Hi,
I love this set and have modified it so all the functions are now remote controlled. It uses the following parts:
2 SBricks and 1 battery box. 1 SBrick is in the cab of the lorry and the second SBrick is mounted on the trailer.
1 XL motor to provide the drive
1 Servo motor for steering
1 Large motor for moving the upper level on the lorry
1 Medium motor for the front ramps on the trailer
1 Large motor for the rear ramps on the trailer
1 Large motor for moving the upper level on the trailer
I have also added an extra function of a winch behind the cab of the lorry using a medium motor. This allows cars to be pulled onto the lower level.
You can see the functions in action on this video: