Various modifications of this type of filling system have been made. A general drawing of the Ford-Parkes design was shown in the previous chapter. The details of the top and bottom are shown by Figs. 51, 52, 53 and 54. The buckets in this design are not delivered on to a scale car, but on to a turntable carrying four bucket seats. This table is rotated 90 deg. at a time, and this rotation takes the empty bucket away and brings a freshly filled one to take its place. When the bucket is at 180 deg. from the position under the skipway, it is filled from the scale car which in this case is the regular hopper type of scale car. The general arrangement of the turntable and the motor for turning it are also clearly shown, also the scale car in position in Fig. 52.

Fig. 49. Details of Neeland top, front elevation.

The general design of the bucket-carrying truck is shown at the foot of the incline, the large quadrant at the front or upper end of the truck, from which the pickup hook hangs, is clearly shown. This quadrant is rigidly attached to the rear wheel of the truck and pivoted on its own center in the center of the equalizer between the two front pairs of wheels. It is evident that if the rear wheel of the truck be swung up around the pivot as a center, that the hook earned by the chain unwinding from the quadrant must move vertically downward. Referring now to Fig. 30, showing the top of the incline, there will be seen the convex curve on which the two front pairs of wheels of the truck run, and above a guiding slot with a sharp reverse curve which acts as a guide for the rear pair of wheels. The upper portion of this guide is a circle struck from the center of the truck in its top position, and this circle permits the rear wheels of the truck to rise while holding the pivot of the quadrant rigidly in its place, and gives the required vertical movement to the bucket as a whole. This seats the bucket on top of the gas seal exactly as is done with the Du-quesne top, but without the assistance of the vertical slide, and therefore somewhat more simply. The return of the rear wheels to their normal position is secured by a heavy counterweight which the rear wheels pick up just before they enter the guide, and which pulls them back down on to the incline as soon as the hoisting rope is slacked. The head-sheave is clearly shown just above the curved guide.

Fig. 50. Details of Neeland top, side elevation.

Other modifications of this type of top have been built, but the principle in any of them is no different from those illustrated.

At one of the most successful plants in the country the bucket is never unhooked from the carriage but rigidly attached to it just as the skip is attached to the hoisting rope, but provision is made for rotating the bucket on its vertical axis to each of three equally spaced directions in turn, this eliminates irregularities in charging it.

Figs. 51-53. Bottom of hoist, Ford-Parkes system.

It will be seen that this type of filling gives precisely the same type of distribution as the double-bell type of top, and with almost the same limitations. That is to say, irregularities due to the way in which the charge is delivered into the top may and generally do occur with either type of filling, and may be more or less completely compensated by the correct rotation of the receiving part to equally spaced dumping points in regular order.

At the same time it must be recognized that the advantage is with the bucket system if the top be not rotated because of the smaller number and lower velocity of transfers of the stock with corresponding reduction of the opportunity for segregation.