Abstract: The invention provides a magneto-optical phase-modulating device employing either the transverse Kerr magneto-optic effect or the Faraday magneto-optic effect and embodying a magneto-optic layer (1) of a ferromagnetic or ferrimagnetic garnet type material which gives rise to an improved performance over known devices. Examples of the garnet type material which may be employed are a bismuth doped garnet, praseodymium and a garnet type material of the group known as orthoferrite materials.The invention finds particular application in laser gyroscopes.

Abstract: A verticality sensor comprises a casing within which is mounted a rotary pick-off device having a body attached to the casing and mounted on a shaft for relative rotational movement with respect thereto, such movement producing an output signal from the pick-off representative of the angular rotation of the casing with respect to the vertical, pendulum means mounted on the pick-off shaft for relative rotational movement with respect thereto, and inertia means fixed to the pick-off shaft and coupled to the pendulum means through a fluid, with which the casing is filled, and through spring means. The arrangement is such that when the pendulum is subjected to lateral accelerations and undergoes rotational movement relative to the pick-off, the spring means is torsioned and thereby attempts to transmit that rotational movement to the inertia member which the latter resists, whereby the effect of lateral acceleration is reduced.

Abstract: A suspension system for a pivotal nozzle of a jet propelled vehicle having a gas generator operable to effect propulsion of the vehicle, the system comprising a plurality of actuators connected to the exhaust nozzle and operable to effect pivotal movement thereof to steer the vehicle in a desired direction. Each actuator comprises a movable member connectible on one side to a source of fluid power to effect nozzle movement with the other side of the member being interconnected with said other side of each other actuator movable member to form a fluid suspension for the nozzle. In use, the suspension is pressurized to produce a force acting on the nozzle in a direction opposite to the load imposed on the nozzle by the gas from the gas generator acting thereon.

Abstract: A combined compensator and off-loading valve comprising a system pressure gallery connected to a tank or low pressure gallery by a plunger valve, the plunger having a greater area than the valve seating, this differential area being exposed in operation to system pressure, the plunger being hollow and being closed at the end opposite the valve setting by a sliding sleeve bearing against a fixed abutment and having a cross-sectional area equal to the plunger differential area, and a pin bearing against a caged compensator spring, the plunger being urged against the valve seating by a light spring, and means being provided for admitting load pressure to the interior of the plunger. The valve plunger may incorporate a pilot relief valve so that the valve opens when the pressure becomes excessive.

Abstract: A device for controlling a hydraulic actuator comprises two servo loops having in common a fluid pressure operated main valve and an electrically operated pilot valve for controlling the main valve. One of the servo loops is for flow control and contains a flow transducer for producing an electrical feedback signal responsively to fluid flow to the actuator and a comparator for comparing the flow feedback signal with a first electrical input signal. The other servo loop is for force control and contains pressure transducing means for producing an electrical feedback signal responsively to the pressure drop across the actuator and a second comparator for comparing the force feedback signal with a second electrical input signal.

Abstract: A hydraulic system including a variable-delivery pump and a pressure compensator having a spring load applied to one end of the compensator spool. Means are provided for applying a force to the other end of the compensator spool proportional to the pressure obtained from a variable pressure-dividing system connected between the pressure line and tank. This pressure dividing system may consist of a pair of restrictors at least one of which is adjustable. Alternatively, it may consist of a spring-loaded check valve between the pressure line and the compensator chamber and a restrictor from the compensator chamber to tank.

Abstract: A flow sensor for producing an electrical signal dependent upon fluid flow has a housing insertable in a bore extending transversely to and intersecting a flow passage in a port plate. A flap pivoted to the housing about an axis transverse to the flow passage is biassed by spring means into a resting position in which the flow passage is obturated. Pivotal movement of the flap from its resting position by fluid flow in the flow passage is converted into an electrical signal by a transducer, such as a potentiometer whose slider is coupled to the flap.

Abstract: A hydraulic system including a compensator connected between the service ports of the control valve and the load and arranged to restrict the flow in one or both of the service lines so as to maintain a constant pressure difference between the supply pressure and the pressure at the valve service port supplying fluid to the load. The compensator may be connected in both service lines and arranged to restrict the flow equally in each of them. Alternatively a single-sided compensator may be used, and if the load is liable to over-run it must be connected in the service line which is downstream of the load when over-running.