A NEW THIRD-SPEED EVERY WEEK.
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By "The Inspector."
NE OF THE contributors to THE COMMERCIAL U MOTOR, whose writings I always enjoy, uses
. the pseudonym " Live Axle." I notice further articles from his pen in recent issues. In these he quite rightly suggests that, at a time when many of us are turning our minds, so far as other preoccupations will permit us, towards imaginings as to what the new designs of the early future will be like, it la by no means without utility to endeavour to recall such constructional progress and improvement in design as has occurred since the commercial-motorvehicle first made its bow to a sceptical public.
Not everyone now proudly boasting a more or less intimate knowledge of the industrial vehicle and its uses is fortunately able to recall experiences of "operation," as it was called, in the early days. Nothing so vividly illustrated the elementary nature of many of the characteristics of early van and lorry design as the heart-breaking efforts which attempts to keep such machines in regular service, entailed on those who, eagerly enough, hadessayed the unknown. task. Those who to-day will tell you with pride that they are maintaining a fleet of this, that or the other Army-type lorry, motorbus, or other high-grade machine, have in few instances but a slight idea if any, of the exceptional shortcomings of models -of 10 or 12 years ago, and of the ways in which failures occurred with heartbreaking persistence.
It fell to my lot, more• than 10 years ago, to be in charge of considerable numbers of three-ton chassis of various types, and in the endeavour to indicate what proved to be the most troublesome and persistent of our many trials, I am inclined after consideration to suggest that it was lubrication. Adequate oiling of engine parts in particular was in those days extremely crude in system. We were asked to believe that if the rotating crankshaft, with its attached bigends, were left to churn up a sufficiency of lubricating oil with which the crank chamber was kept flooded, the so-called mist that would result would ensure a, satisfactory film of oil between all rubbing surfaces, so long as that mist endured. But, varying levels as. the oil got burnt up or leaked out of bearings, or as the chassis climbed or went down a hill, to say nothing of extreme 'variations in the viscosity o f the lubricants often sold in those days as suitable for the purpose, rendered it impossible to be certain that one or other of the crankshaft bearings was not starved for a longer or shorter period. The result was that seized big-ends were of far too c;oinmon happening. The damage did not rest with the running out of the white metal or with the crushing of the gunmetal cages, but, in 'many cases, big-end bolts tore adrift or the nuts were stripped, the rods doubled up, or came away altogether, and it was a general rule that great holes were knocked in the expensive cast-aluminium crank chambers and bases.
Scientific welding was not such a valuable and satisfactory repair in those days as it is now. The task confronting the maintenance engineer who either had to patch with copper plates hammered to the shape of the damaged castings, or to await the convenience of proprietors of available welding plants, was not a happy one in all conscience. Those were not the days of spare engines either, The spare engine, such as is now dropped into the chassis with but an hour or two's delay, was entirely unknown in the spare equipment provided for machines in the early days. If a crank chamber was burst, the whole machine bad to lie up very often for weeks on end, and on occasion for months.
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An almost equally troublesome failure, or perhaps it were better called a weakness of design, and partieularly in fegard to public-service machines, was the difficulty of ensuring sufficiently quiet running of the change-speed gear to satisfy the somewhat meticulous
taste of the licensing authorities, Particularly was the third speed a bugbear of early maintenance engineers. On such chassis as had live axles, and they were few, the final drive was of course a similar worry. Numerous are the tales which could be told of means that were attempted to improve matters in this direction. .1 almost hesitate to hint that I know of a case where, by some miraculous interposition, one operating engineer (blessed or cursed with the care of a particular type of three-ton chassis on which the gearboxes were famed for their groanings and grindings), discovered one such box which was very nearly silent. Nobody knew why, and exhaustive investigations failed to reveal the reason. That particular box satisfied the licensing authorities with regard to the silence of quite a number of distinct and separate chassis, and the manner in which it performed its task is a 'secret which I am not inclined to disclose in print !
Noisy boxes were the subject of all kinds of ingenious experiments. I can recall the filling lip of the webs of certain gear rings with closely fitted and firmly bolted discs, and again with similarly shaped and similarly fixed red-fibre sectors. I recall the use of numberless different types of patented lubricating media with which the gearboxes were filled, varying from an unhealthy-looking mixture of black mineral oil and Russian tallow through different grades of filthiness to that patented gearbox lubricant which consisted to no small extent of sawdust. But it was all to no purpose, and, indeed, many of the expedients which were adopted by operating engineers, driven to their wits' end, resulted in the rapid wearing out of the bearings, antlz curiously enough, in,the almost invariable overheating of the boxes.
These were certainly two of the gravest troubles in connection with the early models of petrol-propelled chassis of the largest types. Practically everything, however, happened on those chassis , which coold happen—and in addition quite a number of things 'which should not. A catalogue of what I may with confidence call trouble would most certainly include plugs that would crack, magnetos in which the insulation would break down, clutches that would slip or seize according to their own sweet fancy and in the end would burn their leathers to a cinder, universal joints that would wear out with irritating regularity, engine arms that cracked and frame members that did likewise. There were brakes that required relining three times a week, third speeds which had to be renewed more frequently than once a week, differentials that stripped, steering rods which fractured, petrol pipes which broke, despite their loopings, every 100 miles or so, oil systems which choked and petrol tanks that would diabolically collect water. from nowhere and send it through the petrol pipes, pressure feed systems of which the principal characteristic was loss of pressure, exhaust joints which blew, cylinder jackets that cracked, fan belts that slipped or came off altogether, and radiators that got rid of more water than they cooled.
These were but a tithe of the troubles that the early engineers knew, and few, if any of them, remain in modern practice. Better materials, better design, recognition of the fact that spares are a necessity and that they must be interchangeable to be of any use, these, with the naturally much improved knowledge of operation, have worked wonders in a few short years.