QUOTE (Peter_Harvey @ 30 Mar 2007, 07:37)
<{POST_SNAPBACK}>I have noticed that on allot of exhibition layout that they shunt without any visible means of uncoupling how's this done its as if they can uncouple at will?
Pete
The answer partly depend on which scale you are modelling in.
Kadee and their clones (00) allow delayed uncoupling so you have a magnet (or electromagnet) at a strategic point (e.g. at the entry to a yard) which uncouples two wagons but allows them to be pushed without coupling again. When the wagon being uncoupled is in the desired place the rest of the train is backed away. Microtrains couplers are similar for N.
There are various kit and DIY solutions for various scales such as Alex Jackson (DIY), Dingham, B&B, DG. A google search should be fruitful with any of those terms and the manufacturers wedsites will explain better than I can.
DCC controlled uncoupling is also possible but it would be expensive to fit every item of rolling stock.
There's also the humble uncoupling ramp for Peco style and tension lock couplers. This is much more limited in scope since any attempt to propel the stock will cause it to couple up again.
Andrew