• CRANES ON LORRIES. Fittings Which Save Time and Labour.
Page 16
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CONSIDERING the vast numbers of lorries now used in the transport of all types of heavy material, it is somewhat surprising to find so few vehicles fitted with some form of lifting crane or lifting tackle. The addition of one of these useful fittings may mean a tremendous saving in the time taken to load or unload a vehicle. Cases, barrels, etc., can be lifted direct from the ground, run into position, or stacked with the utmost facility. A convenient method for certain classes of work is to have a girder runway above and along the centre line of the body, well stayed to withstand reasonable loads. Along this girder can run a small-truck carrying a set of blocks and tackle. If the girder, is extended so that it protrudes slightly over the tailboard of the vehicle, articles can be lifted from theeground and then run to the front portion or the body. Another system is to employ a pillar clamped to the
side of the body towards the rear. This 'pillar can have a swivelling armea,nda small winch ,geare and will be able to work in a very similar manner to the runway apparatus just described. If reqeired, the pillar may be made telescopic se that it will be neither unsightly nor obstructive. Fittings of this description can be supplied by almost any engineering firm, and their april -cation to motor vehicles would be a matter of sinipiwity.
J. J.
STEEL WHEELS v. WOOD WHEELS.
Why Confidence in the Steel Wheel , Has Grown.
MANUFACTURERS are rapidly being converted to the use of all-steel wheels of the cast, or built-up, type for heavy vehicles, or the pressed and welded-type for the lighter machines. Most of the wood wheels still to be seen on new vehicles are en chassis imported from America, and even these are restricted to'the lighter models.
The reason why wood. wheels have been replaced to such a great extent by steel is that, provided a steel wheel is well designed and made from good material, it gives extremely long•,serviee with come paratively little or no trouble, .whereas wood wheels are a.-•pt to shrink in hot, dry weather, causing the spokes to warp, after which disintegration', rapidly follows particularly if the wood fruni.whicl they are constructed is not thoroughly Reasoned. Steel wheels have not, however, escaped .troubles in the past. The built-up, riveted_ type, in certain eases, gave considerable trouble on active service; as vibration quickly loosened, the rivets. Cast-steel wheels also, particularly when designed with a view to their being as light as posible, often cracked *here the spokes entered the rims, this being due to flexion of the rims, whereby a rocking action occurred using the spokes as fulcra. This trouble was experienced to a great extent on -the original B-type London omnibus, and a curious type of cast-steel wheel was evolved by the Associated Equipment Co. to cure this fault. In this wheel the spokes were rounded and, instead of being of large diameter near the hub and small at the rim, they were tapered from the rim to the hub, thus forming buttresses for the rim.
In ether cases, a cure was effected by intrad•ueing a larger number of spokes, or by branching flier spokes near their outer ends, so as to lessen the 'distances between the unsupported portions of the rims. Care was .also taken to remove, as far as possible, initial stresses caused by too rapid cooling of the castings, with the result that east-steel wheels are now perhaps, the most reliable type of wheels on the Market. J, M. 038
AIR PRESSURE IN PNEUMATIC TYRES
Howto. Lengthen the Life of Tyres. THOSE USERS of motor vehicles which have pneumatic tyres should pay the greatest attention to the question of correct inflation pressures. Drivers are apt to consider that if the wheel rim ,does not come into contact with the road the pressure is quite sufficient pothers pump the tyres up until they are .board hard and think that they will obtain the best mileage out of their covers by this
means. -.
It is impossible to lay down here specific pressures, and users should be governed by the pressures recommended by the manufacturers of the tyres. Tyresaprimped to too high a pressure are liable to burst, particularly if they are cut by any sharp article while travelling. If under-inflated, undue wear of the beads will take place, owing to the constant excessive.flexion, and the tyres are apt to creep on the rims, thus tearing the inner tubes. Over rough roads,when the tyres are flabby, it is quite possible that the steel rims will gradually cut or chafe through the canvas.; foundations, .
Some owners of large fleets go so far as to have the pneumatic tyres of their vehicles pumped up to the correct pressure daily; a precaution which has proved :conclusively to give the tyres a longer life.
Whilst on this subject, it would he as well to point out the benefits of overhauling the tyres at . every opportunity ; sharp stoned, nails, etc., become eniheddedlin the thickness of the tread, and if removed in time numerous punctures may be prevented. The lifeeof the tyres will he lengthened if the holes from which these articles are removed are filled with some forth of good plastictyre stopping. This method only applies to very small holes; larger ones should be repaired by vulcanization. Y.Y.M.
THE AGRIMOTOR AND ITS TAX.
An Anomaly in the Classification Which Has Now Been Removed.
F COURSE, the proper claim for me to make, in respect of the removal of the anomaly which X observed in the classification of agrimotors inthe draft scheme of motor taxation,would be
"Alone I did it But the dates would confound me if A were confronted with them in a witness box, a knowledge of which fact only confirms me in a lifelong...determination to keep out of, such evil
places I •
Since I wrote my note upon the subject for publication in a recent; issue Of The. Conmerciril-MOor, the Government,* or the Treasury, or some official or other has caused to be printed and published the terms of the Finance Bill, 1920, in which the Corninane of the United Kingdom of Great Britain and Ireland in Parliament announce to His Majesty the King that they have resolved to grant unto His Majesty the several duties mentioned in • the Bill. Among them, however, is the small sum of 5s. per annum fro-in any ploughing engine, tractor, or agricultural tractor, not used for hauling on the roads, whilst in respect of agricultural traeters which do haul upon the roads, 'but solely in connection with agriculture, the sum of £6 if they: do not, unladen, exceed five tons in weight (which, of course, means every one of them, because I cannot recall one which . weighs More than that—probably, even the Mann steamer would "strip" to it) and ,10 if they do foolishly exceed that all-sufficient ponderosity. So that is all satisfactory, and the lighter machines (that is, lighter than the 2---tons weight. which occurred in the draft scheme) will not have to pay
that &1 which was worrying MC, Ag o•riginally drafted, the scale richly deserved the censure I gave it. A.G.T. .