All Wheel Drive

[VicParticipant @vic]

This is another positive for me about BEV’s. When I learnt to drive, RWD was commonplace and my first few cars were RWD. I found them bad on slippery road conditions. Apart from a couple of AWD cars (which were great in the wet) all my later cars have been FWD. it’s so much easier to make a BEV AWD than an ICE car so I’m glad some manufacturers are taking advantage of this.

[Brian WoodParticipant @brianwood45127]

Showing my ignorance. Please explain what a BEV is and for that matter ICE.

[FulmenParticipant @fulmen]

These are all CAA’s (commonly accepted acronyms)   🙂

BEV = Battery electric vehicle
ICE = Internal combustion engine

 

[Robert Atkinson 2Participant @robertatkinson2]

The AWD is mainly for the manufacturers convenience. It’s easier to make and fit in two 60kW motors than one 120kW.
AWD has always been popular in full hybrids and plug-in hybrids just stick a motor on the currently undriven axle. Als gives the performance aboost in terms of acceleration.

Robert.

[FulmenParticipant @fulmen]

There’s no “undriven axle” on a 2WD, just two hubs. So you do need to add the axle and diff, and if you want independent suspension you’ll need a couple of joints on the drive shafts as well. Not exactly rocket science but it does add complexity.

On the other hand there is less torque to transmit, and as you point out two smaller motors are easier to fit than one large one.

My brilliant idea was to have the ICE on one axle and electric on the other. Can anyone see why that isn’t a good idea?  🙂

[Fulmen]

On Fulmen Said:

[…]  My brilliant idea was to have the ICE on one axle and electric on the other. Can anyone see why that isn’t a good idea?  🙂

I think a quick comparison of  the natural power curves might reveal the answer.

The computing input, and/or variable ratio gearbox, required  to get them matching in ‘real time’ would be enormous … [methinks].

MichaelG.

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Edit: __ Just found an interesting graph:

https://www.i4talk.com/threads/ice-vs-electric-power-and-torque-comparison.8801/

[Fulmen]

On Fulmen Said:

There’s no “undriven axle” on a 2WD, just two hubs. So you do need to add the axle and diff, and if you want independent suspension you’ll need a couple of joints on the drive shafts as well. Not exactly rocket science but it does add complexity.

On the other hand there is less torque to transmit, and as you point out two smaller motors are easier to fit than one large one.

My brilliant idea was to have the ICE on one axle and electric on the other. Can anyone see why that isn’t a good idea?  🙂

Look up “Through The Road Hybrid”; this Wiki does mention some models, though I think there are others
https://en.wikipedia.org/wiki/Hybrid_vehicle_drivetrain

A Series Landrover of course is selectable four wheel drive with normal two wheel drive operation as RWD, with selectable drive to a rigid front axle; front uses UJs rather than CV joints, and no centre differential, so a bit clunky on the road and prone to transmission windup.

Yes I know the Stage 1 was a bit of an exception.

Bill

[Fulmen]

On Fulmen Said:

 

My brilliant idea was to have the ICE on one axle and electric on the other. Can anyone see why that isn’t a good idea?  🙂

Might work if you do diagonally opposite on the other axle.

Seems to work for the WRC boys crossing tyre types across the axles with their different levels of grip. On the Monte last week they had combinations like Studded winter tires front left and rear right and unstudded softs on the other two!

[old martParticipant @oldmart]

That’s why some Teslas have the logo “twin motor” on their most powerful cars, accellerating close to what a big bike can manage. Mind you, the battery milage and the drivers licence would be likely to be at risk.

[Nigel Graham 2Participant @nigelgraham2]

By comparison with these new-fangled electric things, here we are from 110+ years ago:

Most BEVs were rear-wheel drive, with a variety of arrangements typically of a single, central motor and shaft or chain final-drive, but of front-wheel drives:

The North German Lloyd Steamship Company, based in Bremen, made many of its Lloyd Electric lorries (3-ton capacity: separate motor driving each front wheel by direct gearing, and arranged with regenerative braking. The motors looked horribly vulnerable to accidents as they were under-slung in front of the axle beam. No speed-bumps in those days. The Great Eastern Railway successfully trialled one for local freight deliveries in Ipswich, which has some steep hills, early in 1914.   We might wonder if it subsequently bought more….

.

Similar to the Lloyd was the “Orwell”, built by Ransome, Sims & Jeffries.

The ‘CEDEX’: each front wheel had its motor built within it.

.

Those two were British but the French company Fram built a front-wheel drive electric unit intended as the forecarriage for custom trailers, though many were fitted as rigid lorries. These were evidently very successful, with for example Paris City Council using 100 Fram refuse-collection lorries.

.

