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Antonov to Develop 2-Speed Transmission for EVs

Antonov Plc, the UK-based transmission technology specialist, has been awarded, in partnership with Jaguar and MIRA, a project by the UK Government’s Technology Strategy Board to develop a high efficiency 2-speed transmission suitable for use in electric vehicles. The project will run for one year with Antonov as the leading partner on the project and a final aim of demonstrating the transmission in a vehicle application.

Antonov will realize an initial engineering turnover of approximately £200K (US$332K) at this stage. Thereafter, the developed 2-speed should be ready for use in a commercial application, potentially leading to serial production. In parallel, Antonov is actively continuing its efforts to pursue new opportunities for its 2-speed technology.

Antonov’s main product is the TX6 transmission. (Earlier post.) The TX6 is a 6-speed electronically controlled, hydraulically actuated, transverse automatic gearbox for small and medium sized passenger cars and light commercial vehicles. Antonov is also actively involved in the development of small 2-speed automatic gearboxes to optimize the performance and efficiency of engine accessories such as alternators (earlier post), and the development of highly efficient multi-speed transmissions for electric vehicle applications.

The Antonov 2-Speed Mechanical Module (AMM) technology is based on a simple mechanical shift for an automatic transmission system invented 20 years ago by Roumen Antonov. The AMM principle of operation is to control a gear shift from a speed increasing ratio of between 1:1.2 and 1:1.9 and direct drive, 1:1, through the use of mechanical forces generated within the unit by speed and torque. Axial force generated by centrifugal weights acts against spring preload and axial force generated by torque on helical gears.

As the input speed to the AMM increases, at a particular input speed, which can be tuned for each individual application, the axial force generated by the centrifugal weights overcomes the other two forces and the AMM shifts from the overspeeding ratio to direct drive.

Conversely, as the input speed decreases, the axial force generated by the centrifugal weights decreases to a point where it can no longer overcome the spring and gear axial forces, and the AMM shifts to the overspeeding ratio. Because of hysteresis in the system, there is a 200-300 rpm difference between the upshift and the downshift. This means that the AMM does not hunt between the two ratios and is always positively in one ratio or the other.

Antonov has earlier noted that in addition to optimizing the performance and efficiency of engine accessories, the AMM could be used as an automatic transmission for recreational vehicles such as ATVs and boats.



The long term goal with EVs is to have a transmission-less car, with motors in the wheel hub, of course having 2-4 motors, making them operate efficiently between 0-80 mph and on top of that make this system cheap is a challenge but it will provide many benefits over the convention 1 motor transmission with it oil and breakable parts.


Go point Ben.

Why not get rid of as much mechanical parts as possible. AWD e-vehicles would be the way to go.


There may be unsprung weight issues with wheel motors.

Another option may be a center mounted twin electric motor an one axis.

This could have inboard brakes ala Jaguar.
The twin motors could drive forward together, opposite directions for zero circle turning on its own axis (on a single axle unit) rather like a conventional differential action.

Advantages a two speed could be built on each (axle)output (if required) and the mass (almost) all mounted as sprung.
The entire drivetrain drops off with 3? bolts for easy replacement. Wiring fixed to chassis (no flex)

Stick the batteries or ICE in front or underfloor for weight distribution.



The ONLY comment EVER made against wheel motors is unsprung weight, despite the fact commentators have ZERO idea what the weight of a wheel motor is.

If in your argument you quote the famous Jaguar rear end you should also note that Jaguar are the ONLY manufacturer who ever bothered using in-board brakes and only ever used them on the rear axle!

The FACTS you people need to include in any discussion about transmission Vs direct drive wheel motors is that there are energy losses through ANY gear transmission system, as much as 30% in a multi-speed car transmission. These large losses simply don't apply to direct drive wheel motors!


How about this fact that includes mass? - a direct drive wheel motor will consume 4 kg of high energy NdFeB magnet, (each). Compare that with 1 kg for a motor that does the job of two of these wheel motors.

Never mind that a direct drive wheel motor adds 15 kg of unsprung mass to each corner. 4 kg af finished Nd magnet costs at least $300. x2 for 2 wheels; x4 for four wheel motors. If at all technically feasible, not at all economically approachable. And what about the 360's that happen when one of those wheel motors fails and turns into a generator?

A single speed gear reduction loses 3-4%. Multispeed trans lose 8 - 14%. No automotive trans since the dynaflow loses 30% - I don't know where you found that "fact".

Wheel motor are dream material, but sadly, not reality.


"Jaguar are the ONLY manufacturer.."

Lotus also had inboard mounted disk brakes. Be careful using the words like "never, always, only..." those are absolutes and logic will refute those most of the time.

Bob Wallace

Frankbank - "Wheel motor are dream material, but sadly, not reality."

How about Michelin's in-hub motors which they have operating in test vehicles?


And a 'in operation' video...



The 2cv had inboard mounted disk brakes.


Also any 'Tubbed' hot rod worthy of show has stumpy banjo's cut down with axles to suit and 'effectively' inboard discs. Or just home built similar to Jag setup with a choice of diffs.

I wish I could remember the Italian co that built an active 'fly by wire ' suspension system with infra red scanning.

I think there are several similar designs around. Each similar in so far as the wheel retracts before the obstacle or bump.
This is effectively a zero unsprung weight system in any application.
Who's to say that a full (conventional) suspension with this (active) system and wheel motors isn't an option, or just active suspension wheel motors.

