As stated, you won't find them on the web.
Your best bet is the ARHS. They have a Railway Resource Centre at Redfern which has a wide collection of old timetables.http://www.arhsnsw.com.au/resource.htm
The Australian Association of Timetable Collectors has a number of members who have their own collections of timetables. There is no one place you can go to look at them, although there are plans to establish a timetable library at some stage in the future.
Occasionally old timetables can be found for sale on ebay.
If you have a specific query it might be better to post it in the NSW forum.