MOTORS and MOTORING.

Dominion, Volume 19, Issue 48, 20 November 1925, Page 6

MOTORS and MOTORING.

(BY

SPOTLIGHT.”

A COMING EXPERIMENT WELLINGTON’S HOT-MIX PAVEMENTS. A most important ingredient in a bituminious concrete pavement is the mineral filler in the wearing course. In Wellington’s pavements of this type Portland cement and crushed lime dust have been used as a filler. The engineers, however, estimate that a saving of Id. per square yard can be effected if crushed sand is used instead, and arrangements have been made for the necessary plant to supply this new ingredient. The matter is of considerably more than passing interest, as it is generally conceded that the mineral filler is a vital factor in producing a stable pavement that will not shove and wave under traffic. The technical papers m the United States are full of references to research being conducted in connection with this matter.

Sand is the predominating constituent in the wearing course of a bituminous concrete pavement. Sand is composed of grains more or less angular but rounded at the corners, due to the abrasive action of grain upon grain in the process of formation. Consequently the grains move more or less freely against each other under pressure. If these sand grains are bound together with bitumen they are held in position if no pressure is exerted. If pressure is exerted, particularly when the bitumen becomes more or less plastic under summer temperatures, the sand grains are displaced and readjust themselves in new positions. However, if we conceive a sand grading in which the voids formed by adjacent sand particles are occupied by other sand particles decreasing correspondingly in size, and the smallest voids remaining are occupied _ by an angular dust, we have a grading in which the voids have been eliminated as far as it is practicable to do so. The mineral filler thus locks the whole mixture, providing a smooth and stable pavement, 'pleasant to travel on, and free from waves and unevenness.

The specifications of the United States Bureau of Roads lay it down that: “The mineral filler shall consist of limestone dust, dolomite dust. Portland cement, or natural cement.” In a paper read at the annual convention of the American Road Builders’ Association this year, Messrs. Prevost Hubbard and Frederick C. Field discussed the relative value of mineral fillers for asphalt paving mixtures. In the course of it they stated: “Limestone dust and Portland cement are at present more extensively, used a)s fillers than any other materials, and considerable diversity of opinion has existed as to the relative merits of these two products. Slate, silica, hydrated lime, and various other finelygraded materials have also been used to some extent. Of these, hydrated lime is probably the most widely available, although its usefulness for the purpose has not been clearly demonstrated, and it has so far been used only to a very limited extent. This material is extremely fine, and tends to ball somewhat. . . . jn general, it is seen that limestone dust is the coarsest product and hydrated lime the finest, Portjand cement holding an intermediate ’position.” The authors then proceeded to devote the remainder of their paper to the three latter types of filler, and their comparative value. The thoroughness of the American investigations may be judged from the fact that last year the Bureau of Roads laid a circular testing track of 33 sections each with a different asphaltic

pavement, five being bituminous concretes and 28 sheet asphalts. This replaced an earlier testing pavement laid in 1922, on which were 27 asphaltic concrete mixtures of widely varying proportions laid on a concrete base. Traffic was applied in the form of a loaded truck. During the warm weather evervone of these mov.ed, some imperceptibly,. others to the extent of several feet.' In addition to these tests, laboratory compression tests have been made with the various standard fillers, and valuable data therefore is being compiled as to the ingredients and proportions securing the most stable pavement. In nearly all these tests one or other of the three mineral fillers mentioned above appears to be used in varying proportions. The use of crushed beach sand as a mineral filler, as planned in Wellington, thus appears to be an interesting innovation in bituminous concrete work, and the stability of the pavements to be laid locally promises to be very closely wrapped up with the success of this new departure.

W.A.C. YEAR BOOK

NEW ISSUE IN THE PRESS

The Wellington Automobile Club’s handy little year book, which is due in a week or two to make its third appearance. is stated to be a marked advance on last year’s issue. All the old features which met with so favourable a reception in the previous issues are retained, and several new ones have been added, such, for instance, as a list of attractive camping spots for motor campers on tour on the main North Island routes. The road guide section has been considerably expanded, and it is believed that there is scarcely a main or secondary road in the area between Wellington and Auckland of which particulars are missing.

