1952 - 1470

1
646 FLIGHT, 23 May 1952 ELECTRO-HYDRAULIC SELECTOR VALVE M UCH high-pressure piping from the pilot's cockpit to numerous hydraulic jacks can be eliminated if the aircraft hydraulic system is made subject to electric remote control. Known as the Hydel, an electro-hydraulic selector valve has recently been added to the Dowty range of products. Basically, it consists of a hydraulic valve operated by two solenoids which are controllable from the cockpit by any suitable switch. Although light and compact, the valve has been designed to permit a high flow-rate with a minimum pressure-drop. Various types are in production, including four-way, three-way, and two-way units, with twin or single solenoids; a neutral position can be provided and the selected service can be arranged to remain either open or closed after de-energizing. Considering the type 4600-Y four-way, three-selection (blind The Dowty Hydel valve model 4600- Y (left) employs two solenoids which are numbered 1 and 1 in the sectional view (upper right). A ser- vice -to-return head loss of less than 100 Ibjsq in is re- corded with a flow rate of 10 gal/min. neutral) valve as being typical, the operating sequence is as follows : In circuit, the valve is supplied with hydraulic fluid under pump pressure at P (see accompanying drawing) and is connected to the operating jacks (or similar actuators) at C and D; the return line enters at R. With both solenoids de-energized the pump pressure is contained within the servo cylinders and the housing SLIDE VALVE PILOT VALVE OUTER SERVO PISTON INNER SERV,0 PISTON of the spring-loaded piston. The servo pistons are held against their inner stops, thus centralizing the slide-valve to close both service ports C and D. When, for example, solenoid 1 is energized, it moves a pilot valve off its upper seat and on to its lower seat, cutting off the pressure to the related servo cylinder and reducing the contained pressure. The other servo piston then moves forward unopposed, pushing the central slide-valve port over the outlet C and thus placing the pump in direct communication with the actuator served by this outlet pipe. The passage on the right-hand of the slide-valve, now located over the open port D, permits the return flow along R. When the solenoid is de-energized, the pilot valve returns to its upper seat and restores pressure equilibrium. Operating times are very rapid; a service can be selected in 0.12 sec and return to neutral made in 0.03 sec. The solenoids are rated for voltages of between 22 and 28.5; in the event of electrical failure the slide-valve automatically returns to the central (off) position and thus contains operating pressure in the selected circuit. For test purposes, the valve can be operated by depressing the flexible protecting caps over the solenoids. The Hydel valve series can be used in any hydraulic system with an operating pressure of 4,000 lb/sq in or less; the temperature limits are —54 deg C and +70 deg C, and the normal flow capacity 20 gal/min. The twin solenoid unit type 4600-Y weighs 2.5 lb and the single solenoid pattern 1.9 lb. "3M" IN SOUTH WALES A LARGE new factory at Gorseinon, near Swansea, will shortly be opened further to increase the productive capacity of the Minnesota Mining and Manufacturing Co., Ltd. (formerly Durex Abrasives, Ltd.), the makers of an enormous range of abrasive papers and cloths, adhesives and coatings, pressure- sensitive adhesive tapes, magnetic recording tapes, and non-slip surfacing. There can, indeed, be few industries in this country which do not employ "3M" products of one kind or another. With the new factory—a well-designed, light and airy building— in full production not only will industry benefit from the increased output of the company's products, but the employment factor of what is now known as a "development area" will receive a fillip. AMERICAN HYDRAULIC PUMP A VERY compact design of aircraft hydraulic pump is announced by the Hamilton Standard division of United Aircraft. Operating on an "unusual" (but unstated) system, the pump is claimed to deliver up to 25 gal/min at 3,000 lb/sq in. The driving speed of 8,250 r.p.m. would appear to render the pump suitable for direct drive from a gas turbine. Already in limited production, the unit has been chosen for use in the Chance Vought F7U-3. THE R.A.F. AND ROAD SAFETY P UBLIC attention of late having been directed with increasing emphasis towards the subject of road safety, it is of topical interest to record that the Royal Air Force has under consideration the question of equipping all Service long-chassis vehicles with rear and side light-reflectors of a new and outstandingly effective type. Known by the name "Webslight," and manufactured by the Cheshire Engineering Co., Ltd. (Webslight Division), Burwood House ; Caxton Street, London S.W.i, the reflector signs take the form of a coating of minute glass beads (45,000/sq in) bonded to a light-alloy base plate with a special lacquer. Such is the con- struction of the signs, it is claimed, that they meet all B.S.S. requirements in respect of real-light colour both by day and by night, are impervious to weather, require no maintenance, and are exceedingly difficult to damage. They are available in virtually any required design and size. VEST-POCKET NAVIGATION This pocket computor can be used to solve a remarkable number of navigational problems as well as being a handy circular slide-rule and several other things. Known as the Swissair Navigator, it is beautifully finished in anodized aluminium and has a diameter of four inches. It is now available in this country, price £4 4s. from Hudes Mer- chandising Corporation, Ltd., 52, Gloucester Place, London W.1.

