All Wheel Drive

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All Wheel Drive

This topic has 9 replies, 9 voices, and was last updated 31 January 2025 at 21:56 by Nigel Graham 2.

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31 January 2025 at 17:41 #781302
Vic
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@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.
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31 January 2025 at 18:06 #781310
Brian Wood
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@brianwood45127
Showing my ignorance. Please explain what a BEV is and for that matter ICE.
31 January 2025 at 18:16 #781311
Fulmen
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@fulmen
These are all CAA’s (commonly accepted acronyms) 🙂

BEV = Battery electric vehicle
ICE = Internal combustion engine
31 January 2025 at 18:50 #781315
Robert Atkinson 2
Participant
@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.
31 January 2025 at 19:17 #781317
Fulmen
Participant
@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? 🙂
31 January 2025 at 20:05 #781320
Michael Gilligan
Participant
@michaelgilligan61133
On 31 January 2025 at 19:17 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/
31 January 2025 at 20:13 #781321
peak4
Participant
@peak4
On 31 January 2025 at 19:17 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
31 January 2025 at 20:38 #781330
JasonB
Moderator
@jasonb
On 31 January 2025 at 19:17 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!
31 January 2025 at 20:59 #781335
old mart
Participant
@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.
31 January 2025 at 21:56 #781341
Nigel Graham 2
Participant
@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.

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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.

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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.
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