I get the feeling that your references point to two different concepts.
I haven't been able to figure out how the 'bakken met snellopers' work (yet), but I think that in the second example, 'snelloper' refers to a rolling door, i.e. a 'snelloopdeur' or 'snelroldeur':
http://www.novospeedsolutions.com/producten/snelloper.php
=> "De snelloper is geschikt in situaties waar klimaatbeheersing, hygiëne en geluidsisolatie van belang zijn."
They are commonly used in coldstors/chillers etc.:
http://www.labex.nl/koel-en-diepvries/
In your example, the pallets have to pass through a 'sluice' (invoersas) before entering the cold room via the 'snelloper'.