Abstract: A semiconductor contact arrangement comprising a semiconductor wafer having on one of its major faces an area of one type of conductivity and an electrical contact in face-to-face engagement with that area, in which the contact is located with respect to that area and is secured to the sandwich by a stud welded to the wafer and projecting into a hole extending through the contact from the face thereof engaged with the wafer.

Abstract: Fast Fourier Transform methods of analyzing signal frequencies spectra yield results from zero frequencies upwards. Thus, when the frequency band of interest is not at very low frequencies a lot of wasted calculations may be performed, and resolution and computation time have to be traded-off against each other, often falling short of the requirements for both. A technique is described in which the signal to be analyzed is passed through an anti-alias filter and initial transform data is collected by undersampling. In a railway track circuit receiver which is to identify a predetermined carrier frequency or FSK signal, the anti-alias filter is selected to exclude frequencies other than those in a frequency band including the particular track signal so that there is no ambiguity in the calculated transform results.

Abstract: A railway vehicle control system particularly, but not exclusively, suitable for controlling single track working. Transponders are located at fixed positions along the track such as at intersections, points and so on, and a vehicle is provided with sensors for detecting the transponders. A central control office supplies information concerning an identifying characteristic of the next transponders expected to be detected, when this happens the event triggers apparatus on the vehicle to communicate with the central office which then supplies information to identify the next transponder. The same sequence of events ensues as each successive transponder is passed. The transponders may be staggered alternately to opposite sides of the track for identification purposes. If the expected transponder is not detected but instead a different transponder is encountered, then a vehicle safety function such as the emergency brakes, may be brought into operation.

Abstract: A spring applied force actuator having an output member movable from a first position to a second output position, a first power spring by which can be generated on the output member an output force when the member is in its second position, first power means by which potential energy can be generated in the first spring therein to be held until the spring is released to apply its stored force as an output force on the output member, a second spring release of potential energy stored in which moves the output member from its first position to its second output position, and second power means by which the output member can be moved back from its second output position to its first position thereby, at the same time, generating in the second spring the potential energy subsequently to move the output member back to its second output position upon the subsequent release of that second spring.

Abstract: A railway vehicle control system comprises a railway track (1) and a plurality of transponders (N, N+1, N+2) at predetermined positions along the track. A railway vehicle (2) moves along the track, the vehicle having means (20, 21) for detecting each of the transponders. A control location has means (4, 5, 6, 7, 7a) for periodically transmitting vital safety signalling information to the vehicle via a radio link. In response to detection of one of the transponders, the vehicle sends a first message via the link to the control location and in response to reception of the first message by the control location, the vital safety signalling information is sent a first time from the control location to the vehicle via the link, then from the vehicle to the control location via the link and then a second time from the control location to the vehicle via the link.

Abstract: To ensure the safe operation of an electronic circuit, for example an amplitude modulated carrier signal generator, an output of the circuit is analyzed to prove the presence of predetermined signal characteristics, for example the carrier signal, or a modulation frequency. The predetermined signal alternatively may be superimposed on an input to the electronic signal and proved subsequently to be present in the output. The output of the circuit is passed inhibited, according to whether or not the signal characteristics are proved present, by means of an output enable gate which is self-latching providing the output continues to be proved correct. A start-up circuit delays a possible inhibit for a limited period following initial power connection to the circuit in order that the output can become established.

Abstract: An AND function gating circuit for A.C. signals comprising several magnetic circuits around a common limb, each circuit having a separate input winding and a single output winding on the common limb. The magnetic flux level in the common limb is greatly increased when all input windings are simultaneously energized by A.C. signals of the same frequency and in phase relative to the output achieved under other input signal conditions.

Abstract: A railway track circuit arrangement particularly suitable for the short track circuit, down to approximately 40 metres, required in metro transit systems. Based on conventional A.C. track signalling principles for continuous track rails, the boundaries between adjacent track sections are defined by electric separation zones. An electrical short is connected between the running rails and an A.C. signal tuning unit is connected approximately 6 metres away to tune the end loop thus formed to resonance at the selected track signal frequency. The tuning units comprise a capacitor, the value of which is selected for resonance tuning, and a transformer a winding of which is connected in series with the capacitor, and a track circuit signal transmitter or receiver is connected through a second winding of the transformer. In order to reduce mutual coupling between track circuits by longitudinal leakage, in each joint, two electrical short may be connected between the rails spaced apart approximately 0.75 metre.

Abstract: A bridge network 1 of current switching devices 2, 3, 4, 5 is operated in full wave manner by controlling signals A, B, C, D respectively produced by two similar, parallel and pulse width modulated power control circuits 12, 13 connected to receive a common input signal, one pair of opposing switch devices (2, 5) being controlled by one circuit 12 and the other pair 3, 4 being controlled by the other circuit 13. The pulse width control inputs 14 of the circuits 12, 13 are connected to voltage sensing means in the bridge supply circuit so that the pulse width of the control signals A, B, C, D is determined in accordance with the bridge supply level. The arrangement is such that the control circuits 12, 13 although not be designed to fail-to-safety standards operate in a fail-safe manner to provide a constant level output of the input signal.

Abstract: A semiconductor housing particularly useful for very high current devices, e.g. transistors and G.T.O. thyristors, in which a control lead to the base or gate of the device, which also has to carry a relatively high current, passes through an insulating wall of the housing. This control lead is enclosed within a tube which passes through an insulating wall of the housing and which is hermetically sealed to it, the tube is also hermetically sealed to the conductor at either end. The coefficient of expansion of the tube is chosen so as to be substantially the same as the coefficient of expansion of the material of the insulating wall, which may be made of ceramic material or the like. The arrangement avoids corrosion effects as a result of the entrapment of plating salts etc. which are known to adversely affect the assembly and especially the electrical performance of the control lead connection.

