Abstract: An hydraulic booster has a housing provided with an input member, a boost piston, an output member, and connections to a source of pressure and a fluid reservoir. A force applied to the input member is transmitted to the output member and augmented by the boost piston in response to pressurization of a boost chamber controlled by a valve mechanism in response to operation of the input member. An auxiliary chamber is defined between the boost piston and the output member. In a first stage of operation to take up lost-motion in the system, the auxiliary chamber is supplied with fluid from the source to advance the output member relative to the boost piston through a distance determined by a limiting mechanism. In a second stage of operation the output member and the boost piston move together in response to pressurization of the boost chamber. The area of the boost piston on which the auxiliary pressure acts is greater than or equal to the effective area of the boost piston.

Abstract: Valve assemblies for single and dual circuit braking systems are described. An assembly for a single circuit (FIG. 1) has a primary piston provided with a normally open valve seat engageable by a deceleration sensing ball housed in the primary piston. An annular secondary piston is slidably mounted on the larger diameter end of the primary piston. Primary piston has an area (A.sub.2) exposed to outlet pressure in a chamber and a smaller area (A.sub.1) exposed to inlet pressure in a housing bore portion, and is capable of rearward movement against biassing of a spring. Rearward movement of secondary piston is restricted firstly by a flange on the primary piston and secondly by a step on the housing.

Abstract: In an hydraulic booster for a vehicle braking system a boost piston provides an output force in response to pressurization of a boost chamber under the control of a boost valve mechanism, which controls communication between the boost chamber and a pressure source and the boost chamber and a fluid reservoir. The operation of the boost valve mechanism is controlled by pressure in a control chamber which is pressurized by operation of a pedal-operated input piston. A recuperation valve controls communication between the boost and control chambers, and is operated in response to movement of the input piston. Pressure in the boost chamber acts on the input piston to urge it in a direction to keep the recuperation valve closed. This enables the input piston to work in a bore in the boost piston, with the control chamber in the boost piston and forward of the boost chamber.

Abstract: A vehicle gas suspension system consists of a suspension unit, a high pressure reservoir, a low pressure reservoir and an electrically driven pump. Control valves are disposed in connection lines between the unit and the reservoirs for respectively controlling the flow of gas to and from the suspension unit so as to maintain the ride height of the vehicle at a suitably adjusted attitude irrespective of vehicle loading. The pump comprises a tubular barrel, a valve at one end of the barrel, and a piston and flexible seal which reciprocate in the barrel reservoirs. A vacuum relief valve in the wall of the low pressure reservoir allows air to be drawn into the reservoir from the atmosphere, and a dump valve opens to allow gas to flow from the high pressure reservoir to the low pressure reservoir when a maximum permitted pressure is reached in the high pressure reservoir.

Abstract: In dual control assemblies for hydraulic braking systems of vehicles, the valve assemblies comprise a pair of control valves clamped together in side-by-side relationship in each of which a back-up piston works in a greater diameter portion and a hollow spool works in a smaller diameter portion of a stepped bore, the piston and the spool being operated by a push- or pull-rod in turn operated by a pedal. The spool controls communication between pressure spaces of the valves and their respective recuperation, inlet and transfer ports. The recuperation ports are connected to a common reservoir for fluid, the inlet ports are connected to a common hydraulic power source and the transfer ports are interconnected. Each pressure space is connected to a brake via an outlet port.

Abstract: Clips are known in which a worm wheel is meshed with teeth provided on an end portion of a band for encircling the member to be clamped, but such clips are relatively costly to produce and problems arise in maintaining the band threads meshed with the worm. Various clips are described in which an end portion of the band is provided on one side with external screw thread portions which are complementary to the internal screw threads of a nut through which the band end portion extends. The opposite end of the band may be integral with a body on which the nut is supported, or it may be identical to the first end portion also be meshed with the nut threads, so that both end portions of the band are drawn through the nut on turning of the nut.

