MOTOR AND CYCLE

Taranaki Daily News, 30 October 1915, Page 11

MOTOR AND CYCLE

XEWS AND NOTES. Under tlio new by-laws of the Xew Plymouth 'Borough Council it is an offence lor a motor-ejvlist to cany a passenger on the carrier of his machine, and several visitors to the town on Monday last received warning from the inspector. . Very few motor cyclists realise the different forces set up when indulging in passenger-carrying on the carrier. There is little doubt that an extremely large proportion of motor-cycling accidents are attributable to the "pillion peril,'' and it is little wonder when one considers certain facts relative to this dangerous practice. Most of the trouble is caused through less road grip on the front wheel owing to want of balance. The weight registered, when the front wheel of a -I'i-h.p. stands on a scale, is 751bs. With an average-weight rider in the saddle this is increased to 1201bs, but when an additional passenger sits on the carrier, the front weight regis', -v

is ftOlbs. It will thus be noted that the weight of the rider in the saddle adds 451bs to the pressure of the front wheel on the road, but when the "pillion passenger" is aboard, the pressure on the road is reduced by 241bs. although the total weight carried by the machine is doubled. Is it any wonder, then, that the grip of the front wheel is considerably less? As a result there is more likelihood of aggravated front-wheel skids, which are the worst imaginable. The more weight carried the more c«ntrol the driver should have on .his machine. With a passenger on the carrier the reverse is the case. Weight is taken off the front wheel, which means less control in steering in the direction the driver wishes the machine to go. The control of the machine is also considerably effected by the fact that the weight carried behind the back axle tends to fly outwards at a corner, consequently swinging the front of the machine inwards. Another fact motor cyclists fail to realise is that the back forks of the ordinary motor cycle are not designed to carry a person behind them. Again, the ordinary standard tyres are not made to withstand the extra strain, although, to the credit of the tyre manufacturers, many of them do. From all directions the practice is a most undesirable one. The accidents solely attributable to this cause have been so frequent in England that some of the insurance companies absolutely refuse to issue policies to motor cyclists who indulge in passenger carrying, whilst ' other concerns charge 50 per cent, more to cover the risks attendant on this form of motor cycling. That is their experience of'this practice.

In view of the growing importance atI taching to the reduction of weight in the reciprocating parts of a petrol motor—perhaps the biggest factor making for high-revolution speeds—it is not surprising that aluminium pistons are much used for engines 'built especially for racing purposes. It is only recently, however, that their advantages when applied to pleasure car engines appear to have been realised, or perhaps it is that makers have rather fought shy of them ; on account of fancied, or real drawbacks to their use. In America, on the other hand, side by side with the growth of the number of cylinders, which, by itself, renders possible the reduction of weight of reciprocating parts, has grown up the use of pistons of some aluminium alloy. One of the best-known firms over there is specialising in the manufacture of these pistons. Made from magnalium, an alloy of aluminium and magnesium, the weight, size for size, is as one to three as compared with ordinary cast-iron pistons. Magnalium is, in fact, even lighter than pure aluminium, since the specific, gravity of magnesium is only l.v-S, whereas that of aluminium is 2.0, so that the saving in weight, it will be seen, may be fairly considerable. Indeed, the makers state that in one particular case a reduction of no less than 241bs in reciprocating weight was effected by substituting "Magnalite" for the original cast-iron pistons.

From the point of view of the ordinary motorist, of course, the greatest advantage of lightness in the reciprocating parts is not so much the higher maximum speed that is possible as the decreased vibration and wear and tear on the crankshaft and big-end bearings at ordinary revolution speeds. But from whatever point of view it is regarded, the matter of minimum weight here is of enormous importance, alike to the manufacturer and the user. It is sail that the "Magnalite" pistons cost very little more than those made from highgrade cast-iron, for although the metal itself is far more costly per unit of weight there is, of course, less of it, while another factor tending to keep down cost is the ease with whicn magnalium may be machined. An important claim made by the advocates of aluminium pistons is' that the possibility of scoring the cylinder walls in the event of lubrication shortcomings is minimised, since in the event of seizure, partial or absolute, it will be the softer metal of the piston that suffers, leaving the expensive cylinder block Certain it is, however, that only one or two English car-makers are using aluminium pistons fitted as standard, and they appear to give every satisfaction.

One of the most amazing tilings about motorists is the manner in which they neglect tie very first essentials of good driving. In any manual on motor driving one may learn the procedure of starting and stopping. To start, turn ou petrol, switch on, wind up, release the hand brake, declutch, engage gear, and let in the"clutch; to stop—declutch, apply brake, put gear bevel in neutral, put hand brake hard on, switch off, and turn off petrol. Simple enough, and a routine which once adopted, and always practised becomes mechanical, and an assured habit. Yet one constantly hears of cars left stationary on sloping roads setting off on their own through drivers omitting to leave the hand brake hard on; and at not infrequent intervals cases are reported of cars buritt and destroyed through the petrol cap being left open. If in the beginning of a man's initiation into motoring the routine is rigidly observed, the handbrake always applied, the petrol always turned off, a habit is formed which, as we have said, leads to a purely mechanical performance of the duty. It is the careless and inefficient driver who has to run back to see if ho has left the brake on, or who—if nothing worse befall—finds his petrol tank some morning half empty, through a leaking carburetter, and the petrol tap left open.