How We Made A Fundamentally Better Transmission for Next Generation EVs
Two Gears Beat One in EVs—And How Ingear Made It Finally Practical
The Need for Smarter EV Transmissions
Electric vehicle adoption is accelerating at a record pace – nearly 14 million EVs were sold in 2023 (about 18% of all new cars). As the industry scales, automakers face intense pressure to improve range and performance while driving costs down. One often-overlooked opportunity is the transmission: most EVs use a simple single-speed gearbox today, but this “one-size-fits-all” approach forces compromises between acceleration, top speed, and efficiency. Ingear addresses three major gaps in legacy ICE-Age multispeed transmissions by being:
(1) Low cost – it uses proven mechanical technology and common materials rather than expensive exotic components.
(2) High efficiency – its innovative design minimizes energy losses so more battery power translates to vehicle motion and extended range.
(3) Smooth shifting – it shifts gears seamlessly without jolts or pauses in power, preserving the effortless driving feel EV owners expect, while reducing wear on the motor and drivetrain.
We dive deeper on why ICE-age transmission options (traditional multi-speed automatics, dual-clutch gearboxes, CVTs, or the status-quo single-speed) fall short on one or more of these criteria for EVs in our article in “How Transmissions Became A Part Of Every Car, And Why They Will Again In The EV Era”.
In short, Ingear was conceived as the inevitable next step – a transmission designed from the ground up to meet all three needs at once. The result is a patented two-speed system that delivers the efficiency gains of a multi-speed gearbox without the cost, weight, or roughness penalties, making it a game-changer for the EV market.
How Ingear Works: The Engineering Behind the Innovation
A. The Core Transmission Concept
Ingear’s core concept is a purpose-built multi-speed transmission for EVs rather than a repurposed ICE vehicle gearbox. Most EV powertrains today use a fixed reduction gear train (typically totalling around 9:1 ratio) between the motor and wheels. Ingear introduces a second, lower gear ratio for improved launch acceleration and hill climbing, and a higher gear for efficient cruising – but it achieves this with elegant simplicity. Instead of adding bulky gearsets or clutches, Ingear replaces one of the fixed gear stages with a continuous silent chain drive and an innovative morphing sprocket. In essence, the transmission uses a strong chain running over two sprockets (one at the motor output and one at the differential input) to transmit power. By “morphing” the diameter of the output sprocket, the system can switch between a low gear (larger sprocket radius) and high gear (smaller sprocket radius) on the fly. This entire shift mechanism is built in without requiring a traditional clutch or complex multiple gear trains.
Crucially, the Ingear design keeps the architecture lean to avoid the weight and efficiency drawbacks that plagued earlier multi-speed EV attempts. There is no torque converter, no multi-plate clutch pack, no synchros and no high-pressure hydraulic circuit needed to actuate shifts. Instead, a simple solenoid actuator slides the sprocket segments (more on that below) at the precise moment when load on that segment is zero, while the motor controller momentarily adjusts speed to synchronize the shift. Because of this clever timing, shifts complete in under one wheel revolution – in some designs as quick as 19 milliseconds – with virtually no perceptible change in drive torque. The motor never fully “uncouples” from the wheels during a gear change, so the car continues to be pushed smoothly forward even as the ratio changes. This is enabled by what we call our “continuous torque” geometry, meaning the motor’s torque flow to the wheels is never interrupted, even in mid-shift. In practice, the driving experience feels like a single-speed EV – smooth and seamless – except the vehicle gets to leverage a second gear for better performance and efficiency. By designing this system specifically for EV requirements, Ingear maximizes efficiency (only a single gear mesh and a chain are in the power path, with no parasitic drag from idling gears or clutches) and keeps the solution compact. It essentially adds a second gear without adding a full ICE-age gearbox. The result is a transmission that delivers the best of both worlds: multi-speed performance gains with nearly the simplicity, efficiency, and cost of a single-speed drive.