The outstanding new departure this vear, however, is the speciallv compiled road map. This 1 is being printed in two colours, and instead of being printed on a large sheet, which has to be inconveniently folded and unfolded when it is desired to inspect it, the sectional plan has been adopted. That is to sav, the map sheets arc bound in the book as pages, preceded by a key map showing the order of the sections. The metalled and unmetalled roads are clearly distinguished, there is an ample over-lap on each section, so that confusion is avoided on turning from one to the other, the whole design is bold and clear, and altogether the aim has been to produce that long-felt want, a really handy and up-to-date road map for use iti the car.

CHRISTCHURCH TO DUNEDIN

The 241 miles from Christchurch to Dunedin wiljVbe one of the Dominion’s most-travelle'd roads this summer (says a Christchurch writer). The road has little to offer in scenic interest until after Hinds is passed, and the way leads to picturesque Geraldine, and brings the traveller near the hills. Then the first 'undulating portion of the road is reached before Timaru, and the way is much more interesting. But from Oamaru onwards the road traverses delightful country with variety of interest in flats, hills, and views of the ocean, and the run is very pleasurable right on to Dunedin. From Christchurch to Dunedin the main road has been colourmarked—that is, at intervals, a band of cream or yellow, and black, has been attached to telegraph poles. Tourists are cautioned to drive carefully and at a reasonable speed through townships. If a halt is made then obey the parking regulations, and don’t forget all those courtesies which will bring credit on you as a motorist. From the exhibition city the road trails off into a land of romance and charm to be found among the lakes, hills, and valleys of Otago and Southland.

BRITAIN’S NEW CARS

MOTOR FASHIONS AT OLYMPIA.

What is to be the fashion in Britishbuilt motor-cars during the coming vear? This question is answered by 1 the reviews of the exhibits at the recent I Olympia motor show in London to hand by this .week’s mail. The following interesting summary of the trend in British motordom appears in the London “Morning Post” from the pen of thatweteran writer on motoring topics, Mr. H. Massac Buist. Mr. Buist sums the situation up thus: > ' _ Plainly the covered car will increase in favour, particularly in face of the very tempting prices at which bodies are now being offered. No British manufacturer comes forward with an allsteel bodv; Citroen alone exploits this system thoroughly in Europe, but America continues to make various t'we mav regard powdered-hue types, also the speckled-body scheme, such as was introduced tentatively a couple of seasons ago, to have failed to attain a vogue. Nearly all the colours standardised this vear are pure. If the exhibition is any indication of the coming choice of the buyer in regard to cars next year, in the main we shall look for a slight tendency to favour bright, as distinct from sombre, hues. But the eagerly-awaited oil. damp, heat, cold, and tar proof lacquer-finish-ed bodies with which the European industry has been experimenting extensively have not materialised yet, America being, in effect, the sole contributor of this class of coach-work. Of course there are exceptions of sorts. In the main, however, we must wait yet another season for the lacquer body. When we get it undoubtedly we may look for a general tendency to favour brighter and more delicate colours

Standard equipment continues to be elaborated. This year one can say without qualification that the additions to what was considered adequate equipment last season have been confined solely to really practical requisites such as, notably, the mechanically operated windscreen wiper. One maker alone is attacking the dazzle problem by fitting dipping headlights of the type used by the King and other members of the Royal Family on their cars. The rest standardise bn dimmers, the compromise adopted by America. The balloon tire is no longer a mystery. Broadly, the European middlesize and large car industry will not have it. America, whose cars, speaking generally, are not proportionately as well sprung nor as lively, still favours the balloon tire fori a considerable number of large cars.' The British industry in general is fitting its large cars with semi-balloon tires when it is not; using ordinary sections. If the suspension system of a car is designed adequately And skilfully, either sort suffices admirably as far as\ comfortable riding is’ concerned. But the low pressure large section balloon tire continues to be employed in what is its correct branch of service, namely, for the small European car. Smaller Engines. In regard to engine types, several of the new cars introduced have side-by- i side valves; but, unquestionably, the •. overhead valve system makes propor- ! tionately greater progress. With one I exception, no manufacturer introduces ’ an utterly new large engined chassis, i Several bring forward new style middle scale or small machines.

