Patent GB-190211698-A (GB)
Title: Improved Apparatus for the Time Indication for the Stoking of Boiler Furnaces and the like.
Inventor: KILROY WILLIE DICKSON
Filed: 1902-05-22
Granted: 1903-05-14
Abstract: 11,698. Kilroy, W. D. May 22. Signals, indicator or visible, electric, and bell.- Relates to electrical, or mechanical and electrical apparatus for giving visible and audible indications of recurring uniform time intervals, such as those at which the various furnaces in a stokehold require to be fired. The numbers of the various furnaces are marked on a dial, and one number at a time is displayed through an opening, a bell being struck at the same time. The dial is turned by an electromagnet, the circuit of which is completed at recurring intervals by a switch under the control of a mechanical or electrical time regulator or clock in the engine-room or elsewhere. The circuit may include a winding mechanism for the controlling clock. One control apparatus may operate a number of indicators in different stokeholds. The control apparatus preferably adopted consists of a pair of electromagnets with a rocking armature which operates a switch of special construction, and the time occupied by successive movements of the armature is controlled by a Foucault brake, the action of which is adjustable. Fig. 1 is a diagrammatic view of the control apparatus. Electromagnets 1, 2 operate the rocking armature (not shown) and an arm 4 of the switch follows the movement of the armature and makes two contacts on each side, one to reverse the action of the electromagnets, and the other to establish the circuits 6, 6a respectively of one or other of two sets of indicators. A set of resistance coils 10 in a shunt circuit adjust the amount of current passing through the brake magnet. Switches 12 enable the various indicators to be cut out of the circuit. The rotating disc of the Foucault brake is driven by speed-increasing gear from the spindle of the rocking armature ; it rotates between pole pins, one or more of which may be adjustable to vary the strength of the magnetic field. Fig. 4 shows the switch, and the resistance regulator for the brake. On the spindle 14 of the rocking armature, which is not shown, is a disc 15 with two guard flanges 16. Outside the disc 15 the spindle carries an arm 17, the ends of which are connected by spiral springs 18 with the rocking arm 4 of the switch. The upper end of this arm is forked at 4<a>, and the extremities of the fork carry pins which alternately bear on the outer periphery of the guard flanges 16. As the armature rocks slowly under the control of the brake, the spindle 14 turns and oscillates the disc 15 and arm 17. The springs 18 are thus alternately extended and tend to throw the arm 4 over in the contrary direction. It is, however, prevented from moving by one or other of the pins bearing on one or other of the guard flanges until the latter has turned sufficiently to allow the pin to pass, when the arm flies over to its reverse position. The lower end of the arm 4 consists of two spring clips which alternately embrace the two contact-pieces 19 on one side and the corresponding pieces 20 on the other. The brake is regulated by shifting the arm 11 with reference to the contacts 21 of the various resistance coils 10, Fig. 1 ; an external pointer, shown in dotted lines at 22, indicates on a scale the timing of the device. Fig. 8 shows one form of indicator mechanism, comprising an electromagnet 23 with two armatures, one, 24, actuating ratchet gearing to turn the dial and the other, 32, striking a bell. The dial, not shown, is carried by the spindle 26, and one of the figures on it appears through a hole in the casing. The ratchet gear shown is a modification of the locking gear described in Specification No. 24,646, A.D. 1899, [Abridgment Class Mechanism &c.], but ordinary gear may be used, and the ratchet gear may also actuate the bell hammer. In a modified arrangement the bell of the indicator encloses the electromagnet and actuating mechanism. The actuating pawl 28<a> of the ratchet gear shown is pressed up into engagement with the perforations in the cut-wheel 27, and withdrawn therefrom by the tail spring 39 engaging one or other of two stops. Its end carries a pin engaging in a slot in the tail of the holding-pawl 28, which is thus brought into engagement with the cup-wheel or released therefrom. The control and indicator mechanisms are enclosed in suitable protective casings.