So, Daimler, what about your cars?

Posted by Mark Williams on | No Comments
So, Daimler, what about your cars? Maybe hub motors were always the best way to go with electric vehicle

If Daimler deserves credit for anything, it’s maintaining the value of the three-pointed star despite past, er, setbacks. The Citaro articulated buses which briefly starred on London’s streets were known, in the early days, for catching fire. The problem was less widespread than might be supposed, with only four spontaneously combusting, but such was the high profile of ‘bendy buses’ they unfairly got stuck with a ‘Chariots of Fire’ moniker.

The tendency for unintended ignition was jumped upon and resolved very quickly, as you’d expect from Mercedes-Benz. But only a few weeks ago, a vehicle dismantler we spoke to said time-expired Citaros crumble to dust when faced with a cutting torch. So maybe they weren’t as durable as you may suppose.

We can balance this with the performance of such legendary vehicles as Sprinter and a whole series of M-B coach products including the venerable 0303 and more recently the Tourismo which, although accused of ‘buying’ sales with low price, is a very competent vehicle indeed.

It has been noted that Mercedes-Benz does seem a bit late to the electric bus party, but I have a feeling it has been filling its time usefully, not least because it has opted for hub motors for the Citaro electric. The unsprung mass of hub motors may have hampered their inclusion in the modern electric vehicles, but they were always hot favourite.

The direct substitution of electric motor for diesel, driving axles through a diff is, frankly, ridiculous. If there were any point at all in electric vehicles beyond emissions reduction, it’s the reduction in moving parts and subsequent improvement in reliability. To force electric drive through 90 degrees of diff gearing is wasteful of the technology; gain control of the motor speed, and you dispense with so many failure points, such as gearbox, driveshafts and UJs.

An electric vehicle with hub motors offers practically limitless axle articulation (off-road vehicles made this way will be awesome) and removes the mechanical connection between power source and tyres. A vehicle having no propshaft can have a fully flat lowfloor.

But then, I’m not an engineer. If I was, I’d now be designing an ultra-lightweight two-seat electric car with a space frame and pre-formed ABS panels, an insulated saloon space and modest shopping stowage, floor-mounted battery and a modest electric motor which can run for 50 miles at 50mph. I’d create an independent heating/cooling system fuelled by ethanol.

This car would suffice for 90% of all the journeys I make and, if you are honest with yourself, yours too. We fondly imagine we NEED a 1.5-tonne car with 300-mile range, but we don’t. And on the 10% of occasions when we do, we could easily and cheaply hire such a vehicle.

Daimler has gone for the jugular – the rich vein of the 80% of all bus services which never travel more than 150km a day. Unfortunately for me, it doesn’t seem that the car industry is gripped with the same desire to design the electric car for the masses.

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