Typically called "Lifting Decks", the Don-Bur design has been evolving since they first invented them in the late 1980's.
One hydraulic ram is typically located under the chassis which is compressed (and retracted) using an electric power pack located under the main chassis. Electric power can be supplied from either the bay, tractor unit or independent trailer batteries.
The ram is connected to 4 high tensile steel cable ropes which are guided to 4 structural vertical columns on the outside of the body via a number of pulleys.
Each rope travels up the column, over a top pulley and down to a slide plate which attaches the rope to the "floating" upper deck. It is referred to as "floating" because the deck hangs from the 4 top pulleys; a system which allows some limited deck shift without jamming.
Others systems may include any number of hydraulic rams which extend in a synchronised fashion under the deck. In Don-Bur's experience, although cheaper to manufacture, this method of raising an upper deck can be prone to jamming.
Published: Fri 17 Nov 2023
Updated: Tue 09 Jan 2024