Patent GB-115280-A (GB)
IPC: G08B5/36
Abstract: 115,280. Sterling Telephone & Electric Co., Bell, F. G., and Davey, W. C. .May 8, 1917. Mine signalling systems; order apparatus.-Relates to cancelling- mechanism for mine signalling systems in which an arm rotated by by the winding-engine operates a. cancelling contact. In order that further signals may be received while the engine is running, means is provided for preventing repeated engagement between the rotating arm and the contact-operating device. In the construction described, the rotating arm is slidably mounted on a disk driven by the engine and is withdrawn by centrifugal action, when the engine reaches a determined speed, so that the contact-operating device is no longer in its path. Means is provided to prevent a signal given while the engine is running from being can. celled when the engine comes to rest. Construction of switches 199, Fig. 1. A block 198, mounted on and rotated by a disk 199 driven by the winding-engine, is formed with a Y-shaped extension 207, sliding in a strap 208 and projecting beyond the periphery of the disk 199. During each revolution, the extension 207 engages a pivoted triangular member 209, the base of which is engaged by a leaf spring 212. The snap return movement of the spring alter the passage of the extension 207 may be arranged to open momentarily the cancelling-contact 214, 215, Fig. 5. Preferably, the end of the leaf spring 212 carries a pin 216, Fig. 4, on which rests a balanced lever 217, and the snap movement of the spring may open a contact between the parts 216, 217 or close a contact between a spring 222 and a pin 221 on the shaft of the lever 217. The cancelling-contact is thus operated once in each revolution of the disk 199 at low speed but, when the engine reaches a determined speed, centrifugal force acting on the block 198 withdraws the arm 207 so that it ceases to engage the member 209. The block 198 engages a contact 204, Fig. 1, at low speeds and a contact 205 at high speeds. Circuit connexions. In order to prevent signals sent while the engine is running from being cancelled by the member 207 when the engine is coming to rest, an additional self-locking differential relay WR, Fig. 6, is provided. This Figure shows parts of the relays R<2>, R<3>, of a system similar to that shown in Fig. 2 of Specification 112,497, the relay R<2> being energized momentarily by each signal impulse and the relay R<3> being energized and locked up during the pause between the first and second impulses. During the first revolution of the disk 199, the member 207 momentarily closes contact 209, 231, thus energizing winding 229 of relay WR, which locks up over contact 233 and by attracting its armature 256 momentarily disconnects the battery B from the lead 101, thus releasing all the relays and indicators. During the running of the engine, a further signal may be received, as the battery B is connected over contact 234 to lead 101. When the engine comes to rest, contact 204 is closed, preparing the circuit of the differential winding 230, but this circuit is only completed over contacts 237, 23 by the first impulse of the next signal. The relay WR then de-energizes, momentarily disconnecting the battery from the lead 101, and thus cancelling the signal given when the engine was running.