As far as I know the wheel motor uses a passive 'short travel suspension for the wheel components only, not the entire assembly. So right, It will be interesting to see it in the various versions already announced. The steering angles described in some versions are 'something else'.

The two speed I am suggesting would mount between a center motor and an inboard disc brake as such would lose minimal efficiency compared to a bevel drive or extensive drive train.

This is the main point I was trying to make, IE not impressed with the undescribed announcement from Antinov. But who am I to say - the announcement tells us very little. Especially the mounting location.
The EV reference could also be better worded (series parallel EV?)

A center mounted motor in the fashion I've described could easily be liquid cooled.
I dont understand your rear wheel drive only comment as there would be little difference if fitted to two axles.

Otherwise the engine and drive design I suggest is 'conventional' as far as manufactures and factory setup is concerned.
Also suits retro fitment.




"Never mind that a direct drive wheel motor adds 15 kg of unsprung mass to each corner."

May not be technically correct.
More likely ' adds 15kg? of mass to each corner' and that also is relevent.


Several mainstream Alfa Romeos also had inboard brakes.

I think the 15 kg per wheel estimate reflects current wheel motor designs, but future versions will doubtless be much lighter. Note that the Michelin in wheel design uses a 7 kg motor rated at 30 kW continuous, 60 kW peak. The remaining mass in their design is largely suspension and braking components that could partly be body-mounted instead, offsetting unsprung weight issues.


Wheel motors bring some design contraints as well as the disadvantages mentioned above and offer too few advantages - but they are cute.

The electric motors (and regenerative braking) are probably best frame mounted in the center.

The friction brakes will go where it's cheapest - they need only be heavy enough to do "part of" the braking (except one time emergency use).

I do not know the tradeoffs for motor rpm vs. wheel rpm (i.e. a fixed ratio gearbox or not), but a SHIFTING gearbox, that handles torque both ways, does not sound good.


In-wheel motors are IMHO more suitable for racetrack than for affordable electric cars.
Preferred design with frame mounted e-motor without multi-speed gearboxes, just a reducer - like Tesla roadster or Mitsu iMiev.
By using two instead of one e-motor one could get rid of differential (a reliable but somewhat lossy component), but would introduce more potential points of critical failure. Two motors (and inverters) of 60 kW are also more expensive than one of 120 kW.
It's worth noting that no production electric car is being built (or announced) with more than one e-motor per set of wheels (front or rear ones).

Hardly any need for multi-speed transmissions for regular passenger cars - most current e-motors work efficiently in rpm range 10:1. Perhaps they could be used for high-performance electric cars and/or commercial vehicles with ratio of loaded/unloaded weight above 1.4 (approximately).

Regarding the weight of in-wheel motors, PML-flightlink wheel weighs 18 kgs for 40kW (Max), with electronics. They say "Hi-Pa Drive is ultra high power density".
No idea how much they could cost (now and in the future, with possible tight supply or RE magnetic components)

In-wheel motors are generally considered vulnerable to occasional deeper puddles of water (? deep snow too, melting in contact with warm motors) and wheel thefts. Just wondering if they would survive high pressure hosing in touchless car wash.

Bob Wallace

"In-wheel motors are generally considered vulnerable to occasional deeper puddles of water...."

Then there are electric trolling motors which mount their motors below water. And come to think of it, I've got a submersible pump down in my well....

richard schumacher

Wheel motors still have the problem of requiring an awkwardly-large RPM range. Individually driven wheels of any type have the problem of torque steer in the event of one motor failure.

Better to avoid these by use of a Toyota-style power split device driven by two identical electric motors, which in turn drives a conventional differential and axle. Of course this has the disadvantage that a transmission maker would get no grants to develop it: it merely requires paying a license fee.

richard schumacher

I should have written, "inconveniently large maximum RPM requirement". The bottom of the RPM range is of course zero in any case.


Differentials, like many systems are more a psychological challenge to the repairer than anything difficult if you understand the basics.
They are in fact simple and tough as all get out.

They are however completely unnecessary undesirable and energy wise a real drag.

A Siamese electrical engine may have need for dual controllers processors and interleaving style of operation (sound familiar?)

I remember an article recently extolling the virtues of twin drive motors as they allow much smaller controller components and so save money and engineering challenges by using readily available power components.

There are designs for contra rotating wind turbine stator and rotor Also the one I'm trying to recall Emotor with a (one?) central stator sandwiched between two rotors , Can't recall the exact application but contra rotating is not necessary if there is at least a differential power split (in or out) that can be managed by ABS, Traction Management, Regen braking.


"Wheel motors still have the problem of requiring an awkwardly-large RPM range."

Ellica has in-wheel-motors and achieved 320km/h record.

0-160km/h Eliica:7.04sec Porsche:9.20sec



Non geared wheel motors have to go from 0 to 1000 rpm. If the car can go 90 mpg at 1000 rpm, that may be adequate. The Ellica wheel motors are geared and there are six of them, the car weighs quite a bit, it is expensive but was an exercise in making a luxury electric car. It had trouble getting funding after the initial prototype was built.

Four wheel motors each producing 30 hp in a car under 3000 pounds should perform nicely. I do not buy into the unsprung weight argument. This may be important in rally or race cars, but less important in day to day use. You could go inductive rather than permanent magnet to save weight. That would prevent cogging as well.

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