The Mechanical Handling and Storing of Material

126 THE MECHANICAL HANDLING OF MATERIAL as possible, formed as free wheels. Each pair of wheels is bored, turned, and keyed on a steel spindle, running in bushed and automatically lubricated bearings. The wheels of the conveyor chain are thus at rest and move round with the curved wheel rims, thus minimising friction and preventing wear at these important points where the stress is greatest on the conveyor chain. By this improved and combined provision for movement a great reduction in the driving power has been effected. The tightening curve is provided with slide-blocks and tension screws, which enable it to be moved so as to take up any slack in the chain which may be formed. The automatic continuous filler consists of a short endless chain, carrying seven funnels and supported in a frame, the funnels successively covering the buckets of the conveyor, and as the filler chain is driven by contact with the conveyor chain, the spacing and filling is accurate and uniform. These funnels and chains move round an oval track formed in the filler frame, and are supported on wheels similar to those of the conveyor chain. The driving gear is so designed as to propel the chain by means of pawls which successively engage with the cross studs of the chain (see Fig. 168) and give a central thrusting action. The two parts of the chain are driven equally and simul- taneously. Robt. Dempster & Sons build a similar conveyor fitted with the Toogood Patent Equalising Gear, a description of which is given on page 192. The Babcock & Wilcox Gravity Bucket Conveyor.—This is also on the original Hunt system, but improved in details. To begin with, the chain links are bushed and the supporting rollers are carried on the bushes, and the parts are not only inter- changeable, but the axles and bucket studs are also reversible, and in practice it has been found that where lubrication is well attended to during the earlier stages of the installation, fine smooth surfaces are obtained in all the wearing parts of the chain. Each bucket is stamped out of one sheet of mild steel. The driver and wheel curve bearings are now made self-aligning, with larger bearing surfaces, consequently binding and extra friction is avoided in the driving gears and shafting. For complete installations of this conveyor see Chapters XL. and XLI. The Bradley or Pan and Bucket Conveyor.—This conveyor is the design of W. H. Bradley, of the Consolidated Gas Co. of New York, and is built by the Steel Cable Engineering Co., of Boston, U.S.A., and others. In its perfected form it differs considerably from the original type, and includes a great number of improvements. It consists of a continuous trough built in sections, and supported on axles and guide wheels running on suitable rails. There is one axle to each segment of the trough, and in each segment a bucket is pivoted to the sides. The axles are securely clamped to two endless steel cables instead of the chains which are generally used on conveyors of a similar type. This conveyor can be loaded when ascending, in which case the material is fed from a spout, and the process is similar to the feeding of an elevator. Material can also be fed at any point on the lower horizontal strand, as the conveyor itself consists of an endless trough similar to a con- tinuous trough conveyor. Thus, when the conveyor runs horizontally, the endless trough receives the feed; but as soon as the ascent begins, each short section of trough empties itself into its respective bucket, so that when ascending the buckets are separately suspended from their pivots, and the trough runs empty at the side. The discharging of the buckets is performed by a tipping device which can be so set that the contents of the buckets can be discharged at any desired point. The upper