The Anonymous Widower

Axle Mounted Motor For Retrofit To DMU’s To Enable Zero Emissions In Stations

This project was one of the winners in the First Of A Kind 2022 competition run by Innovate UK.

In this document, this is said about the project.

Project No: 10038683

Project title: Axle Mounted Motor For Retrofit To DMU’s To Enable Zero Emissions In Stations
Lead organisation: WABTEC UK LIMITED
Project grant: £59,450

Public description: This project provides a solution to substantially reduce emissions including NOx and PM when
diesel passenger trains are idling.
There are over 3,500 passenger rail vehicles in the UK currently fitted with a diesel engine, the
large majority of these would significantly benefit from emissions reduction, especially in and
around stations, where diesel engines currently continue to idle, or elevated idle whilst stationary,
sometimes for up to 30 minutes at a terminal station. This is a significant contributor to local air
quality issues from NOx, PM emissions etc.

Furthermore, rail vehicles require large amounts of energy and power to accelerate (and therefore
contributing more emissions), and yet, on the approach to stations significant amounts of energy
are “lost” through “braking”.

This project will address both issues by recovering the braking energy during deceleration and reusing it for auxiliary loads in station and traction to accelerate out of station, this will enable diesel
engines to be isolated in and around stations, whilst also reducing the average emissions such as
PM and NOx over a complete drive cycle by up to 35% and operational costs by up to 30%.

Our objective is to develop and integrate a small, low mass, yet high peak torque and peak power,
axle mounted motor, for retrofit and upgrade for DMU/DEMU passenger vehicle applications. This
motor shall enable kinetic energy recovery during the braking application and also provide power to
the trailer bogie wheels whilst accelerating.

This project will enable several key cost and decarbonisation benefits to the railway.

  • It shall enable zero emissions, including NOx and PM, in and around the station, by
    enabling a DMU to approach, dwell and depart from a station with the engine switched off.
  • It shall enable a proportional average reduction in all emissions, through reduced fuel consumption resulting from the electrical energy recovery from regenerative braking and re-deployment through auxiliary and traction use.
  • It shall enable less brake wear thus reducing particulate emissions from brake pads especially around stations.
  • It shall enable reduced operating costs for the train operator through fuel saving, engine/transmission maintenance savings and brake pad saving.
  • It will not require any modification to the existing diesel engines or drivetrain and will compliment any other decarbonisation initiatives.
  • It shall provide a substantially lower cost and risk solution when compared to any other previous or current hybrid solutions.

My Thoughts And Conclusions

This is a classic simple solution, that could have big benefits.

I suspect, it can also be paired with Wabtec’s other proposal; Zero Emission Powering of Auxiliary Loads In Stations.

November 18, 2022 - Posted by | Energy, Transport/Travel | , , ,


  1. […] 10038683 – Axle Mounted Motor For Retrofit To DMU’s To Enable Zero Emissions In Stations […]

    Pingback by First Of A Kind 2022 Winners Announced « The Anonymous Widower | November 18, 2022 | Reply

  2. Well that’s £59450 that could have been better spent on the Rolls Royce MTU and Magtec hybrid drives for DMUs.
    Absolute nonsense.

    Comment by fammorris | November 18, 2022 | Reply

    • I totally disagree! Especially, as this is only a minor modification to the train, whereas the Rolls-Royce mtu solution is a major transmission transplant.

      I wouldn’t be surprised to see that Equipmake are in there somewhere.

      Comment by AnonW | November 18, 2022 | Reply

      • On the contrary. You may well be able to install a motor onto one axle within a trailer bogie but you’ve still got the issue of providing a motor with sufficient power to accelerate the train to let’s say 20 mph before you cut in the traditional drive. In that sense addition controls and train wiring modifications are still needed.
        Putting in sufficient torque onto one axle (unlike the arrangement of the hybrid drives where the power is distributed over the coupled wheelsets) further raises the question of adhesion between wheel and rail. You only have to recall Class 142 Railbuses and wheel wear to recognise this.
        This is further exacerbated because DMUs do not have a sophisticated WSP system, relying as they traditionally do on the speed reference between the trailer and power bogies . Then there’s the question of storing the power for that motor. It too, like the hybrid drives, requires the same batteries and inverter.
        It is not as if DMUs have a trailer car with better possibilities for battery installation, no all DMU cars are powered so the benefit of easier installation does not exist.
        Equally the motor doesn’t sit in glorious isolation, like any other traction motor it will have to be supported around the axle shaft whether it’s a direct drive or via a gearbox, or alternatively the motor is bogie frame mounted driving the axle by a gearbox. Mounting of the motor will require modifications to the bogie frame, which while not terribly difficult still complicates the concept.
        Some may debate the point but I think this will require a third type of axle in addition to the existing trailer and power axles. It will also require a torque reaction rod that must be elastically attached to the bogie frame, yet another modification.
        The installation of a motor shouldn’t be hampered by the siting of disc brakes on stock following on from the tread braked Class 150s, but no it really isn’t that simple.
        Thinking back about the day rate we used to charge twenty years ago for the professional services of a Chartered Engineer equivalent the award of £60k isn’t going to get much of a return.
        I’d really like to have more detail of their proposals.

        Comment by fammorris | November 18, 2022

  3. A motor on the drive axle would add substantially to the unsprung weight with multiple attendant disadvantages, however most motors in DMU’s are mounted inboard in the bogies. What might work is essentially a “mild hybrid” where a small battery somewhere (in the bogie or the carriage – the connection is only a wire) is charged during decceleration by the existing motor acting as a dynamo / alternator and discharged to provide motive power during acceleration. Saves wear on the brakes too. If BMW can do it I am pretty sure Rolls Royce can…

    Comment by R. Mark Clayton | November 24, 2022 | Reply

    • I do wonder, if this project is using Equipmake technology from Norfolk. Given what Chapman got up to, the idea is quite Normal for Norfolk.

      A similar idea has also been used on Equipmake’s electric Routemaster.

      Unfortunately, my Lotus engineering expert friend died a few years ago.

      Comment by AnonW | November 24, 2022 | Reply

  4. Mark it is not entirely necessary to mount the motor directly to the axle and thereby increase the unsprung mass. Motors can, and on modern wheelsets are partially or fully suspended on the bogie frame to obviate the consequences of unnecessary unsprung mass.
    I’m not exactly sure what you mean by saying …”most motors in DMU’s are mounted inboard in the bogies”. Voyager, Super Voyager and Meridian DEMUs have body frame mounted alternator and motor arrangements.
    I assume when referring to BMW you are talking of current cars equipped with the 8-Speed ZF 8HP automatic transmissions, which can be configured as a full, mild or plug-in versions.
    It’s instructive to compare the detail of ZF 8HP with the ZF EcoWorld for rail applications, which features an integrated reversing function and the transmission arrangement to be found in the Rolls-Royce HybridFLEX solution. I’d say the transmission that is an element of HybridFLEX and contains an inbuilt motor/generator is ZF derived and that the arrangement directly owes its existence to ZF technology from the 8HP, after all MTU and ZF are both in Friedrichshafen (I know people who have worked for both companies). In that sense the BMW/Rolls-Royce connection already exists.
    Of course if you just want a mild hybrid driveline I think ZF or Voith with their DIWARail NXT mild hybrid could replace the existing Voith Hydraulic Transmissions much in the way you suggest.

    Comment by fammorris | November 24, 2022 | Reply

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