Powerpack (drivetrain) in the context of "Hydraulic modular trailer"

A hydraulic modular trailer (HMT) is a platform trailer unit that features swing axles, hydraulic suspension, independently steerable axles, two or more axle rows, compatibility to join two or more units longitudinally and laterally, and uses a power pack unit (PPU) to steer and adjust height. These trailer units are used to transport oversized loads, which are difficult to disassemble and are overweight. Trailers of this type are manufactured using high-tensile steel, which allows them to support heavy loads. They are operated by one or more ballast tractors that push or pull the trailer using a drawbar or gooseneck connection. This tractor-trailer arrangement is commonly referred to as a heavy hauler.

Typical loads include oil rig modules, bridge sections, buildings, ship sections, and industrial machinery such as generators and turbines. Also, militaries use HMT for tank transportation. There is a limited number of manufacturers who produce these heavy-duty trailers because the market share of oversized loads is very thin when we talk about the overall transportation industry. There are self-powered units of hydraulic modular trailers, which are called Self-propelled modular transporters (SPMTs), which are used when the ballast tractors are unable to be used due to space.