February 2022 Volume 4

EQUIPMENT & TECHNOLOGY

Electric Axle Technologies: Forging Opportunities for Presently Non-Automotive Players By Josh Carney

It is a present reality that petrol-fueled vehicles are facing obsolescence in-leu of more oil-independent and climate-friendly transportation. This ousting of the internal combustion engine is in part a result of ever-increasing legislative and social pressure to combat climate change. It is also the result of concern that our world is nearing or perhaps past peak oil and that alternative energy sources are needed. Even the existing and highly efficient petrol/electric 'hybrid' drive vehicles will likely be replaced in the not to distant future by all- electric vehicles. Interestingly, as electric vehicle development is increasing and regulations favoring their sales are championed by lawmakers, all this is happening without a significant reduction in gasoline and diesel powertrain production for existing light and heavy vehicles (i.e., semi-tractors). As forgings are used in many of the engine and drive components of road vehicles, the question one might ask is, "what does this mean for the automotive forgings market, and are electric vehicles an opportunity for untold fortunes?" Considering a Rear-wheel Drive Vehicle In a rear-wheel-drive vehicle, such as a truck, the power is delivered from the engine to the rear axles (wheels) via a series of rotating gears and shafts. The axles are connected by gears to a driveshaft connected to the engine through a transmission that communicates the rotational power produced in the engine. The rear axles of traditional petrol-fueled rear-wheel drivelines can range from 15 inches to more than 30 inches in length. Axles (and hubs) are usually forged of one component for strength and are produced in great numbers. Producing forgings of this length requires purpose- built forging presses to make the upset forgings. The billet heating, material handling, straightening, andmachining operations are also designed to handle longer workpieces. Engines also have long forged components such as the crankshaft, and due primarily to weight, require particular billet heating and handling equipment.

Figure 1: Basic rear axle differential

Enter the eAxle The basic design of an all-electric vehicle uses a battery, motor controls, and motor-driven electric axle or 'eAxle' powertrain. The eAxle takes the place of the conventional engine, transmission, and driveshaft, with the battery supplying the power. An eAxle driveline combines an electric motor, gear-train/transmission, and power electronics (these control the motor) and put them into one compact package resulting in a high power-to-weight density.

Figure 2: Basic design of an eAxle Present designs of eAxle transmissions locate the gear train at or near the drive wheels; this reduces the length of transmission components. One significant consequence of this design is that the forged components' overall length is significantly reduced when compared with the traditional petrol drivetrain.

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