In surveying the new middle-size cars it is plain that nearly all have either overhead or sleeve valve engines; whereas the proportion of overhead to side-by-side-Valve engines in the smaller cars is about equal. One observes, too, that in th middle Categories practically all the new cars have 6-cyhnder engines; whereas in the smaller _ categories, ' of course, the vast majority have 4-cylinder engines, though there are two notable exceptions wherein 6 cylinders are employed, both of them

r coming from abroad, one from Italy, the other from Austria. Another feature of this exhibition is undoubtedly the increased number of eight-evlinder engined cars. There is the beginning, too, of a tendency to supplv eight cylinders instead of six, for middle size and large cars. As for four wheel brakes, there is no longer anv pretence by members of the industry to hold out against them. It is greatly encouraging to observe that the majority of those who, hitherto, have marketed cars with quarter elliptic springs are not guilty of the folly of attempting to fit them with brakes to all four wheels. A greater number of manufacturers is also emboldened to employ servo, hydraulic or other mechanism to assist’ in the application of these brakes. Others, chiefly newcomers to the practice of fitting four wheel brakes, are beginning cautiously by employing direct mechanical means of application only. Not a few European manufacturers who. hitherto, have standardised central gear change and hand-brake lever controls, have changed to right-hand control, thereby clearing up the space about the front seats. The argument often advanced in defence of the central control, which is cheaper to make, was that it was impossible to fit a door to the driver’s seat in such a way that it could be used conveniently if the hand-brake and gear change speed levers were also set at the side. But sundry manufacturers have shown in past vears, and a greater number do this vear, that any inconvenience in that connection can be eliminated entirely by taking a little thought when designing. ACCIDENT CLINICS

NOVEL AMERICAN SAFETY FIRST

SCHEME. How to stop the massacre of the innocents by reckless or criminal automobile drivers is a subject occupying the attention of an American committee of which Mr. Hoover, the Secretary of Commerce, is chairman. One of the remedies proposed is the creation ip every large city of an “accident clinic,” composed of a medical examiner with psychiatric experience, a psychologist, a' traffic engineer, and a statistician. Whenever an accident occurs it will be the duty, of this clinic to make a careful examination to ascertain all the facts, because the committee believes few accidents can be attributed to a single cause, and in nearly every case there are several contributing factors of equal importance. The clinic would endeavour to discover precisely what happened and the conditions existing at the time of the accident; the driver’s physical and mental state, his experinece, whether unI duly fatigued, his manner of applying the' brakes and slowing down, his fal I miliarity with the car; facts about the persons involved as disclosed by a medical, psychological and psychiatric examination. Some persons, the committee believes, owing to temperamental and physical defects, ought not to be permitted to drive a car; there are other persons who ' have defects un- ! known to themselves, but which are ! remediable. Provision should also be , made for the periodical examination of I drivers who reach a certain age limit, ns with age comes handicaps of which the person is unaware. A c’>ic of the character indicated is being experimented with in a limited way in Boston, and, while it is too early to express an opinion on its value, ' it has already revealed, the committee i is advised, many cases of drivers suffering from physical or other defects 1 which eventually would cause them to lose control of their cars.

JOTTINGS

Two and a half acres of floor space is allotted to the motor-car exhibit at the JJunedin Exhibition, aiid the products of 70 motor vehicle manufacturers are on view, the American article as usual markedly predominating.

The Wellington Automobile Club has in hand a large number of new road direction signs, which, it is stated, will be ejected before the holiday season.

The success of the system of appointine country agents to further the interests of motorists, was favourably commented upon by several members of the Auckland Automobile Association at the I last meeting of that body. It was stat:ed that the innovation was preferable Ito the formation of substdiarv branches. ,The question of the association’s future ipolicy with reference to the appoint'ment of agents was referred to a com•mittee.

; Success attended the Christchurch Olvrnpia of 1925 (states the “Sun”), ilhe attendance, reckoned on the takInsrs, totalled 35,000, which is ahead of Auckland, and 3000 ahead of last year. Business was excellent, and apparently the lower prices of cars stimulated the Remand. Over 200 cats were sold in tlie course of the show, and the traders are highly satisfied with business prospects.

