RUNNING ) UPKEEP AND OVERHAUL.
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Interesting Contributions from Maintenance Engineers, Drivers and Mechanics.
A Mirror for Indicating Rearlight Failure.
A S there are many lorries running on 1-1whielt electric lights are not installed, so that oil lamps have to be relied upon, the suggestion of "
of Old Cumnock, Ayrshire, may be of value to other drivers. He points out that with such lamps the driver is always in a state of nervous fear that his rear light may jolt out and that he may have to answer a summons at the local police court.
To see whether the rear light is all right when a lorry body is between the driver and the light is no easy matter, so our correspondent has fixed up a mirror which can be seen without difhamity from the cab by lookingat the ordinary driving mirror.
Such a mirror, he suggests, need not he of looking glass, which may get broken, hot that any piece of polished metal will do as well. He mounts it on the end of a piece of rod fixed to the body and provided with a screwed part and two nuts. During, the daytime the mirror can be turned inwards, as shown in his sketch.
When the rear_ lamp is fitted with a side light, as many are,the mirror need only reflect from the -side, hut when the lamp is without a side light the mirror can be placed farther back, so that it may catch the red light.
Stripped Axle Nuts : Some Suggestions to Promote Safety.
WITHOUT suggesting any better method of securing hubs to their axles than by the nut, which appears to strip its thread oftener than most of us realize, a correspondent, "11.J.0.," of Highgate, points out that in the matter of securing wheels to their axles, motor manufacturers might do as they have done before, viz., copy the methods of the old coaehbuilder. The motor designer, with all his scientific knowledge, has never,been able to invent any better spring than the semi-elliptic, as used on carts and carriages, or the quarter-elliptic, as used on the Costermonger's barrow, which looks like a come-down for the scientist.
In the old coaching days, the trouble of securing wheels to their axles was with the makers just as it appears to be with us to-day. Linchpins and other devices wore tried, but the risk of a failure was always there, although it is not easy to see how a well-spread-out, laminated linchpin could fail.
That all the various devices did fail on occasions is evident by the introduction of what was known as the "Mail Coach" axle, in which all efforts to secure the wheel at the outer end of the
rifle were abandoned. A collar was placed on each end of the axle before welding it up in the centre, these collars being allowed to bear against the flange which was forged on the ftxle, as shown in the sketch, and three or four bolts ran through the nave and were fitted with nuts at their outer ends. The bolter were a driving fit in the nave and were burred over on their nuts; by this means the risk was spread over a number of bolts. The old books on coaching tell us that this form of construction entirely Prevented the serious accidents that used to happen when wheels came off their axles.
Our correspondent, after telling us all these interesting facts about the old coaches, comes right up to date by sending us a sectional view of what he suggests would entirely prevent accidents to life and limb should an axle nut strip its thread. His suggestion is that at the inside of many hubs there is a flange which could be so arranged that a guard piece, as shown, could engage it only in the event of the nut failing.
Trouble with Springs.
THE writer, " 0.T.Y." of the letter on
"Trouble With the Springs of a Trailer," which appeared in our issue of November 6th, writes us regarding our criticism of his method. He states that the hollows he filed in the edges of his springs were so shallow that they diel not exceed the extent of the rounded edge of the _spring steel, so although there was a sliedit hollow which was sufficient to give a holding for the extra bolts, the spring was net materially weakened. He also tells us that the springs he treated in this manner have been running for over two years in constant work without a breakage occurring.
Our opinion, based on experience, is that the commonest cause of the trouble of springs cutting off the central bolt and shifting their position is the foolish practice of some designers of placing the nuts, which tighten the spring bolts, at the bottom of the bolts, so that rust can form in the hole through which the bolts pass, as well as at the nuts. This prevents a careful drive: from periodically tightening the bolts, for pull as he may on a spanner, if the bolts be rusted in their long holes, he will not be able to tighten them, so the springs soon get slack. The nuts should undoubtedly he at the top end of the bolts.
Air Cleaners for Employment . on Tractors.
AN Orpington correspondent, "F.S.," tells us that he hes had a goad deal of experience with air cleaners on farm tractors, where he considers them an absolute necessity, for in ploughing when there is a following wind the tractor works in a cloud of dust. He points out that the class of cleaner which requires attention at intervals to clean it from duct that has adhered to a felt filter or an oil-soaked labyrinth formed of strip metal would in all probability not get it in the hands of the ordinary haulage contractor, although it might be attended to in the ease of a well-organized fleet His suggestion is that if the intake pipe were brought to some part under the bonnet where dust is least likely to be found it would do all that is necessary for our dustless roads, He points out that in the fitting of carburetters this matter appears to be entirely ignored by many designers.