In the USA:

The ‘Couple-gear Freight-wheel Company’ (snappy name, eh?) sold front-wheel / motor units whose motor was diametrically across the interior of the hub. A bevel-gear on each end of the shaft emerging from both ends of the motor, engaged its own of two crown-wheels. To permit this, the motor was set slightly askew.

The General Motor Company, Baker Electric Vehicle Company and General Electric Company (of America) each built their own commercial vehicles but with more conventional arrangements of separate motor and final-drive train to the rear wheels.

………

On the railways:

Those who recall Ron Jarvis’ models, on a par with Cherry Hill’s for quality and for replicating pioneering or unusual engines, might remember he built a miniature of a very early battery-powered tram “locomotive”. It comprised mainly a big, open, lead-lined tank on a four-wheel wagon. This tank was the battery, and speed control was by a hand-gear that raised and lowered the plates in the acid. The driver stood on a precarious perch on the front, between the acid bath and the risk of falling into the path of his own steed.

[VicParticipant @vic]

One thing I hadn’t considered is better weight distribution of two motors. Downside of having a motor in the back though is probably reduced boot space?

Two of my old Honda’s had automatic AWD, that is to say they were front wheel drive only until it lost grip, then the rear wheel drive kicked in. It seemed to work well. One was conventional five speed manual, the other CVD automatic.

[Vic]

On Vic Said:

One thing I hadn’t considered is better weight distribution of two motors. Downside of having a motor in the back though is probably reduced boot space? […]

It’s tempting to think of the new-ish VW van as a concept vehicle

< would insert demonic smiley here if I wasn’t abstaining >

https://www.volkswagen-newsroom.com/en/press-releases/world-premiere-of-the-new-id-buzz-gtx-with-4motion-all-wheel-drive-18306

MichaelG.

[not done it yetParticipant @notdoneityet]

Putting down 300HP through two wheels can be interesting at times.  Using all 4 wheels for extra grip, at road intersections, can seriously improve tyre life.  Think, here, of maximum torque being delivered at low speed for the electric motors used for BEVs.

Front wheel drives of 200HP are renowned for hard acceleration slippage at lower speeds.

Some (not all) completely disconnect the front wheel drive under ‘normal’ motoring – although there are still range losses due to the still-rotating drive shafts, etc.  About 10% range loss seems typical although that is often masked by wheel/tyre size differences.

Front to rear weight balance is not really a problem, with any BEV.  The battery mass can readily be slightly shifted, fore or aft, by the manufacturers.

As far as the Series Landrovers were concerned – they were never particularly good road holders – the advantage of the part-time 4 wheel drive was in traction, nothing else much.  Increased tyre wear, due to transmission ‘wind-up’, was an obvious problem, but quite a lot of muppets didn’t realise they were also encouraging serious gearbox failures by the practice.

[Speedy Builder5Participant @speedybuilder5]

CAA

or C.A.A.
abbreviation for
Civil Aeronautics Administration: a former agency of the U.S. government, reorganized into the FAA.

[Brian WoodParticipant @brianwood45127]

Thank you Fulmen for taking the trouble to shine a light on my ignorance; the world is full of abbreviations and there are inconsistences as Speedy Builder has shown above with another interpretation of CAA.

The time may come when we all have to speak in jargonese.

Brian

[Fulmen]

On Fulmen Said:

There’s no “undriven axle” on a 2WD, just two hubs. So you do need to add the axle and diff, and if you want independent suspension you’ll need a couple of joints on the drive shafts as well. Not exactly rocket science but it does add complexity.

On the other hand there is less torque to transmit, and as you point out two smaller motors are easier to fit than one large one.

My brilliant idea was to have the ICE on one axle and electric on the other. Can anyone see why that isn’t a good idea?  🙂

You still have to suppory the two rear hubs. A lot of FWD cars use a beam axle to to do that.

Your Idea is a bit late. My Outlander Plug-in Hybrid Electric Vehicle (PHEV) does that with a twist. The ICE can drive tha front wheels via a continiously variable transmission (CVT). It also drives a generator. The rear axle has a 60kW electric motor. The twist is that there is also a 60kW electric motor driving the front axle alongside the CVT.
The system can use any combination of these depending on load and state of charge. The system tries to keep the ICE at an efficent load and speed. If the load lis less it also charges the battery. If it is more then one or both motors kick in The switching between ICE / series / parallel operation is undetectable in the cabin un less you look at the status display. Typically on the motorway you can sit at constant speed with  ICE driving and charging. When a charge builds up or the is a slight down hill it will switch to electric. On a long steep downhill it will charge purely from the potential energy.
Under heavy loads both motors and the ICE power the car.

Robert.

[Author]

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