Abstract: The invention is directed to an improved joint between building panels, e.g. molded roof panels for prefabricated bay windows, wherein the joint consists of a slot in the edge of one of the panels. The slot has side walls, each of which is at a different angle relative to the plane of the panel. The edge of the other panel is inserted into the slot and the respective side walls thereof are engaged by one side or the other of the edge of the other panel to locate the other panel in one angular position or another with respect to the plane of the first panel.

Abstract: In a fluid-pressure-operable relay valve a control piston works in a bore in the valve housing to control sequential communication between an inlet port and an outlet port, and between the outlet port and an exhaust port. An exhaust valve seating on the control piston is engageable with an exhaust valve member coupled to one end of a lever pivotally mounted in the housing, and a spring acts on the exhaust member to urge an inlet valve member towards an inlet seating surrounding the inlet port. Since the spring acts in opposition to fluid pressure at the inlet port, a relatively small `cracking force` is required to the urge the inlet member away from the inlet seating to open the inlet valve.In alternative constructions the inlet and exhaust members are combined into a single valve member which is urged directly by the spring towards the inlet seating.

Abstract: In an hydraulic power booster a boost piston working in a bore in a housing is of stepped outline having at least three axially spaced portions of at least two different diameters. The two end portions carry seals having slidable sealing engagements with complementary portions of the bore, and a stationary seal is fixed in the housing. An intermediate portion of the piston disposed between the end portions and of smallest diameter has a slidable engagement in the stationary seal.

Abstract: An anti-skid braking system incorporates a modulator assembly through which fluid from a source is supplied to a brake. The modulator assembly comprises a de-boost piston working in a bore in a housing, an expander chamber connected to the brake and defined in the bore between one end of the piston and a first valve, and a second valve for controlling the application to the piston of support fluid to determine the relative position of the piston in the bore, the second valve being manipulated in response to a skid signal. The first valve is normally biassed in to a fully open position, and the operation of the first valve is controlled independently of the piston. An inhibit device is incorporated to ensure that at the termination of a skid signal first valve is maintained in a closed position at least until the piston has returned to an advanced position in which the effective volume of the expander chamber is at a minimum value.

Abstract: An apportioning valve for controlling the pressure applied to the rear brakes of a vehicle comprises an inlet to receive actuating fluid and an outlet for connection to the rear brakes. The inlet and outlet are normally connected via an inlet chamber, and an auxiliary chamber is connected to the inlet chamber via a throttle and to a vent valve seat. A pendulum is biased against the valve seat during deceleration and thus closes the valve seat and allows pressure to build up in auxiliary chamber. When pressure in the auxiliary chamber is sufficiently high control pistons move to isolate the inlet from the outlet.

Abstract: A booster for a vehicle braking system has an input piston, a boost piston and an output piston working a bore, the boost piston being advanced in the bore in response to pressure fluid from a source pressurizing a boost chamber under control of a valve.The operation of the valve is dependent on the pressure in the system, and the valve has a valve mechanism working in a bore in the boost piston of which one part has a pressure-responsive face, the valve being operative, on initial movement of the input piston to cause pressurization of the braking system to the threshold level, and application of pressure fluid to the pressure-responsive face to move the part relative to the input piston to place the boost chamber in communication with the pressure source. Threshold pressurization of the braking system may be achieved by pressurization of the boost chamber, or an auxiliary chamber forward of the boost piston to a predetermined level.

Abstract: A helmet 1 adapted for use by hay fever sufferers is shaped to fit over the head and face of the wearer and has filtered air supplied to its interior by way of an air supply duct 5 from portable filter means remote from the helmet and adapted to be carried by the wearer. The filter means removes pollen, dust and such airborne matter from the air supplied to the helmet. The filter means comprises disposable filters 9, a battery operated electric motor 8 and a fan 7 driven by the motor which draws air from the atmosphere through the filters and supplies it to the air supply duct 5. The battery 13 energizing the motor is in a separate box 14 from a box 6 containing the filters, motor and fan. Both boxes are adapted to be attached to a belt to be worn by the helmet wearer. There may alternatively be just one pack. The helmet has supports 4 which seat on the wearer's shoulders.

