The Mechanical Handling and Storing of Material

22 2 THE MECHANICAL HANDLING OF MATERIAL grain, and with it the foreign matter, very near to the top of the blades. A mechanically operated tipper, owing to its slow movement and its much greater depth of receiver, whilst giving the advantages of the rotary seal, entirely overcomes its defects. A similar type of elevator, but mounted on wheels and a rail track on the quay, is shown in Fig. 302. In this case the inclined pipes will be seen leading into a “ canister” from which the grain is discharged into a bucket elevator, and raised into a weighing machine, then re-elevated for delivery into pockets in the warehouse wall; this installation was also built by Henry Simon, Ltd. Small Pneumatic Grain Elevators.—-Installations of small capacities have recently been introduced, particularly for the use of millers, maltsters, oil-mills, and the like. The one here described is that at Messrs Leetham & Sons’ Flour Mills, York. Fig. 303. Pneumatic Grain Elevator at Messrs Leetham & Sons’ Flour Mills, York. Fig. 303 shows the whole installation in diagrammatic form. As these small plants are very similar to the large ones already fully described, it will suffice to mention that D is an existing elevator into which the pneumatic installation has to discharge its load, G is the receiver, f the filter, c the blower, b the air trap, and a the exit for the spent air; e is another air trap through which the dust from the filter may be drawn off into sacks. The capacity of the plant is 18 tons of grain per hour, and the driving power con- sumed is 15 H.P. It has, however, handled up to 22 tons per hour, with an expenditure of 18 H.P. These figures are very satisfactory, principally owing to the lift being only about 15 ft. The only details which deserve a fuller description are the air traps b and E, Figs. 304 to 307. They consist each of a wheel with six compartments fitting as nearly air- tight as possible into a frame, which is cast in one piece with the grain inlet; the same frame also carries a small countershaft with a pinion which is geared into a large wheel,