The cask filling is not the most glamorous stage in whisky production, but it is one that takes place at every distillery you are likely to visit. Whenever we've seen it done it's been a manual process, with casks manouevered by hand to an area below the raised spirit receiver (or vat). The spirit is then fed via pipes into the cask. When full, a bung is fitted in place and the cask moved off to the warehouse to begin the slow process of becoming Scotch whisky.
As is obvious from the photographs on this page, cask filling is a process that varies in its detail and setting from distillery to distillery. It is also one that some distilleries steer visitors clear of on health and safety grounds.