Transfer Trucks

Normal

In this picture you can see how the truck and trailer are hooked up normal.

Here the truck is back up to the "rails" on the trailer and it acts similar to train tracks guiding the "can" into the dump bed.

Here is how the "Can" is locked down and ready to dump.

Here is the dump. After this you just reverse all of the steps and then you are ready to roll again.

One of the main advantages of using a transfer truck is that you can haul more material per trip and still maintain the maneuverability on the job site when it matters.
The only drawback to this is "transfering" takes time. Although it does save you time in total amount of trips throughout the day. Often times If the total trip is over 20 minutes away these are often more cost effective.
These help and are extremely useful when paving parking lots. Because they have a shorter wheel base than super 10s