The Ingear Difference
A transmission that is as simple in concept and construction as many single-speed gearboxes, yet markedly superior in what it enables.
Challenging the ICE age “Gear”- Box Paradigm
Electric vehicles today overwhelmingly use fixed ratio helical gear drivetrains. The common reasoning is that electric motors have a broad constant power band across a wide speed range, making multiple gears seem unnecessary. However, this single-speed approach can either force a compromise in the vehicle performance or force motor designers to ever higher speeds to meet the desired specs without compromise. High-performance EVs have quietly acknowledged there is another way - models like the Porsche Taycan, Dodge Charger EV, Mercedes CLA and Rimac Nevera employ two-speed transmissions to boost both low-end acceleration and high-speed efficiency. As is often the case, new technology starts in performance cars and makes its way to the mainstream. We’ve explored in depth why multi-speeds are inevitable for EVs - but Ingear has an engineering elegance that really sets it above the ICE age gear.
Chain-Drive Advantages: Efficiency, NVH, and Design Freedom
A key feature of Ingear’s technology is the use of a chain drive on the secondary reduction instead of a gear mesh. This choice yields several technical advantages that improve efficiency, noise/vibration/harshness, and even allows reductions in manufacturing complexity and cost.
A chain and sprocket system inherently spreads the transmitted load over multiple teeth at once, unlike a single pair of meshing gear teeth. Technical literature from Tsubaki (a major chain manufacturer) notes that “sprockets have many engaging teeth; gears usually have only one or two” in contact at a given time. Because of this, chain and sprocket mesh have greater torque transfer engagement than gear mesh. Lower contact stress also means each tooth and link sees less contact stress, which has several implications. Wear is reduced, friction is reduced so the material strength and hardness requirements are less extreme. Moreover, the elimination of helical gears means no tapered roller thrust bearings are needed to absorb side forces (straight-cut sprocket teeth and chain produce negligible axial load). Instead, simple deep groove ball bearing suffices to support shafts, which are cheaper and have lower friction than the tapered roller bearings used in many gearboxes.
Next, the chain drive contributes to lower noise/vibration/harshness (NVH) levels. With many teeth sharing the load, the transmission of torque is smoother and there are smaller fluctuations in force as the mechanism rotates. Additionally, unlike helical gears that generate thrust loads and gear whine from sliding contact, a chain’s roller engagement is more of a rolling action with minimal slipping. Less energy is dissipated as friction and noise, leaving more energy to the work. The Ingear’s efficient transfer of power means there is simply less energy converted to sound. Supporting this, real-world usage of chain-driven power transfer in other vehicles has proven to be quiet and smooth. For instance, a silent chain and sprocket system is used in the Chevrolet Volt’s electric mode. Ingear leverages the same silent chain technology from well known suppliers such as BorgWarner and Tsubaki. These chains are known for their high strength, durability and quiet operation. There’s also a compliance in these chains, not found in gears, that provides damping. This, coupled with the continuous engagement across multiples of teeth result in a noise signature that is lower in amplitude and more benign in frequency than a traditional gearset’s whine.
The Ingear’s use of chain and tensioner also provide the degree of compliance needed to eliminate the transmission “clunking” that comes from rapid torque reversals. Helical gears strive to eliminate the clunk through precision, zero backlash or control. Either one requires increased cost of precision or the increased cost of controls. Ultimately to manage it to manage cost it will require a compromise at the expense NVH. Not so for Ingear.
The chain architecture also brings flexibility in packaging and design. Unlike high precision gear pairs, a chain drive can accommodate a greater degree of manufacturing variability in both the sprockets (straight cut) and input/output center distances. Tolerances are far more forgiving: the chain’s tensioner can compensate for variations in center distance and alignment between the sprockets. A chain drive can still function efficiently even if the positioning is at the extreme end of the tolerance stackup; whereas a gear mesh would fail prematurely or at least be more noisy under such misalignment. The Ingear can also be packaged coaxially. Ingear’s design even wraps the chain around the differential, allowing a very compact layout within the rear or front axle assembly. All this means the Ingear is a more package friendly, manufacturing friendly solution.
Furthermore, changing the overall ratio is largely a matter of sprocket selection, all managed within the existing transmission case, which is much simpler than changing the ratio of a helical gear-train. That inherent flexibility means the technology can be custom-tailored without changing the transmission case. The nature of a chain drive and its adaptable implementation make it a very versatile solution for OEMs and Tier 1s looking to implement multi-speed EV drivetrains without case modification and without having to revalidate the entire transmission.
Simplified Manufacturing and Quality Assurance
One of the most compelling aspects of the Ingear architecture is how it simplifies manufacturing and assembly, translating to significant cost advantages. Traditional gearboxes, especially multi-speed ones, demand extremely tight machining tolerances and precision assembly. Gear meshes require exact center distances, parallelism, high strength, high hardness and high precision surface finish to avoid noise and premature wear. This often means expensive machining of the housing, more quality control, and sometimes selective assembly or shimming to get everything just right. Ingear’s chain-based design relaxes many of these requirements. As discussed, the chain tensioner can compensate for minor discrepancies in part dimensions. The manufacturing process doesn’t need to chase nearly zero defect rates for critical alignments – the system is inherently tolerant to variation. The result is lower scrap rates and less rework during production, and possibly the ability to use lower-cost production techniques (for example, die casting, injection molded polymers and powdered metal.)
