Standard DC rack rail distance, front to back question

Thu Apr 27 18:13:11 UTC 2023

A bunch of devices (eg Juniper MX240) come with a "small mounting shelf" —
see Figure1, Figure 2 at
https://www.juniper.net/documentation/us/en/hardware/mx240/topics/topic-map/mx240-installing-the-router.html#id-installing-the-mx240-router-mounting-hardware-for-a-rack-or-cabinet

Their theory is that these get mounted on the "back" of the front rail, and
it supports the weight of the chassis. I generally just put these on the
font of the rear rail, and rest the back of the router on that. Seems to
work well - the chassis is narrow enough to slide if the cabinet is very
shallow, and the shelf is usually wide enough to deal with deeper
cabinets...

The other option is "Universal Rails" (AKA "those funny sort of L bracket
half shelf thingies") — e.g:
https://www.cablesandkits.com/racks-cabinets/rack-mount-shelves-and-rails/rackmount-rails/ck-rckmntrls/pro-18146

W

On Thu, Apr 27, 2023 at 10:03 AM, Mel Beckman <mel at beckman.org> wrote:

> We use shelves rather than hanging all the weight of racked gear on the
> ears. That rarely works well, but a 4-post shelf for every half-dozen or so
> devices works wonderfully. These shelves are usually quite adjustable.
>
>  -mel beckman
>
> On Apr 27, 2023, at 6:54 AM, Chuck Church <chuckchurch at gmail.com> wrote:
>
> 
>
> Hey all.  Question about standard 4 post racks.  We bought some that are
> adjustable.  Unfortunately, the posts are very flimsy, as these are some
> fancy cabinets with spacing on the sides for vertical patch panels, etc.
> We found that 2 post mounting of most Cisco devices (namely Cat 9500 1RU
> switches) are sagging quite bad.   We’re used to the new server type rails
> that extend to support most reasonable distances front rails to back for 4
> post mounting.  However, for a Cisco ASA1001, there aren’t rails, but
> rather front and back ‘ears’ you use to hit both front and back posts.
> These would appear to not have any adjustability, the front to back post
> distance would seem to need to match the ears, I assume they don’t adjust
> placement on the router much.  Is there a ‘standard’ distance between front
> and back rails that devices usually adhere to?  Googling didn’t find an
> answer readily.  These are 19” wide cabinets by the way.
>
>
>
> Thanks,
>
>
>
> Chuck
>
>
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