Individual-wheel drive (IWD) is an

automobile design Automotive design is the process of developing the appearance (and to some extent the ergonomics) of motor vehicles, including automobiles, motorcycles, trucks, buses, Coach (vehicle), coaches, and vans. The functional design and development o ...

in which the

vehicle A vehicle () is a machine designed for self-propulsion, usually to transport people, cargo, or both. The term "vehicle" typically refers to land vehicles such as human-powered land vehicle, human-powered vehicles (e.g. bicycles, tricycles, velo ...

has an

all-wheel drive An all-wheel drive vehicle (AWD vehicle) is one with a powertrain capable of providing power to all its wheels, whether full-time or on-demand. Types The most common forms of all-wheel drive are: ;1x1 : All unicycles Reflects one axle with ...

powertrain In a motor vehicle, the powertrain comprises the main components that generate engine power, power and deliver that power to the road surface, water, or air. This includes the internal combustion engine, engine, transmission (mechanics), trans ...

that consists of multiple independent

traction motor A traction motor is an electric motor used for propulsion of a vehicle, such as locomotives, electric vehicle, electric or hydrogen vehicles, or electric multiple unit trains. Traction (engineering), Traction motors are used in electrically powe ...

s each supplying

torque In physics and mechanics, torque is the rotational analogue of linear force. It is also referred to as the moment of force (also abbreviated to moment). The symbol for torque is typically \boldsymbol\tau, the lowercase Greek letter ''tau''. Wh ...

to a single

drive wheel A drive wheel is a wheel of a motor vehicle that transmits force, transforming torque into tractive force from the tires to the road, causing the vehicle to move. The powertrain delivers enough torque to the wheel to overcome stationary forc ...

. The term was coined to identify

electric vehicle An electric vehicle (EV) is a motor vehicle whose propulsion is powered fully or mostly by electricity. EVs encompass a wide range of transportation modes, including road vehicle, road and rail vehicles, electric boats and Submersible, submer ...

s with a four-motor

layout In general terms, a layout is a structured arrangement of items within certain limits, or a plan for such arrangement. Specifically, layout may refer to: * Page layout, the arrangement of visual elements on a page ** Comprehensive layout (comp), ...

, where each wheel is driven by an individual

electric motor An electric motor is a machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a electromagnetic coil, wire winding to gene ...

, as opposed to the differential

drivetrain A drivetrain (also frequently spelled as drive train or sometimes drive-train) or transmission system, is the group of components that deliver mechanical power from the prime mover to the driven components. In automotive engineering, the driv ...

seen in conventional

four wheel drive The Four Wheel Drive Auto Company, more often known as Four Wheel Drive (FWD), was a pioneering American company that developed and produced all-wheel drive vehicles. It was founded in 1909 in Clintonville, Wisconsin, as the Badger Four-Wheel Dr ...

(4WD) ICE vehicles and the dual-motor 4WD design seen in many

plug-in electric vehicle A plug-in electric vehicle (PEV) is any road vehicle that can utilize an external source of electricity (such as a wall socket that connects to the power grid) via an detachable power cable to store electrical energy within its onboard rechar ...

Characteristics

These vehicles inherently have a range of characteristics built-in that can exceed the level of control commonly attributed to

four-wheel drive A four-wheel drive, also called 4×4 ("four by four") or 4WD, is a two-axled vehicle drivetrain capable of providing torque to all of its wheels simultaneously. It may be full-time or on-demand, and is typically linked via a transfer case pr ...

vehicles or vehicles with extensive control systems. These characteristics may include: * Precise individual control of torque to each wheel * Anti-skid * If one motor fails, the other motors are powerful enough to drive the vehicle to the nearest repair shop * Easier replacement of motors * No – possibly long and heavy – drive shafts, no central gear box and no mechanical differentials or lockers, reducing vehicle weight, reducing or eliminating transmission losses and simplifying its construction * On the spot, zero-radius turning like a tracked vehicle by rotating the drive-wheels in opposite directions * On the fly switching between

front-wheel drive Front-wheel drive (FWD) is a form of internal combustion engine, engine and transmission (mechanics), transmission layout used in motor vehicles, in which the engine drives the front wheels only. Most modern front-wheel-drive vehicles feature ...

rear-wheel drive Rear-wheel drive (RWD) is a form of engine and transmission layout used in motor vehicles, in which the engine drives the rear wheels only. Until the late 20th century, rear-wheel drive was the most common configuration for cars. Most rear-whee ...

and

drive configurations The motors that are used in these vehicles are commonly

wheel hub motor A wheel hub motor, hub motor, or in-wheel motor is a motor that is incorporated into the Wheel#Hub, hub of the wheel. Wheel-hub motors are commonly found on electric bicycles. Electric hub motors were well received in early electric cars, but ha ...

s, since no transmission components are then required. Alternative layouts with inboard motors and drive shafts are also possible.

Hydraulic wheel drive

Hydraulic wheel drives share many of the same features as an electric wheel drive. They also lack the need for a central gear box, mechanical differentials, drive shafts, and provide on the fly switching between front, rear and all-wheel drive. Hydraulic individual wheel drives are standard in various machines, such as

zero-turn mower A zero-turn riding lawn mower (colloquially, a ''z-turn'' or ''zero turn'') is a standard riding lawn mower with a turning radius that is effectively zero when the two drive wheels rotate in opposite direction, like a tank turning in place. D ...

s, multi one lifts / front end loaders, and

forklift A forklift (also called industrial truck, lift truck, jitney, hi-lo, fork truck, fork hoist, and forklift truck) is a powered industrial truck used to lift and move materials over short distances. The forklift was developed in the early 20th c ...

s. Hydraulic drives are primarily found in machines that serve uses which benefit from the ability to "turn on a dime", i.e. with an exceptionally short

turning diameter The turning radius (alternatively, turning diameter or turning circle) of a vehicle defines the minimum dimension (typically the radius or diameter) of available space required for that vehicle to make a semi-circular U-turn without skidding. Th ...

, and move between forward and reverse modes without shifting gears, such as lawn mowers and loading equipment.

Examples

Quad-motor

* Rivian R1S * Rivian R1T * Zeekr 001 FR * Yangwang U8 * Yangwang U9 * Mengshi 917 * Lotus Evija * Rimac Nevera * Mercedes-Benz G 580 with EQ Technology * Jetour Shanhai T7 * Lightyear 0

Tri-motor

* Tesla Cyberbeast – The tri-motor version has individual motors on the rear wheels and a third motor shared between the front wheels.

References