Through tire agency of the Otago Motor Club a camp has been provided at Tahuna Park, Dunedin, for motorlists visiting the exhibition. This camp (will be 'availabk to members of motoring organisations affiiated with the [South Island Motor Union. Arrangements have been made for an electric light to be set up on the camp site and gas rings are to be installed for cooking purposes. Portable boilers will-be used, water being laid on to the park. The use of the shelter sheds (open front, and sides) has been arranged for, and it will not- be'necessary for campers to bring tents unless they prefer to do so. Tent-flies and motor-covers will be useful, as they can be placed round the sides and front of the sheds to make them quite comfortable.

Probably many motorists are not aware of the fact that if they drop a bottle or broken glass of any sort on jthe roadside it is their duty to go back 'to pick up the pieces. A reminder .was given to this effect at the Hamilton [Court, when a youthful motor-cyclist [admitted that after accidentally dropping a bottle from his machine'in Victoria Street, leaving broken glass strewn over the carriage-way, he had ineglected to go back and gather up ithe remnants. As the prosecution was the first of its kind in Hamilton, he was let off with the payment- of costs, 7s.

The New Zealand Tourist League is at present urging towns to set aside camping areas for the use of tonring motorists, and the question of obtaining a suitable site in Hamilton was iraised at the meeting of the Hamilton lAutomobile Association last week. It I was stated that Tauranga, Te Aroha, ‘and Te Kuiti had already set aside .camping sites, and in the two former ■ places electricity and other conveniences were provided. The Minister of 'Lands had offered to consider the setting aside of areas of Crown laud /along the unsettled parts of the highways. A committee was set up to enJdeavour to secure a camping area in (Hamilton.

The Auckland Automobile Association is much dissatisfied with the action of the Main Highways Board in refusing lull subsidy on a concrete road from Otahuhu to Papakura, on the Great South Road out of Auckland. The association declares that there will be a vast increase in traffic when the road is improved.

Te Awamutu Borough Council lias set up a committee to select a site for a motor camping ground adjacent to the borough.

The Auckland Automobile Association keeps its service officer, Mr. Champtaloup, busily on the move about the (country. His programme for the current month includes sign-posting the roads between Hamilton and Napier, Paeroa and Waihi, Tauranga-Opotiki, Gisborne, and Whakatane-Rotorua, and addressing meetings of motorists at various points •en route

Since the opening of the Rangiriri deviation, race meetings at H am ilton have attracted many Auckland motorists, and the traffic has been remarkably heavy. A resident of Bombay, who took a tally pf cars bound southward on the Great South Road on Labour Day, counted 120 motors in one hour, an average of two a minute.

Referring to the registration of mofor vehicles, Mr. Couzins, secretary of - the (Motor Traders’ Association;' stated at a Christchurch gathering that the Government had promised to publish a complete register, but when the cpst had been ascertained, it could not see its way to carry out the promise. The association had considered that the information was essential to the trade, and had' secured the rights to publish it. The record would be of immense value 'to those who sold cars on the hirepurchase svstem. Every car in New •Zealand hacl a complete file in Wellington, and all the transactions in relation ■to that car were included. If the name of one person who had owned the car was supplied, it could be traced from start to finish. It was a most important thing for the trade and the motor owner, that such should be the case. The Automobile Division of the De-

partment of Commerce at Washington is stated to have issndd a warning to American motor-car manufacturers that thev .must immediately cope sqmvrely 'with the problem of competing with the rapidly growing popularity of the small tvpe European, car if they desire to hold no their export records.

Recognising the need for uniformity in introducing the white line on roads at bends and corners, the British Ministry of Transport has issued instructions to its divisional engineers of the Jtoad Department urging the adoption 'of this safety line and pointing out that the procedure should be standardised las far as practicable. Approved expenditure incurred in marking white lines will - rank for grants from- the Road Fund, in the same way as the ordinary expenditure upon the maintenance of highways.

I That not enough ' motor bodies are built locally is the. complaint of the New Zealand Coach and Motor Body Builders’ Association. In an official 'statement the, secretary of the Tariff Committee of that organisation says: "It is obvious some assistance must be afforded forthwith by either restricting the importation of motor bodies by providing that one chassis should accomnanv everv three complete cars, or bv a substantial increase in the body tax by jl'vving ad valorem rates on the cost iof the completed car at the port of export, of, sav, 5 tier cent. British and 10 'per cent, foreign in place of the present (flat rate now levied.”