Four-wheel drive

However, "four-wheel drive" typically refers to a set of specific components and functions, and intended off-road application, which generally complies with modern use of the terminology.

[2][3] SAE International's standard J1952 recommends only the term "all-wheel drive" with additional subclassifications that cover all types of AWD/4WD/4x4 systems found on production vehicles.

[11] This is often coupled with some sort of antislip technology, increasingly hydraulics-based, that allows differentials to spin at different speeds, but still be capable of transferring the torque from a wheel with poor traction to one with better.

The described system handles extremely well, as it is able to accommodate various forces of movement and distribute power evenly and smoothly, making slippage unlikely.

The development also incorporated Bramah's Pedrail wheel system in what was one of the first four-wheel drive automobiles to display an intentional ability to travel on challenging road surfaces.

Ferdinand Porsche designed and built a four-wheel-driven electric vehicle for the k. u. k. Hofwagenfabrik Ludwig Lohner & Co. in Vienna in 1899, presented to the public during the 1900 World Exhibition in Paris.

The vehicle was a series hybrid car that used an electric hub motor at each wheel, powered by batteries, which were in turn charged by a gasoline-engine generator.

The first four-wheel-drive vehicles to go into mass production were built by (what became) the American Four Wheel Drive Auto Company (FWD) of Wisconsin, founded in 1908.

[23] The early Marmon-Herringtons proved to be the exception to the rule — 4WD cars and trucks developed in the 1930s were mainly built for governments, with (future) warfare applications in mind.

The Timken transfer case was the first part-time design,[25] that allowed the driver to engage or disengage four-wheel drive using a lever inside the cab.

The modern Geländewagen such as the Mercedes-Benz G-Class still feature some of the attributes, with the exception of fully independent suspension, since it can compromise ground clearance.

"Civilian use" may be a bit of a misnomer, as most, if not all, were used by the Soviet government and military (as command cars), but the GAZ-61-73 version is the first four-wheel-drive vehicle with a normal closed sedan body.

Elements of the chassis were used in subsequent military vehicles such as the 1940 GAZ-64 and the 1943 GAZ-67, as well as the postwar GAZ-69, and the properly civilian GAZ-M-72, based on the rear-wheel drive GAZ-20 "Victory" and built from 1955 to 1958.

[30] The American Dodge WC series and Chevrolet G506 4x4 variants were also produced by the hundreds of thousands, as well as the Canadian Military Pattern trucks, of which 4x4s were by far the most prevalent of their various driveline configurations.

All told, North America built about 1+1⁄2 million 4x4 driven vehicles during the war,[31][32][33] Availability of certain critical components, such transfer cases and especially constant-velocity joints affected development.

Produced up to the war by a few specialized firms with limited capacity, from spring 1942, Ford, Dodge, and Chevrolet joined in fabricating these in a quantity more than a 100-fold greater than in 1939.

By contrast, the Axis powers' closest equivalent to the jeep, the VW Kübelwagen, of which only some 50,000 were built, though being equipped with portal gear hubs, only had rear-wheel drive.

Due to the ubiquitous World War II Jeep's success, its rugged utilitarianism set the pattern for many four-wheel-drive vehicles to come.

Not only was it technically innovative, with independent front suspension and the first automatic transmission coupled to 4WD, but also it was equipped and finished as a regular passenger automobile.

American Motors Corporation (AMC) acquired Kaiser's Jeep Division in 1970 and quickly upgraded and expanded the entire line of off-road 4WD vehicles.

Subaru introduced the category-expanding Leone in 1972, an inexpensive compact station wagon with a light-duty, part-time four-wheel-drive system that could not be engaged on dry pavement.

[39] Due to full-time AWD, which relieved the driver of getting out to lock hubs and having to manually select between 2WD and 4WD modes, it dominated all other makes in FIA rally competition.

AMC's Eagles came with the comfort and high-level appointments expected of regular passenger models and used the off-road technology for an extra margin of safety and traction.

[43] The Eagle's thick viscous fluid center differential provided a quiet and smooth transfer of power that was directed proportionally to the axle with the greatest traction.

All these F1 cars were considered inferior to their RWD counterparts, as the advent of aerodynamic downforce meant that adequate traction could be obtained in a lighter and more mechanically efficient manner, and the idea was discontinued, though Lotus tried repeatedly.

[54] One example is the Audi R18 e-tron quattro (winner of 2012 race, the first hybrid/4WD to win Le Mans), using an electric motor in the front axle with the gasoline engine in the rear.

Examples of these with two rear, one front axle are the six-wheeled Pinzgauer, which is popular with defense forces around the globe, and 10-wheeled GMC CCKW made famous by the U.S. Army in World War II.

Prompted by a perceived need for a simple, inexpensive all-terrain vehicle for oil exploration in North Africa, French motor manufacturer Citroën developed the 2CV Sahara in 1958.

Volkswagen Motorsport, with the help of Austrian company Kaimann Racing for the development, used a twin engine Golf Mk2 for the 1985, 1986 and 1987 Pikes Peak International Hill Climb.

Some hybrid vehicles such as the Lexus RX400h provide power to an AWD system through a pair of electric motors, one to the front wheels and one to the rear.