Page:EB1911 - Volume 28.djvu/494

Rh the 4- weight is being lifted. But at the same instant that the cutoff takes place the rider weight is lifted off the end of the balance by a self-acting arrangement, and the sugar in transitu takes its place in the bag. And, if the rider weight has been correctly adjusted, the bag of sugar will be shown to weigh exactly by the beam vibrating in equipoise.

Automatic Coal Weighing Machine (fig. 18).—This machine weighs the coal delivered into factories, &c., by charges up to 20 cwt. at a time, and records and sums up the weights of the charges so as to exhibit the total weight delivered. The whole of this work is effected automatically.

The coal is dropped into a hopper by a grab. The hopper is carried on two knife-edges, one on each side, and is prevented from tipping over fore and aft by a pair of parallel motion bars on each side. The knife-edges on which the hopper rests are on two horizontal levers, one on each side of the hopper. These levers are carried by knife-edge fulcra in bearings on the frame of the machine, and transmit the weight of the hopper by means of an intermediate lever and a vertical rod to the indicator lever. And the long arm of the indicator lever pulls vertically upon the spring of an ordinary spring balance, which registers the load, and with the addition of suitable counting mechanism sums up the weights of any number of successive loads.

The charges of coal fall into the hopper with a heavy shock, and in order to save the knife-edges there is a strong pin in each side of the hopper below the knife-edge, which, before the charge of coal is dropped into the hopper, is acted on by a strong horizontal flitch-plate, which heaves the hopper off the knife-edges and relieves them from the shock. The heaving-up of the flitch-plate and hopper is effected by a cam on the end of a horizontal shaft which runs along the back of the machine behind the hopper. The flitch-plate rests at one end on the top of this cam, and at the other end is shackled to the horizontal arm of a bell-crank lever which is pivoted on the frame.

When a charge of coal is dropped into the hopper, the bell-crank lever receives a violent jerk from the shackle of the flitch-plate, and this jerk by means of suitable mechanical arrangements throws a pinion on the cam shaft into gear with a wheel on a counter shaft, which is kept constantly running by means of a belt and pulley driven by an engine. The cam shaft and the cam then begin to revolve, and the flitch-plate is gradually lowered till the knife-edge bearings of the hopper are received on the knife-edges of the main measuring levers, and the load is then weighed by the levers and the spring-balance. Shortly after this is done the mechanism at the back of the hopper automatically opens the doors at the bottom of the hopper, and the coal drops out. The rotation of the cam shaft continues till the cam has again heaved up the flitch-plate, when the pinion on the cam shaft is thrown out of gear with the wheel on the counter shaft, and the cam remains steady till another charge of coal is dropped into the hopper and the action is renewed. The coal when dropped out of the hopper runs down a shoot into a receptacle, from whence it is lifted by a Jacob's Ladder and distributed to the boilers, &c., of the factory.

Automatic Coal Weighing Machine (fig. 19).—This machine is designed to weigh and total up the weight of materials passed over it during a considerable course of operations. The trucks or other receptacles containing the coal, &c., are drawn upon the platform of the machine, and the pull of the load is transferred by a vertical rod at the left-hand end of the machine to the knife-edge on the short arm of the steelyard, whose fulcrum is carried on bearings in the frame. Behind the pulley at the top of the machine and on the same shaft is a spur wheel, which drives both of the spur wheels shown in the diagram. The small spur wheel is mounted on the steelyard, and this wheel and the one that drives it arc so arranged that their line of