Abstract: A sectional hydraulic valve has clamped together an inlet section, an outlet section and at least one working section which can be integral with the inlet and/or outlet sections. Fluid supply and return passages are formed in the sections and are in register at each junction where there are formed contiguous planar sealing surfaces. A depressed area is provided in one of the surfaces surrounding the contiguous planar sealing surfaces of the supply and return passages and a groove containing a sealing ring is formed in one of surfaces around the depressed area. A drain passage leading to a low pressure region opens into the depressed area and should there be leakage between the sealing surfaces of the supply and return passages, particularly as a result of the presence of high pressure in said passages, the leaked fluid merely passes into the depressed area and flows through the drain passage to the low pressure region without subjecting the sealing ring to pressure and possible leakage there past.

Abstract: A mechanical brake actuator has rotatable and non-rotatable cam components provided with confronting helical grooves between which ball bearings are arranged to form a helical thrust bearing. A push rod, connecting rod or the like acts generally tangentially on a lever arm on the rotatable cam component for turning the latter. The lateral reaction arising from the lateral force due to the push rod is transferred from the rotatable cam component to the non-rotatable cam component by the helical thrust bearing, thereby avoiding the need to provide a separate journal bearing for the rotatable cam component. The rotatable cam component acts on a tappet member via an axial thrust bearing and an automatic adjuster mechanism.

Abstract: Apparatus is disclosed for bonding a plurality of cores of a multi-core ribbon electric cable in side-by-side relationship by heating the insulation of the cores to bond together the insulation of adjacent cores. Instead of continuously bonding the cores together along their entire length, the apparatus is designed to interrupt the bonding at predetermined intervals so that when the cable is cut at a sectional interval it is not necessary to separate the insulation of one core from the next.

Abstract: An anti-skid braking for a vehicle comprises a wheel having an hydraulic brake applicable by supplying thereto fluid under pressure from a master cylinder, a sensor to sense the presence of skid conditions at the wheel during braking and thereupon to produce a skid signal, a dump valve operative to cause fluid to be displaced from the brake in response to a skid signal so as to relieve the brake pressure, and a flow-control regulator valve arranged to regulate flow of fluid to the brake so as to re-apply the brake pressure at a controlled rate. The flow-control valve comprises a first restriction of predetermined size connected in series with a second restrictor defined between two relatively movable members and located upstream of the first restriction. The first restriction is defined at least in part by the member of which that member is biassed by a valve spring against the action of the pressure difference across the first restriction.

Abstract: A wormwheel (1) has teeth (2) over at least a portion of its periphery. The teeth (2) are shaped such that the pitch diameter (5) is greater at one face (3) of the wormwheel than the other and does not increase along the path of the tooth from said one face (3) to the other face (4). Because of this tooth shaping the wormwheel may be cast and is thus suitable for mass production. Wormwheels of this type are particularly, but not exclusively, suitable for use in valve actuators. In order to facilitate the casting process the wormwheel is formed with only one integral bearing (10) and has an internally splined opening (8) in which can be received a bearing sleeve (18) which may also be adapted to receive the valve stem within its own axial opening (21). A variety of bearing sleeves suitable for use with different valve stems may be provided for cooperation with the same wormwheel thereby eliminating the need for special adaptors and reducing the number of parts required to construct a range of valve actuators.

Abstract: A heater for heating a liquid including a housing defining a closed elongate heating chamber therein with a cylindrical chamber surface, a rotor body rotatably journalled in the heating chamber with a cylindrical peripheral surface thereon concentrically of the chamber surface so as to define an annular space between the chamber surface and the peripheral surface on the rotor body, drive means for effecting relative rotation between the rotor body and the housing, and pump means for circulating the liquid through the annular space so that the rotation of the rotor body heats the liquid passing through the annular space.