Page:EB1911 - Volume 28.djvu/493

Rh have to be provided for, and the machinery is complicated, so that a general description of the action of the machine is all that will be here given.

The tea is fed into a hopper, which has a large opening at the bottom, and this opening is entirely closed by two cylindrical brushes, which are mounted end to end on a horizontal shaft. As they revolve these brushes engage the tea in the hopper, draw it out by degrees, and drop it into a compartment of a circular drum which hangs on one end of a scale-beam. The brushes have the same diameter, but one is much longer than the other, and they move independently of one another. For the bulk of the filling both brushes arc in operation, but when the load is nearly complete the longer brush is stopped and the filling is completed by the shorter brush only. When the load is complete the shorter brush also is stopped while the compartment of the drum is emptied. And the action is then renewed. All these operations are effected automatically.

The circular drum is divided into four equal compartments by radial diaphragms. And in a pan at the other end of the beam (which is counterbalanced for the weight of the drum) is a weight to weigh the tea. As the uppermost compartment fills, the weights end of the beam rises, and by means of a vertical rod successively operates on detents connected with the rotation of the two brushes, and stops them in turn. And when the short brush is stopped a rod from the shaft frees a spring detent which keeps the drum in position and tips it over. The tea is shot out and falls into a receptacle below, and the drum makes a quarter of a revolution, and is again held in position by the detent with an empty compartment at lop ready for the next filling.

The power is applied by a belt round a pulley, which is mounted on the end of the horizontal shaft which carries the brushes. The brushes are carried by sleeves which run loosely on the shaft, and to each sleeve is rigidly fixed a ratchet wheel. Next the ratchet wheel is a disk which is keyed on to the shaft. The ratchet wheel and the disk are automatically connected by clutch mechanism in order to effect the rotation of the brushes. The clutch mechanism is freed at the proper time by the action of the vertical rod at the end of the beam, and the brushes then stand still while the load is discharged. The beam then recovers its original position and the action of the machine is renewed.

Automatic Sugar Weighing Machine (fig. 17).—This machine is adapted for weighing out granulated white sugar in parcels of 1-, 2- and 4- weight. The sugar is run into a conical hopper and is delivered into the open mouth of a bag which is placed on the goodspan of a balance. The balance consists of a pair of equal-armed beams rigidly connected together and acting as a single beam. A 4- weight is placed in the weights-pan of the balance, and is the only loose weight used with the machine. The pair of beams are hung centrally by rods and hooks from knife-edges in the forked end of a strong beam, which is carried at its fulcrum by the top plate of the frame of the machine. This beam is heavily counterbalanced at its further extremity. I underneath the top plate of the machine, and strongly framed to it, is a box, which contains the horizontal rods to the ends of which are attached the slides which regulate the flow of sugar from the bottom of the hopper. These rods pass through holes in the front and back plates of the box, and are furnished with spiral springs, which (when the rods are forced back by hand) are in compression between the back plate of the box and shoulders on the rods. The rods are held in this position by detents which take hold of the shoulders of the rods, and are acted upon from the front end of the upper beam and the weights-pan end of the lower beam respectively, in order to release the rods at the proper times—and reduce or cut off the flow of sugar from the hopper. The upper slide has the shape of a truncated cone, and it reduces the orifice of flow so as to render the flow of the sugar more manageable. The lower slide is simply a cut-off slide. When it is desired to use the machine, a 4- bag is placed under the orifice -of the hopper upon the goods-pan of the balance, and the .slide rods are thrust back by hand till they are held by their detents, and the sugar flows rapidly into the bag. When the bag is nearly charged to the weight of 4, the weight of the bag of sugar overcomes the resistance of the counterbalance of the upper beam, and its front end drops a certain distance. In dropping it dislodges the detent of the reducing slide, and the slide springs forward and reduces the flow of the sugar. The diminished stream of sugar continues to flow till the 4 weight in the weights-pan is lifted (the end of the upper beam being for the time brought up against the frame and unable to descend further), and in lifting it dislodges the detent of the cut-off slide. The slide springs forward and cuts off the flow. The filled bag is then removed and replaced by an empty bag and the action is renewed.

In order to ensure the correct weight of the bag it is necessary to consider that when the cut-off slide acts, a certain quantity of sugar is in transitu and has not at that moment taken its place in the bag. This is allowed for by means of a rider weight, which is arranged so as automatically to add its weight to that of the sugar in the bag while