Before installing the T640 router into an open-frame rack, you must first install the large mounting shelf on the rack. If you are front-mounting the router, you must remove the center-mounting brackets from the chassis. In an open-frame rack, center-mounting is generally preferable to front-mounting because the more even distribution of weight provides greater stability. The small mounting shelf and the spacer bars are not needed.
To install the mounting hardware for an open-frame rack (see Figure 1):
The router is shipped with each spacer bar attached to the rear of each front-mounting flange. Remove each spacer bar by removing the screws that fasten the spacer bar to the front-mounting flange.
Front View of Router Chassis shows the front-mounting flanges.
Figure 1: Installing the Mounting Hardware for an Open-Frame Rack

Table 1 specifies the mounting holes in which you insert the mounting screws (an X indicates a mounting hole location), and cage nuts if needed. The hole distances are relative to one of the standard U divisions on the rack. For reference, the bottom of all mounting shelves is at 0.04 in. (0.02 U) above a U division.
Table 1: T640 Open-Frame Rack Mounting Hole Locations
Hole | Distance Above U Division | Large Shelf | |
|---|---|---|---|
59 | 34.13 in. (86.7 cm) | 19.50 U | X |
53 | 30.63 in. (77.8 cm) | 17.50 U | X |
50 | 28.88 in. (73.3 cm) | 16.50 U | X |
44 | 25.38 in. (64.5 cm) | 14.50 U | X |
41 | 23.63 in. (60.0 cm) | 13.50 U | X |
35 | 20.13 in. (51.1 cm) | 11.50 U | X |
32 | 18.38 in. (46.7 cm) | 10.50 U | X |
31 | 17.75 in. (45.1 cm) | 10.14 U | X |