Talk:Dual-motor, four-wheel-drive layout

Does this article depict established knowledge?

This article strikes me as odd, and sure enough, it doesn't cite any engineering literature. I couldn't find books that support the claims in this article. As far as I know, there are typically three different drivetrain layouts for electric lorries (and vehicles alike):

• Center Drive, with a traditional axle, and a traditional differential gearbox, with a single electric motor connected to the differential with a driveshaft

• Axle Integrated Drive, with a single electric motor integrated into the axle differential gearbox

• Wheel Selective Drive, with two electric motors – one for each wheel – and no differential gearbox.

The latter can be designed with either the motors installed inside the wheelhubs (In-Axle Drive), or where in a conventional lorry the differential gearbox would be (Near-Wheel Drive). As far as I can tell, the article seems to be describing Axle Integrated Drive, but also discusses Wheel Selective Drive (Audi e-tron). However, there are some weird portions of text: The article claims that there is no need for a drive shaft – while this is true for a center drive shaft from the main gearbox to the rear differential, a drive shaft from the motor to the wheels may still be required. The article doesn't discuss the main challenge of such a drivetrain layout, which is the high motor speed (13,000…25,000/min) that requires a substantial reduction gearbox, good lubrication, and heavy duty bearings, as well as better sealing, and a clever gear tooth design to reduce annoying gearbox whining noises. I also find some of the wording very misleading, for instance why would a distribution of electrical horsepower maximise torque and power in response to anything? That makes as much sense as for instance that an increase in velocity increases the speed and reduces the time required to cover a certain distance. See, in a shaft motor/engine, power is the product of the torque and the shaft's angular velocity. The Audi e-tron section about Wheel Selective Drive is also misleading, because two motors are often used to allow a reduction of the power output – this is not used to "achieve greater power output". Let's say that a car designer wants to send 100 kW of power to the rear axle. With a single-motor setup (i.e. Axle Integrated Drive or Center Drive), a 100 kW motor is required. In a Wheel Selective Drive layout with two motors, however, the designer can install two smaller 50 kW motors. The smaller motors don't have to be that beefy and may simplify the entire production. This is even true for the Audi e-tron GE: The standard version of the car has a 140 kW AKA 320 motor, whereas the three-motor model has two ATA 250 motors with 100 kW each. Best regards, --Johannes (Talk) (Contribs) (Articles) 17:01, 10 July 2022 (UTC)