised center section  133 . In one embodiment, raised center section  133  is integral to sliding rail member  104  and is produced by displacing the material along the horizontal centerline of sliding rail member  104  outward (relative to the electronic device) by a specified amount. The amount of the offset of raised center section  133  will be seen as determining the engagement of latch point  124  of latching mechanism  106  with fixed rail member  102 . The presence of raised center section  133  also provides a clearance over the protrusion of punched locating points  110  and provides a larger area of engagement with latch point  124 . 
   It will be appreciated by one skilled in the art that sliding rail member  104 , like fixed rail member  102 , may also be produced as a stamped and formed part from low carbon, cold rolled steel. While member  104  could also be fabricated from individual components attached to each other by a process such as welding, stamping and forming provides advantages of cost and simplicity. In the preferred embodiment, sliding rail member  104  may be made of low carbon, cold rolled steel. 
   If made from steel, sliding rail member  104  may be plated with a material such as zinc to provide protection against atmospheric corrosion. Alternatively, sliding rail member  104  may be made from precoated steel such as electrogalvanized steel, if the lack of corrosion protection at the stamped edges is acceptable for the application. In yet another embodiment, sliding rail member  104  may be made from a stainless steel alloy, incurring a cost penalty for the material, but eliminating the need for a subsequent finishing operation. As with fixed rail member  102 , the discussion of possible materials and finishes for sliding rail member  104  is not intended to limit the anticipated variations or embodiments, but to make clear the advantages of the current invention. 
   As has been previously discussed, in the depicted embodiment fixed rail member  102  receives sliding rail member  104  in tabs  112  formed at the bottom surface of fixed rail member  102 , as can be seen in FIG.  1 A. In this embodiment, sliding rail member  104  provides a physical extension of apparatus  100  to connect to the front corner of the rack and, while it is implemented as a cantilever beam, it carries none of the load of the electronic device. 
   In an alternative embodiment, another plurality of tabs could be formed from or attached to the top surface of fixed rail member  102 . This plurality of tabs would typically oppose the plurality of tabs  112  and would contact the top surface of sliding rail member  104  and serve to mechanically couple sliding rail member  104  to fixed rail member  102 . The effect of this mechanical coupling would be to transfer a portion of the weight of the electronic device being mounted to sliding rail member  104 . The force on sliding rail member  104  resulting from the weight of the electronic device would then be transferred to the front corner support of the rack through mounting features  135 . In the alternative embodiment, sliding rail member  104  acts in combination with fixed rail member  102  to form a doubly supported beam with both ends fixed. In this configuration, apparatus  100  could support a heavier electronic device. In another embodiment, a single continuous lip located at the top surface of fixed rail member  102  could be used in place of a plurality of discrete tabs to transfer the weight of the electronic device from fixed rail member  102  to sliding rail member  104 . 
   Now turning to latching mechanism  106 ,  FIG. 3  depicts an embodiment of “inch-worm” latching mechanism  106  in its position on sliding rail member  104  shown in top view. In this embodiment, latching mechanism  106  comprises a latch lever  116  and a tension member  118 . 
   Turning to latch lever  116 , which is shown in profile view from the top in  FIG. 3 , latch lever  116  includes a handling tab  120 , a pair of opposing pivot arms  122 , a latch point  124 , a catch  126 , and an attachment point  132  for tension member  118 . Latch lever  116  is constrained to sliding rail member  104  by ribs  128  that may be formed from sliding rail member  104  and contact opposing pivot arms  122  and by catch  126  which contacts sliding rail member  104 . Opposing pivot arms  122  extend at right angles to the body of latch lever  116 . Tension member  118  provides the force necessary to hold pivot arms  122  of latch lever  116  against ribs  128  and catch  126  against raised center section  133 . 
   As its name implies, latch lever  116  is a lever comprising a rigid bar pivoted on a fixed point and used to transmit force, as in raising or moving a weight at one end, by pushing down on the other. Handling tab  120  is a point at which force may be applied. Attachment point  132  for tension member  118  is the other point to which the force (weight) to be opposed is exerted. Opposing pivot arms  122  form the fixed point upon which the lever rotates. 
   In the depicted embodiment, latch point  124  of latch lever  116  is a point which protrudes through sliding rail  104  at one locating points  110  on fixed rail member  102 . It is located at the end of latch lever  116  opposite to handling tab  120 . In the depicted embodiment, latch point  124  is located at the distal end of latch lever  116 , the end farthest away from the front of the rack. The protrusion of latch point  124  into one of the plurality of locating points  110  prevents relative motion between fixed rail member  102  and sliding rail member  104 , thus setting the overall length of apparatus  100 . 
   Continuing with latch lever  116 , as shown in  FIG. 3 , catch  126  of latch lever  116  contacts raised center section  133  of sliding rail member  104  when latch mechanism  106  is engaged. When latch mechanism  106  is engaged, the insertion of latch point  124  into any of locating points  110  that are integral to fixed rail member  102  sets the gross adjustment of the length of apparatus  100 . The location of the outer surface of raised center section  133  and the placement of catch  126  on latch lever  116  combine to determine the depth to which latch point  124  penetrates into one of the plurality of locating features  110 . 
   Continuing further with latch lever  116 , it is seen that in the embodiment portrayed in  FIG. 3 , handling tab  120  is located at the proximal end of latch lever  116  with latch point  124  at the distal end. Handling tab  120  is formed on latch lever  116  to produce a flat surface parallel to the vertical surface of sliding member  104 . The installer pushes upon handling tab  120  to disengage latch mechanism  106 . In the depicted embodiment, handling tab  120  is shown as an integral part of latch lever  116 . In an alternative embodiment, it may be formed as a separate part and affixed to latch lever  116  by welding. 