Powder metallurgy processes are not only cheaper than forging and machining steel gears, but also enable high-volume production with excellent consistency. This is one way that Ingear’s unconventional architecture drives down cost while maintaining strength where needed.
Consider the tolerance stack-up in a typical gearbox: variations in gear manufacturing, bearing dimensions, and case machining can add up, requiring careful control at a cost. Ingear sidesteps much of this stacking issue. Any variability in the center distance dimensional stackup is addressed by the tensioner. Ingear does not demand the ultra-tight build tolerances that geared transmissions do. This can simplify not only manufacturing but also the fixturing and tooling needed for assembly. Jigs and assembly robots do not need the same level of precision (and expense) to put the unit together, which further cuts down the production cost.
The design also reduces the part count and complexity of the shift elements. It uses five moving sliders, a carrier drum, an open loop actuator, a shift guide and a tensioner – all simple components. There are no multi-plate clutches, dog clutches, planetary gearsets, oil pumps, closed loop actuators, or solenoid valve body that you’d find in a conventional multispeed. Of the Ingear, MotorTrend noted that “no torque gets transmitted while the segments are moving, [so] none is required to keep them in either position, and… there is no need for a hydraulic pump”. In other words, because Ingear avoids transmitting torque through a partially engaged gear (unlike a slipping clutch in a DCT), it doesn’t need complex mechanisms or high pressure oil to modulate or hold torque during shift. A lever and a wedge (the simple machine kind) handle what hydraulics and servos do in other transmissions. All of this contributes to easier assembly and lower QA overhead – if there are fewer parts, there are fewer things that need inspection.
Shift repeatability, a measure of quality and reliability, is a high bar set by the Ingear shift technology. Since Ingear avoids high-wear components like clutch friction plates and has no oil circuits, there are fewer failure modes and control points to address. With fewer things to monitor or adjust over life, an Ingear-equipped drive unit might also require less end-of-line calibration or control system complexity in the vehicle. This again circles back to cost: simpler assembly, less end-of-line work, and lower warranty risk due to fewer failure modes all contribute to a lower cost of quality.
Inside the Ingear Architecture: Seamless Two-Speed Shifting
“Ingear has solved the ‘torque hole’ problem”, Tier 1 OEM Powertrain Executive.
Perhaps most impressively, all of this is achieved with no clutches, no synchronizers, and no hydraulic actuators. Ingear’s power shifts are inherently coordinated by the geometry rather than by complex electronics. As the MotorTrend technical analysis observed, the mechanism “works like some variable-valve-lift cam-lobe-shifting devices and requires no closed-loop control to account for wear, etc.” The segments only move when they are not under load (when the chain isn’t actively pulling on that segment). This means the actuator doesn’t fight against torque being transmitted through the chain during a shift; it needs only a modest force to slide the sprocket pieces since it operates during naturally occurring gaps in chain contact. The entire system is fundamentally open-loop.
By solving the shifting challenge in a novel way, Ingear delivers the best of both worlds: the efficiency and performance of a multi-speed, with the elegance and reliability of a simple mechanical system.
Conclusion: Lower Cost, Higher Performance – No Compromises
The engineering and business case for Ingear’s multi-speed EV transmission architecture is compelling. It challenges the status quo by showing that you can have the best of both worlds: the efficiency and performance benefits of a multi-speed drivetrain, delivered in a system as elegant and robust as a single-speed. From an engineering standpoint, Ingear achieves this by stripping away the usual complexity – no clutches, no fluid circuits, no bulky add-ons – and leveraging clever geometry and control to shift seamlessly. The result is a transmission that is as simple in concept and construction as many single-speed gearboxes, yet markedly superior in what it enables. As one industry writer quipped, Ingear “checks all of the boxes that OEMs have been looking for” by improving cost, range, performance, and efficiency simultaneously.
The commercial advantages are equally clear. In an EV market where every percent of efficiency and every dollar of cost matter, Ingear offers a rare win-win. For OEMs, Tier-1 suppliers and the end users (you and me), adopting Ingear does not require a leap of faith into unproven technology but rather a partnership on a well-developed innovation protected by a strong patent portfolio and real-world test results. It’s the rare true mechanical technology, in today’s squishy AI and software world, that can be licensed and implemented on your terms.
About Inmotive Inc.
Inmotive is a pioneering developer of ultra-efficient multi-speed powertrains for electric vehicles. The company’s flagship product, the Ingear™ transmission, delivers superior efficiency and performance for a wide range of EV applications. Committed to advancing sustainable mobility, Inmotive partners with leading manufacturers to redefine what’s possible in electric and alternative energy transportation.