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A PHYSICIST WRITES . . .

(April 2010)

Sometimes looking back can be rewarding. Iíve just been reading Heather Grevesí article in the last Thames Valley Group newsletter, about her first car (a Morris 8). She ended by saying that her second one was a Morris Minor. Well, so was my first car, as I mentioned here once before, though all I said was that one day I applied the jack to the correct place below the centre door-pillar and started turning it: the jack rose up but the car didnít...

For more than two years, though, she had transported me willingly enough. She cost £180 (lent to me by my father) in 1965, and came with a full tank. In due course, when the fuel level looked low, being an impoverished student I asked nervously at a garage (no self-service in those days) for one gallon. Afterwards, with a different sort of nerve, I enquired why the needle hadnít risen visibly.

Did (or does) any popular car have more attractive body-curves than the Morris Minor? Like Heatherís Morris 8, my car also featured those little trafficator arms that swung out smartly to announce an intention to turn left or right. Itís hard to imagine a less effective way of indicating ó or is it simply that we rely too much nowadays on bright winking lights, instead of thinking properly about what other drivers are likely to be planning, and what their vehicles are actually doing or are lining up to do?

Trafficators were fitted to several different vehicles in those days, but I believe the shape of the arm was always the same, with its distinctive triangle at the end, holding the bulb. Itís said that this shape was derived from the diamond-ended signal arm in use on the Royal Bavarian Railway at the end of the nineteenth century, with half of the diamond removed so as not to stick out when the trafficator was retracted. Thus it is that a little bit of history connects with us.

There were several ways of starting the engine of the Morris Minor. I forget exactly what was provided on the dashboard, but under the bonnet was a button you could push. This was rather dangerous if you had left the car in gear. Then when the battery faded, as mine did in that cold winter of 1965/6, out came the starting handle (dangerous likewise). You fed it through a hole in the front bumper to connect with the crankshaft, and then turned it as sharply as possible ó while trying not to grip it firmly in case it jerked forward or back. What a feeling of achievement when at last the engine sprang into life!

One of the servicing jobs on the Morris was pumping a grease gun into the lubrication nipples on the steering joints and elsewhere. To refill the gun, you opened it up and pressed it into a tin of grease, which had a loose metal disc inside with a hole in it. The stuff then squeezed through the hole and into the gun. That same grease tin (very nearly empty today) is the only souvenir I have of my first car...

Now for a look back at this yearís previous columns: in January I reported my research into those strips of hatching with a solid border that are spreading along the left-hand side of ordinary roads. Please donít call me in evidence, but what I said was that driving over them is perfectly legal (according to the Department for Transport), as this combination of hatching and border isnít even shown as a Ďprescribed markingí in the regulations, let alone included in the Ďkeep-offí list. The Highway Code doesnít cover it either. Encouragingly, a reader wrote in my support, pointing out that if the hatching was intended to be a no-go area, the prohibition would surely also apply to cyclists, which would be truly absurd.

Furthermore, I havenít seen any instruction that you should only cross solid-border hatching if itís safe to do so (which is certainly the rule if the border is a broken line, as stated in the regs and in the Highway Code).

In fact there is a diagram of hatching on the left bordered by a solid line in the regulations, but itís clearly pictured and labelled as marking the end of a hard-shoulder section on a motorway (though even here, surprisingly, it isnít specified as forbidden territory). But hang on a minute: Iíve just found a DfT report on the design of roundabouts, referring to this very diagram from the regs, and strongly suggesting that its hatching can be laid down at the side of any road, to indicate areas that ďvehicles should not enter unless it is seen as safe to do so.Ē Does this amount to official permission to local authorities to use an unofficial marking for an regulated purpose? Anyway, I hereby give up trying to make any sense of hatching!

In February I discussed the habit some people have of coasting in neutral. One of several reasons I offered for not doing this was that you might need to steer and brake suddenly at the same time, and at tick-over speed the engine vacuum might not be enough to power-assist both functions. Well, Iím still unsure on that question, but it does occur to me that if the engine happened to stall while you were coasting, you would definitely lose servo-assistance. Result: feeble brakes and laborious steering. And Iíve learnt that thereís another situation too where you will lose control this way (because of lack of vacuum), namely a wide-open throttle and a racing engine...

...which brings me to last monthís column and the run-away Toyotas (very rare things, letís not forget). I said that their accelerator pedals had been jammed either by floor-mats or by the friction attachments to the pedals ó but apparently not all the incidents can be explained this way. Some were reportedly due simply to driver error: the accelerator was pressed in mistake for the brake pedal, maybe, and then in panic and confusion the driver tried to Ďbrakeí even harder.

Another idea that is increasingly being mooted (though itís strongly denied by Toyota) is a temporary malfunction of the onboard computer, for whatever reason. The problem with this explanation, as I understand it, is that if the computer has misbehaved, thereís unlikely to be any trace of the event to be found within it afterwards. And black boxes arenít going to be fitted any time soon to every car, as they are to every aircraft, to record all possible evidence just in case of an accident. Not much chance, then, that investigators will establish for certain whether or not this has been the cause of particular Toyota incidents.

Or, to balance what I said at the beginning, sometimes looking back can be unrewarding!

Peter Soul

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