   As a further refinement, handling tab  120  may be coated in some colorful, comfortable-to-touch material such as vinyl. Such coating may be done either in a dip process or by the application of a separate handling tab cover. By these means the handling tab is prominently marked as a point to be contacted by an installer, a human factors benefit. 
   Continuing with latch lever  116 , it can be seen in the embodiment pictured in  FIG. 3  that latch lever  116  includes an opposing pair of pivot arms  122 . As the name implies, these arms, which protrude from each side of latch lever  116  in the area of the center of latch lever  116 , act as pivots about which latch lever  116  rotates. Pivot arms  122  are engaged by ribs  128  of fixed rail member  102  and are held in place against ribs  128  by the force applied by tension member  118 . 
   In the depicted embodiment, latch lever  116  includes an attachment point  132  for tension member  118 . In this embodiment, attachment point  132  is a tab formed outward and perpendicular to the flat surface of latch lever  116 . Attachment point  132  includes an aperture into which tension member  118  affixes. 
   It will be understood by one skilled in the art that latch lever  116  is a complex, 3-dimensional part. In the embodiment shown in the accompanying drawings, latch lever  116  is envisioned as a casting. In casting, molten metal is poured into a mold that is a hollow form replicating the negative geometry of the part to be produced. When the molten metal solidifies, the part is produced. The use of a casting process allows the formation of a complex 3-dimensional geometry. 
   The choice of material for latch lever  116  is dependent upon the process to be used and the strength requirements imposed by tension member  118 . A possible material is a zinc alloy, which provides advantages of lower cost over other casting alloys. 
   In an alternative embodiment, latch lever  116  may be produced as a stamped and formed part from cold rolled, low carbon steel. Handling tab  120  is twisted 90 degrees relative to latch lever  116  body in a forming operation to produce the required geometry. Attachment point  132  may be formed from latch lever  116  body as well. Lever arms  122  can be added to the basic stamping in the form of a pin with a larger center section that is press-fit into an aperture in latch lever  116 . The formation of latch lever  116  as a stamped and formed part may provide advantages of cost over a cast part. Electroplating may be done after forming to provide additional corrosion prevention. Similar to fixed rail member  102  and sliding rail member  104 , latch lever  116 , if produced as a stamped and formed part, may be produced from precoated steel such as electrogalvanized steel if bare steel edges are acceptable for the application. 
   Continuing to tension member  118 , the force provided by tension member  118  is balanced by the force of pivot arms  122  against ribs  128  of sliding rail member  102  and catch  126  against sliding rail member  104 . Tension member  118  may be any appropriate material and form which provides the force and deflection necessary to maintain engagement of latch point  124  with one of locating points  110  in fixed rail member  102  and to allow the rotation of latch lever  116  required to engage or disengage latch point  124 . One embodiment of tension member  118  is as a coil extension spring, as shown in FIG  3 . In an alternative embodiment tension member  118  may be in the form of elastic bands which will also provide the necessary force. 
     FIG. 4  depicts an embodiment of apparatus  100  showing latching mechanism  106  in close up view, as viewed from the device side of the apparatus. Latching mechanism  106  is visible on the outside of apparatus  100  with handling tab  120  of latch lever  116  located in the “up” position—displaced away from what would be the inside of the rack. Tension member  118  is also seen, stretched between attachment points  130  and  132 . Latch point  124  is shown protruding through one of locating points  110  in fixed rail member  102 , thus setting the gross length of the adjustable rail apparatus. Catch  126  rests against sliding rail member  104 , preventing over engagement of the latching mechanism. In an alternative embodiment, latch mechanism  106  could be positioned on the inside of apparatus  100  and fixed rail member  102  is received in sliding rail member  104 . Mounting features  108  and  135  are modified to face inward within the rack and horizontal shelf  114  is modified in width to accommodate the increased distance between the pair of apparatus  100 . 
   To adjust the length of apparatus  100 , handling tab  120  is depressed inward toward rails  102  and  104  by the installer, latch lever  116  rotates on pivot arms  122 , and latch point  124  moves out of a particular locating points  110 , allowing fixed  102  and sliding  104  rails to move relative to each other. When a length slightly larger than the desired length of apparatus  100  is reached, handling tab  120  is released and is pulled outward away from rails  102  and  104  by tension member  118 . Latch lever  116  pivots on pivot arms  122  and latch point  124  inserts into another one of locating points  110 . Catch  126  comes to rest against raised center section  133  of sliding rail member  104 . Apparatus  100  is inserted into the rack between front and back vertical posts. Upon insertion into the rack, the length of apparatus  100  decreases by a fine longitudinal movement of sliding rail member  104  relative to fixed rail member  102 . Said fine movement is made possible by the relative length of ribs  128  and opposing pivot arms  122 . Ribs  128  are longer than pivot arms  122 , thus allowing latch lever  116  to move on pivot arms  122  within the length of ribs  128 . Tension member  118  extends to accommodate the relative longitudinal movement of fixed rail member  102  and sliding rail  104 . By means of the relative motion of the two rails,  102  and  104 , after the gross length of apparatus  100  is fixed, fine differences in rack depths may be accommodated, thus allowing fine adjustment of the length of apparatus  100 . 
   It will be apparent to those skilled in the art having the benefit of this disclosure that the present invention contemplates an improved apparatus to create adjustable side rails for a mounting rack. The installation of apparatus  100  requires only one installer to adjust and set the length of the rails without tools. Thus a supplier of a device such as a server is freed from the problem of supplying specific length rails for racks of differing depths which a customer for the device may already own. It is understood that the form of the invention shown and described in the detailed description and the drawings are to be taken merely as presently preferred examples. It is intended that the following claims be interpreted broadly to embrace all variations of the preferred embodiments disclosed.