Patent GB-191009880-A (GB)
Title: Improvements in Railway Signalling.
IPC: B61L23/12
Filed: 1910-04-22
Granted: 1911-04-20
Abstract: 9880. Sykes Interlocking Signal Co., W. R., Sykes, W. R., and Tarrant, R. W. April 22. Combinea electrical and mechanical systems; signalling-instruments; signalling-instruments, interlocking; slots, reversers, and like apparatus. - In a railway block - telegraph system wherein the release of a normally locked element situated at one end of a section is dependent upon the completion of a series of electric impulses of predetermined number and order, the release of the element is controlled by rendering it dependent upon the receipt of a succession of impulses, some of which are of positive and some of negative polarity, means being provided for enabling such impulses to be transmitted from the controlling-end through polarized mechanism at the controlled end to release the normally-locked element. The invention is described with reference to its application to the Sykes lock-and-block system, the modified apparatus being shown in Fig. 2, in which the lever lock is adapted to be released by the receipt of a positive followed by a negative, impulse, the apparatus shown being arranged for the passage of trains from A to B only. The usual controlling - magnet at the station A is replaced by a permanent magnet H, Fig. 5, provided with inverted U-shaped softiron pole-pieces Q', Q<2> apertured to support cores q<1>, q<2> upon which are coils H<1>, H<2> wound in series, one end of the windings being earthed, and the other connected to the middle contact l of the switch L. Two armatures R<a>, R<b> are provided, one bridging the limbs Q<1a>, Q<2a> and the other the limbs Q<1b>, Q<2b>, and they are carried by bell-crank levers r<a>, r<b> pivoted at r and carrying rollers which normally project under the spur J<Î>, and so hold up the locking- rod J. The lever r<b> passes under the armatures R<a> which cannot therefore fall until after the armature Rb. The windings are so arranged that a positive current releases the armature R<b>, and a negative current the armature R<a>; when the armatures fall, the springs press the other arms of the levers r<a>, rb from under the spur J<Î>. The line-indicator M has its arm normally vertical, and the direction of movement thereof shows the direction of current in the line. The apparatus at the station B is modified for transmitting the double current, two batteries O<1>, O<2>, provided for sending positive and negative current into the line, being connected at one side to switch members s<1>, s<2>, and at the other to a switch m which, when closed, earths the batteries at this side. The switch m is normally held open by the rod n<1> carrying the indicatorplate K<2>, which rod is normally held up by the detent n resting on the rod n<2>. A vertically sliding rod S is also provided, which is adapted to be raised by the lever T, which is moved about its pivot, when the plunger N is depressed by the cam roller t<2>. The rod carries switch members S', S<2>, and when the pressure on the plunger is removed, the lever T is released from the pivoted catch T<1>, and the lever S falls, its rate of fall being governed by a dash-pot U. A switch member s<3> is connected to a switch S', which, according to the position of the plunger hook P, makes contact at m<1>, m<2> in the circuit of weak batteries M<1>, M<2> placed in parallel and connected at the other side to the earth side of batteries 0', O<2>. When A calls up by bell &c. B accepts the train by pressing the plunger N, which raises the levers T, S so that the switch arm S<1> is above the contact s'. When the plunger is released, the detent n is released, and the rod n<1> falls to close the switch m and to move the indicator KB to " train on." The rod S then begins to fall and closes the circuits of batteries O<1>, O<2> in succession through contacts S<1>, S<2>, the current flowing to station A through members S', S<2>, s, line ab, indicator M, and coils H<1>, H<2>, which are thus actuated successively by a positive and a negative current. The rod J then falls, showing " free " on the indicator KA and lifts the lock F from the notch f<1>. When the lever EA is moved to lower the signal D the cam j<1> again lifts the rod J, the lock F falls into the notch f<2> and back-locks the lever EA and the rod in rising lifts the armatures, which are again held by the magnet H, the line current having been cut off by the movement of the switch L through the lever connexion L'. After the member S<1> passes off the contact s<2> on to the contact s<3>, the batteries O<1>, O<2> are cut out, and one of the batteries M<1>, M<2> operates the indicator M, until the lever EB, having been moved to admit the train, is returned and thus, by resetting the rod n<1>, breaks the circuit at the switch m. The lever EA is unlocked by the passage of the train over the treadle G, thereby connecting it to earth. The treadle is connected to one side of batteries G<1>, G<2> corresponding to batteries 0', O<2>, and their other sides are connected to contacts g<1>, g<2>. A switch g is moved with the arm D to connect contacts g<1>, g<2> when the arm is at " safety " and " danger " respectively, and is connected to the wire 2 leading to the member l<2> of the switch L, part of the current passing through a Sykes automatic signal-reverser d to earth. When the train passes on to the treadle, the switch g is making contact at g<1>, and consequently positive current passes to the reverser d to reset the signal, and to the coils H', H<2>. As soon as the signal is returned, the battery G<2> is placed in circuit, and negative current is sent. The lock F is thus released as before, and the return of the lever sets the instrument back to normal. Fig. 10 shows an alternative arrangement for taking off the backlock. In this arrangement, the movement of the rod d<1> raises a rod V, having a dash-pot, and otherwise arranged similarly to the rod S, Fig. 2, but which is held after being raised by a catch v<Î>. The rod V controls the circuits of batteries G<1>, G<2>, the latter of which actuates the reverser d when the treadle G is operated. The reverser is thus actuated, and returns the arm to " danger," at the same time tripping the catch v<Î> and reversing the switch d<Î>, thus earthing the batteries G<1>, G<2>, which in succession, owing to the movement of the member V<1> over contacts v<1>, v<2>, send positive and negative currents through the coils H<1>, H<2> to take off the lock as before. When the signal is returned, the counterweight d<2> drops, and the switch d<Î> is again returned on to the contact d<1Î>, thus cutting-out the batteries. Arrangements may be employed in which the unlocking is not dependent upon the automatic return of the arm. Thus the passage of a train over a treadle may cause displacement in opposite directions of a body of mercury, which normally occupies a mid or inactive position, thus successively closing the contacts of two batteries in parallel as before. Or a fouling-bar may be employed in conjunction with a treadle to operate a switch to cut-out one battery, which is normally in circuit, and to place in circuit a second battery while the train is still depressing the treadle. Or the normally-energized relays of an insulated track-circuit system may control the circuits of two batteries in parallel, the relay armature in its normally held-up position closing the negative circuit, and, when released, closing the positive circuit, the relay in the next section, when de-energized, closing a break in the same circuit to allow the current to pass to the coils H', H<2>. In these arrangements also, part of the current may be arranged to actuate the reverser. The sequence of currents may with advantage be negative and positive.