B. Segmented Gear Design
At the heart of Ingear’s innovation is its morphing output sprocket – a segmented gear that can change its effective diameter during a shift. Rather than two separate fixed gears for high and low, Ingear uses one gear built from multiple interlocking segments that slide one at a time to alter the gear ratio. In high-gear mode, these segments retract inward, forming a smaller-radius sprocket. In low-gear mode, the segments extend outward to create a larger-radius sprocket that slows the output relative to the motor for increased torque. During a shift, an actuator pushes a track out to slide one “free” segment at a time into the chain’s path, “assembling” the larger sprocket step by step. Thanks to careful geometry, the chain stays engaged on the smaller-radius portion until the new segment is almost fully in place, so torque continues flowing through the already-engaged part of the sprocket. As the vehicle’s output shaft rotates, five segments move to form the new gear before the shift completes. When downshifting (high to low gear), the first segment to move has a special curved lead-in that smoothly lifts the chain onto the expanding sprocket without any jerk or binding. Likewise, when upshifting, the last segment to retract has a guide that eases the chain back down to the smaller radius. This ingenious segmented approach means the chain never has to derail or jump between sprockets; it always runs in-plane, and the effective gear ratio changes within one rotation of the wheel.
This segmented design enables smooth, reliable shifting with minimal mechanical complexity. It avoids the clutches, synchromesh, or heavy gearing found in traditional transmissions, making it well-suited for efficient mass production using standard materials and processes. The result is a durable, low-cost system that delivers multi-speed benefits without sacrificing simplicity.
C. 3-Post Chain Configuration
Ingear’s power transfer uses a 3-post chain drive configuration: the chain wraps around three sprockets forming a triangle – the drive sprocket from the motor, the driven (morphing) sprocket at the output, and a third sprocket that functions as an idler/tensioner. This design was inspired by the efficiency of chain drives (like those in motorcycles or timing drives) but avoids the lateral chain shifting of a bicycle derailleur system. By keeping the chain on a single plane, Ingear can use a robust automotive chain (a BorgWarner HY-VO type, similar to those used in 4x4 transfer cases) which is proven to handle high torques reliably. Chain drives are actually highly efficient – the Ingear prototype’s chain is slightly more efficient than the helical gear it replaces in a traditional EV reducer. In fact, overall bench testing by a major OEM showed the Ingear transmission reaching over 99% peak efficiency , a level of minimal loss that essentially bests a single-speed gearbox. This is partly because a well-designed chain drive has very low friction – modern roller chains under proper lubrication can exceed 98% efficiency in power transfer – and partly because Ingear eliminates one of the meshing gear stages that a single-speed would otherwise use. There are no parasitic losses from multiple gear meshes being engaged at once, as can happen in multi-speed planetary transmissions, and no sliding friction “rolling” losses between gear teeth. The chain engagement is positive and rolling, with negligible slip.
The 3-post layout improves load distribution and durability. The chain wraps around a large portion of each sprocket, spreading the force over many teeth, unlike a gear mesh where typically only a couple teeth share the load at any instant. The additional contact and wrap angle provided by the tensioner sprocket means smoother force transfer and less stress per link in the chain. Furthermore, using straight-cut sprocket teeth (as opposed to helical gears) means the forces stay in the plane of the chain without generating axial (sideways) thrust. This allows the use of low-friction ball bearings instead of bulky thrust bearings , and it also avoids the efficiency loss and heat generated by sideways forces and gear sliding. In fact, because Ingear’s chain and sprockets do not create significant side loads or friction, the unit requires no dedicated oil pump for lubrication or cooling – simple splash lubrication is sufficient. This contrasts with conventional multi-speed automatics or even some single-speed reducers that need oil pumps and coolers to manage heat. By simplifying the cooling and lubrication, Ingear saves energy (no pump draw) and weight, further contributing to vehicle efficiency.
