LOADING AND UNLOADING.
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Some Devices Described which Facilitate Operations.
IN A RECENT SERIES of articles we dealt with the mechanical principles involved in the various methods by which much of the time at present wasted at terminals during the work of loading and . unloading can be saved. By way of a supplementary note itmay be interesting to make some brief reference to a few of the actual devices which are available for such purposes and embody certain of the principles to which we referred. In particular we dealt with the use of the inclined plane as a method of moving goods, and also emphasized the desirability of replacing sliding friction by rolling friction. These two. principles are embodied in what are known as gravity carriers or runways.
Thus, for example, the British Mathews' Patent Gravity Carrier, as supplied by Messrs. W. and C. Pantin, of 147, Upper 'names Street, conveys fairly heavy packages automatically and without the exertion of power down a gradient of no more than 2i per cent. A carrier of this kind does not cost much in the first instance and costs practically nothing to maintain and work. The goods are loaded on to it at the point where they have been stored or collected and move steadily down it even though there may be fairly sharp corners on the way ; this without the application of power.
The capacity of the carrier is only limited by the rate at which it can be loaded and unloaded. 'Nses move along it round sharp curve's just as surely and easily as along a straight length. A carrier can either be a fixture attached to the structure of a building or can be supported on adjustable stands mounted on wheels. In the latter case it can be led exactly to the desired point and the goods discharged on to a lorry at the desired height. What may be described as by-passes may be provided by means of which packages can be easily diverted at a number of different points en route. The carrier consists essentially of sectional frames about 8 it. in length carrying a number of rollers, usually 14 ins. long and 21 ins, in diameter. These rollers are made of seamless steel tubes and arc mounted on ball bearings. The distance between their centres depends on the size of the pabkages to be conveyed, as each package must be able to span at least three rollers. Obviously, however, if a number of small packages have to be dealt with, all that would be necessary would be to collect them upon a light tray of suitable size. A variety is the wheel carrier, mhiela consists of 2.1 in. steel wheels on ball bearings bolted to two flat parallel rails, the width depending upon the size of the paCkages. This. method is recommended as against the roller carrier for packages not exceeding about 1 cwt. as being cheaper .and requiring even less gradient. Fig. 2 shows a portion of a gravity carrier suitable for dealing with baulks of timber, and illustrates how the load is carried round a corner and also the ease with which the carriers could be set up so as to deliver their load at any required point. Fig. 4 shows a carrier conveying cases of aerated water.
Obviously, the one weak spot which is inherent to the principle of any gravity carrier is that the packages to be loaded must always move upon a down gradient. ThiS clearly implies that, prior to loading, they must by some means have been brought to a higher elevation, which in many cases must have involved the expenditure of power, though in some instances it will be possible to arrange for incoming goods, or goods prepared for despatch, to be brought together, upon a level sufficiently higher than that at which lorries would stand while taking their loads. In that case the lorry itself would subsequently use the road as an inclined plane and expend a certain amount of power in getting hack to the higher elevation.
Assuming that the goods to beloaded start. at ground elevation and have to be distributed to the platforms of a number of lorries standing upon the same level. In that, case it would be necessary to introduce an elevator which, of course, must absorb a...certain amount of power. The elevator may take the form illustrated in Fig. 3. The goods on reaching the top of the. elevator would pass automatically on to a gravity carrier. There are, of course, "a number of 'other forms of elevator, but the 'one shown is selected for illustration, because it could be adapted to deal with a considerable variety of goods.
Another type of gravity runway or carrier is that known as the Ardonaite, which is marketed by Messrs. Rownson; Drew, and Clydesdale, of 225, Upper Thames Street.. The principle involved is, of course, the sathe as that already described, but there are differences in the details of construction. Among points to be mentioned are the ease with which sections can be.ctonnected to one another and the . provision of a curved top lip upon the members on which the roller axles are mounted. This lip protects overhanging material, such as snacks, from catching on the side. Details of the roller itself are given in Fig. 7, which illustrates the type of roller bearing provided' with a view to distributing Om& and minimising wear. The rollers of these bearings are, of course, constructed of hardened steel. Roughly speaking, the cost of a runway of this type, if 12 ins, wide, is in the neighbourhood of 12s. per foot, with a slight addition if curves have to be introduced. A runway 24 ins.
wide would cost about £1 a foot.. The exact price varies according to the pitch of the rollers. Fig. 1 shows a runway mounted Upon adjustable legs, an arrangement which might be an advantage in connection with the sort of use which we are contemplating. For some classes of work, overhead runways are used and the loads to be conveyed are suspended by hooks. Such a runway is shown in Fig. 8 working with a band conveyer for unloading carcases from Ships and bringing them up to a convenient point for loading into lorries. The details of the Arclee system of overhead runway are shown in Figs. 5 and 6. .
Itxwould 'be possible to continue indefinitely to 'illustrate various methods of applying runways or gravity carriers either alone or in combination with various formssof elevator, but the examples shown will probably suffice as suggestions to the motor lorry owner who takes the trouble, as advised in our previous-articles, to look attli&whole question from the point of view' of ,first principles. He must remember that, once the principle is established, the adaptations of that principle are almost endless, and that it is quite probable that the particular adaptation which would fit his case is already available in a concrete form and is such that, when put into use, it will save many hours of valuable time during which his lorries are at present standing idle because of a foolish adherence to the old and obvious system of depending entirely upon hand labour both for loading and for unloading.