From Our Australian Correspondent.
Page 12
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N.S.W. Government Buys Tower-wagons.
1 am almost amused to see that the New South Wales. Government is calling for tenders for the supply of two motor tower wagons for its tramways. It is, of course, almost needless to add that these engineers, who appear to be at last considering it possible that the • dirigible road motor may be of some use, have prepared specifications to show haw the chassis has to be constructed, and amongst other things it is to be of 25-30 li.p. It is probable that, after having gone to the trouble -of preparing an elaborate specification, they will be content with some standard make, as has been usual with other :similar bodies in the past. I do not feel able to regard this as anything in the nature of an awakening, as I fear it is more than likely that the purchase of these two machines will be used as a means to show deliberate inaction in the use of motors for passenger conveyance.
Large-diameter Wheels.
At the time I left England, nearly two years ago, the question of greater wheel diameters was practically settling itself, and it was becoming generally admitted that, whatever arguments might hold good in favour of small wheels, those in favour of large ones far outweighed them. I was certainly one of those who, although favouring the large-diameter wheel, did not regard it as of great importance, and I should certainly not have felt justified in making alterations to any car in order to provide it with larger driving wheels. Since I have been out here, however, my views have changed considerably. So much so, that I have COMB to regard a large-diameter driving wheel as one of the determining factors in the choice of cars for particular work. Smooth and even road surfaces are particularly not to be -found ; small wheels sink right into :almost every depression in the road surface ; as a large percentage of these have sharp edges, the effective action is almost one of the wheel levering itself more or less severely into the hole, and using the sharp edge as a fulcrum. This action, of course, is bound to cut deeply into the tire, with the result that its life is materially reduced. Two other points in connection with the road surface itself are worth noting. The one is that there are a number of gullies going transversely across the road, into which small wheels will accurately fit; the
• other is the number of wooden bridges
• which have to be crossed in all directions. These nearly all have a gap of several inches between the road and the wood, and are rarely on the same plane as the road surface, with the result that here again small wheels will give a tremendous bump to the whole vehicle. Having mentioned the action on tires, it merely remains to refer to the effect such treatment will have on the springs, axles and working parts generally. Increased diameter of as little as two or three inches has a mostmarked effect on the running of vehicles, and, incidentally, of course, on the life of tires. So much for the one side of the question.
Effect on Platform Height.
The other side of course, comprises the old and wen-worn arguments of raising the centre of gravity and increasing the height of the platform above the road. The former, I think, may well be neglected, as it has been proved over and over again that the raising of the centre of gravity by two or three inches., so far as commercial vehicles are concerned, is a practicallyunimportant matter. Of course, in England, some people have a rooted aversion to doing anything that would increase the road clearance, but, although I do not at all agree with those who go about crying that on Colonial roads clearances of 16 in. and 18 in. are a necessity, I still think that a small increase in the road clearance is quite desirable. Big-clearance adherents paint dreadful pictures of breakages, due to rocks and stumps in the roadway, or to deep ruts into which the car is liable to fall. I quite admit that most of these arguments have been originally raised with respect to touring cars, but the same people, for want of better knowledge, are raising the same arguments with respect to commercial vehicles. Now, as this journal deals exclusively with utility vehicles and tractors, I confine myself to the case as it concerns those types only, and I may state that I have had a fair amount of experience of commercial vehicles in service on country roads, and also of touring cars. I have never yet found a rock or stump which, if it obstructed the roadway, could not with ease be circumvented, and which, if the road were at all used, was not regularly circumvented by every conveyance, with the result that what was in effect a deviation resulted. In the matter of particularly-deep ruts, which are made in the first place by the wheels of horsedrawn vehicles and deepened to an almost-dangerous degree through the passage of storm water, I have equallyinvariably found it practicable either to travel with one of these between the track of the wheels, or else to avoid it altogether. When they are once properly formed, these ruts reach depths of anything up to 2 ft., and leave heightened and uneven backs at their edges; hence, I do not think that any clearance of 16 in. or 18 in. would be sufficient effectively to prevent as accident, in the event of a wheel's getting into one, and, in addition to this, the angle at which the vehicle would be situated would be so great that. the load, if not the vehicle itself, would be in danger of toppling over. Apart from that, of course, is the danger of a broken wheel through the decreased stability in the long spokes. The only conditions which warrant a greater road clearance are those found ia crossing some of these gullies, which are frequently approached over a slight ridge and a drop, which might easily account for as much as 10 in., so that, with a full load, a vehicle might conceivably be situated with it* back wheels in the gully, and the base of the differential casing resting on the top of the ridge. All danger of this, however, could be overcome by a clearance of 11 in. or 12 in., and this could be effected by providing a very-desirable addition in the shape of largerdiameter wheels. It is probably scarcely necessary to make any reference to the differences in gear ratio, as it is nowadays generally regarded as a simple matter to alter them to suit local conditions,
Good Oil Necessary.
I was recently invited to examine an Albion lorry which had been dismantled, and in doing so came to a fuller realization than over before of how an engine should not be lubricated. As everybody knows, the method of lubricating Albion cars is both simple and efficient, yet, in this particular case, the bearings were either gummed up, or for the same reason had only been lubricated in parts. What oil was used has not transpired, but I rather suspect that, not only was it a bad and cheap oil, but it contained acid as well! Here, again, there is room for the local buyer to learn from earlier experience. It is hardly likely that any appreciable number of people could be so stupid as the owner of this particular lorry, but there is yet a large field between extremes such as the one mentioned. I am coming to the conclusion that, with the hot climate which we have here, lubrication has to be considered more carefully than in England, and I have already made one or two experiments in the way of mixing a thick with a thin oil, for engine lubrication, with good results. At the present moment, I am arranging to lubricate a car with a very high-grade and at the same time fairly-thick oil, and I shall watch the results with considerable interest. I anticipate that it will not prove wasted labour.