From a reliability standpoint, chain drives have come a long way – they are widely used in engines and drivelines with long life. Ingear’s chain operates in a sealed environment and stays within normal tension limits, so it doesn’t suffer from stretch or excessive wear. As noted, extensive durability testing showed no measurable chain wear after an accelerated lifetime of use. Noise is also well-controlled; straight-cut gears and chain might sound old-fashioned, but in practice a properly tensioned chain drive can run very quietly. (For instance, the Chevrolet Volt employed a chain in part of its drive system, and it remained inaudible in electric mode.) Ingear leverages these advantages: an efficient, cost-effective, and compact chain drive that replaces a bulky second gearset. By using common materials (hardened steel links and sprockets) and established manufacturing processes (the chain is off-the-shelf from a Tier-1 supplier, and the sprockets can be made with standard methods), the Ingear is truly OEM-friendly. Automakers can integrate this 2-speed unit around the existing differential with minimal re-engineering – it’s designed to fit where a single-speed reducer would fit , only adding a modest amount of mass. In return, they get a significant boost in performance and efficiency.
D. Integrated Tensioning System
A key enabler of Ingear’s smooth operation is its integrated tensioning system. The third “post” in the 3-post design is not just an idler but an active tensioner that automatically maintains the correct chain tension through all operating conditions. In the cutaway image above, this is the spring-loaded arm pushing on the chain loop. The tensioner takes up slack when the sprocket segments retract (upshift) and lets out a bit of slack when the sprocket expands (downshift), so the chain is never overly loose or tight. This prevents any lag or snatch in torque transfer during a shift – there’s no whiplash in the chain and no need for a motor torque pause to wait for engagement. By optimizing force distribution, the tensioner ensures each link and tooth carries just the right load, which prevents power loss due to slippage and eliminates excessive strain on components.
Ingear’s tensioning system is designed to react instantaneously and in concert with the shift. When an upshift or downshift occurs, the control software momentarily modulates motor torque (using a torque-fill algorithm) to make the shift ultra-smooth, while the mechanical tensioner keeps the chain perfectly taut. The result is that passengers cannot even tell a shift is happening – tests indicate shifts are imperceptible in normal driving. Even during regenerative braking, which effectively puts force through the drivetrain in reverse, the tensioner manages the chain slack so that regen can continue uninterrupted through a gear change. Many simpler two-speed setups would have to temporarily suspend regeneration or use clutches to shift, but Ingear’s system keeps regeneration continuous, including during downshifts, again thanks to the coordinated tensioner and motor control. This is a unique advantage in real-world driving: whether accelerating or decelerating, the vehicle behaves seamlessly as if it were single-speed, with the extra gear ratio only making itself known by improving efficiency and performance.
By maintaining proper chain tension and eliminating shock loads, the tensioner reduces wear and enhances durability. Fully sealed and designed to last the vehicle’s lifetime, it requires no periodic adjustment. This blend of simple mechanical design and smart software coordination exemplifies Ingear’s approach: achieving multi-speed performance with minimal complexity.
Bringing it all together:
The result is a transmission that extends range, sharpens performance, and reduces system stress—without introducing new trade-offs. Ingear maintains over 99% peak mechanical efficiency, enabling OEMs to either shrink battery size or deliver longer range at no added cost. Less heat, less waste, and smoother torque delivery make it easier to meet efficiency targets and simplify thermal management. For platforms under pressure to compete on both performance and price, Ingear unlocks meaningful gains using existing components and familiar architectures.
The Next Generation of EV Transmissions Is Already Here
The transmission problem in EVs has been solved—and it’s no longer theoretical. Ingear is already undergoing validation with major OEMs, showing measurable improvements in drivability, range, and system efficiency. It’s built from standard components, designed for mass production, and proven to work in real-world conditions. Independent testing confirms it’s the most efficient 2-speed EV transmission available today.
Unlike legacy gearbox concepts adapted from internal combustion, Ingear was built from the ground up for electric powertrains. The result: smoother torque delivery, over 99% peak mechanical efficiency, and a design that integrates cleanly into existing vehicle architectures. No rare-earth materials. No exotic manufacturing. No need for clutches, pumps, or complex controls. Just a compact, validated drivetrain upgrade that enables platform-wide cost and performance gains.
The window is open for OEMs to gain a fast follower advantage. Those who act now can unlock vehicle-level savings and performance improvements their competitors are still chasing—and send a clear signal to markets and customers that they’re building EVs for what comes next.
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.