please help me sleep at night and tell me what they are 
well someones gonna tell i,m wrong but it s a walking floor trailer instead tipping trailer i.e chuck the rubbish in the floor is like a escalator it kinda walks the rubbish ,paper woodchip or what ever out instead of tipping the thing up and risking it falling over ( wait for it )
eyup Neil.
A walking floor is a series of planks, alloy or steel which are linked to a crank in a trailer which shuffles the load to the back. Bulk Refuse lorries sometimes use it or even box vans with pallets.on airfreight. Its not like a rooler bed where the load runs on wheels, the floor actually moves in short jerky movements, 
The refuse lorries can unload on a soft site without tipping the body up and dont fall over.
You dont need one on your job
Exactly what it says on the tin!
A walking floor trailer has a moving floor which helps the unloading process,
A good example is a company I know moves wood shavings, And a walking floor trailer is used, So they don’t need tipping trailers and its more stable than a tipper, you don’t need a flat surface to unload like you would with an artic tipper.
There are many uses for a walking floor, and there are loads of different designs, I have seen a conveyor belt design and a load of slats that move towards the back of the trailer a few inches, as it moves it raises the slats up which has the effect off moving the load, Then as it goes back it is flat, then again it raises up and moves backwards until the load is off.
Hope this answers your question. 
many thanks gentlemezzzzzzzzzzzzzzzzzzzzzz
Walking floor trailers are the best ever threat to use if you get stuck with a long wait at an RDC, offer to tip yourself. Just open the doors, switch it on and drive forward slowly, watch the pallets tumble out the back as you go 
(They dont really work that well, a pallet always twists and jams!!!)
There you go…a piccy of me and my walking floor 
Bully
Thats enough to frighten the bairns away Bully hahahahaha 