Abstract: A governing factor of the switching characteristics of a thyristor device is base layer resistivity, for example in a gate turn-off device, to maximize load current it is preferably low but, the reverse breakdown voltage of the emitter-base junction is improved if the resistivity is high. The invention proposes a modified base layer dopant diffusion process in which the dopant diffusion process in which the dopant source is removed before completion in order that the peak of concentration is diffused-in below the surface so as to produce a graduated resistivity profile which increases nearer the surface. In shorted-emitter thyristors the surface region is masked during subsequent emitter diffusion so that the remaining short columns contain higher resistivity material.

Abstract: This invention relates to braking systems for railway vehicles in which a fall in brake pipe pressure is employed to initiate braking via a brake cylinder inlet valve.In accordance with the present invention, the brake cylinder inlet valve is rendered in-operative by the absence of auxiliary reservoir pressure, thus dispensing with the need for a complicated mechanical sequence requiring fine machining tolerances etc. and avoiding the necessity of employing an additional valve.The brake cylinder (BC) inlet valve 60 is operable by a diaphragm 54. When the system is fully charged, the brake cylinder inlet valve 60 is closed as shown in the accompanying drawing. The diaphragm 54 is subject to brake pipe pressure in chamber C and to auxiliary reservoir pressure in chamber D. In the absence of auxiliary reservoir pressure in chamber D, the pressure in chamber C holds the diaphragm in the position shown and prevents the ball valve 60 from being opened, thus preventing brake application until braking is demanded.

Abstract: A plug-in "universal" information display module for use in an information display system, e.g. a train describer system, of the kind in which all information to be displayed is multiplexed onto a data highway routed to all display locations. The heart of the module is a microprocessor which "listens" to the multiplexed messages on the data highway, selects for decoding only those containing the address of its location and produces a decoded message in the form of a two-dimensional matrix display format suitable for scanning to drive an L.E.D. matrix display panel. An address programming means is connected to an address input to the microprocessor so that a module is normally programmed with a location address at the time of connection to the data highway either by a manual operation or automatically upon mating of the plug connector.

Abstract: A railway vehicle braking system is provided with snow-brake control means operable in freezing temperatures for overriding the normal full brake release condition in a vehicle coasting or traction situation to apply a small brake force for prolonged periods to engage blocks or shoes on the vehicle wheels to reduce icing. The snow brake control means itself includes an override arrangement for, from time-to-time, effecting complete but temporary release of such a snow brake application so as to enable whatever slack adjustment is necessary to thereby insure continued validity of the brakes for a service application despite brake wear resulting from prolonged snow brake application.

Abstract: An electronic or computer-based railway control system including further safety checks in addition to normal safety interlocking. The present system carries out checks to see that operations, such as print switching and signal setting, are carried out in the correct sequence for a given route having regard to the position and movement of a train as indicated by track circuits. In a computer-based system appropriate checking routines may be written into the computer soft-ware.

Abstract: A continuous quick service device is proposed for use in conjunction with a direct release brake controlling triple valve and which, while not interfering with the emergency valve operation, operates by employing quick action chamber air both as a reference against which brake pipe pressure reductions are detected and as a source of air to operate a pressure responsive device in a reciprocating manner to discharge pulses of air from a reducing brake pipe to afford quick service operation of the triple valve both for initial application from a brakes released condition and for subsequent brake pipe pressure reductions giving rise to increased brake applications.

Abstract: This disclosure relates to a directional sensing arrangement including a rotatable member having a plurality of permanent magnets which magnetically influence a first and second spaced stationary sensor. The rotation of the member causes the magnets to sequentially operate the first and second sensors so that neither, either or both are actuated. The first and second sensors are coupled to a logic network which deciphers the sequential actuations for determining the direction of rotation of the rotatable member.

Abstract: A mounting device is provided for mounting a door to a door supporting mechanism, the device including a mounting member which is slideable in a slot and which projects to be rotatably engageable with an eccentric aperture in a further mounting member which when assembled is itself rotatably located in a further aperture, the arrangement affording easy levelling and positioning adjustment and locking means being provided for locking the members together after such adjustment.

Abstract: An emergency valve device for a direct release triple valve for use in braking systems is proposed and which for rates of fall of brake pipe pressure below a given rate permits a discharge via a restriction to atmosphere of quick action chamber reference pressure but for higher rates this discharge cannot keep up with the rate of fall of brake pipe pressure and the valve device moves further cutting off the restriction and produces a servo action to operate a vent valve connected to the brake pipe and produce an emergency application by connecting the emergency reservoir to the brake cylinders.

Abstract: A vital type of transformer circuit including a saturable core transducer having an input and an output winding. A source of d.c control voltage is coupled to the input winding via a four-terminal capacitor to control the impedance of the secondary winding. The output winding is coupled to a transformer having a primary, a secondary and at least one closed tertiary winding. A source of a.c. voltage is coupled through the output winding to the primary winding for inducing a.c. voltage signals in the secondary winding when d.c. control voltage is applied to the input winding and for causing the closed tertiary winding to load the transformer so that little, if any, a.c voltage is induced into the secondary winding in the absence of d.c. control voltage on the input winding.