Unimog® is a line of four-wheel drive vehicles that was first introduced in Germany shortly after World War II. These vehicles are still found in agricultural and other civilian contexts, and some militaries also use them. There have been several different vehicle platforms within the Unimog® line, and they all share some general characteristics. Four-wheel drive, ruggedized construction, and high ground clearance are some of the features that have defined these vehicles over the years. These same features have helped many of the vehicles within the line to be useful in a variety of different applications and terrains.
The first Unimog® prototype was built in 1946, which is when the term "Universal-Motor-Gerät" was coined and then shortened to create the official name. These first prototypes were meant to be a new type of tractor with four wheels of the same size like a car or truck, an enclosed cab, and high ground clearance. Most of the design choices that went into the first Universal-Motor-Gerät were utilitarian and meant to allow the vehicles to function in harsh environments. Attachments were designed so that the vehicles could pull loads, and power take-off (PTO) systems were created to operate various farm implements.
In the early 1950s, the first commercially available Unimog® trucks were released. One popular line that was first offered in the early 1950s ultimately remained in production for around thirty years. Though the vehicles remained popular in agricultural settings, the ubiquitous four wheel drive and high ground clearance also made them useful in other civilian and military operations. Since these vehicles can travel across rough terrain, they have been used to fight fires, transport equipment, and clear snow. Some motorsport events that take place in harsh conditions also use Unimog® trucks.
The two main features that Unimog® vehicles tend to share are exceptional ground clearance and all-wheel drive. These vehicles tend to have a higher ground clearance than other trucks of a similar size, which is made possible through devices known as portal gears. Most vehicles have drive axles that are situated in the center of the tires, so the ground clearance can be no greater than the radius of the tires, and is technically less than that due to the size of the axle itself in addition to differentials, transfer cases, and other components. A portal gear is a device that allows the axle to be situated at the top of the wheel rather than the center, which can dramatically increase ground clearance.