Individual wheel drive

Individual-wheel drive (IWD) is an automobile design in which the vehicle has an all-wheel drive powertrain that consists of multiple independent traction motors each supplying torque to a single drive wheel.^[1] The term was coined to identify electric vehicles with a four-motor layout, where each wheel is driven by an individual electric motor,^[2]^[3] as opposed to the differential drivetrain seen in conventional four wheel drive (4WD) ICE vehicles and the dual-motor 4WD design seen in many plug-in electric vehicles.

Characteristics

These vehicles inherently have a range of characteristics built-in that are more commonly attributed to four-wheel drive vehicles or vehicles with extensive control systems. These characteristics can be:

Four-wheel drive, i.e. the distribution of available power to all the wheels of a four-wheeled vehicle
Anti-lock braking system
Anti-skid

Other features

If one motor fails, the other motors are powerful enough to drive the vehicle to the nearest repair shop
Low maintenance^{[citation needed]}
Easier replacement of motors
No central gear box
No mechanical differentials or lockers
No long and heavy drive shafts
On the spot, tank/wheelchair-like turning by rotating the drive-wheels in opposite directions
On the fly switching between front-wheel drive, rear-wheel drive and all-wheel drive drive configurations

The motors that are used in these vehicles are commonly wheel hub motors, 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 mowers, multi one lifts / front end loaders, and forklifts. 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, and move between forward and reverse modes without shifting gears, such as lawn mowers and loading equipment.

Although one may be conflicted in considering such systems as a direct drive system, being that a motorized pump must drive the hydraulic system from a position other than the wheel hub. Nonetheless the drive is provided directly from the hydraulic rotary motor found in or adjacent to the wheel hub.

Examples

Quad-motor

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

^ "The top five electric 4x4s we want in Australia". CarsGuide. Retrieved 2021-09-20.
^ "The All New Lotus Evija: The Electric Car on Steroids". The Chic Icon. 2020-12-23. Retrieved 2021-09-20.
^ "What's the Difference Between AWD and 4WD?". Chainsaw Journal. 2020-04-04. Retrieved 2021-09-20.

[1] "The top five electric 4x4s we want in Australia". CarsGuide. Retrieved 2021-09-20.

[2] "The All New Lotus Evija: The Electric Car on Steroids". The Chic Icon. 2020-12-23. Retrieved 2021-09-20.

[3] "What's the Difference Between AWD and 4WD?". Chainsaw Journal. 2020-04-04. Retrieved 2021-09-20.

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