This roller coaster (also usable as a "normal" coaster) functions
fully automatic and without clock.

Functionality:

If you put a certain item into the crate (here: Redstone) it will be automatically 
issued a lore and started 5 seconds later. At the end of the track 
the lorry drives against a cactus and drops, by a before it 
the hopper, the trolley is automatically collected and transported to the 
Start point moved back. Since the dispensers via the Loren dispensing system 
with signals, you can even save the clock if you use 4-5 
Loren into the system.

Instructions:

First we build a customs station to handle the payment. Important 
here is that you rename the items in the upper funnel at the anvil so that 
you can really only use a certain item (except of course the item in the first slot!). Who would like to make the track usable for free can instead of the customs office also simply a 
Use switch.

In both cases, a thrower must be placed over the first rail of the lane. 
be, this, of course, must be an accelerator track. Behind the 
Accelerator rail MUST be a solid block so that the trolley can 
the launcher is placed on the rails then can also start when the 
Signal comes 5 seconds later. 

Under the last track comes a hopper to collect the trolleys and 
directly behind it a cactus so that the lorries also drop and back again 
into the system.

The routing itself is up to you, I have only provided an example here.

In the pictures you should be able to see everything quite well who needs help 
may as always with pleasure announce themselves ;)


Customs office:



Thrower from behind:


Top View:


Repeater to delay the start:



View of the starting point in operation:




Development platform: XBox360 (Screens in PE on Android)