Abstract: A spring brake actuator is proposed which is provided with an arrangement accessible from the outside for manually releasing the brake in the absence of fluid pressure to release it, the releasing arrangement comprising a member which rotates a splined force applying member relative to a force transmitting member against the force of a return spring which holds abutting ends of the splines of the elements mutually aligned.

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 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: 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: 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: 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.