Abstract: A valve arrangement is provided for giving a continuous quick service facility in a triple valve controlling rail vehicle brakes in response to brake pipe pressure reductions. The arrangement comprises a pressure responsive member which responds to more than a predetermined brake pipe pressure reduction in relation to a reference pressure to operate a pulsator which discharges repetitive pulses of air from the brake pipe for as long as the pressure reduction persists.

Abstract: A transistor drive circuit arrangement in which the collector current of a transistor is passed through the primary or control windings of a direct current current-transformer or transductor and the secondary or output windings of the current-transformer or transductor control the passage of alternating current via rectifying means which provides base current drive for the transistor. Thereby the base current is directly related to instantaneous collector current which results in significant power economies relative to prior art arrangements in which the base is continuously over-driven to ensure permanent base-emitter saturation.

Abstract: An air operated brake actuator has an air pressure operated brake force applying member, the application to and removal of pressure from which member determines the brake force, another such member which must be separately pressurised to follow the first member to lock in a brake force, and yet another member which requires to be additionally pressurized to effect unlocking of the brake force.

Abstract: A fluid operable brake control valve apparatus is provided which includes a brake cylinder valve for controlling the supply of fluid pressure into and out of a brake cylinder. The valve is operable by a main pressure responsive member moveable in response to changes in pressure when applied to a brake pipe. A quick service valve is operable in response to such a change tending to cause a brake application for connecting a quick service volume to the brake pipe to enhance the change at commencement of an application. An accelerated release valve device is operable in response to release of fluid pressure from the quick service volume to connect a charged accelerated release reservoir to the brake pipe to assist a change of pressure in the brake pipe causing such a release.

Abstract: A railway air brake pipe pressure gradient reduction arrangement, wherein pressure gradients along the pipe indicative of a brake pipe pressure fall activate a valve arrangement to temporarily vent the pipe and so speed the brake applying pressure reduction. A further valve arrangement is included for inhibiting venting when a pressure gradient is present due to a pressure rise.

Abstract: A driving and locking mechanism which employs pivoted links for coupling and transmitting motion between driving and driven members. During motion, the links are constrained to a particular mutual position for transmission of driving forces, but at one end of the range of movement, the constraint is removed and the links pivot so that one link comes into normal or over-normal contact with an abutment and so locks the driven member in position. Forces on the driven member will not move it (except in the case where the abutment is resilient to allow limited movement of the driven member in the "locked" position) and movement of the driven member can only be accomplished by movement of the driving member. Thus a separate locking or latching mechanism is not required. The mechanism is particularly applicable to sliding doors, such as those of railway vehicles, where the door needs to be locked or latched in the closed position against forces applied to the door to tend to open it.

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.

Abstract: A magnetic amplifier is disclosed which has improved fail-safe characteristics, the amplifier has a pair of saturable magnetizable cores with d.c. control winding turns on each which are mutually decoupled in known manner with regard to input a.c. windings and the a.c. windings also have linked with them a further magnetizable core, the output from the transductor being derived from a secondary winding on the further cores. The arrangement enables various applications of a magnetic amplifier to be made which might otherwise be objectionable by reason of the reduced operational failure-to-safety characteristics. These applications include use in a brake control circuit.

Abstract: An improved method of constructing a semiconductor device of the encapsulated type wherein a stack of members including a semiconductor element is encapsulated along with spring means ensuring compressive contact to the element contact areas. Hitherto up to five spring washers were needed to keep total spring deflection to within a value giving a desired compressive force, due to accumulated thickness tolerances of the stack members. In the present invention, a plastically deformable member is included in the stack initially along with a thickness gauge member such that bringing together the encapsulation housing parts round the stack flattens a single included spring washer and deforms the deformable member by a certain extent. This certain extent is such that when the stack is re-assembled without the thickness gauge, the plastically deformable member is now of a thickness to cause the spring to deform by an amount giving a desired compression force in the finished stack.

Abstract: A pneumatic liquid level sensing apparatus for marine tankers has a dip tube which by having air or gas applied to it bubbles into the liquid in a tank and produces a back pressure corresponding to the depth of the tube in the liquid, a pressure responsive valve device responsive to the back pressure relays a signal to a remote indicator and the provision of a balance pipe above the surface of the tanker liquid connected to a balancing input of the valve device enables the output of the valve device to be independent of the value of the air or gas pressure in the tank.

Abstract: A brake control valve apparatus is proposed for the respective cars of a train controlled from one end or the other to be braked by an analogue signal of variable mark-to-space form which operates on each car to gate bursts of train-wire carried a.c. supply which after rectification are used to regulate the brake pressure via an E.P. converter. Additionally in order to enable release of a braked car which fails to release its brake in a tunnel, a train brake release wire is provided which in one example operates in an energized-to-release mode to release a single failed brake or in another example operates in a de-energized to release mode to connect local supplies to operate dump valves on all the brake actuators of the train so providing total release in addition to the normal release by the control valve.

Abstract: A train braking system is provided which operates conventionally to effect braking by a reduction of pressure in a brake pipe and which includes on a car of the train a fluid flow sensor operating in response to a pressure gradient due to flow over a length of the brake pipe in the car or over an interposed restriction in the brake pipe, the fluid flow sensor being sensitive to such flow to operate a valve via which fluid is permitted to be applied to or removed from the brake pipe ahead of the restriction or brake pipe section having regard to the direction of propagation to tend to enhance a pressure change being caused by the flow.

Abstract: A fluid pressure comparison apparatus including a pressure responsive member displaceable by the difference between two pressure sources being compared to vent fluid from one of the sources, when its pressure is greater than the other, through a port whose aperture is varied by the displacement of the pressure responsive member. The flow of vented fluid is measured in one of many possible ways to determine the excess pressure. The measurement may be displayed on an indicator or applied to control associated equipment. Various arrangements embodying the apparatus may be used for flow indication, flow control, leakage detection and indication and as warning or control equipment. The pressure responsive member is shown as a nylon reinforced rubber diaphragm but the nature of the member will depend on the absolute as well as the relative values of the pressures compared.

Abstract: This disclosure relates to a vehicle speed signal pulse generator employing a multi-limbed magnetic stator structure and a rotatable magnetic rotor. The multi-limbed magnetic structure includes a pair of magnetic core members about which are wound a primary and secondary winding. A permanent magnet is located in the multi-limbed magnetic structure to cause polarized magnetic flux to flow through each of the magnetic core members. A source of oscillating signals is connected to the input terminals of the primary winding to produce a.c. oscillations in the secondary winding when the vehicle is at rest. The magnetizable rotor includes a plurality of circumferential teeth disposed adjacent the magnetic stator structure to modulate the a.c. oscillations so that the modulated signals developed on the output terminals of the secondary winding will be indicative of the speed of the moving vehicle.

Abstract: An improvement in the battery charging control circuit of our co-pending Application Serial No. 400,001, and more particularly a new means for detecting the onset of gassing during the charging of a battery, such as lead-acid battery.In the exemplary embodiment described in our co-pending Application Serial No. 400,001, the onset of gassing was assumed to be imminent upon the attainment of a particular battery cell voltage. The present invention provides an improved means for determining the true onset of gassing by recognition of a unique point in the temporal pattern of the differences between successive registered battery voltages as measured during interruptions of charging.