A different sort of road safety campaign

Posted on June 30th, 2007 in Opinion by Julian Edgar

1244_4mg1.jpgOver the last two or three decades we’ve seen just about every driver road safety campaign possible.

From overt blood and guts to more subtle psychology.

From a big stick to a plaintive plea.

From massive enforcement of laws never originally designed to be policed with such technology (technology that’s so superior to that of cars that manufacturers deliberately build in conservative speedos lest they be caught out), to changes in social norms that are quite radical to experience in just half a generation.

But one of the primary causes that I see of accidents is relatively little mentioned: the concept of driving to the conditions.

To toe-in or toe-out on bump?

Posted on June 16th, 2007 in Opinion,Suspension,Technologies by Julian Edgar

0913_11mg.jpgNow forgive me if this seems pretty esoteric: it probably is. In fact, I’d never really even thought about it until a year or so ago; I’d never actually experienced it until today.

Most of you would be familiar with the idea of ‘toe’. Toe-in is where the wheels point inwards – when viewed from above, they’re constantly steering towards the centreline of the car. Toe-out, as you’d soon guess, is where the wheels are constantly steering outwards from the centreline. Zero toe means the wheels are parallel to the centre line.

Most cars these days run zero toe or just a very small amount of toe-in. Toe, usually measured in millimetres (although degrees would make far more sense), is at most only 1 or 2mm: the amount the wheels steer inwards or outwards is very small indeed.

OK – so that’s static toe. But what about when the suspension moves up and down?

If, during suspension travel, the wheels stay steering exactly in the directions they were originally steering in, the suspension is said to have zero bump steer. If the wheels steer inwards on bump, they’re said to have toe-in on bump. Toe-out on bump is defined as you’d expect it to be. (Note that in all these quoted cases, the steering wheel is held still – it’s the suspension itself that’s doing [or not doing] the steering.)

Weight and per person fuel consumption

Posted on June 2nd, 2007 in Opinion by Julian Edgar

2591_7mg.jpgAny vehicle designed to transport people must move two masses – the mass of the vehicle itself and the mass of the people and/or goods it is carrying.

So a bicycle, the most efficient means of transporting just one person, has (say) a total mass of 100kg, of which 85kg (so 85 per cent) comprises the load being carried. (A skateboard does even better.) A Holden Calais weighs 1700kg to carry about 450kg – or to carry 21 per cent of the total mass. A Peugeot 206 GTi has a mass of 1050kg and can carry probably about 350kg, or about 25 per cent of the total.

But these are theoretical maxima.

What if there’s just the driver in the Calais? Then the mass being carried is just 4.5 per cent of the total vehicle weight! More than 95 per cent of the weight moving along the highway is not the primary load being transported!

Even in the lightweight Peugeot, a single person aboard will still mean that 93 per cent of the mass being moved is not the load.