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  • 646 FLIGHT, 23 May 1952

    ELECTRO-HYDRAULIC SELECTOR VALVE

    MUCH high-pressure piping from the pilot's cockpit to numerous hydraulic jacks can be eliminated if the aircraft hydraulic system is made subject to electric remote control.

    Known as the Hydel, an electro-hydraulic selector valve has recently been added to the Dowty range of products. Basically, it consists of a hydraulic valve operated by two solenoids which are controllable from the cockpit by any suitable switch. Although light and compact, the valve has been designed to permit a high flow-rate with a minimum pressure-drop. Various types are in production, including four-way, three-way, and two-way units, with twin or single solenoids; a neutral position can be provided and the selected service can be arranged to remain either open or closed after de-energizing.

    Considering the type 4600-Y four-way, three-selection (blind

    The Dowty Hydel valve model 4600- Y (left) employs two solenoids which are numbered 1 and 1 in the sectional view (upper right). A ser-vice -to-return head loss of less than 100 Ibjsq in is re-corded with a flow rate of 10 gal/min.

    neutral) valve as being typical, the operating sequence is as follows : In circuit, the valve is supplied with hydraulic fluid under pump pressure at P (see accompanying drawing) and is connected to the operating jacks (or similar actuators) at C and D ; the return line enters at R. With both solenoids de-energized the pump pressure is contained within the servo cylinders and the housing

    SLIDE VALVE

    PILOT VALVE

    OUTER SERVO PISTON

    INNER SERV,0 PISTON

    of the spring-loaded piston. The servo pistons are held against their inner stops, thus centralizing the slide-valve to close both service ports C and D.

    When, for example, solenoid 1 is energized, it moves a pilot valve off its upper seat and on to its lower seat, cutting off the pressure to the related servo cylinder and reducing the contained pressure. The other servo piston then moves forward unopposed, pushing the central slide-valve port over the outlet C and thus placing the pump in direct communication with the actuator served by this outlet pipe. The passage on the right-hand of the slide-valve, now located over the open port D, permits the return flow along R.

    When the solenoid is de-energized, the pilot valve returns to its upper seat and restores pressure equilibrium. Operating times are very rapid; a service can be selected in 0.12 sec and return to neutral made in 0.03 sec.

    The solenoids are rated for voltages of between 22 and 28.5; in the event of electrical failure the slide-valve automatically returns to the central (off) position and thus contains operating pressure in the selected circuit. For test purposes, the valve can be operated by depressing the flexible protecting caps over the solenoids.

    The Hydel valve series can be used in any hydraulic system with an operating pressure of 4,000 lb/sq in or less; the temperature limits are 54 deg C and +70 deg C, and the normal flow capacity 20 gal/min. The twin solenoid unit type 4600-Y weighs 2.5 lb and the single solenoid pattern 1.9 lb.

    "3M" IN SOUTH WALES A LARGE new factory at Gorseinon, near Swansea, will shortly be opened further to increase the productive capacity of the Minnesota Mining and Manufacturing Co., Ltd. (formerly Durex Abrasives, Ltd.), the makers of an enormous range of abrasive papers and cloths, adhesives and coatings, pressure-sensitive adhesive tapes, magnetic recording tapes, and non-slip surfacing. There can, indeed, be few industries in this country which do not employ "3M" products of one kind or another. With the new factorya well-designed, light and airy building in full production not only will industry benefit from the increased output of the company's products, but the employment factor of what is now known as a "development area" will receive a fillip.

    AMERICAN HYDRAULIC PUMP AVERY compact design of aircraft hydraulic pump is announced by the Hamilton Standard division of United Aircraft. Operating on an "unusual" (but unstated) system, the pump is claimed to deliver up to 25 gal/min at 3,000 lb/sq in. The driving speed of 8,250 r.p.m. would appear to render the pump suitable for direct drive from a gas turbine. Already in limited production, the unit has been chosen for use in the Chance Vought F7U-3.

    THE R.A.F. AND ROAD SAFETY PUBLIC attention of late having been directed with increasing emphasis towards the subject of road safety, it is of topical interest to record that the Royal Air Force has under consideration the question of equipping all Service long-chassis vehicles with rear and side light-reflectors of a new and outstandingly effective type.

    Known by the name "Webslight," and manufactured by the Cheshire Engineering Co., Ltd. (Webslight Division), Burwood House; Caxton Street, London S.W.i, the reflector signs take the form of a coating of minute glass beads (45,000/sq in) bonded to a

    light-alloy base plate with a special lacquer. Such is the con-struction of the signs, it is claimed, that they meet all B.S.S. requirements in respect of real-light colour both by day and by night, are impervious to weather, require no maintenance, and are exceedingly difficult to damage. They are available in virtually any required design and size.

    VEST-POCKET NAVIGATION

    This pocket computor can be used to solve a remarkable number of navigational problems as well as being a handy circular slide-rule and several other things. Known as the Swissair Navigator, it is beautifully finished in anodized aluminium and has a diameter of four inches. It is now available in this country, price 4 4s. from Hudes Mer-chandising Corporation, Ltd., 52, Gloucester Place, London W.1.